Influence of Dynamic Properties of Rainfall on Urban Drainage Infrastructure

Abstract

Temporal and spatial variability of rainfalls have a significant impact on the operation of urban drainage systems. Stormwater storage reservoirs are particularly sensitive to these variations. This paper presents the results of research on the impact of the direction and speed of rainfall movement over an urban catchment of total area 560 ha on required volume of the storage tank. Simulations (using SWMM5 software) showed that movement of rainfall cells has a moderate impact on the peak-flows (around 20% increase in comparison to static variant), however, significantly affect the volume of stormwater accumulated in storage tanks. The most unfavorable variant is the rainfall moving in the direction and with velocity close to the general direction and average velocity of stormwater flow in the drainage system. The estimated increase of the unit volume of stored stormwater resulting from the dynamic properties of rainfall is about 6.5 to 8.0 m3 per hectare of impervious surface in comparison to static scenario.