Assessment of Cross-Sectoral Damage from Water Deficits under Changing Climate and Regional Development in Nan River Basin, Thailand

摘要

Nan River Basin contributes about 25 to 40 percent of annual flows in the Lower Chao Phraya River Basin, Thailand. Land use and climate change result in change in meteorological and hydrological conditions in Nan River Basin. In addition, water demand in the basin has been increasing from the economic development. Understanding cross-sectoral interactions from both water resources and economic points of view provides better insight in planning and management. This study proposes an integrated framework of hydrological and economic analysis to assess impacts of water deficits under changing climate and regional development. The objectives of the study are to analyze water supply under climate change scenarios, estimate water demand under economic development scenarios, and assess cross-sectoral impacts of water deficits. A Rainfall-Runoff model, Integrated Flood Analysis System (IFAS), was calibrated, verified, and used to simulate runoff. Regional Input-Output Model was developed for Nan River Basin to assess economic impacts of water deficits. Analysis of water deficits under climate change scenarios and economic development scenarios was carried out during the period of 2040-2059. Runoff simulations under climate change scenarios using two GCMs, IPSL-CM5A-MR and MIROC5 under RCP4.5 and RCP8.5 showed increasing trend. Water demand projections of all sectors also showed increasing trend especially in agricultural sector. The uncertainty of water supply under the climate change scenarios is found to be relatively small compare to the uncertainty of water demand under the economic development scenarios. Assessment of indirect economic loss from cross-sectoral analysis is found to be two to three times higher than the direct loss. The results demonstrate the need to consider the indirect economic loss across sectors inwater allocation planning and water deficit mitigation policy.