| Groundwater overexploitation is a serious problem in the Turpan-Hami Basin,causing a continuous drawdown in groundwater level and causing ecological and environmental problems such as Karez drying up and lake shrinkage.In this paper,some important groundwater indexes of the Turpan-Hami Basin,including the hydrogeological conditions,the groundwater recharge and discharge,the amount of groundwater resources and the extractable amount,the characteristics of groundwater level dynamics are analyzed and evaluated using the groundwater equilibrium method,mathematical statistics,GIS spatial analysis and numerical simulation.The evolution of the Turpan-Hami Basin’s groundwater dynamic field,as well as groundwater recharge and discharge elements,is being studied in depth from 1960 to 2020.Then the reasons for these changes are discussed,and the future trend of groundwater resources is forecasted.This research is extremely important for the rational use of groundwater resources and the management of over-extraction areas in the Turpan-Hami Basin.The following are the main conclusions:(1)In 2020,the total amount of groundwater resources in the Turpan-Hami Basin is 9.65×10~8m~3/a,with the Turpan Basin and the Hami Basin accounting for 6.02×10~8m~3/a and 3.63×10~8m~3/a,respectively.The total amount of extractable groundwater is 6.29×10~8m~3/a,of that which 3.66×10~8m~3/a is found in the Turpan Basin and 2.63×10~8m~3/a is found in the Hami Basin.(2)The groundwater level in the Turpan-Hami Basin continued to fall from 1975 to 2020,and the rate of drawdown was accelerated until 2012,after which it was slowed down by the policy influence.The cumulative drawdown in 45 years is generally 25～50 m,with some areas reaching 60～70 m.The groundwater sink center of the Turpan-Hami Basin has not undergone considerable change in the past 45years,while the groundwater gradient in fine soil plain area has evolved from 4.0‰～7.1‰at the beginning to 2.7‰～4.3‰at present.(3)The groundwater recharge in the Turpan Basin decreased by 56.8%from 15.69×10~8m~3/a in 1980 to6.77×10~8m~3/a in 2020 and the groundwater discharge decreased by 36.3%from 15.66×10~8m~3/a in 1980 to9.97×10~8m~3/a in 2020.The groundwater recharge in the Hami Basin falls from 8.26×10~8m~3/a in 1975 to4.08×10~8m~3/a in 2020 and the groundwater discharge falls from 8.26×10~8m~3/a in 1975 to 5.67×10~8m~3/a in2020,resulting a 50.6%and 36.2%reduction,respectively.The reduction rate of groundwater recharge is greater than that of discharge,and the recharge is always less than the discharge,resulting in a negative equilibrium,which is the true cause of the Turpan-Hami Basin’s continuous drawdown in groundwater level.(4)Since 1975,the groundwater recharge and discharge balance of the Turpan-Hami Basin has been decreasing,and the decay rate has been accelerating and then decelerating,with a total consumption of groundwater storage of 174.39×10~8m~3 in 45 years,including 99.21×10~8m~3 in the Turpan Basin and75.18×10~8m~3 in the Hami Basin.(5)According to the regional water resources plan,the Turpan-Hami Basin receives a total of4.00×10~8m~3/a of external water sources,of which 2.67×10~8m~3/a is allocated to replace groundwater sources in the Turpan Basin,reducing annual groundwater extraction to 4.05×10~8m~3/a;1.33×10~8m~3/a is allocated to replace groundwater sources in the Hami Basin,reducing annual groundwater extraction to 2.88×10~8m~3/a.The overall groundwater level in the Turpan-Hami Basin is expected to remain stable until 2041,according to simulation projections.The substitution of external water sources for groundwater extraction not only reverses the trend of continuous groundwater level drawdown,but also ensures water demand,making it a viable solution for sustainable groundwater use in the Turpan-Hami Basin. |
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