陕西渭河下游湿地环境风险因素分析

运用统计计算和RS/G IS方法,分析渭河下游湿地环境的水文特性、水污染特征、土地利用/覆被状况及其演变特征等湿地环境风险因素,结论为:①渭河下游水沙量年际变化大、年内水沙量分配不均,且呈现减少趋势;汛期黄河洪水倒灌渭河,降低了由于水沙供给变化而导致的湿地水文环境风险度;②湿地水环境日趋恶化的变化趋势降低了湿地的生态净化功能,增加了湿地水环境风险度;③1989~2000年渭河下游新增湿地12.76km²,年均增长率2.70%;湿地裸地化和盐碱化形势严峻;④以加强湿地保护立法、完善流域水污染治理、重建河岸植被带、强化湿地管理等重点措施确保湿地环境安全和湿地资源的可持续利用。

Analysis on Environmental Risk of Wetland along the Lower Weihe River

By statistical computation and RS/GIS method,the environmental risk factors,including hydrological characteristics of wetland,water pollution,land-use/cover and their evolution in lower reaches of the Weihe River,were analyzed.The results are as follows.(1) The quantities of the water and sand are changing dramatically in recent years,and their distribution with the decreasing tendency are not even.In flood season water from the Yellow River flows backward to the Weihe River,which relieves the threat resulted from the decreasing of water and sand supply,and reduces the risk for wetland brought by the changing mentioned above.(2) The degeneration of the hydrological environment of wetland lowers its purification capability,and increases its hydrological environment risk.(3) From 1989 to 2000,in the lower reaches of the Weihe River,the area of the wetland increasesd 12.96 km2 with an annual increase rate of 2.7%,and there were 2.002km2 and 0.94km2 of wetland become bare and saline land,respectively.In addition,0.03 km2 wetland was occupied by urban construction.(4) By some measures,such as strengthening lawmaking,fathering water pollution,reconstructing vegetation and enhancing management,environment safety and resources sustainable use will be come tuer.