7. Insights from NAEW experiences for establishing new experimental watersheds

Many paths can be followed to establish new experimental watersheds to conduct watershedscience research ("outdoor laboratories for water and land-management research") such as the NAEW. Watershed science involves expertise in the biological and physical sciences to solve national problems. Occasionally required expertise can be acquired from university, government, and private-sector partners and stakeholders. The 81-year experience of managing experimental watersheds may be useful for establishing new experimental sites at the scale of the NAEW, and some important considerations from the NAEW experience are listed below.

3. Monitoring a large experimental watershed requires sufficient funding to sustain scientists, support staff, and experimental resources. The value of experimental watersheds is that they can provide an uninterrupted record of runoff, water quality, etc., spanning years, with dry years producing insufficient numbers of runoff events and longer periods of runoff records may be required. Furthermore, watershed-science research can be considered long-term and high risk because experiments are subject to weather extremes (e.g., droughts and other project factors that are affected by the weather). It is expensive to maintain such a record, and continuous funding must be maintained—temporary grants will interrupt long-term records after the grant period is completed, and a sufficient record of runoff may not be recorded.

Landfills: Lysimeter data validated an engineering design model for a new type of landfill cover that utilized the ET processes in the soil to minimize water percolating to ground water [33]. Other research: Other research conducted at the NAEW (not exhaustive list) were projects related to water quality of spent foundry sand, dairy wastes, and nursery operations. Frozen

Emerging issues: A significant advantage of the NAEW facility is its long-term data base and the permanent monitoring infrastructure. It has been used for many investigations which were never imagined at the outset. Examples are placement of impervious structures for urbanization studies, evapotranspiration landfill caps, macropore investigations, advanced modeling, organic agriculture, climate change, ground-water recharge studies, spent foundry sand, nursery operations, dairy wastes, filter socks, carbon sequestration, pathogens and estrogens in runoff [48], biofuels, surface mining and reclamation, paper mill sludge, and long-term water-

7. Insights from NAEW experiences for establishing new experimental

Many paths can be followed to establish new experimental watersheds to conduct watershedscience research ("outdoor laboratories for water and land-management research") such as the NAEW. Watershed science involves expertise in the biological and physical sciences to solve national problems. Occasionally required expertise can be acquired from university, government, and private-sector partners and stakeholders. The 81-year experience of managing experimental watersheds may be useful for establishing new experimental sites at the scale of the NAEW, and some important considerations from the NAEW experience are listed below. 1. When establishing new experimental watersheds, "representativeness" is important, and newer GIS technology should be used to identify potential sites. However, there will be other research benefits discovered as a facility is managed. In the case of the NAEW, the geological and soil characteristics became important for potentially providing new knowledge on hydrological processes such as nonuniform runoff generation, interflow, macropore flow, perched water tables, etc. Other potential site benefits should be consid-

2. For an ideal comprehensive watershed-science program, the three original NAEW objectives are required. However, funding may become a problem and pursuit of the three objectives can be spread at more than one location (e.g., one location can perform modeling and another field experimentation). However, having modelers conducting field research is also of value to experience data characteristics and natural variability found in landscapes to help formulate algorithms. It is important to have field data for validation of

soil, rain gauges, soil moisture, soil characterization, etc., have also been topics.

quality response times in natural systems.

16 Hydrology of Artificial and Controlled Experiments

watersheds

ered in site selection.

watershed models.

8. Instrumentation selection is important in managing experimental watersheds. Two important measurements are runoff and precipitation. For runoff, it is known that large sediment concentrations in runoff can affect the rating curve of H flumes [51], a commonly used flow-measuring device. A weir that has been tested for a wide range of field conditions under large sediment loads (including rocks) is the drop-box weir [7]. Drop-box weirs of any size can be constructed from small runoff/erosion plots to large watersheds with incised channels. It is important to house weirs from freezing weather to prevent damage and maximize the opportunity for good winter runoff records.

12. It should be recognized that some investigations will be affected by watersheds with low runoff potential (e.g., some forested sites). It may take many years for such watersheds to

Experimental Watersheds at Coshocton, Ohio, USA: Experiences and Establishing New Experimental Watersheds

http://dx.doi.org/10.5772/intechopen.73596

19

13. Knowledge of challenges in conducting watershed research in disturbed lands in particu-

14. It is highly likely that as an emerging issue arises, that an experimental watershed facility would be a likely place for pertinent investigations. The permanent monitoring infrastructure allows for a relatively rapid implementation of a proposed land treatment and mon-

15. Another opportunity for monitoring experimental watersheds is off site from the home site. This was necessary for monitoring watersheds with three different coal seams in the

16. It is important for all data to be checked and be made available on the internet as soon as

The North Appalachian Experimental Watershed (NAEW), in east-central Ohio near Coshocton, Ohio, was one of the three large watershed facilities established in 1935 to advance watershed science of agricultural lands to improve their economical and physical sustainability. It was an outdoor laboratory for land and water management research. The original objectives were to test management practices on small watersheds (small swales in the hilltops), investigate scaling of runoff and erosion to larger areas, and provide a way to extrapolate the results to ungauged areas (modeling). The NAEW was in an unglaciated sedimentary geological setting (strata nearly horizontal) and originally spanned an area of approximately 2000 ha. The facility was equipped with a permanent infrastructure consisting of runoff stations and rain gauges for watersheds ranging in size from 0.26 to 1854 ha. After about 1970, the NAEW was reduced to a 425-ha area consisting of mostly small watersheds ("test beds") ranging in size from 0.26 to 3.07 ha but with a few up to 123 ha. The smaller watersheds were equipped with the well-known Coshocton Wheel composite runoff samplers. The NAEW was in operation for approximately 81 years with an approximate 79-year record of runoff and other data for various watersheds, and was closed in 2015. Eleven large monolith lysimeters

A wide variety of experiments were conducted on the NAEW with many high impact accomplishments (listed in the section titled, Examples of Accomplishments of the NAEW). Many investigations used the facility for emerging national issues that the founders never envisioned (e.g., surface mining impacts, landfill caps, organic agriculture, climate change, filter socks, carbon sequestration, pathogens in runoff, biofuels). Nearly 500 publications were developed

disturbed land (coal mining) project conducted at the NAEW [58], Figure 11.

provide enough data for evaluations to experience larger infrequent rainfalls.

lar is presented in [58] and is pertinent to selecting new watersheds.

itoring. Funding for such issues is important.

were also constructed to investigate small scale water balances.

from investigations during the 81-year history of the facility.

possible after collection.

8. Summary

### 8. Summary

8. Instrumentation selection is important in managing experimental watersheds. Two important measurements are runoff and precipitation. For runoff, it is known that large sediment concentrations in runoff can affect the rating curve of H flumes [51], a commonly used flow-measuring device. A weir that has been tested for a wide range of field conditions under large sediment loads (including rocks) is the drop-box weir [7]. Drop-box weirs of any size can be constructed from small runoff/erosion plots to large watersheds with incised channels. It is important to house weirs from freezing weather to prevent damage

9. Precipitation measurement is a persistent problem because the gauge shape and orifice height affect the wind flow around the orifice, resulting in an under catch of precipitation. This is because smaller diameter rain drops and light weight snowflakes are carried with the wind away from the orifice. This error can be as high as a 20% under catch on average during the winter and approximately 2% during the nonwinter months [52]. True ground-level precipitation measurements for individual events can be much higher during events with high wind speeds. Furthermore, often-used tipping bucket rain gauges do not measure snowfall, and under catch of precipitation is complicated by using heaters to melt the snow because precipitation is evaporated [53], and snow intensities will not be measured. In arid areas this may not be a problem. The effects of under estimating precipitation are to under estimate runoff, erosion, and water quality in watershed modeling [49] in a nonlinear manner. Suggestions for improved precipitation measurement include shielded gauges such as the dual fence gauge of the Climate Reference Network [54] that was evaluated by US Forest Service [55]. Their study suggested that the CRN gauge is the best available. A set of dual gauges (one shielded and one not shielded) were not tested in the Forest Service study, but is likely to be a contender and should be investigated [56]. Furthermore, weighing buckets are preferred measuring technology compared with tipping buckets. Advances in other emerging

10. Water quality sampling is important for evaluations of the performance of land treatments. Two types of sampling are possible—composite and discrete sampling. For composite sampling, the same fraction of the flow is sampled for each flow rate during the runoff event and only one sample is obtained for the event. The Coshocton Wheel has been a useful tool for composite sampling of small watersheds [6, 39]. Larger watersheds require smaller fractions of flow sampling to manage the size of a composite sample and for a range of runoff volumes. Commercial samplers and the Coshocton Vane sampler [57] are available for this purpose. An instantaneous sample is pumped for discrete sampling a preselected times or changes in runoff depth, and many samples are obtained for an individual event. This type of sampling is more expensive and may not be as useful as composite sampling unless there is a research objective for this sampling strategy. For evaluations of water quality effects of land treatments, a composite sample is adequate (and may be preferred). For either sampling type, a flow measurement record is required.

11. It is possible that experimental watershed investigations can be affected by a changing

climate. Climate was found to be changing at the NAEW.

and maximize the opportunity for good winter runoff records.

technologies should also be explored.

