Estimation of available water resources and potential irrigation land area in Asia

At present, one-half of the world's population lives in Asia. The population in Asia is expected to grow continuously. It is feared that water resources would become scarce. Will the Asian farmers always have sufficient water to cultivate rice? Focusing on rice-cropping zones in Asia, available water resources for cultivating rice in a typical rice-cropping season were calculated. The potential irrigation land area under the present climatic conditions was also evaluated. It was found that water resources in Southeast Asia are abundant in the first rice-cropping season but not in the second rice-cropping season, and those in South Asia are scarce. It would be necessary to efficiently utilize the water resources for rice cropping in these regions by establishing an effective irrigation system. The potential irrigation area for each major river basin is larger than the irrigated cropland area. Most potential irrigation areas are also larger than the agricultural land area. The river basins of Ganges, Amur and Huanghe have scarce water resources. Thus, the use of these water resources must be made efficient for sustainable agriculture.