Impact Of Environmental Change On Water Environmental And Hydrological

Nanjing is an important gateway to promote the economic development of central and western regions,sustainable utilization of water resource has a magnificent meaning on economic development.Qinhuai River is facing a series of water problems such as the deterioration of water environment,river shrinking,flood disaster and so on,driven by rapid economic development and global climate change.Hydrological model is an effective tool to predict the impact of climate change and land use change on hydrology and water resources.While it is hard to construct watershed hydrological model due to two outlets(bifurcation-a split in the flow in a channel)in Qinhuai river.Considering regional characteristics and watershed water problems,This paper use multivariate statistical method to determine characteristic of runoff,water pollution,land use,temperature,precipitation,construct CLUE-S model and SDSM model to predict future land use and climate respectively,and then establish SWAT model to study the impact of urbanization and climate change on runoff and water pollution.For a start,multivariate statistical method was used to determine the characteristic of runoff and water pollution.Owing to water flushing and washing from Yangtze during non-flood period and flood diversion of Qinhuaixin river,seasonal runoff in wudingmen station showed increase trend,especially in non-flood period.while TN?NH4+-N?TP?CODcr?CODMN were the main pollutants;on temporal scales,water quality in 2011-2014 is better than that in 2000-2010,but which is still worse than that in 1990-2000;In spatial terms,cluster analysis showed that high,middle,light polluted areas are concentrated in Geqiao,Shangfangmenqiao,Chenjiabaqiao respectively;the main cause of water quality deterioration are non-point source pollution,industrial wastewater discharge,domestic sewage emissions,etc.Moreover,CLUE-S model was constructed to predict future land use after the analysis of land use change.This study indicated that the increasing geographical areas of built-up land were the conversions of decreasing cropland areas.Economic development,population growth are the main forces of land use changes.Compared to S2 scenario,owing to consider land demand of basic farmland and environment protection,the expansion of township under S2 scenario are much more reasonable.land use under S2 scenario is more in line with the requirements of sponge city construction.Newly,watershed model were established to disscuss the characteristic of hydrology and water environment in different situations.In view of two outlets in watershed,water inlet was considered after water gate generalization.And then hydrological and non-point source pollution model was constructed to assesst the impact of environmental change on runoff and non-point pollution.Urbanization could increase streamflow volumes and non-point source pollution.Climate change could increase streamflow volumes,while that could decrease non-point source pollution.If both of them were to be changed,these change could increase streamflow volumes and non-point source pollution.And the amount of increase were greater than that were considered respectively.The impacts of climate change on streamflow may outweigh those from urbanization,while consequences of urbanization may outweigh those from climate change for nonpoint pollution by comparing the scenarios.Finally,the coupling model of SWAT model,land use forecasting model,climate prediction model were used to assess the impact of future environmental change on runoff and non-point source pollution.Coupling model result showed that streamflow and non-point source pollution are still increase under future land use scenarios,while the increase of streamflow and non-point source pollution under S2 scenario are much more reasonable than that under S1 scenario.Future climate change also could increase streamflow volumes and decrease non-point source pollution.The change of runoff and water quality would be amplified when both climate and land use changes were simultaneously considered.Urbanization is the main reason for the increase of streamflow and the deterioration of water quality in the future.Watershed protection measures in response to changing environment were put forward,so as to promote the coordinated development of water resources,water environment and water ecology.