Simulation of Extreme Flood and Inundation in 2011 in the Upper Ping River Basin, Thailand

Abstract

Large floods occurred frequently in the upper Ping River basin and their potential damages are increasing due to the growth of cities and economical activities. Therefore, the information for flood protection is needed to reduce the damages, especially for city areas. This study attempts to establish a model to simulate flood and inundation against extreme rainfalls in the upper Ping River basin in Thailand for analyzing causal factors of inundation and proposing countermeasures. CASC2D model, a two dimensional hydrologic model was applied for this purpose. The model was calibrated and verified with flood discharge and inundated areas observed during the devastating floods in 2011. The simulation results were evaluated using two indices: Nash-Sutcliffe efficiency (NSE) and coefficient of determination (r 2) to show acceptable model performance. The model performance of inundated areas was improved by modifying topographic conditions. It showed predicted areas of local inundation along rivers and in the agricultural fields after storm events.

Flood Inundation Mapping and Hazard Assessment for Mitigation Analysis of Local Adaption Measures in Upper Ping River Basin, Thailand

“…Upper Ping River basin, a sub-region of Chao Phraya basin located in north of Thailand is home to about ~11.5 million population, rice dominated region with a high economic growth rate. Large fraction of population (~90%) in the basin lives in rural areas and exposed to river flooding due to storage of flood water in rice fields (UN 2003;Reda et al 2012;Komsai et al 2016). The flooding in Ping basin is associated to heavy monsoon rainfall, tropical storms, typhoons, and land-use changes (Wood and Ziegler 2008;Gale and Saunders 2013;Komsai et al 2016;Takata and Hanasaki 2020).…”

“…Large fraction of population (~90%) in the basin lives in rural areas and exposed to river flooding due to storage of flood water in rice fields (UN 2003;Reda et al 2012;Komsai et al 2016). The flooding in Ping basin is associated to heavy monsoon rainfall, tropical storms, typhoons, and land-use changes (Wood and Ziegler 2008;Gale and Saunders 2013;Komsai et al 2016;Takata and Hanasaki 2020). Available literature on climate change assessment in the basin though very limited, reports significant increase in temperature extremes and insignificant decrease in mean and extreme precipitation in the basin (Sharma and Babel 2013;Masud et al 2016;Saengsawang et al 2017).…”

“…Available literature on climate change assessment in the basin though very limited, reports significant increase in temperature extremes and insignificant decrease in mean and extreme precipitation in the basin (Sharma and Babel 2013;Masud et al 2016;Saengsawang et al 2017). Several other studies on floods highlight the occurrence of extreme events in past in 1994, 1995, 1996, 2001, 2003, 2005, and 2011 (Wood and Ziegler 2008;Gale and Saunders 2013;Komsai et al 2016). For example, the 2011 flood in Thailand caused heavy damage to agriculture, transport, fishery, tourism and industry.…”

“…Synthesis of the literature available on flood hazard mapping and evaluation of mitigation options in Ping River basin reveals a major drawback. The scope of almost all the studies was limited to assess flood characteristics using simple rainfall-runoff and 1D hydrodynamic models (e.g., Wood and Ziegler 2008;Mapiam and Sriwongsitanon 2009;Sriwongsitanon 2010;Boonrawd and Jothityangkoon 2015;Komsai et al 2016) and no study has yet been conducted for flood hazard mapping at sub-district scale for improvement in potential of locally available mitigation options.…”

Flood inundation mapping and hazard assessment for mitigation analysis of local adaptation measures in Upper Ping River Basin, Thailand

“…Annual pluvial and fluvial floods typically happen during the monsoon period in Thailand. They lead to disastrous impacts on people, their properties, government and commercial infrastructures, and socio-economic activities (Gale and Saunders 2013;Jular 2017;Salunkhe et al 2018). Aside from these effects, the floods also disrupt the daily life activities of residents in both rural and urban regions at a significant scale.…”