Development of a System for Evaluation of the Effects of Adaptation Strategies in a Catchment Ecosystem ---Taking the Hanjiang River Basin as an example---
An integrated evaluation system for water and material cycles in a catchment ecosystem has been developed to detect the vulnerabilities in water cycles (e.g. water shortages and floods) and material cycles (e.g. water pollution) caused by changes in climate, land use, and industries, and to evaluate effects of adaptation strategies (e.g. SNWD: the South-to-North Water Diversion and RFCL: the Reforestation of degraded Cultivated Land Initiative) on water resources and water qualities. As a case study, the nitrogen and phosphorus dynamics were evaluated in the Hanjiang River basin, the largest tributaries of the Changjiang River. The simulation results show that SNWD (in the case that 10 billion m3 of water were transferred) would cause an obvious decrease in both the river discharge (-35.2%, P<0.01) and the total sediment loading (-37.9%, P<0.01) significantly. However, SNWD would greatly increase the concentration of water pollutants, such as NH4-N (45.7%, P<0.01) and T-P (29.4%, P<0.01). The simulation results also show that RFCL (in the case that cultivated lands with a slop larger than 15 degree were reforested) would cause a slight decrease of the total water yield (-4.4%), but the decrease in total sediment loading is substantial (-56.2%, P<0.01). RFCL would greatly decrease the organic N (-42.6%, P<0.01), NO3 yield in surface flow (-37.1%, P<0.01), and sub-surface flow (-25.5%, P<0.01), as well as the loads of phosphorus to decrease.
catchment ecosystem vulnerabilities in water cycles adaptation strategies the South-to-North Water Diversion (SNWD) and the Reforestation of degraded Cultivated Land Initiative (RFCL)
Qinxue Wang Qingan Xiao Chen Liu Kelin Wang Min Ye
Center for Regional Environmental Research, National Institute for Environmental Studies, Tsukuba, J Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China Changjiang Water Resources Protection Institute, Changjiang Water Resources Commission, Wuhan, China