Study On Delineating Groundwater Source Protection Zones In Sihe Alluvial Fan

As a result of the unreasonable excessive exploitation,the groundwater level around the urban area of Jining has dropped significantly,causing the over-exploited funnel area,and geological disasters of land subsidence have also occurred.At the same time,due to urban development,urban and surrounding areas are undergoing,or have been undergone large-scale construction,so the urban areas of Jining has no potential for reconstructing large-scale water sources.In addition,most existing wells have been already located in urban areas,but with the continuous expansion of the city,the wells can not meet the environmental protection requirements and guarantee the safety of water sources.Therefore,it is necessary to explore new water sources outside of the urban over-exploited area with the most abundant water,the best water quality,and the most favorable water sources protection conditions.In this paper,the groundwater numerical simulation software GMS is used to established the groundwater flow numerical model in the study area based on the simulation period of 2008-2017 years.It based on the existing supplemental data and analyzing the hydrological and geological conditions.The validated model was used to predict the groundwater from 2018 to 2042 and analyze it.The average annual recharge of groundwater in the study area is 9352.32×10~4m~3/a,and the recharge modulus is39.76×10~4m~3/km~2·a.Among them,the largest source of recharge is precipitation recharge,reaching 4434.35×10~4m~3/a,followed by lateral flow recharge,reaching 2844.73×10~4m~3/a;the annual average total excretion in the area is 9361.86×10~4m~3/a,and the main excretion is groundwater exploitation,reaching 4530.67×10~4m~3/a,followed by evaporation,reaching3881.85×10~4m~3/a,and once again lateral outflow,reaching 949.34×10~4m~3/a.During the simulation period,the groundwater level was basic in a state of equilibrium and the consumption of water was minimal.This paper offers three kinds of water source mining plans and uses prediction models to predict groundwater level and storage in the study area.Taking Scheme 3 as an example,the main source of exploitation is the piracy of streams phreatic evaporation(51.92%),followed by capture of lateral outflow(28.55%),and re-induction of lateral inflow(19.53%).All the mining schemes are in accordance with the mining constraints,scheme three has the largest amount of exploitation(25000m~3/d)and determines it is the best mining plan.Using the proposed formula and numerical method to divide the protected area of the proposed water source,it shows that the numerical method is more scientific by compared the division result.Then the final protected area was established:10689 m~2 in the first-grade protection zone,2.56 km~2 in the second-level protection zone,and 5.73 km~2 in the quasi-protection zone.With reference to the newly revised"Technical Guideline for Delineating Source Water Protection Areas"(HJ 338-2018),different management and protection proposals are provided according to the protection level.