Question

Why do we need to build large dams? List four reasons. What are their demerits?

Answer 1

for generating hydro electricity
first irrigation purpose
for water supply
to prevent from flood




demerits
surface run off
it affects aquatic life
earthquake
danger of flood after breaking
hope it helps you

Answer 2

Hello friend;

Dams are built for multipurpose projects, which serve for:
1. Fishing
2. Irrigation
3. Flood control.
4. Generation of hydroelectricity.

Demerits of dams:
1. They use up a lot of space which could be used for agriculture.
2. They affect ecosystem.
3. They harm the marine animals.
4. When there is a rain of high intensity, water from dam is released which leads to more flood.