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. 558 pages on this wiki. A drainage basin is the area within the drainage basin divide (yellow outline), and drains the surface runoff and river discharge (blue lines) of a contiguous area.rainage basin. 558 pages on this wiki. A drainage basin is the area within the drainage basin divide (yellow outline), and drains the surface runoff and river discharge (blue lines) of a contiguous area.
The word watershed is sometimes used interchangeably with drainage basin or catchment. Ridges and hills that separate two watersheds are called the drainage divide. The watershed consists of surface water--lakes, streams, reservoirs, and wetlands--and all the underlying ground water.atersheds are important because the streamflow and the water quality of a river are affected by things, human-induced or not, happening in the land area above the river-outflow point.