18 Hydrology of Artificial and Controlled Experiments

The North Appalachian Experimental Watershed (NAEW), in east-central Ohio near Coshocton, Ohio, was one of the three large watershed facilities established in 1935 to advance watershed science of agricultural lands to improve their economical and physical sustainability. It was an outdoor laboratory for land and water management research. The original objectives were to test management practices on small watersheds (small swales in the hilltops), investigate scaling of runoff and erosion to larger areas, and provide a way to extrapolate the results to ungauged areas (modeling). The NAEW was in an unglaciated sedimentary geological setting (strata nearly horizontal) and originally spanned an area of approximately 2000 ha. The facility was equipped with a permanent infrastructure consisting of runoff stations and rain gauges for watersheds ranging in size from 0.26 to 1854 ha. After about 1970, the NAEW was reduced to a 425-ha area consisting of mostly small watersheds ("test beds") ranging in size from 0.26 to 3.07 ha but with a few up to 123 ha. The smaller watersheds were equipped with the well-known Coshocton Wheel composite runoff samplers. The NAEW was in operation for approximately 81 years with an approximate 79-year record of runoff and other data for various watersheds, and was closed in 2015. Eleven large monolith lysimeters were also constructed to investigate small scale water balances.

A wide variety of experiments were conducted on the NAEW with many high impact accomplishments (listed in the section titled, Examples of Accomplishments of the NAEW). Many investigations used the facility for emerging national issues that the founders never envisioned (e.g., surface mining impacts, landfill caps, organic agriculture, climate change, filter socks, carbon sequestration, pathogens in runoff, biofuels). Nearly 500 publications were developed from investigations during the 81-year history of the facility.

Experiences in the operation of the facility during the 81 years provide insights for establishing new experimental watersheds in the future. Watershed science involves the expertise in the biological and physical sciences and engineering to solve national problems. Sixteen suggestions for new facilities are presented covering site selection, funding, site specificity, extrapolation of results, generation of runoff in different physiographic regions, collaboration, off-site investigations, and instrumentation. Instrumentation suggestions are particularly important for precipitation because it is a major driver of watershed responses and must be more accurately gauged than commonly measured. Runoff measurements also can be affected by large sediment concentrations using common flow-measuring devices. Watershed modeling will be sensitive to precipitation inputs and validation of runoff amounts in modeling will be affected by runoff measurements.

[4] Ramser CE, Krimgold DB. Detailed working plan for watershed studies in the North Appalachian Region relating to water conservation, flood control, and run-off as influenced by land use and methods of erosion control; 1935. WHS#1, November, 1935 [5] Kelley GE, Edwards WM, Harrold LL, McGuinness JL. Soils of the North Appalachian

Experimental Watersheds at Coshocton, Ohio, USA: Experiences and Establishing New Experimental Watersheds

http://dx.doi.org/10.5772/intechopen.73596

21

[6] Brakensiek DL, Osborn HB, Rawls WJ. Field Manual for Research in Agricultural Hydrology. U.S. Dept. of Agriculture, Agriculture Handbook No. 224. Washington, DC: U.S.

[7] Bonta JV, Pierson FB. Design, measurement, and sampling with drop-box weirs. Applied

[8] Harrold LL, Triplett GB, Youker RE. Watershed test of no tillage corn. Journal of Soil and

[9] Shipitalo MJ, Edwards WM. Runoff and erosion control with conservation tillage and reduced-input practices on cropped watersheds. Soil andWater Tillage Research. 1998;46:1-12

[10] Shipitalo MJ, Owens LB, Bonta JV, Edwards WM. Effect of no-till and extended rotation on nutrient losses in surface runoff. Soil Science Society of America Journal. 2013;77:1329-1337

[11] Edwards WM, Shipitalo MJ, Dick WA, Owens LB. Rainfall intensity affects transport of water and chemicals through macropores in no-till soil. Soil Science Society of America

[12] Shipitalo MJ, Dick WA, Edwards WM. Conservation tillage and macropore factors that affect water movement and the fate of chemicals. Soil & Tillage Research. 2000;53:167-183

[13] Owens LB, Van Keuren RW, Edwards WM. Hydrology and soil loss from a high-fertility, rotational pasture program. Journal of Environmental Quality. 1983;12(3):3441-3346 [14] Owens LB, Van Keuren RW, Edwards WM. Nitrogen loss from a high-fertility, rotational

[15] Owens LB, Bonta JV. Reduction of nitrate leaching with haying or grazing and omission

[16] Owens LB, Shipitalo MJ. Runoff quality evaluations of continuous and rotational overwintering systems for beef cows. Agriculture, Ecosystems & Environment. 2009;129(4):

[17] Owens LB, Barker DJ, Loerch SC, Shipitalo MJ, Bonta JV, Sulc RM. Inputs and losses by surface runoff and subsurface leaching for pastures managed by continuous or rotational

[18] Owens LB, Edwards WM, Van Keuren RW. Baseflow and stormflow transport of nutrients from mixed agricultural watersheds. Journal of Environmental Quality. 1991;20(2):

pasture program. Journal of Environmental Quality. 1983;12(3):346-350

stocking. Journal of Environmental Quality. 2012;41(1):106-113

of nitrogen fertilizer. Journal of Environmental Quality. 2004;33(4):1230-1237

Experimental Watershed. USDA Misc. Publ. #1296; 1975. p. 145

Government Printing Office; 1979. p. 547

Water Conservation. 1967;22(3):98-100

Journal. 1992;56(1):52-58

482-490

407-414

Engineering in Agriculture. 2003;19(6):689-700


*Supporting open minds since 2005*

Food Security in Africa http://dx.doi.org/10.5772/intechopen.77894 Edited by Barakat Mahmoud

#### Contributors

Bukelwa Grwambi, Nokuthula Vilakazi, Kumbukani Nyirenda, Emmanuel Vellemu, Yiseyon Sunday Hosu, Lubabalo Qamata, Mahamat Kabirou Dodo, Samkelisiwe Nosipho Hlophe-Ginindza, N.S. Mpandeli, Michael N.I. Lokuruka

#### © The Editor(s) and the Author(s) 2021

The rights of the editor(s) and the author(s) have been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights to the book as a whole are reserved by INTECHOPEN LIMITED. The book as a whole (compilation) cannot be reproduced, distributed or used for commercial or non-commercial purposes without INTECHOPEN LIMITED's written permission. Enquiries concerning the use of the book should be directed to INTECHOPEN LIMITED rights and permissions department (permissions@intechopen.com).

Violations are liable to prosecution under the governing Copyright Law.

Individual chapters of this publication are distributed under the terms of the Creative Commons Attribution 3.0 Unported License which permits commercial use, distribution and reproduction of the individual chapters, provided the original author(s) and source publication are appropriately acknowledged. If so indicated, certain images may not be included under the Creative Commons license. In such cases users will need to obtain permission from the license holder to reproduce the material. More details and guidelines concerning content reuse and adaptation can be found at http://www.intechopen.com/copyright-policy.html.

#### Notice

Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book.

First published in London, United Kingdom, 2021 by IntechOpen IntechOpen is the global imprint of INTECHOPEN LIMITED, registered in England and Wales, registration number: 11086078, 5 Princes Gate Court, London, SW7 2QJ, United Kingdom Printed in Croatia

British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library

Additional hard and PDF copies can be obtained from<EMAIL_ADDRESS>
Food Security in Africa Edited by Barakat Mahmoud p. cm. Print ISBN 978-1-78985-733-7 Online ISBN 978-1-78985-734-4 eBook (PDF) ISBN 978-1-83962-166-6


**Nikolaos Giannekas \*, Yang Zhang and Guido Tosello**

Department of Mechanical Engineering, Technical University of Denmark, Produktionstorvet, Building 427A, DK-2800 Kgs. Lyngby, Denmark<EMAIL_ADDRESS>(Y.Z<EMAIL_ADDRESS>(G.T.)

**\*** Correspondence<EMAIL_ADDRESS>Tel.: +45-4525-4747

Received: 8 October 2018; Accepted: 12 November 2018; Published: 15 November 2018

**Abstract:** Injection molding has been increasing for decades its share in the production of polymer components, in comparison to other manufacturing processes, as it can assure a cost-efficient production while maintaining short cycle times. In any production line, the stability of the process and the quality of the produced components is ensured by frequently performed metrological controls, which require a significant amount of effort and resources. To avoid the expensive effect of an out of tolerance production, an alternative method to intensive metrology efforts to process stability and part quality monitoring is presented in this article. The proposed method is based on the extraction of process and product fingerprints from the process regulating signals and the replication quality of dedicated features positioned on the injection molded component, respectively. The features used for this purpose are placed on the runner of the moldings and are similar or equal to those actually in the part, in order to assess the quality of the produced plastic parts. For the purpose of studying the method's viability, a study case based on the production of polymer microfluidic systems for bio-analytics medical applications was selected. A statistically designed experiment was utilized in order to assess the sensitivity of the polymer biochip's micro features (μ-pillars) replication fidelity with respect to the experimental treatments. The main effects of the process parameters revealed that the effects of process variation were dependent on the position of the μ-pillars. Results showed that a number of process fingerprints follow the same trends as the replication fidelity of the on-part μ-pillars. Instead, only one of the two on-runner μ-pillar position measurands can effectively serve as product fingerprints. Thus, the method can be the foundation for the development of a fast part quality monitoring system with the potential to decrease the use of off-line, time-consuming detailed metrology for part and tool approval, provided that the fingerprints are specifically designed and selected.

**Keywords:** precision injection molding; quality control; process monitoring; process fingerprint; product fingerprint


**1. Introduction**

This volume appears at an especially propitious time for psychiatry, clinical psychology, social work, and all the systematic attempts to ameliorate the morbidity and the mortality that is associated with abnormal function of the mind. One can say with conviction that many of the assumptions held by mental health professions for the last half century have come to be challenged and may prove to be false. What do I mean by this?

At this watershed moment in the mental health sciences, it is a particularly apt time to present an illustrious array of international experts and the scholarship that they bring to central and foundational issues in the field. The topics our author addresses range from substance abuse to anxiety, to prenatal factors, to the pathogenic effects of combat. These chapters are grounded in clinical observation and the best research practices. They represent a fascinating array of different perspective appropriate to the beginning of a new era in the mental health sciences.


