Question

The changes in hydrology indicators caused by increase in watershed impervious cover include (check all that apply): Increased frequency of bankfull flows Less predictable flows Increased baseflow Decreased peak discharge Increased volume runoff

Answer 1

Impervious cover in a watershed reduces the amount of water that can infiltrate the subsurface and flow as ground water. Thus, lesser water is recharged as groundwater, and more and more ends up as surface runoff.

This increasing surface runoff leads to an increased volume of runoff. Since lesser water enters as subsurface recharge, the increased runoff needs more place to flow, which can lead to new stream flows depending on the amount of runoff collecting at different paths. These paths need to be studied using scientific methods, and are generally less predictable flows Since more runoff ends up in the stream, there is an increased frequency of bankfull flows, as well as an increased baseflow.