The Research On Mountain Disasters' Impact On Water Quality In Drought Valley Areas Of Minjiang River's Upper Stream--A Case Study Of Longdong Gou Valley In Mao County

Mountain disasters are a sort of disaster phenomena in mountain areas caused by the combination of many natural elements in the process of special mountain areas' evolvement, which have some bad effects on the activities of human's production and lives, and even the survival conditions of humans.Drought river valley areas in upper stream of Minjiang river have outstanding environmental problems: forest vegetation destroyed badly, frequent severe mountain disasters and eco-environmental destructions. As a result, these factors arouse a series of environmental problems, among which effects on water quality caused by mountain disasters are more remarkable .The paper emphatically discussed the influencing process, approaches and characteristics of the effects on water quality in the valley caused by mountain disasters by means of analyzing the types and characteristics of mountain disasters and the relationship of human's activities and the disasters. The studies take Longdong gou in Mao county as sample researched, belonging the cooperative project "The study on recovery of deterioration of typical ecosystems and rebuild of experimental cases" in China Academy of sciences and Sichuan province.As pollution of water quality aroused by mountain disasters appears inlarge-scale areas and is typical non-point source pollution, the paper presented a new concept, non-point source pollution caused by mountain disasters.The study shows that mountain disasters are not only carriers in the process of polluting water quality in the valley but also pollution sources, for a lot bad chemicals are brought through extreme erosion of water and soil, and a great many sands and solids are also physical pollution for water quality in the valley.The paper took Longdong gou in Mao county as a research sample and make conclusions by analyzing and sampling:1.In the mountain areas where the disasters severely happen, the total salt and the value of ESP in the water commonly can be regard as two important indexes reflecting the degree of mountain fragmentation. In general, when the total .salt is higher, the value of ESP lower, the degree of mountain fragmentation deeper, and the eco-environment worse. So when we control mountain disasters, the two indexes can be taken as a warrant to judge the degree of eco-ertvironment renewal.2.As soon as the mountain disasters happen, water quality have the trend of deterioration, and main indexes of water quality in the valley will be changed, especially the total N and the value of P will evidently rise. This shows mountain disasters have remarkable effects on the degree of the super nutrition of water.