Multi-scale drought risk analysis of rainfed lowland rice environments
2000
Kam, S.P. | Hossain, M. | Tuong, T.P. | Bouman, B.A.M. | Fajardo, S.D. | Rala, A.B. | Banik, P. (International Rice Research Inst., Los Banos, Laguna (Philippines))
The paper describes approaches and methodologies developed for characterizing drought in Asia at continental scale, and at regional scale for rainfed lowland rice areas in two plateau regions in South and Southeast Asia. At continental scale, GIS techniques were applied to analyze the extent and severity of drought risk within predominantly susceptible rainfed rice environments, i.e. shallow rainfed lowland rice and upland rice. Gridded climatic surfaces of monthly moisture availability index based on least assured rainfall at 75% probability were used to determine the humid period during the main rice growing season. The resulting gridded surface of drought severity was cross-tabulated with province-level estimates of percentage area of susceptible rainfed rice. At regional scale, a model that takes into account climatic factors (rainfall and Penman reference evaporation) and soil hydraulic factors (threshold soil moisture content and percolation) was developed to stimulate weekly rice field water storage (i.e. soil moisture content in the root zone plus ponded water). This analysis was carried out for the Korat Plateau of Northeast Thailand and the Bihar Plateau of Eastern India. For each site, a "typical" soil type was assumed throughout the region. The simulated water storage surfaces reflect the climatic influence on spatial variability in available water for rice
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