Hydrodynamic modelling for stormwater management for river basin planning: a case study of welipenna river

Abstract

Storm induced flash floods are very common in southern part of Sri Lanka especially in South-Western monsoon. The I situation is more severe in Welipenna River, which faces around five major floods per annum. A model developed by HEC-RAS one dimensional hydrodynamic model with field assessment results and hydrologic analysis results was used to evaluate the stormwater management options. Furthermore, same model was used to assess the probable development scenarios Model results shows that calibration error was 35% and increasing the bridge span by one [ meter can reduce the water surface elevation by 3mm for spans of 50m to 100m.