*2.1. Study Design and Site Selection*

This study used a cross-sectional design to survey women utilizing the WIC services in NH. In order to represent the entire state, all four local agencies providing WIC services in NH with catchment areas covering all ten counties in the state were utilized in the study.


**Selected Predictors of the Importance Attached to Salt Content Information on the Food Packaging (a Study among Polish Consumers)**

#### **Paweł Bryła**

Department of International Marketing and Retailing, Faculty of International and Political Studies, University of Lodz, Narutowicza 59a, 90-131 Lodz, Poland<EMAIL_ADDRESS>Tel.: +48-4266-55830

Received: 20 December 2019; Accepted: 19 January 2020; Published: 22 January 2020

**Abstract:** This paper aims to identify selected antecedents of the importance attached to salt content information (ISCI) placed on food labels, on the basis of a representative survey of 1051 Polish consumers. The study was conducted with the use of the CAWI (Computer Assisted Web Interviews) method in 2018. Quota sampling was applied with reference to the following five criteria: sex, age, education, place of living (urban and rural areas), and region. In a multiple regression model, ISCI depends on the respondent's: sex, age, evaluation of the quantity of nutrition claims, importance attached to nutrition claims, willingness to pay a price premium for products with nutrition claims, attention paid to health and nutrition claims, agreeing with the opinion that unreliable nutrition claims are a serious problem, evaluation of healthiness of one's diet, self-rated knowledge about healthy nutrition, buying organic food, and reading front-of-package (FOP) labels during and after the purchase. The strongest effects on the importance attached to salt content information on the food packaging were displayed by the importance of nutrition claims, attention paid to nutrition and health claims, respondent's age, FOP label reading at home, and agreeing that the use of unreliable nutrition claims is a serious problem.

**Keywords:** salt information; salt content; salt label; sodium label; sodium information; nutritional information; nutritional labeling; salt information use; nutrition knowledge

#### **1. Introduction**

Consumer preferences for information vary widely and an optimal policy should provide different labels for different market segments. Increasing the amount of information may reduce its effectiveness among the low-income consumers it is intended to help [1]. Food consumers understand and value easily recognizable logos more than the information found on nutritional composition labels [2]. Front-of-package labels that include content descriptors are more effective in helping consumers to select lower-sodium products, and traffic light labels, which incorporate content descriptors and color coding, turned out most effective at helping participants select low-sodium products [3]. In a restaurant setting, traffic light and red stop sign warning labels significantly reduced sodium ordered compared with a control. Warning labels also increased knowledge about high sodium content [4]. More accurate use of the nutrition facts panel moderates the effect of product nutrition value on consumer evaluations [5]. Nutrition knowledge has a strong effect on general label use, degree of use, and on use of nutrient content [6]. A literature review demonstrated no consensus on the effect of age, income, or working status on nutritional label use. However, education and gender were found to positively affect label use. It also appears that consumers who are more concerned about nutrition and health are more likely to use nutritional labels. Consequently, consumers on a special diet, organic buyers, and those aware of the diet-disease relation are more likely to search for on-pack

nutrition information than others [7]. Although consumers evaluate the nutrition table most positively, it receives little attention and does not stimulate healthy choices. Health goals of consumers increase attention to and use of nutrition labels, especially when these health goals concern specific nutrients [8]. In another study, age, education, income, household size, and nutrition knowledge had an impact on nutritional label use [9].

Excess sodium intake has an important, if not predominant, role in the pathogenesis of elevated blood pressure, one of the most important modifiable determinants of cardiovascular diseases. The strategies to reduce sodium intake include: (1) public education, (2) individual dietary counseling, (3) food labeling, (4) coordinated and voluntary industry sodium reduction, (5) government and private sector food procurement policies, and (6) regulations to modify sodium's generally regarded as safe (GRAS) status [10]. Globally, the average daily dietary salt intake is more than double the recommended level. Key sources of salt in the diet include commercially prepared or manufactured food products and discretionary salt added by consumers during cooking and consumption. Therefore, a significant lowering in the current salt intake requires a shift in both commercial foods and consumer behavior [11]. Regan et al. [12] called for a multi-actor approach that utilizes co-designed, participatory tools to facilitate the involvement of all stakeholders, especially consumers, in making decisions around how best to achieve population-level salt reduction. In 2011, 10 countries had front-of-pack salt labelling schemes [13]. However, emphasizing salt reduction by means of a front-of-pack label can have a negative effect on taste perception and salt use [14]. It is worth noting salt labeling rules differ across countries, e.g., in Malaysia, only 62% of instant noodles displayed the salt content on their food label [15]. In my opinion, it may be advisable to consider some basic standards of salt labeling at the global level. Providing information about the salt content is necessary to encourage a healthy choice, but the claims placed on the packaging seem to be insufficient, as they contribute to the avoidance of the product. Increasing consumer awareness of nutrition claims of foods is required [16]. Consumers' knowledge about their health is a precondition for changing related behavior, which entails objective knowledge about salt intake, sources of salt, and ultimately the salt information on food labels [17]. It is necessary to identify strategies to improve individuals' health and nutrition literacy, to develop strategies that help consumers comprehend and apply Nutrition Facts Label information, and to assess the impact of label usage on dietary behaviors [18]. Smartphone apps may be effective in supporting people, especially with cardiovascular diseases, to make lower salt food purchases [19]. Culture-specific awareness campaigns on salt intake and its association with health are needed [20].

There is a large variation of salt content information use across countries and over time as well as according to certain socio-demographic criteria. In the UK, in 2005, 38% of respondents looked at labelling to find out salt content, and 33% said that salt content would always affect their decision to buy a product [21]. In New Zealand, most participants did not know how to interpret the nutritional information, and many underestimated the salt content of the product by confusing it with sodium content [22]. Similarly, in Japan, few people could convert sodium content to salt, which suggested difficulty in using food labels to control their salt intake [23]. In Melbourne, 69% of respondents reported reading the salt content of food products when shopping. Salt label usage was significantly related to shoppers concern about the amount of salt in their diet and the belief that their health could improve by lowering salt intake. Approximately half of the sample was unable to accurately use labelled sodium information to pick low salt options [24]. In 2007, 70% of Australian consumers correctly identified that most dietary salt comes from processed foods but only a quarter regularly checked food labels for salt content. Even fewer reported that their food purchases were influenced by the salt level indicated (21%) [25]. In a more recent study, conducted in 2015, 89% of Australians were aware of the health risks associated with a high salt intake, 75% correctly identified salt from processed foods as being the main source of salt in the diet, but only 28% could correctly identify the maximum recommended daily intake for salt [26]. Brazilian consumers were concerned about the amount of salt (sodium chloride) in the products they consumed, regardless of educational levels, income, age, lifestyles, or health conditions. The majority of respondents rarely read the sodium content on food

labels; however, men and older individuals were more likely to read label information on sodium content [27]. In China, only 5% of respondents understood the meaning of NRV% (Percentage of Nutrient Reference Values), 48% did not know the relationship between sodium and salt, and 13% reported they frequently read the label when shopping. Factors for why people were more likely to choose a product because of its low level of salt shown on the label included income level and their level of awareness of the link between salt and diet [28]. In Korea, the proportion of female college students who read the nutrition information reached 62% but it was only 32% for the sodium information. Their intention to buy low sodium foods increased up to 40% if sodium information was provided on the food label [29]. In Lebanon, only 38% of respondents checked for salt label content, 44% reported that their food purchases were influenced by salt content, and 39% tried to buy low-salt foods [30]. Among Pakistani women, a relationship was found between knowledge about low-salt foods and using low-salt labels [31]. In Pakistan, people of upper castes, people in large families, respondents who were advised to lower salt intake, and who checked salt/sodium labels were less likely to consume higher amounts of salt [32]. In the United States, 19% of respondents agreed they were confused about how to figure out how much sodium is in the foods they eat, and 47% reported they check nutrition labels for sodium content as a tactic to limit salt. Consumers with a high school education or less were more likely than college graduates to report they were confused about sodium content on labels and less likely to check labels for sodium as a tactic to limit salt intake [33]. In Denmark, most consumers are willing to purchase salt-reduced food products, even without having a salt reduction goal. Personal and social norms reveal the strongest influences on intention to change dietary habits, whereas personal norms, knowledge, and awareness of health consequences exert the strongest influences on willingness to purchase salt-reduced food products [34]. In Poland, even commodity science students could not correctly interpret information provided by the Guideline Daily Amount (GDA) system, despite their declarations of full or partial understanding of nutritional labeling [35]. According to Polish food processors and distributors, the information on the content of salt was the third most important type of nutritional information on the food packaging, following content of sugar and of fat [36], whereas among Polish consumers, the information on the salt content ranked fourth after the content of sugar, vitamins, and fats [37]. However, the fact that information about salt content information is missing in some product categories (e.g., cereal products) makes consumer choice more difficult [38]. In a large-scale international survey in Germany, Austria, USA, Hungary, India, China, South Africa, and Brazil, it was found that while salt reduction was seen to be healthy and important, over one third of participants were not interested in salt reduction and the majority were unaware of recommendations [39]. A recent review of 24 studies across 12 countries showed that while consumers were aware of the health implications of a high salt intake, fundamental knowledge regarding recommended dietary intake, primary food sources, and the relationship between salt and sodium was lacking. Moreover, many participants were confused by nutrition information panels, but food purchasing behaviors were positively influenced by front of package labelling [40].

