Application of PCSWMM to Explore Possible Climate Change Impacts on Surface Flooding in a Peri-Urban Area of Pathumthani, Thailand

Under climate change scenarios, many urban areas in Southeast Asia may become increasingly susceptible to localized flooding due to greater rainfall extremes. This study focused on Rattanakosin Village, Thailand, a peri-urban area near Bangkok. Rainfall data from Don Mueang International Airport showed 2000 was similar to the 30 y norm, 1980-2011, and therefore was used as the baseline against which climate change scenarios were compared. PCSWMM, run at hourly increments with the 2000 rainfall, suggested 11 nodes in the village would flood for > 24 h, with an annual flood volume of 367 200 000 L. The hourly synthetic rainfall time series for this area, generated by linking the ECHAM4 General Circulation Model with the PRECIS Regional Climate Model under the IPCC emission scenario B2, were run through PCSWMM for the years 2021, 2016, and 2091. PCSWMM results showed the number of nodes flooded for > 24 h increased by 3 over the base case scenario and annual flood volume progressively increased from 370 554 000 L to 483 060 000 L between 2021 and 2091. The annual flood volume in 2091 was similar to that generated by simply increasing the 2000 rainfall by between 10% and 20%. Increases in evaporation also were explored using PCSWMM, but compared to the changes in rainfall, evaporation had a smaller impact.