Acknowledgements

This study was partly done while at the Institute of Hydrology and Water Resources of Tsinghua University in cooperation with the Akesu River Administrative Agency, and was funded by the World Bank. The authors would like to express their acknowledgement to all the scientists involved in the field work especially to Prof. Lei, Zhidong and Prof. Yang, Shixiu of the Tsinghua University. This work was also supported in part by the Japanese Ministry of Education Science Sports and Culture (Monbusho).