This paper aims to identify selected antecedents of the importance attached to salt content information (ISCI) placed on food labels, on the basis of a large-scale, representative survey of Polish consumers. To the best of my knowledge, this is the first study to investigate the ISCI in a representative, nation-wide sample of Polish consumers. As the literature review showed large differences across nations, it is necessary to examine this issue in the biggest Central European country. The age-standardized estimated sodium intake for persons aged 20 and over was at the level of 3.84 g/day in Poland in 2010, which was similar to the global average of 3.95 g/day [41]. However, within the European Union, Central European countries, including Poland, rank at the top of the table of estimated salt intakes. Poland ranked fifth in the EU with the average salt intake of as much as 11.5 g/day, and five out of the six countries with the highest consumption of salt per capita in the European Union were from the Central European region (Czech Republic, Slovenia, Hungary, Poland, and Romania), with the exception of Portugal taking the fourth place [42]. A wide range of potential predictors were analyzed to see if they differentiated the ISCI in a statistically significant way. Next, a multiple regression model was constructed to examine the simultaneous impact of various independent variables. Finally, a simplified model with only significant predictors was arrived at. The main contribution of this paper lies not only in studying the phenomenon in a new geographic context, but also identifying new predictors of the importance attached to salt content information, in particular concerning various aspects of the attitude to nutrition claims and the context of reading labels (at home rather than in the shop).

#### **2. Materials and Methods**

The study was conducted with the use of the CAWI (Computer Assisted Web Interviews) method in 2018. The online survey was administered by a specialized research agency commissioned by the University of Lodz. The author of this manuscript designed the questionnaire and set sampling criteria. The respondents were informed that the results would be used only for scientific purposes with the respect of the principle of anonymity. The sample size amounted to 1051 persons. Quota sampling was applied with reference to the following five criteria: sex (males and females), age (the following age intervals: 15–24, 25–34, 35–44, 45–54, 55–64 and 65 and more), education (primary, secondary, tertiary), place of living (urban and rural areas) and voivodeship (all 16 Polish regions). Thanks to this approach, the structure of the sample was similar to the general population of Polish consumers according to the aforementioned criteria.

The sample comprised of 560 women (53.3%) and 491 men (46.7%). Regarding the age structure, the sample was composed in the following way: 15–24 years—15.0%, 25–34—17.3%, 35–44—17.9%, 45–54—13.9%, 55–64—15.7%, 65 and more—20.2%. The mean age amounted to 45.0. As far as the household size is concerned, the structure was as follows: 1 person—9.5%, 2—31.7%, 3—24.6%, 4—19.1%, 5—7.7%, 6 and more—7.3%. Regarding the number of children in the household, the sample was structured in the following way: 0 children—52.4%, 1—25.1%, 2—16.9%, 3—3.8%, 4—1.2%, 5 and more—0.5%. The sample resembled the general population in terms of the education level, with 47.7% of respondents having primary and vocational education, 31.6%—secondary, and 20.7%—tertiary. Regarding professional activity, the sample had the following characteristics: white-collar workers—13.3%, blue-collar workers—28.0%, unemployed—4.7%, students—10.5%, not working and caring for the family—9.5%, old age pensioners and disability pensioners—29.7%. As far as the family monthly net income is concerned, the structure was as follows: under 2000 PLN—15.0%, 2001–3000—23.8%, 3001–4000—21.9%, 4001–5000—18.2%, 5001–6000—10.5%, over 6000—10.7%. 61.7% of the respondents lived in the urban areas, while 38.3% were rural inhabitants. Regarding the size of city, the structure was as follows: rural areas—38.3%, town up to 50,000 inhabitants—18.4%, city of 50,000–500,000—18.6%, city having more than 500,000 inhabitants—14.7%. All 16 Polish regions were represented in the sample, with the highest shares from the most populated regions—Mazowieckie (with the national capital Warsaw)—13.5% and Sl ˛ ´ askie (Silesia)—11.4%.

The operationalization of the key variables used in this study is provided in Table 1.

In order to analyze the collected empirical material, *t*-tests, analyses of variance (ANOVAs), Pearson correlation coefficients, and multiple regression models were applied. The analyses were conducted in Statistica 12.0 (TIBCO Software Inc., Palo Alto, CA, USA).

**Table 1.** Operationalization of variables included in the regression models.

#### **3. Results**

My dependent variable was the importance attached to salt content information on food packaging (ISCI). It was measured with the use of the following question: 'How important is the following information on the packaging of food products?—Salt content' with five answer options: very big, rather big, average, rather small, none, which were subsequently coded in the scale 5-1.

Sex differentiated the level of ISCI. Women attached higher importance to salt content information on food packaging than men (Mean: 3.896 versus 3.635, t = 4.134, *p* < 0.001).

Age correlated positively with the ISCI (r = 0.137, *p* < 0.001), meaning that older respondents declared a higher importance of this type of information.

The importance attached to salt content information on food packaging was analyzed with the use of ANOVAs based on selected characteristics of respondents: place of living (size of the city), household size, number of children in the household, respondent's education level, occupational status, household income, evaluation of the quantity of nutrition claims, and the most important information during the first purchase of a food product (Table 2).

The place of living, understood as the size of the respondent's city, did not affect in a significant way the importance attached to salt content information. The household size did not affect in a significant way the importance attached to salt content information.

The number of children in the respondent's household marginally affected the importance attached to salt content information. Respondents from families with no children and 1 child attached higher importance to this kind of information compared to those with 2 or more children.

The importance attached to salt content information depends on the level of education. The higher the education, the more importance is attached to this kind of information.

Occupational status influenced the level of importance attached to salt content information. The highest importance was declared by pensioners (including old age pensioners and disability pensioners) and white-collar workers, whereas the lowest was displayed by students, which is at least partly related to the age structure of these groups.

Income marginally affected the importance attached to salt content information on food packaging. The highest importance was observed in the group of respondents with middle income—3001–4000 PLN (approximately 700–900 EUR) of total monthly disposable income of their household. The lowest importance of this kind of information was indicated by respondents with extremely low and high income.

The evaluation of the quantity of nutrition claims on food packaging affected the importance attached to salt content information significantly. Respondents feeling that there were too many nutrition claims attributed less importance to salt content information than those who believed that this quantity was appropriate or insufficient.

The ISCI depended on which information was the most important for respondents when they bought a food product for the first time. Price was deliberately excluded from the catalogue of answers, and the respondents were asked to consider only non-price attributes. It turned out that the highest ISCI characterized those who indicated nutrition information as the most important type of information during the first purchase.

Being on a special diet for health reasons significantly increased the declared importance of salt content information (4.006 versus 3.728, t = 3.271, *p* = 0.001).

Body Mass Index (BMI) correlated positively with the level of importance attached to salt content information (r = 0.378, *p* < 0.001), meaning that people with higher BMI paid more attention to the salt content information.

Self-rated health correlated strongly with the ISCI (r = 0.917, *p* < 0.001). Respondents evaluating their health more favorably attributed more importance to the salt content information.

**Table 2.** The importance attached to salt content information on food packaging by selected characteristics of respondents (analyses of variance—ANOVAs).

Notes: (1) Households with over 6 members were not included in the ANOVA. They were represented by 2.7% of the respondents. (2) Households with over 4 children were not included in the ANOVA. They were represented by 0.5% of the respondents. (3) Average monthly disposable income of the respondent's household. (4) Evaluation of the quantity of nutrition claims on food packaging. (5) The most important information on the label (excluding price) during the first purchase of a food product. Respondents indicating 'other' and 'don't know' were excluded from the ANOVA. They accounted for 0.6% and 2.1% of the sample, respectively. Significant results indicated in bold.

The ISCI correlated strongly with understandability of nutrition claims (r = 0.913, *p* < 0.001), showing that understanding nutrition claims better increased the importance attached to salt content information.

There was a strong correlation of ISCI with the perceived credibility of nutrition claims (r = 0.928, *p* < 0.001), underlining the link between the importance attached to such information and trust in its accuracy.

The ISCI was strongly associated with the importance attached to nutrition claims on food packaging (r = 0.945, *p* < 0.001) as well as with the importance of other types of information placed on the packaging, such as: health claims (r = 0.944, *p* < 0.001), list of ingredients (r = 0.943, *p* < 0.001), expiry date (r = 0.932, *p* < 0.001), country of origin (r = 0.926, *p* < 0.001), culinary recipes (r = 0.914, *p* < 0.001), brand (r = 0.922, *p* < 0.001), organic label (r = 0.936, *p* < 0.001), quality signs (r = 0.938, *p* < 0.001), recommendations of scientific institutes (r = 0.930, *p* < 0.001), and price (r = 0.917, *p* < 0.001). As the importance of these types of information was highly correlated (correlation coefficients exceeding 0.9), I selected the importance attached to nutrition claims only for further analyses.

The ISCI was also strongly correlated with the importance ascribed to other types of nutrition information, such as: energy value (r = 0.954, *p* < 0.001), fat content (r = 0.968, *p* < 0.001), sugar content (r = 0.967, *p* < 0.001), protein content (r = 0.959, *p* < 0.001), vitamin content (r = 0.960, *p* < 0.001), roughage content (r = 0.961, *p* < 0.001), and Omega-3 fatty acids content (r = 0.961, *p* < 0.001). These results indicate that those attaching high importance to one type of nutrition information tend to appreciate highly also other types of such information. There are very strong correlations between these measures (correlation coefficients exceeding 0.95). Therefore, I excluded the importance attached to particular types of nutrition information from further analyses with the exception of the ISCI.

I also found strong correlations of the ISCI with the importance of all analyzed health claims, concerning the impact of the product on: lowering the cholesterol level (r = 0.942, *p* < 0.001), lowering the risk of heart diseases (r = 0.946, *p* < 0.001), strengthening bones (r = 0.947, *p* < 0.001), the digestive system (r = 0.948, *p* < 0.001), reducing tiredness and fatigue (r = 0.939, *p* < 0.001), maintaining proper vision (r = 0.943, *p* < 0.001), proper development of children (r = 0.929, *p* < 0.001), and proper functioning of the heart (r = 0.944, *p* < 0.001). Due to the very strong correlations among these variables (correlation coefficients above 0.9), they were not included in further analyses.

