Study On The Impact Of Non-point Source Pollution Load On Eutrophication Of Qiaoqiao Reservoir

Models have been proved to be effective tools for identifying major environmental objectives,especially in regard to the watershed management of agricultural non-point source pollution.The GWLF model results suggest that:the model is relatively simple,with fewer parameters,and the required input data is small and easy to get.The Regional Nutrient Management(ReNuMa)model was employed to interpret the main environmental problem(nitrogen contamination)generated within Yuqiao Reservoir Watershed.This study selected the Shahe Watershed to calibrate the model parameter,which was a sub basin in Yuqiao Reservoir Watershed.The Nash-Sutcliffe efficiency of the calibration and validation in Shahe Watersherd about the runoff,dissolved total nitrogen and dissolved total phosphorus were 0.83,0.86;0.65,0.64;0.53,0.46,respectively.The result in Yuqiao Watersherd indicated that the nonpoint source pollution had the highest ratio of the annual average DN load accounted for 81.6%,and average DP load accounted for 82.6%.Among all the land uses,farmands contributed most to DN load in Yuqiao watershed,indicating that human dominated agricultural activities were the major contributor of nonpoint source pollution.Besides,seasonal differences of the contribution ratio from DN and DP pollution source were significant.Runoff was the major pollution source in wet season;however,septic system and point source were more significant in dry season.In order to efficiently reduce and control nitrogen pollution in Yuqaio Watershed,it is necessary to consider the difference of pollution source constitution between wet season and dry season in the formulation of pollution reduction plan and control measures preference.The result in all Yuqiao Reservoir Watershed was showed that Luanhe-Tianjin Water Diversion Project had the highest ratio of the DN load accounted for 58.2%,and DN load accounted for 45.2%.And Shahe,Lihe and Linhe Watersherd of DN and DP load accounted for 23.4%and 29.2%.Then the multivariate statistical software PRIMER was further used to study phytoplankton community structure and its relations to environmental factors in the paper.It mainly refer to correlationtes test(RELATE)and biota-envionment stepwise analysis(BIO-ENV)in PRIMER software to study the relationship between nutrients and phytoplankton community.The result suggested that the most influencing environment factor were DP,COND and DN.So the non-point source pollution load nitrogen and phosphorus was an important factor affecting eutrophication of Yuqiao reservoir.The results showed that the non-point source pollution load of nitrogen and phosphorus had obvious effect on the eutrophication of Qiaqiao reservoir,and the risk of water bloom occurred in the wet season from July to September each year should be paid more attention and countermeasures were put forward.