If you're thinking about buying a retractable awning, consider the value, longevity and cost. Purchasing a retractable deck awning is a big investment. While smaller, less-expensive awnings start at around $500, larger, higher-quality awnings can cost as much as $2,000 or more. Before you make the decision to buy a retractable awning, you should learn as much as possible about their benefits and drawbacks. Here are the top three pros and cons to consider.
Drainage basin (catchment area) is the area which supplies a river system, lake or reservoir with water. The whole area consists of smaller sub-catchments supplying tributaries of the main ri-ver and direct catchments, which drain straight into a lake or main river (Box 3.1).ts purpose is to co-nvey excess water from a drainage basin, which will include the products of weathering and addi-tional loads of solutes produced by man. This pro-perty makes a drainage basin an integrator and its operation is reflected in the quantity and quality of the river run-off.
A healthy catchment is one that is still able to function as a catchment should. It should be able to filter and clean water as it flows overland and seeps through the ground, and there should be lots of opportunities for water to seep into the ground so that it can be used by plants.very inch of land on the Earth forms part of a catchment. Catchments can range greatly in size from small urban sub-catchments such as Prospect Creek that feeds part of the larger Georges River Catchment, to massive catchments such as the Murray-Darling Basin that spans three states.