Table of Contents
Water shedding Definition
A region from which rainwater runoff is collected and drained is a watershed in environmental science. In the same way, it might refer to a drainage basin or a catchment area. A watershed might be as tiny as a few hectares in the case of small ponds or as large as hundreds of square kilometres in the case of rivers. Every watershed may be broken down into smaller sub-watersheds.
A watershed has physical-biological characteristics and socio-economic and political characteristics, all of which must be considered throughout the planning and management process.
Water shedding reasons
In this particular case, what we will be discussing is what applies to specific points in watersheds. These points are called impervious or pervious areas, where precipitation can not penetrate the ground and move through them. This can either be cement surfaces or soil that does not allow water to pass through it quickly.
Water shedding occurs when surface runoff would have been if there were no waterproof cover collects on these types of surfaces and starts to flow down a slope within a channel at high speeds until eventually coming to a slower moving area where it pools together and creates what is called overland flow.
Water shedding effect
- Water shedding can have many adverse effects if not controlled or thought about what they are. Including what is commonly referred to as urban flooding or, more scientifically known as “sheet flood.” This occurs when the rate of rainfall on impervious surfaces exceeds what can be absorbed by soils and vegetation at low elevations, thus creating surface runoff that moves downhill without dissipating into the ground.
- Along with this, you will also notice what is called reduced infiltration, which results in more water flowing out of storm drains than entering through streets (typically during high-intensity rain events). The result of decreased infiltration combined with high-intensity rain events often causes stream channel erosion, causing loss of soil volume and sediment clogging waterways, causing reduced channel storage, which can lead to reduced channel storage, what is called flooding.
- What typically happens next is what is known as “Urban Flooding Underflow Events,” where water backs up on these impervious surfaces, and what you end up having is what flows down the streets into waterways that flow downstream. This then increases the load on commonly sub-watersheds that have already reached their overflow capacity by rainfall alone.
Water shedding solutions
This problem of what happens within watersheds has many solutions, but they all depend on its current management. Some examples include increasing infiltration with porous surfaces, removing the waterproof cover in particular areas, possibly expanding waterways, or changing them completely to allow faster passage of what is called peak flows instead of what they currently do, which is what is known as slow release.
One thing to remember about all of this is what happens over the long term with constant urbanization where watersheds are being built upon and soils that have previously been able to absorb what are now impervious surfaces. This leads to rainfall events with higher intensity storms causing flash floods because there isn’t enough room in these areas to contain what would otherwise be absorbed by soil if an impervious surface did not cover it.
The impacts mentioned here can be limiting, especially for those who think that having a small or medium-sized impervious cover will not create any problems. This happens when what is known as “Common Property Externalities” occur, which means that their effects can affect those who aren’t even involved in what caused what to happen.
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