Water Resource Exploitation of the Mekong River Basin and the Influences on the Inland Fisheries of Cambodia

摘要

Inland fisheries in the Tonlesap Lake of Cambodia play an essential role in providing with protein and cash income to the poor around the lake. However, the fisheries face a crisis of fish resource depletion due to excessive catch, water pollution and decline in the water level of the Lake. We analyzed the relation of fish catch amounts with the maximum water level in the rainy season and the fish catch in the past, and found that 1% decrease in the water level reduces the catch amounts by 1.25%.What water level can be predicted for the future? To answer this question, we made two models; the one is the water demand-supply model by industry and the other is the water cycle model for the Mekong basin. Depending on various scenarios on the economic development and hydropower dam construction, the reduction in the maximum water level of the Lake would be around 4%, which would lead to a decline in the catch amounts by 5%. In addition to these water quantity issues, we have to consider the inflow of nutrition for which dam constructions would prevent, as well as water pollution of the lake and the excessive catch. Therefore, our estimation on the amount of fish catch reduction in the future is regarded as the conservative minimum one, and the actual catch reduction would be more severe and harmful for livelihoods of the people around the Lake.