Study On Time Response Relationship Between Soil Erosion And Algae Bloom In Lake Taihu Basin

Agricultural non-point source pollution is one of the important pollution sources of lake eutrophication. The influence of the non-point source pollution on water quality is not instantaneous, but needs a process. The predecessors did not conduct in-depth research and discussion of the time effect for the impact of non-point source pollution on water quality, and making clear about the time effect on the impact of non-point source pollution on water quality is useful for the basin management, and provides the theory basis for the division of the bringing areas. Therefore, study on the time response of the relationship between non-point source pollution and water quality has positively practical significance.Soil erosion is the critical factor of agricultural non-point pollution and algae blooms is the main form of lake eutrophication. The study on the relationship between soil erosion and algae bloom is of great significance. In this article, linear fitting was used to model the correlation of soil erosion and algae blooms in three study areas within 40km zone, such as Meiliang Bay, Zhushan Bay and the West Coast area. We analyze the time response relationship of soil erosion and algae bloom in three study areas from 2000 to 2012 based on the decision coefficient.The results show that, in Taihu basin, the effect of soil erosion on algae bloom exist hysteresis and the lag time is one quarter. What’s more the impact of soil erosion amount on algae blooms is more significant in Meiliang and Zhushan Bay than the West coast Area, mainly embodied in the following:(1) The character of delay was different in various buffer zones. Meiliang and Zhushan Bay had a more significant delay character than West Coast Area which was the result of joint action of land use pattern, terrain and density of river. It mainly reflected the leading role of forest land in lkm buffer and the joint action of all the factors in 10-40km buffer zones.(2) The lag character only reflected in larger buffer zones if the study area had no cushion buffer just like the forest land along lake shore in Meiliang and Zhushan Bay. Such as West Coast Area, the delay character only reflected in 20-40km buffer zones and the lag time was 1-2 quarters.(3) The effect of forest buffer zones is more significant than any other factors. The hysteresis of the effect of soil erosion on algae bloom in Meiliang and Zhushan Bay is more obvious than the West Coast Area which is the results of the forest buffer zones. And the West Coast Area is dominated by slope and elevation as there is no forest buffer zone.