Reservoirs

A reservoir is an impoundment located on the main channel network of a watershed. No distinction is made between naturally-occurring and man-made structures. The features of an impoundment are shown in Figure 8:1.1.

Figure 8:1.1: Components of a reservoir with flood water detention features (After Ward and Elliot, 1995).

The water balance for a reservoir is:

$V=V_{stored}+V_{flowin}-V_{flowout}+V_{pcp}-V_{evap}-V_{seep}$ 8:1.1.1

where $V$ is the volume of water in the impoundment at the end of the day (m$^3$ H$_2$O), $V_{stored}$ is the volume of water stored in the water body at the beginning of the day (m$^3$ H$_2$O), $V_{flowin}$ is the volume of water entering the water body during the day (m$^3$ H$_2$O), $V_{flowout}$ is the volume of water flowing out of the water body during the day (m$^3$ H$_2$O), $V_{pcp}$ is the volume of precipitation falling on the water body during the day (m$^3$ H$_2$O), $V_{evap}$ is the volume of water removed from the water body by evaporation during the day (m$^3$ H$_2$O), and $V_{seep}$ is the volume of water lost from the water body by seepage (m$^3$ H$_2$O).