The ISCI was associated with the willingness to pay (WTP) a higher price for products with nutrition claims compared to similar products without such claims. The WTP was operationalized in two ways in my research. First, it was an answer to the question: 'Are you willing to pay more for products with nutrition claims (compared to similar products without such claims)?' The following answer options were proposed: definitely yes, rather yes, I don't know, rather not, and definitely not, and subsequently coded in the scale 5-1. The second operationalization of the WTP was numerical. Those respondents who answered 'definitely yes' or 'rather yes' to the above question were asked to estimate how much higher a price (on average) they would be willing to pay for products with nutrition claims (compared to similar products without such claims), expressed in percentage. It turned out that the ISCI correlated significantly with both types of WTP. For the former, the correlation coefficient amounted to 0.925 (*p* < 0.001), whereas for the latter it was 0.152 (*p* = 0.001). The former measure of the WTP was selected for further analyses.

Unsurprisingly, the ISCI was strongly correlated to paying attention to health and nutrition claims (r = 0.945, *p* < 0.001).

More surprising was a very strong correlation between the ISCI and the opinion that the use of unreliable nutrition claims is a serious problem in Poland (r = 0.928, *p* < 0.001). Paradoxically, respondents who confirmed the existence of this problem attached a higher importance to salt content information. They might have a better knowledge of this negative phenomenon, which did not prevent them from paying attention to nutrition claims.

Consumers evaluating their diet as more healthy indicated a higher importance of salt content information on the packaging (r = 0.944, *p* < 0.001).

The ISCI was also related to the self-evaluated knowledge on a healthy diet (r = 0.941, *p* < 0.001).

Consumers purchasing certain types of products were characterized by significantly higher importance attached to salt content information (Table 3). It applied to: dietary supplements, organic food, functional food, and fair trade products.

**Table 3.** The importance attached to salt content information on food packaging by purchasing certain products (*t* tests).

Note: the category 'No' includes those who answered 'No' and 'Don't know'.

The ISCI was significantly related to reading food labels, both during the purchase in the point of sale, and at home after the purchase (Table 4). It was correlated with front-of-package and back-of-package labels in both contexts. Please not that this variable was operationalized as the percentage share of products during and after the purchase of which the respondent reads information placed on the packaging. This measurement approach reduces potential bias between heavy buyers and those who do not engage in food shopping frequently, as I focus on the relative, not absolute frequency of reading labels.

**Table 4.** Correlation coefficients between the importance attached to salt content information on food packaging and reading labels (the share of food products for which the respondent reads FOP or BOP labels in the shop or at home).

Note: FOP—front-of-package labels, BOP—back-of-package labels.

Variables which significantly affected the importance attached to salt content information in the *t* tests, correlation coefficients, and ANOVAs (with the exception of those that were highly correlated with similar independent variables) were included in a multiple regression model in order to test their simultaneous impact on the dependent variable (ISCI) (Table 5). The initial regression model included 27 independent variables, 11 out of which turned out to be statistically significant predictors of the ISCI at the level of *p* < 0.05. The whole model was highly significant (*p* < 0.001) and explained 32.8% of the variance of the dependent variable.

In order to arrive at a more parsimonious model, I gradually eliminated from the full model those predictors that failed to reach statistical significance (*p* < 0.05), starting with those that had the highest statistical significance in the initial model. The implementation of this procedure led to the emergence of the final multiple regression model (Table 6). It explains almost the same amount of the variance of the dependent variable (R2 = 0.320, *p* < 0.001), with a considerably smaller set of predictors (12 variables). It is worth noting that all independent variables which were significant in the initial model remain significant in this modified model, and one variable which failed to reach statistical significance previously has now become significant (sex).

**Table 5.** Selected predictors of the importance attached to salt content information on food packaging (the initial multiple regression model).

Note: the operationalization of the variables is included in Table 1; SE—standard error. Significant values are shown in bold.

**Table 6.** Selected predictors of the importance attached to salt content information on food packaging (the final multiple regression model).

Note: the operationalization of the variables is included in Table 1; SE—standard error. Significant values are shown in bold.

The importance attached to salt content information on food packaging depends on the respondent's: sex, age, evaluation of the quantity of nutrition claims, importance attached to nutrition claims, willingness to pay a price premium for products with nutrition claims, attention paid to health and nutrition claims, agreeing with the opinion that unreliable nutrition claims are a serious problem, evaluation of healthiness of one's diet, self-rated knowledge about healthy nutrition, buying organic food, and reading front-of-package labels during and after the purchase. Being a woman increases the ISCI. Older consumers attach more importance to salt content information. Evaluating the quantity of nutrition claims as appropriate and insufficient reinforces the ISCI. Higher importance attached to nutrition claims in general translates into a higher ISCI. Being more willing to pay a higher price for products with nutrition claims increases the ISCI. Paying more attention to health and nutrition claims increases the ISCI. Agreeing with the opinion that the use of unreliable nutrition claims constitutes an important problem boosts the ISCI. Evaluating one's diet as healthy contributes to a higher ISCI. Displaying better (self-rated) knowledge about healthy nutrition also improves the ISCI. Buying organic food is positively related to the ISCI. A bit surprisingly, reading front-of-package information in the shop actually reduces the ISCI, whereas reading the same kind of information on the label after the purchase at home increases it.

The multivariate model can be used for profiling consumer characteristics more prone to value ISCI. I estimated the predicted ISCI for a sensitive set of combination of covariates in the regression model (Table 7). The predictions for different levels of a given independent variable were made on the assumption that the remaining covariates were at their mean level observed in the sample.

On the basis of these calculations, we can notice, for instance, that the difference in the predicted ISCI between men and women is 3.831 − 3.710 = 0.121. In relative terms, it is 0.121/3.710 = 0.0326, i.e., 3.26%. The ISCI values for men and women actually observed in the sample were 3.635 and 3.896 respectively, which means a difference between sexes of 0.261 or 7.18%. Does it mean that the above predictions are inaccurate? Not necessarily, because we should bear in mind that the multiple regression takes into account the simultaneous impact of all predictors included in the model. For example, if women in the sample tend to be younger than men and age is positively correlated with ISCI, the impact of age is not reflected in the ISCI ANOVA for sex, but it is taken into account in the multiple regression with ISCI as the dependent variable and both sex and age included as predictors. Ceteris paribus, being older by 10 years leads to a higher predicted ISCI by 0.091. Ceteris paribus, those who consider the quantity of nutrition claims on the food packaging as insufficient have a higher predicted ISCI than those who think there are too many nutrition claims by 0.272. Ceteris paribus, those who attach very high importance to nutrition claims have a predicted ISCI higher than those who consider their importance as none by as much as 1.092. Ceteris paribus, those who declare they are definitely willing to pay more for products with nutrition claims than for analogous products without such claims have their predicted ISCI higher by 0.279 than those who definitely would not pay more. Ceteris paribus, those who definitively pay attention to health and nutrition claims have their predicted ISCI higher than those who definitively do not by 0.725. Ceteris paribus, those who definitively agree with the statement that the use of unreliable nutrition claims is a serious problem have their predicted ISCI higher by 0.497 than those who definitively do not agree with this opinion. Ceteris paribus, those who consider their diet as very healthy have their predicted ISCI higher than those who consider it very unhealthy by 0.484. Ceteris paribus, those who evaluate their knowledge about healthy nutrition as very big have their predicted ISCI higher than those who think it is very small by 0.383. Ceteris paribus, buying organic food leads to an increase in the predicted ISCI by 0.117. Ceteris paribus, those who declare they read FOP labels for 90% of food products in the shop have their predicted ISCI lower by 0.255 than those who declare reading such labels for 10% of food products in the point of purchase. Ceteris paribus, those who declare reading 90% of FOP labels at home have their predicted ISCI higher by 0.298 than those who read only 10% of such labels after shopping.

Notes: the operationalization of the variables is included in Table 1; CI—confidence interval.

#### **4. Discussion**

Only two out of the 12 statistically significant predictors of the importance attached to salt content information were demographic (sex and age), while the remaining 10 were behavioral and psychographic. The strongest effects on the importance attached to salt content information on the food packaging (|β| > 0.1) were displayed by the importance of nutrition claims, attention paid to nutrition and health claims, respondent's age, FOP label reading at home, and agreeing that the use of unreliable nutrition claims is a serious problem. Therefore, front-of-package labeling plays a key role in salt content communication, which is congruent with references [2–4,39]. Second, this study confirmed the impact of gender, age, buying organic food [7], and consumer knowledge [6,34] on the nutritional label use. Contrary to some previous studies [9,33], education, income, and household size did not affect the importance attached to salt content information in the multiple regression model. Contrary to a study conducted in Brazil [27], not men, but women attached more importance to the salt information.

The contribution of the current study is related to the fact that it enabled to focus on the importance attached to salt content information (regardless of its form on the label), rather than nutritional information in general on the one hand, and specific nutrition claims on the other hand. Furthermore, my findings indicate the importance of several new predictors of the ISCI, including various aspects of the attitude to nutrition claims and the context of reading FOP labels (at home rather than in the shop). Third, it is the first attempt to study this phenomenon in a representative sample of the inhabitants of Poland, the largest country in the Central European region, which is characterized by very unfavorable salt intake statistics within the European Union.

