How human activity can lead to flooding in a drainage basin?

Question

i need about 4 points of how human activity can effect flooding i a drainage basin

Answer 1

1. We divert all water straight to a river using drains and gutters, where naturally it would take a lot longer to get to the nearest river therefore the river fills up more than it would naturally

2. We tarmac and concrete everything, therefore limiting the amount of water that can soak into the ground, again going to the nearest river.

3. We cut down forests which allows soil to run off into the river, therefore raising the river bed which can make floods more common.

4. We tend to straighten rivers to help control flooding but further downstream the water suddenly slows down causing flooding.

Answer 2

'Human activity' means lots of people (we tend to cluster together in towns and cities), lots of concrete surfaces, some industrial processes, and a lot of 'utilities' (power supply, food chain, transport services, etc)

Each of these will interact in positive or negative ways, to increase the way water builds up in a particular place, or to make the way water collects there naturally seem like a flood.

You shouldn't have any trouble making four points out of all that information, and you'll probably get better nmarks if you can find images to illustrate each point.

Answer 3

destruction of wetlands that serve the purpose to contain and slowly release floodwaters

An increase of impervious surfaces (roofs, parking lots) results in increased runoff, in many cases into storm sewers. The water is then deposited into the main stream system with less lag time, and peak discharge is increased.

clear-cutting and farming removes the natural vegetation that traps rainwater and reduces infiltration, increasing runoff

channelization, or the process of straightening a stream channel, reduces flooding in the immediate area but can increase it downstream

These are just the few I can remember, though I had to rack my brain to get the fourth, and there are surely more. Plenty of stuff on google will give you more detail.