Assessing Climate Change Impacts on River Flows in the Tonle Sap Lake Basin, Cambodia

Chantha Oeurng,Mathias Kondolf,Mauricio Arias,Thanapon Piman,Sarit Chung,Thomas Cochrane

doi:10.3390/w11030618

Abstract

The Tonle Sap is the most fertile and diverse freshwater ecosystem in Southeast Asia, receiving nurturing water flows from the Mekong and its immediate basin. In addition to rapid development in the Tonle Sap basin, climate change may threaten natural flow patterns that sustain its diversity. The impacts of climate change on river flows in 11 sub-basins contributing to the Tonle Sap Lake were assessed using the Soil and Water Assessment Tool (SWAT) model to quantify the potential magnitude of future hydrological alterations. Projected river flows from three General Circulation Models (GFDL-CM3, GISS-E2-R-CC and IPSL-CM5A-MR) for three time horizons (2030s, 2060s and 2090s) indicate a likely decrease in both the wet and dry season flows. The mean annual projected flow reductions range from 9 to 29%, 10 to 35% and 7 to 41% for the 2030s, 2060s and 2090s projections, respectively. Moreover, a decrease in extreme river flows (Q5 and Q95) was also found, which implies there could be a decline in flood magnitudes and an increase in drought occurrences throughout the basin. The results of this study provide insight for water resources planning and adaptation strategies for the river ecosystems during the dry season, when water flows are projected to decrease.

Highlights

Climate change is an important part of the challenges of sustainable development in developing countries
The Tonle Sap Lake Basin consists of the Tonle Sap Lake and 11 major tributaries, with a total catchment area of 86,000 km2 (Figure 1a)
These results indicate that overall, future flood magnitudes would withdrawals for irrigation and urban water supply were not included in the model, and these are be reduced for all sub-basins under the GISS scenario over the majority of time horizons, and that increasing, so that will likely have a much and greater effect in the

Summary

Introduction

Climate change is an important part of the challenges of sustainable development in developing countries. Climate change represents one of the greatest environmental, social and economic threats facing the world today [1]. Future changes in river flow and watershed hydrology that are caused by one of the drivers such as climate change, have become increasingly important topics for water resource management. Developing countries are faced with immediate concerns that relate to land degradation, freshwater shortages, food security, and air and water pollution. Climate change will exacerbate these concerns, leading to further water shortages, land degradation and desertification [1]. Across Southeast Asia, the mean annual temperature by the end of the 21st century is expected to rise from 0.8 ◦ C in the lowest emissions scenario to 3.2 ◦ C in the highest emissions scenario, while a moderate increase in precipitation is projected for this region, from 1% to 8% by 2100 [2]

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