There are a few implications of my findings. First of all, there is a need to increase the importance attached to salt content information in certain segments of the population, especially among men and younger consumers. Second, it is advisable to conduct education campaigns stressing the importance of nutrition claims placed on food products, explaining the meaning of nutrition information presented on the labels, and increasing consumer knowledge about healthy nutrition. Third, it is recommended to augment consumers' attention to health and nutrition claims, e.g., by allocating a more prominent place on the packaging to this type of information, using bigger fonts of the typeface, using graphical symbols alongside textual information, and emphasizing them in other forms of marketing communications, in particular advertising. Fourth, it is recommended to run social marketing campaigns in favor of more healthy diets. Fifth, it is recommended to stimulate the development of the organic food market. Sixth, it may be beneficial to encourage consumers to read food labels after the purchase at home, e.g., by running loyalty programs requiring consumers to use promotion codes placed on the packaging. Seventh, the use of nutrition claims and other similar types of information on the food labels should be controlled by independent public authorities so as to minimize the concern about unreliable claims. Eighth, it may be advisable to consider the expansion of the obligation of salt content labeling to other food product categories.

It is worth noting that all measures used in this study were self-reported, rather than observed, which may be considered a limitation. Second, due to the intention-behavior gap, it is hard to translate the declarations of importance of particular information types into actual purchasing behaviors. However, our variable of interest was importance attached to salt content rather than just reading salt labels, which may be considered more accurate in predicting consumer behavior in my opinion.

Future research may focus on the perception of various types of salt content information by different segments of consumers. Second, structural equation modeling may be used to examine various paths of causal relationships, mediators, and moderators. Third, long-term purchasing data in consumer panels may be used to investigate the impact of socio-demographic variables on the preferences for low sodium products and the relationship between reading salt information, attaching importance to it, and implementing healthy diet practices.

**Funding:** This research was funded by the National Science Centre, Opus grant number 2015/17/B/HS4/00253. The APC was funded by the National Science Centre, Opus grant number 2015/17/B/HS4/00253.

**Conflicts of Interest:** The author declares no conflict of interest. The funder had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

#### **References**

© 2020 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

*Article*


**1. Introduction**

Over the past decades, carbon-fiber-reinforced polymer (CFRP) composites have shown a constant increase in a variety of applications such as car or aircraft components, sports and medical equipment [1], and recently also additive manufacturing [2–4]. Their main benefit lies primarily in the relatively high strength/weight ratio or the ability to customize the material properties for dedicated purposes by changing the stacking sequence and related fiber orientation. A relative drawback of CRFP composites is the lack of ductile-like behavior and the corresponding absence of pre-warning phase before the structural collapse [5,6] leading to the brittle failure. CRFP composites are also characterized by the accumulation of damage inside the structure without any evidence on the structure surface [6] thus leading to a relatively challenging damage assessment. There are many non-destructive testing approaches, which can be applied on composite structures, namely infrared tomography [7], eddy current testing [8], ultrasonic testing [9], and X-ray tomography [10].

One of the most promising approaches, especially coupled with other methods [11] such as Scanning Electron Microscopy (SEM), is the acoustic emission (AE) method, which is also used in various applications as a real time monitoring tool [6]. The AE method exhibits great sensitivity including considerable reliability of active cracks detection [12], even in the case of initiation phase [13]. The AE technique is even capable of detecting the onset of plastic deformation [14], which has the character of white noise with low energy [15]. For gaining a more detailed insight into the damage monitoring process within

**Citation:** Šofer, M.; Cienciala, J.; Fusek, M.; Pavlíˇcek, P.; Moravec, R. Damage Analysis of Composite CFRP Tubes Using Acoustic Emission Monitoring and Pattern Recognition Approach. *Materials* **2021**, *14*, 786. https://doi.org/10.3390/ma14040786

Academic Editor: Michele Bacciocchi Received: 12 November 2020 Accepted: 28 January 2021 Published: 7 February 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

the meaning of AE source characterization, it is favorable to incorporate an adequate signal analysis tool. The supervised/unsupervised pattern recognition (UPR) approach [16] has become a very suitable and promising approach to tackle a wide variety of problems such as fatigue tests [17], structure health monitoring [18], and condition assessment of pressure vessels [19] and pressure components in operation [20]. Numerous studies [21–26] have been conducted in order to assess characteristic features of the AE transients originating from various failure mechanism in the CFRP composites such as matrix cracking, delamination, fiber break, and debonding (see Table 1 for further explanation).

**Table 1.** Basic characterization of damage mechanisms occurring in carbon-fiber-reinforced polymer (CFRP) composites.

Although Chou [21] points to a discrepancy concerning, in particular, the signal amplitude, duration as well as frequency spectra of the individual damage mechanisms, it was possible to compile a general overview, which is given in the following table (Table 2).

**Table 2.** Summary of the acoustic emission (AE) signal characteristics for given damage mechanisms in CFRP composites

\* A—amplitude, D—duration.

In the last decade, several/numerous studies utilizing advanced techniques for classification of failure modes, such as the use of statistical analysis of wavelet coefficients [27] or infrared thermography (IT) [28], have been conducted. Another interesting approach can be found in the work published by Munoz et al. [29], who identified and further characterized the damage mechanisms in the unidirectional CFRP composites subjected to axis and off-axis static tensile tests using the acoustic emission method and infrared thermography. Further utilization of unsupervised pattern recognition technique together with the IT method resulted in the identification of the failure mechanisms such as matrix cracking, fiber breakage, and interface failure, for which the characterization in terms of the signal amplitude or energy has been performed. In 2011, Gutkin et al. published an extensive research [30], in which the AE signal data from various test configurations were analyzed by three different pattern recognition approaches. The analysis resulted in characteristic frequency spectra for matrix cracking, delamination, debonding, fiber pull-out, and fiber failure. It has to be noted that the given findings in terms of the frequency spectra are to some extent similar to the results summarized in Table 2 and therefore confirms the factual accuracy of the study [30].

The main objective of this study is to investigate and comprehensively describe the AE signal characteristics of the damage mechanisms in three different types of CFRP composite tubes using a two-step method combining the unsupervised pattern recognition approach with the utilization of the boundary curve. The construction of the boundary curve has been conducted on the data from the preliminary carbon fiber sheaf tensile tests. The already identified boundary curve has then been used for further refinement of the data across individual clusters. Using the presented approach, it was possible to identify a total of four damage mechanisms presented in Table 1 with subsequent comparison of the obtained results with the already published research papers. The part of the study is also the comprehensive AE waveform analysis of the representative signals belonging to the individual clusters.

### **2. Experimental Procedure**

#### *2.1. Test Sample Characterization*

The experiments were carried out on three types of CFRP tubes with a different number of layers, their orientation, and woven fiber density of the used material (see Figure 1), where each type of CFRP tube has been represented by three test samples. The samples labeled "A" were manufactured using four layers of unidirectional carbon woven fabric with density of 200 g/m2 and one layer of aramid/carbon woven fabric (0–90◦) with density of 175 g/m2 and average wall thickness of 1.45 mm. The production of samples labeled "B" included the use of two layers of unidirectional carbon woven fabric with density 300 g/m2 and one layer of carbon woven fabric (0–90◦) with density 280 g/m2 with average wall thickness of 0.9 mm, while samples labeled "C" were manufactured using solely four layers of unidirectional carbon woven fabric with density of 300 g/m2 with average wall thickness of 1.42 mm. Table 3 summarizes the specification of the tested CFRP tubes.

**Figure 1.** CFRP composite tubes under test; A—A series sample, B—B series sample, C—C series sample.

**Table 3.** Specification of the tested CFRP tubes


**5. Cassini mission experience**

Cassini-Huygens is a "Class A" Flagship mission, which requires that it be configured as a low risk, high robustness design with all practical measures taken to assure mission success. Numerous analyses and test programs were required before launch approval could be obtained for Cassini by NASA, in order to assure the mission's technical worthiness. These programs were also needed to fulfill mission requirements, which consisted of spacecraft loads analyses to demonstrate that all structural margins met expected safety standards, including a modal test program that yielded experimental data to verify the spacecraft and instruments via a finite element model arranged in the launch configuration. Dynamic tests of the spacecraft and instruments were also performed, as well as acoustic/vibration tests [7–10]. Thermal analyses provided environmental verification, proving the functionality of all components. Also, verified were the heater power and the radiator area for engineering, as well as transducer performance [11, 12].

For Cassini, JPL's "conceptual life cycle strategy" was implemented. This consisted of splitting the development effort into several phases [13]:

**137**

*Robotic Autonomous Spacecraft Missions: Cassini Mission-To-Saturn Example*

Once in Phase E, Cassini's operations phase was also divided into phases. Each phase was executed by way of several uplinked command sequences which were stored and executed onboard the spacecraft (sequences were designated as "C" for

The Launch Phase spanned from launch (L) to L + 30 days, during which time launch activities and essential engineering checkouts and calibrations were required to prepare for the first main engine maneuver at L + 25 days. The Inner Cruise Phase encompassed the trajectory interior to Earth's orbit, included two Venus flybys and an Earth flyby. In this phase, the two close flybys of Venus and Earth were required to gain the needed velocity boost through gravity-assist maneuvers, to allow Cassini's trajectory to continue on to Saturn (via the next flyby at Jupiter). The science activities during this period were limited to instrument checkout exercises, with limited science performed during the Venus and Earth flybys. Since Cassini was in close proximity to the sun, the HGA was used to shield the spacecraft to prevent overheating. During the Outer Cruise Phase, the HGA was used for data transmission (instead of the LGA) since the relative distance between Cassini and the sun was now increasing rapidly and overheating was no longer an issue. Instrument checkout activities continued during this phase, as well as checkout of the Huygens probe. Also included was the final gravity-assist flyby of Jupiter, where extensive science activities began. The Science Cruise Phase began 2 years prior to arrival at Saturn, in order to prepare for Cassini's arrival. Science activities increased during this time,

The Saturn Approach Phase included a one-time opportunity flyby of the Phoebe moon and the SOI deceleration burn. After launch, the SOI burn was the most crucial activity of the entire mission since it not only allowed Cassini to be captured into Saturn's orbit, but also was an opportunity to view the planet at the closest range of the entire Prime Mission. The Probe Mission Phase was completed on the third encounter (flyby) with the moon Titan. The Tour Phase began at SOI and continued for 13 years (including the two extended missions, Equinox and Solstice). The moon Titan was massive enough to offer gravity-assist capability, and

*DOI: http://dx.doi.org/10.5772/intechopen.82161*

• Launch and Deployment (C1–C4 sequences)

• Science Cruise Phase (C33–C41 sequences)

• Saturn Approach Science Phase (C42–C44 sequences)

• Inner Cruise (C5–C16 sequences)

• Outer Cruise (C17–C32 sequences)

• Saturn Tour (S01–S06 sequences)

• Huygens Probe Mission (S07 sequence)

• Tour (all three tours; S08–S101 sequences)

and final instrument calibrations were completed.

