7.8C Impact of Human Activity on Watersheds

crops are grown for animals as well as humans.

farms are situated on the sides of mountains.

an extended drought leads to little or no rain.

the growing season of the crops is longer.

clogging narrow streams and preventing water from flowing properly.

increasing the amount of nutrients available to fish in lakes and streams.

causing rapid algal growth that decrease oxygen levels and choke aquatic life.

raising the water level in nearby rivers to levels leading to flooding.

These chemicals are expensive to produce.

Runoff carries these chemicals into lakes and streams.

Storage space for these chemicals is limited.

Theses chemicals cannot be purchased in large bulk.

Local pond life

Rainfall rates

Direction of river flow

Available space for crops

Heavy rains caused oversaturation of soil foundations.

Overbuilding in the area polluted the ground water.

Runoff from fertilized land created a dead zone. Excessive removal of water weakened the ground.

Excessive removal of water weakened the ground.