what percentage of precipitation that falls on land becomes runoff?
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Summary of the Water Cycle Similar storms occurring in the Amazon jungle and in the desert Southwest of the United States will produce different surface-runoff effects. Surface runoff is affected by both meteorological factors and the physical geology and topography of the land. Only about a third of the precipitation that falls over land runs off into streams and rivers and is returned to the oceans. The other two-thirds is evaporated, transpired, or soaks (infiltrates) into groundwater. Surface runoff can also be diverted by humans for their own uses.
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Runoff (surface water runoff) Credit: USGS View full size. 1  That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled (not regulated by a dam upstream) surface streams, rivers, drains or sewers. 2  The sum of total discharges described in (1), above, during a specified period of time.
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Impervious surface The total coverage by impervious surfaces in an area, such as a municipality or a watershed is usually expressed as a percentage of the total land area. The coverage increases with rising urbanization.
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Runoff curve number The runoff curve number was developed from an empirical analysis of runoff from small catchments and hillslope plots monitored by the USDA. It is widely used and is an efficient method for determining the approximate amount of direct runoff from a rainfall event in a particular area. The runoff curve number is based on the area's hydrologic soil group, land use, treatment and hydrologic condition.
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- Definition: Surface water runoff is a step in the water cycle on Earth. When precipitation occurs, water only has a few locations where it can go. Water can infiltrate into the ground, evaporate, or become runoff.
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- In undevelopedwatersheds, smaller storms of less than 1-inch rainfall maynot produce any significant runoff. On an annual basis, about20 percent of the total average annual rainfall (8 to 10 inches)becomes surface runoff and stream flow in undeveloped watersheds (see Figure 2-8).
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- The concentration of phosphorus (P) in runoff from agricultural land is assumed to have two components, an 'incidental' loss that relates to management, such as the application of manure and fertiliser, and a 'systematic' loss that relates primarily to the concentration of soil P and P-buffering capacity (Hart et al.
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Water - When...How...HowMuch Water - When...How...How Much. Water is essential to all life...too little water and we die, too much and we drown. The same is true of the grass in our lawns. Water makes up 70% to 80% of the weight of our lawn grasses and the clippings alone are nearly 90% water. While most people are concerned about not watering their lawns enough, the fact is that more lawns are damaged or destroyed by over-watering.
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Surface runoff Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the earth's surface.urface runoff can be generated either by rainfall,snowfall or by the melting of snow, or glaciers. Snow and glacier melt occur only in areas cold enough for these to form permanently.
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(n). Introduction to Surface Runoff Surface Runoff If the amount of water falling on the ground is greater than the infiltration rate of the surface, runoff or overland flow will occur. Runoff specifically refers to the water leaving an area of drainage and flowing across the land surface to points of lower elevation.
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3. Rainfall-runoff analysis 3.1 Introduction. As defined in Chapter 1, water harvesting is the collection of runoff for productive use. Runoff is generated by rainstorms and its occurrence and quantity are dependent on the characteristics of the rainfall event, i.e. intensity, duration and distribution. There are, in addition, other important factors which influence the runoff generating process. They will be discussed in section 3.5.
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Surface Runoff - The Water Cycle The runoff in this case is flowing over bare soil and is depositing sediment into the river (not good for water quality). The runoff entering this creek is beginning its journey back to the ocean. As with all aspects of the water cycle, the interaction between precipitation and surface runoff varies according to time and geography.
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- Example: 1500 square feet of roof area x 15 inches of rain x 0.623 = 14,017 gallons. Landscapes and hard surfaces can be designed and modified to hold, direct and distribute rainwater to plants with rainwater harvesting. Preventing water from rapidly running off of the landscape is of primary importance.
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Measuring Precipitation Precipitation (which is most commonly rainfall but also includes snow, hail, sleet, and other forms of liquid and frozen water falling to the ground) is measured in units over a given time period.he first is a simple measurement of the snow on the ground with a stick marked with units of measurement (like a yardstick). The second measurement determines the equivalent amount of water in a unit of snow.
