| Wusu city is located in the economic belt of the north slope of Tianshan Mountains,with a total area of about 14,388 km2.Kuitun River,Sikeshu River and Guertu River originate from the foot of Tianshan Mountains,providing favorable conditions for regional water resources utilization.The development and utilization of groundwater is also extensive,mainly for agricultural irrigation.Over the past 10 years,the area of cultivated land and the amount of groundwater extracted have shown an overall upward trend,leading to problems such as the decline of the groundwater table and over-exploitation.In this paper,the dynamic change of groundwater depth and the driving factors of human activities were analyzed,and the quantity of groundwater resources,hydrochemical characteristics and their changing trend in different periods were defined,and the numerical model of groundwater flow in the research area was established by using numerical simulation software(Processing MODFLOW)to simulate the dynamic changes of groundwater level under different conditions.The main research conclusions are as follows:(1)The dynamic change of groundwater level is influenced by human activities.The annual data of the monitoring well showed that during the peak period of agricultural irrigation water consumption from April to October each year,the water level varied widely,basically above 10m.The annual variation data showed that the change rate was between-0.85?-1.71 m/a,and the water level was decreasing as a whole.Changes in land use area,irrigation water volume and irrigation method affected the groundwater level.From 2008 to 2017,the land use area increased from 66.4×103 hm2 to 142.83×103 hm2,an increase of 2.2 times,and the amount of groundwater extraction increased from 1.33×108 m3 to 3.24×108 tn3.Based on the analysis of grey correlation degree,the main driving factors of the dynamic changes of groundwater level in this region were the reduction of surface water and the increase of groundwater exploitation.(2)The dynamics process of groundwater level in Wusu city is an objective index of the variation of groundwater resources.According to the calculation of groundwater equalization method,the total recharge of groundwater resources was 5.5016×108 m3/a,the total discharge was 6.2379×108 m3/a and the equilibrium difference was-0.7363×108 m3/a.Based on the Comparing the amount of groundwater resources in the study area in 1998,2011,and 2014 with the results of this calculation,the results showed that the groundwater was in negative equilibrium,and the amount of groundwater resources was decreasing during the water level decline.(3)Through the sample data,the chemical types of phreatic water in the study area was SO4·Cl-Na and Cl-Na,the potential of hydrogen(pH),total hardness(TH),total dissolved solids(TDS),K++Na+,Cland SO42-exceeding the standard are more in the diving samples,the phreatic water with salinity greater than 1 g/L was mainly distributed near the groundwater overflow zone and in the northern mass farm,and the water quality was relatively poor.The hydrochemical type of confined groundwater was HCO3·SO4-Ca water with few samples exceeding the standard,the water quality was generally good,which can be used as domestic and irrigation water.By comparing the water quality evaluation results in 1998,2011 and 2018,the hydrochemical characteristics and salinity of the study area have not changed significantly.(4)The change of water level in 2025 and 2030 is predicted by the establishment of the numerical model.If Wusu city continues to exploit groundwater with the current exploitation amount the groundwater balance difference will gradually expand in the medium and long term,and the area of buried depth within 20 meters will be reduced,so the groundwater will inevitably develop to the deep buried depth.When groundwater is developed under the control of total water consumption,the equilibrium balance of groundwater changes from negative to positive in the medium and long term,the area of shallow buried depth will increase,and the water level will rise gradually,which can achieve the control effect,the groundwater resources gradually will increase in 2025 and 2030 gradually,the area of shallow buried depth within 0?2 meters are 320.72 km2 and 510.14 km2,respectively,providing guarantee for water level recovery.For the problem of salinization caused by the significant rise of water level after treatment,the exploitable amount is selected as the index to simulate,the area of shallow buried depth within 0?2 meters are 320.72 km2 and 510.14 km2,respectively,it can reduce the risk of soil salinization. |
PDF Full Text Request