• Phase C: Detailed design

• Phase D: Build & test

• Phase E: Operations

cruise or "S" for science):

*Robotic Autonomous Spacecraft Missions: Cassini Mission-To-Saturn Example DOI: http://dx.doi.org/10.5772/intechopen.82161*

*Aerospace Engineering*

**4.6 Meeting challenging problems through FP & FSW uploads**

health and fault condition to support fault recovery).

visibility added to the downlinked telemetry stream.

**5. Cassini mission experience**

• Prephase A: Advanced studies

• Phase B: Preliminary design

• Phase A: Mission & systems definition

To aid in many of the above challenges, onboard autonomous Fault Protection routines are implemented into the computers' FSW to monitor the spacecraft's many systems and devices to autonomously detect fault occurrences and respond to anomalous conditions. FP consists of "canned" automated responses that can swap to redundant devices (if available), command actions (like closing valves, commanding alternate targets, etc.) and/or place the spacecraft into a "safe state" using preprogrammed instructional routines. A general-purpose, "Safe Mode" fault response routine is typically executed if the fault condition interferes with the onboard running sequence (along with other corrective actions performed by FP if required), which terminates the onboard running sequence, configures the spacecraft to a lower power state by powering off all nonessential spacecraft loads, commands a thermally safe attitude and safe state for the hardware, establishes a low uplink and downlink rate for earth communications, and commands the LGA antenna (to accommodate the low rates). This safe, predictable spacecraft state allows the SOFS sufficient time to evaluate the fault causes and determine a solution [6]. On Cassini, FP was implemented early in the design phase. In general, FP responsibility is allocated to both the SOFS team and the spacecraft (which must deliver sufficient information on its

Unexpected conditions and problems can potentially exist for spacecraft missions that are exploring unknown parts of our solar system. New devices never flown in space before can experience unexpected faults due to the adverse flight environment. For these reasons (and those stated above), designers provide the SOFS team with the ability to upload FSW patches (replacing the memory locations within the onboard FSW with new data), and to replace entire CDS, AACS, or instrument FSW loads so that unknown problems can be addressed and increased

Cassini-Huygens is a "Class A" Flagship mission, which requires that it be configured as a low risk, high robustness design with all practical measures taken to assure mission success. Numerous analyses and test programs were required before launch approval could be obtained for Cassini by NASA, in order to assure the mission's technical worthiness. These programs were also needed to fulfill mission requirements, which consisted of spacecraft loads analyses to demonstrate that all structural margins met expected safety standards, including a modal test program that yielded experimental data to verify the spacecraft and instruments via a finite element model arranged in the launch configuration. Dynamic tests of the spacecraft and instruments were also performed, as well as acoustic/vibration tests [7–10]. Thermal analyses provided environmental verification, proving the functionality of all components. Also, verified were the heater power and the radiator

For Cassini, JPL's "conceptual life cycle strategy" was implemented. This con-

area for engineering, as well as transducer performance [11, 12].

sisted of splitting the development effort into several phases [13]:

**136**

• Phase E: Operations

Once in Phase E, Cassini's operations phase was also divided into phases. Each phase was executed by way of several uplinked command sequences which were stored and executed onboard the spacecraft (sequences were designated as "C" for cruise or "S" for science):

The Launch Phase spanned from launch (L) to L + 30 days, during which time launch activities and essential engineering checkouts and calibrations were required to prepare for the first main engine maneuver at L + 25 days. The Inner Cruise Phase encompassed the trajectory interior to Earth's orbit, included two Venus flybys and an Earth flyby. In this phase, the two close flybys of Venus and Earth were required to gain the needed velocity boost through gravity-assist maneuvers, to allow Cassini's trajectory to continue on to Saturn (via the next flyby at Jupiter). The science activities during this period were limited to instrument checkout exercises, with limited science performed during the Venus and Earth flybys. Since Cassini was in close proximity to the sun, the HGA was used to shield the spacecraft to prevent overheating.

During the Outer Cruise Phase, the HGA was used for data transmission (instead of the LGA) since the relative distance between Cassini and the sun was now increasing rapidly and overheating was no longer an issue. Instrument checkout activities continued during this phase, as well as checkout of the Huygens probe. Also included was the final gravity-assist flyby of Jupiter, where extensive science activities began. The Science Cruise Phase began 2 years prior to arrival at Saturn, in order to prepare for Cassini's arrival. Science activities increased during this time, and final instrument calibrations were completed.

The Saturn Approach Phase included a one-time opportunity flyby of the Phoebe moon and the SOI deceleration burn. After launch, the SOI burn was the most crucial activity of the entire mission since it not only allowed Cassini to be captured into Saturn's orbit, but also was an opportunity to view the planet at the closest range of the entire Prime Mission. The Probe Mission Phase was completed on the third encounter (flyby) with the moon Titan. The Tour Phase began at SOI and continued for 13 years (including the two extended missions, Equinox and Solstice). The moon Titan was massive enough to offer gravity-assist capability, and was used as "the tour engine" enabling orbit rotation, orbital period, and inclination changes needed to study Saturn's geometry, as well as to set up the many icy satellite encounters.


Preface

**Section 3 High-Speed Optical Communication: Optical Systems 143**

Chapter 6 **Application of Complex Wavelet Packet Transform (CWPT) in**

Chapter 7 **Wired/Wireless Photonic Communication Systems Using**

Delgado, Ana Lilia Leal Cruz and Alicia Vera Marquina

Chapter 8 **New Results in DF Relaying Schemes Using Time Diversity for**

Alejandro García Juárez, Ignacio Enrique Zaldívar Huerta, Antonio Baylón Fuentes, María del Rocío Gómez Colín, Luis Arturo García

Rubén Boluda-Ruiz, Beatriz Castillo-Vázquez, Carmen Castillo-

**Coherent Optical OFDM (CO-OFDM) Communication Systems 145** Y. Ben-Ezra and B.I. Lembrikov

**Optical Heterodyning 169**

**VI** Contents

**Free-Space Optical Links 195**

Vázquez and Antonio García-Zambrana

#### **High-Speed Optical Communication**

High-speed optical communication is very much useful part in our advanced fibre-based telecommunication systems, data processing and networking systems. It consists of a trans‐ mitter that encodes the message signal into an optical signal, a channel/ link that carries this optical signal to its desired destination, and a receiver that reproduces the original message from the received optical signal. It presents up to date results of the communica‐ tion systems, along with the explanations of their relevance, from leading researchers in this field. The chapters of this book cover the general concepts of high-speed optical com‐ munication, devices used for optical communication, optical communication systems. In recent years, the optical components or devices and other enhanced signal processing func‐ tions are also considered in depth for high-speed optical communications systems. The researcher has also concentrated on optical devices such as light emitting diodes and pho‐ todetectors application in optical communication. This book is targeted at research, devel‐ opment and design engineers from the teams in manufacturing industry, academia and trlecommunication industries.

This book presents a high level technical overview of the emerging technologies of highspeed optical communication systems. It is intended as an introduction to the field for opti‐ cal communication and professional engineers, such as higher degree research students, research academics and design engineers. Although it is intended for professionals who al‐ ready have some technical background, it is nevertheless relevant to anyone wishing to un‐ derstand high-speed optical communication systems.

The following figure 1 illustrates a schematic diagram of a simple high-speed optical com‐ munication system. It consist of three separate parts or blocks, such as, (i) the transmitter part contains a constant optical/ light sources as laser or light emitting diodes (LEDs) and a modulator, (ii) the channel or link part is an optical fiber about 100-kms long that carries the information from the transmitter to the receiver, and (iii) the receiver consists of a semicon‐ ductor photodetector that detects the received signal and a semiconductor amplifier for the amplification of received signal from the channel/ link. The optical pulses are created using lasers or LEDs and transmitted through the transmitter via the links/ channels and receiving it at the receiver side. A list of bits (such as, '1's and '0's are as input data signal) are sent into the transmitter in the form of data/ signal levels (high '1' or low '0'), where they control a modulator, which alters the power of a light beam produced by a light sources such as lasers or LEDs. The laser or LED light sources produce a constant-power light beam, which experiences different amount of attenuation as it passes through the modulator, depending on the bit value is being sent. The light emerging from the modulator is a series of optical pulses of high '1' or low '0' power levels. These optical pulses travel to a long distance, such as ~100-kms by total internal reflection inside the core of the fiber until they reach at the other end of the fiber, where they are focused onto a light detector (as a semiconductor pho‐ todetector that detects the received signals). In general, the following Fig. 1 covers all parts/ chapters concept of this book. These are: General concepts of high-speed optical communi‐ cation, Optical devices used in optical communication, and Optical communication systems.

