Evaluation of the Potential Impact of Rainfall Intensity Variation due to Climate Change on Existing Drainage Infrastructure

Abstract

The potential impact of climate change on the existing drainage infrastructure has been an essential aspect of many hydrological studies. Climate change that will increase the intensity of precipitation will also increase the magnitude of the design discharge and thus would probably result in adverse effects on the existing drainage facilities. This paper aims to evaluate the potential impact of rainfall intensity variation due to climate change on the existing drainage infrastructure by investigating whether (1) the stormwater drainage infrastructure designed for preclimate conditions is able to sustain future higher discharges, and (2) new design guidelines are necessary to be established to include the potential rainfall intensity variation due to climate change. A case study was conducted using 34 years of rainfall data (1980–2013) obtained from the National Climatic Data Center (NCDC). These data and the weather scenario data projected by the four run global circulation model (GCMs) under the three emissions scenarios coupled with stochastic weather generator model which generates daily weather time series statistically were used to update the current intensity-duration-frequency curve to reflect the rainfall intensity variation due to climate change. Furthermore, runoff simulation using a storm and sanitary software program was performed to analyze whether the increase in the intensity of rainfall due to climate change would have an adverse impact on the current drainage system to convey excess runoff. The results showed that most elements of the current drainage infrastructure in the boundary of the study area were inadequate to convey excess runoff. However, climate change magnifies the problems that already exist in an aging drainage infrastructure. Furthermore, considering the rehabilitation or replacement rates of these aging infrastructures are relatively slow, emphasis must not lie only on the future climate change, but also on identifying the weak spots in the system coupled with, the economic and environmental factors before any changes in design criteria can be recommended due to climate change.