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- Due to the relatively flat landscape and the control of natural water regimes, which date back to the nineteenth century, a very high proportion (86.4 percent) of the total land area is productive land (Table 1).
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Surface runoff Surface runoff. Surface runoff is water, from rain, snowmelt, or other sources, that flows over the land surface, and is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called overland flow. A land area which produces runoff draining to a common point is called a watershed.
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- Definition. Subsurface runoff is the water that infiltrates in the vadose zone (unsaturated zone), from rain, snowmelt, or other sources, and moves laterally towards the streams. Vadose zone extends from the top of the ground surface to the water table.
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Hydrologic Cycle Precipitation is the movement of water from the atmosphere to the Earth's surface. Precipitation in the form of rain, snow, sleet, or hail is the source of nearly all the fresh water in the hydrologic cycle. Precipitation. Water that falls to Earth as precipitation follows many paths on its way back to the atmosphere.
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Surface runoff This might occur because soil is saturated to full capacity, because rain arrives more quickly than soil can absorb it, or because impervious areas (roofs and pavement) send their runoff to surrounding soil that cannot absorb all of it. Surface runoff is a major component of the water cycle. It is the primary agent in soil erosion by water. Runoff that occurs on the ground surface before reaching a channel is also called a nonpoint source. If a nonpoint source contains man-made contaminants, or natural forms of pollution (such as rotting leaves) the runoff is called nonpoint source pollution.
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- Thus, the rainfall distribution begins at a value of zero at the beginning of. the storm and ends at a value of 1.0. NRCS hydrologic models WinTR-20, WinTR-55, and SITES, referenced at various places in. this chapter, utilize storm rainfall depth and rainfall distribution to calculate runoff. hydrographs.
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- All rivers are surrounded by a certain amount of land that is higher in altitude (upgradient) than the actual river. Precipitation that falls in this area eventually flows downhill towards the river. At any particular point on a river, the land upgradient of the point is the river's watershed, or drainage basin.This example of a watershed gives a rough idea of how precipitation flows downhill into rivers (and lakes). What separates two watersheds from each other are ridges of higher land.ll rivers are surrounded by a certain amount of land that is higher in altitude (upgradient) than the actual river. Precipitation that falls in this area eventually flows downhill towards the river. At any particular point on a river, the land upgradient of the point is the river's watershed, or drainage basin.
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Erosion and Deposition by Flowing Water As the runoff flows, it may pick up loose material on the surface, such as bits of soil and sand. Runoff is likely to cause more erosion if the land is bare. Plants help hold the soil in place. The runoff water in Figure below is brown because it eroded soil from a bare, sloping field.
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Rain: A Water Resource Volume and weight. 1  One inch of rain falling on 1 acre of ground is equal to about 27,154 gallons and weighs about 113 tons. 2  An inch of snow falling evenly on 1 acre of ground is equivalent to about 2,715 gallons of water.
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RESEARCH PAPEREffect of vegetation on runoff-sediment yield relationship at different spatial scales in hilly areas of the Loess Plateau, North China Therefore, vegetation cannot change the runoff-sediment yield relationship at the watershed scale. This implies that vegetation reduces sediment yield only by reducing runoff volume and the sediment-reduction rate approximates the runoff-reduction rate at the watershed scale.
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- Water is applied in excess of that which infiltrates, and the excess water flows, or advances, across the orchard. When water reaches the lowest part, or end, of the orchard, “tailwater”. runoff begins unless the water is shut off or the end of the orchard is blocked. with berms to keep the water in the orchard.
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Science in Your Watershed Sustained or fair weather runoff. In most streams, base runoff is composed largely of groundwater effluent. (Langbein and others, 1947, p. 6.) The term base flow is often used in the same sense as base runoff. However, the distinction is the same as that between streamflow and runoff.