Question

Consider a 5.5km^2 catchment which contains a wetland with an area of 1.9km^2 situated at the catchment outlet (see figure). The wetland area receives 65ML/yr of effluent and discharges 120ML/yr in environmental flows. The mean annual rainfall is 980mm, the mean annual potential evaporation rate is 1210mm. Estimate the runoff coefficient for the catchment area surrounding the wetland area using a steady state water balance. Provide your answer acurate to 2 decimal place

I GOT 253 but the answer is 0.14. And i dont know what im doing wrong.

Answer 1

Mean annual potential evaporation rate = 1210mm = 0.21 Mean annual rainfall = 980mm = 0.98m Catchment area = 5.5 km² = 5.5x100m Wetland area = 1.9 km = 1.9x108m Wetland area inflow = 65 Milyr = 65x103 m² yo Wetland outflow = 120mclyn = 120x103 m3lyr. We have, change in volume = precepitation - Evaporation + Surface in flows - Surface outlows. = 0.98 - 6-1-21 #(65 x103) 11.8x106 1.8x106 4665x103) 120x10 120 06 = 0.98-1:21+ [-0.9305) - 0495m. - 0.2605m = -490.5 mm -260.5mm Here negative indicate the runoff ie outflowe

Runoff Coefficient = Amount of runoff ISFPF Amount of precipitation = 260.5 980 = 0.2651