| With the acceleration of urbanization and industrialization,drinking water sources are under various threats.The safety of water quality is closely related to the protection of people’s livelihood and social stability.The protection of drinking water sources has become a hot issue in global research.The most effective way to protect water source areas is zone protection.China has formed a complete legal protection system.In the process of water source protection,the division of protected areas is the most critical step.Before 2007,there was no scientific basis for the division of protected areas,which resulted in the lack of scientific and normative nature of the divided protected areas,and the safety of water quality could not be effectively guaranteed.Therefore,in order to ensure the safety of water quality and maintain social stability,it is urgent to redefine the scope of unscientific water source protection zones.This study takes the water source area of the Tanghe Reservoir as an example,analyzes the problems of the original zoning,investigates the sources of pollution and risks,and systematically analyzes the hydrological status of water quality.Based on the emergency time response method,EFDC numerical simulation software was used to simulate and analyze the Tanghe Reservoir.Finally,the original protected area was adjusted based on the results of the analysis.The results of the investigation and analysis show that the main source of pollution in the water source area of the Tanghe Reservoir comes from the livestock and livestock industry and domestic pollution sources.The water quality of the reservoir area and the rivers in the reservoir is generally good,and only in some months the water quality exceeds the standard.The water body of the reservoir area is in a state of eutrophication for a long time,and the possibility of eutrophication of the water body is small.The cycle of the hydrological flow in and out of the reservoir changes significantly,and the amount of water changes greatly.The calculation grid of Tanghe Reservoir was divided by using the Delft3D model.After adjustment,the main calculation area orthogonality and smoothness meet the requirements.A hydrodynamic-water quality model of the Tanghe Reservoir was constructed using EFDC,and the results were good.The EFDC model simulation results show that the reservoir water age has a spatial distribution difference and a long time.The difference between the typical water ages of about 100 days and the dry water age reaches the longest458 days.The inflow river has a great impact on the water quality of the reservoir in the case of running for 6 months beyond the standard.Almost all of the reservoir areas are polluted in high water years,and the ammonia nitrogen and total phosphorus at the outlets exceed Class II water quality standards by 1.18 and 4.8 times.The emergency time response distance of the inflow river is 3.9km,1.7km and 2.5km.After modelling the sudden accidents at the Xidahe Bridge and Erdaohe Bridge,it was found that the pollution spread rapidly in 0.25 days,and the pollutants began to affect the water quality of the outlet for about 360 days since 94days.After the adjustment of the Tanghe Reservoir water source protection area,the protected areas at all levels are:first-level protected area 39.66km~2,second-level protected area227.18km~2,quasi-protected area 1148.75km~2.Among them,the secondary protected area has the largest change,with a reduction of 211.61km~2,which is almost half of the original protected area.More than 50%of pollution sources and risk sources are transferred to secondary protection areas.Finally,measures to prevent water source risks and strengthen water quality safety are proposed.After adjusting the scope of the Tanghe Reservoir water source protection area.Water source safety guarantee is more effective,and the scope of Tanghe Reservoir can be developed sustainably.Achieved the common success of water quality assurance and regional development. |