**Figure 1.** A simple schematic diagram of a high-speed optical communication system/ link, where the transmitter con‐ tains a constant-power, optical/ light source as laser or LEDs and a modulator, the channel/ link is an optical fiber about 100-kms, and the receiver consists of a semiconductor photodetector and amplifiers.

#### **Organisation of the Book**

The authors with whom I have had the pleasure to collaborate have written chapters that report recent developments in high-speed optical communication and networking. They cover a number of themes, which include the basic concepts of optical communication, devi‐ ces used for high-speed optical communication, such as photodetectors and semiconductor amplifiers, optical communication systems as described above. No book of the current length can encompass the full scope of the subject but I am pleased at the range of topics that we have been able to include in this book.

In this book, the chapters have been grouped as part according to the following themes: High-speed Optical Communication: Part 1, General Concepts; Optical Communication: Part 2, Optical Devices, such as Photodetectors and Light Emitting Diodes; Optical Commu‐ nication: and Part 3, Optical Communication Systems, such as Optical Transmission Sys‐ tems; Optical Communication. These categorisations of parts are not fully perfect because some of the chapters are mixed or overlapped i.e., like an inter-disciplinary topic. However, all of the chapter are within an easily identifiable subject boundary that is a positive sign of the indicators of scientific progress in high-speed optical communication.

I acknowledge to all the authors for their contribution in the book chapters from different organisations (Universities and industries).

I acknowledge to Professor Zhu Quan Zang, Head of the Department of Electrical and Com‐ puter Engineering, Professor Michael Cloke, Dean of School of Engineering and Science, Curtin University Sarawak, Miri, Malaysia and Dr Yee Hong, Head of the Department of Electrical and Computer Engineering, Professor Syed Islam, Department of Electrical and Computer Engineering, Curtin University, Perth, Australia for their continuous support and encouragement to complete this task. I also acknowledge to Dr Mohammad Razaghi, Uni‐ versity of Kurdistan, Iran for his continuous support, encouragement and collaboration to complete this book.

I am very much grateful to Ms Danijela Duric, book publishing process manager/ Head at Intech, for her prompt responses to my queries in regards to complete this book. I wish all of my collaborators every success in their future research activities.

pulses of high '1' or low '0' power levels. These optical pulses travel to a long distance, such as ~100-kms by total internal reflection inside the core of the fiber until they reach at the other end of the fiber, where they are focused onto a light detector (as a semiconductor pho‐ todetector that detects the received signals). In general, the following Fig. 1 covers all parts/ chapters concept of this book. These are: General concepts of high-speed optical communi‐ cation, Optical devices used in optical communication, and Optical communication systems.

**Figure 1.** A simple schematic diagram of a high-speed optical communication system/ link, where the transmitter con‐ tains a constant-power, optical/ light source as laser or LEDs and a modulator, the channel/ link is an optical fiber

The authors with whom I have had the pleasure to collaborate have written chapters that report recent developments in high-speed optical communication and networking. They cover a number of themes, which include the basic concepts of optical communication, devi‐ ces used for high-speed optical communication, such as photodetectors and semiconductor amplifiers, optical communication systems as described above. No book of the current length can encompass the full scope of the subject but I am pleased at the range of topics

In this book, the chapters have been grouped as part according to the following themes: High-speed Optical Communication: Part 1, General Concepts; Optical Communication: Part 2, Optical Devices, such as Photodetectors and Light Emitting Diodes; Optical Commu‐ nication: and Part 3, Optical Communication Systems, such as Optical Transmission Sys‐ tems; Optical Communication. These categorisations of parts are not fully perfect because some of the chapters are mixed or overlapped i.e., like an inter-disciplinary topic. However, all of the chapter are within an easily identifiable subject boundary that is a positive sign of

I acknowledge to all the authors for their contribution in the book chapters from different

I acknowledge to Professor Zhu Quan Zang, Head of the Department of Electrical and Com‐ puter Engineering, Professor Michael Cloke, Dean of School of Engineering and Science, Curtin University Sarawak, Miri, Malaysia and Dr Yee Hong, Head of the Department of Electrical and Computer Engineering, Professor Syed Islam, Department of Electrical and Computer Engineering, Curtin University, Perth, Australia for their continuous support and encouragement to complete this task. I also acknowledge to Dr Mohammad Razaghi, Uni‐ versity of Kurdistan, Iran for his continuous support, encouragement and collaboration to

about 100-kms, and the receiver consists of a semiconductor photodetector and amplifiers.

the indicators of scientific progress in high-speed optical communication.

**Organisation of the Book**

VIII Preface

that we have been able to include in this book.

organisations (Universities and industries).

complete this book.

Foremost' I would like to thank my wife Mrs Varoti Das, son Nishikanta Das and daughter Nandita Das for their strong patience' understanding, continuous encouragement and sup‐ port to complete this book.

#### **Narottam Das**

Department of Electrical and Computer Engineering Curtin University Sarawak, Miri, Malaysia

Department of Electrical and Computer Engineering Curtin University, Perth, Australia

**High-Speed Optical Communication: General Concepts**


**6.4 Encryption algorithm speed**

In real-time application, the run time is considered as a main constraint. Eqs. (11) and (12) are used to calculate the speed (*S*) and the number of cycles per byte obtained by a specific algorithm running on the processor.

#### *Lightweight Cryptographic Techniques and Cybersecurity Approaches*

#### **Table 8.**

*Entropy and correlation values.*

**Table 9.**

*Performance results and comparison with the state of the art.*

$$\text{SS} = \frac{\text{data size}}{\text{Time}} \text{MB/s} \tag{11}$$

$$number\text{ of cycles}/\text{byte} = \frac{Frequency}{\text{S}}\tag{12}$$

A comparison with related works is given in this state (**Table 9**). The comparison proves that the suggested scheme has the best findings in terms of speed.

## **7. Conclusion and future work**

In this paper, we have put forward a strong hybrid cryptographic framework for image encryption, decryption, and authentication. The algorithm has combined a hash function and symmetric and asymmetric algorithms. The keccak hash function has been used for the initial secret key generation related to the plain image and owner's signature. The RSA encryption system has been used for the secret key exchanging and authentication. For image encryption, we have utilized the AES-256 bits with CTR mode. The main advantages of this mode are the rapidity of treatment and the no error propagation. The evaluation and analysis results prove that our proposed algorithm allows high performance and security. It can resist most known cryptanalysis attacks. For future work, we aim to design a mechanism for dynamically changing the S-box values of the AES.

*Hardware Implementation of an Improved Hybrid Cryptosystem for Numerical Image Encryption… DOI: http://dx.doi.org/10.5772/intechopen.105207*


**2. Methodology**

#### **2.1 Climate**

The climate of Lesotho is largely determined by the country's location in the centre of the Southern African Plateau. It is sub-humid to temperate cool with warm and rainy summers and cool to cold dry winters. The mean minimum temperature during winter is around 0°C which is common in June (the coldest month), with the lowlands recording �1 to �3°C and the highlands recording �6 to �8.5°C. The mean annual temperatures recorded are 15.2°C and 7°C for the lowlands and the highlands respectively. In January, which produces the highest mean maximum temperatures throughout the country, temperatures range from 20°C in the highlands, and 32°C in the lowlands. The mean annual precipitation ranges from 500 mm in the Senqu River Valley to 1200 mm in the North and East of the country. Eighty-five percent of the rainfall is received between the months of October and April. Frost and snow are common in winter. The mountains of Lesotho are regularly covered by snow during winter months.

## **2.2 Land use**

Land use is often used as a surrogate for disturbance and has been correlated with biological attributes in wetlands [11, 29]. In Lesotho, agricultural activity (i.e. grazing and livestock watering) coupled with climatic change is the predominant disturbance to seasonal wetlands in all agro-ecological zones. Wetlands can be characterized into low or high impact based on local land use characteristics [5, 30], with low impact wetlands having little or no agricultural activity within 150 m of the wetland boundary and high impact wetlands having agricultural activity within 10 m of the wetland boundary.

#### **2.3 Descriptions of the experimental sites**

The study sites were located within Lesotho at an elevation ranging between 1800 m and >2000 m above sea level (asl) (**Table 1** and **Figures 1** and **2**) in two agro-ecological zones (AEZ): the Foot-Hills and the Mountains. Shrubs co-dominate at higher elevations in the Mountains AEZ, wile in the Foot-Hills, the dominant vegetation is grasses (i.e. *Cyperus spp*)*.*

#### **2.4 Selections of wetlands in relation to utilization**

Wetlands were selected for this research were characterized as either low, medium or highly impacted based on (i) local land-use characteristics [31]; and (ii) the intensity of anthropogenic pressures such as mining, smelting, and discharge of an industrial pollutant into the wetlands. Low impacted wetlands has little (i.e. <5%) or no agricultural activity within 150 m of the wetland boundary [5, 32]. The wetlands classified as highly impacted had agricultural activities; within 10 m of wetland boundary (i.e. ffi33% of the wetland area is impacted). The medium impacted wetlands had agricultural activities between 5 and 32% of the wetland boundary. Using the probability sampling approach [33], coupled with accessibility and ease of continuous monitoring, two wetland types lacustrine and riverine systems were identified in two different AEZs of Lesotho (**Table 1**).

*Wetland Health in Two Agro-Ecological Zones of Lesotho: Soil Physico-Chemical Properties… DOI: http://dx.doi.org/10.5772/intechopen.101836*

**Figure 1.** *view of* Khalong-la-Lithunya *showing the three transects.*

**Figure 2.** *View of* Ha-Matela *showing transects and stream.*