3.7. Changes in annual water balance
Fig. 9a shows the baseline levels of various components of the
water budget in the watershed. The largest component in the baseline
is potential evapotranspiration, followed by the baseflow. Climate
changes can affect the watershed’s ability to store water for
longer periods as ground water. Soil types have limitations on
the amount of water that can infiltrate the soil with the increase
in rain intensity caused by climate change. This process can be
exacerbated by increased precipitation occurring in intense intervals
or increase in impervious surfaces within the watershed.
Fig. 9 presents the effects of climate change with major increases
in runoff under each of the future scenarios. BMPs such as rain gardens
allow increase in infiltration rate of precipitation. Fig. 9b
shows the percent change from the baseline under near-future scenario.
The flows from impervious surfaces had the greatest reduction
to 3% below the baseline levels with the use of BMPs. In Fig. 9c
under the far-future scenario, BMPs result in a reduction of 6% in
flows from impervious surface.