Distribution Of Medium Salinity Groundwater And Water Quality Assessment In Tarim Basin Plain

Tarim Basin is an important irrigated agricultural area which is located in the south of Xinjiang, includingMongolian Autonomous Prefecture of Bayingolin （hereinafter referred to as Bazhou）, Akesu Prefecture, HotanPrefecture, Kashi Prefecture and Kergez Autonomous Prefecture of Kizilsu（hereinafter referred to as Kezhou）.The basin is dry all the year around with scarce precipitation, hot summer and cold winter lead to quite shortage ofwater resource. The shortage of surface water and fresh groundwater resource has become one of the mostsubstantial clauses restricting economic development. The development and utilization of medium salinitygroundwater was an important measure to alleviate the crisis of water resource in Tarim Basin. In recent decades,disturbances of human activities and climate change increased rapidly, which result in deteriorating water quality.Therefore, determination of distribution and resource extent of medium salinity groundwater in Tarim basinbecame a crucial point of regional development, management, protection. As an important part of water resourcesmanagement, water quality analysis and evaluation played a very important role and significance of waterresources management.The medium salinity groundwater which has total dissolved solids values range between2⁷g/L, can be usedfor agricultural irrigation directly or indirectly. Based on GIS, the author estimated the resource quantity ofmedium salinity groundwater in Tarim Basin plain of Xinjiang in this paper. Analysis on chemical characteristicsand forming reason were made by means of Piper trilinear diagram, mathematical statistics and some other means.In addition, irrigation water quality was evaluated. The main conclusions were reached as follows:（1） It is the seriously shortage of surface water and fresh groundwater in Tarim Basin. Exploitation andutilization of medium salinity groundwater is beneficial to improvement of saline-alkali soil, developmentof high-new water-saving irrigation agriculture and improvement of guaranteed rate of agricultural water supply.（2） Combination of groundwater resource moduli calculation method with GIS technology was introduces todetermine the total resource quantity of medium salinity groundwater, which was2.332×109m³/a in Tarim Basin,in which irrigation district total recharge accounted for50.48%, mainly distributed in Akesu Prefecture of AksuRiver Basin, Bazhou of Kaikong River Basin, Kashgar Prefecture of Yeerqiang River Basin and Hotan Prefectureof Hotan River Basin.（3）The general change law of total dissolved solids is lower piedmont and higher desert fringe. That is to say,the distribution of medium salinity groundwater is mainly along the desert. The dominant hydrochemistry type isCl SO₄-Na Mg, Cl SO₄-Na following. The concentration of Cl-and SO₄^2-in Tarim Basin is high. There was agood correlation of Cl-and SO2-4with TDS. In recent years, groundwater quality of Tarim Basin is deteriorating.（4） As irrigation water, the quality of medium salinity groundwater is poor in Tarim Basin, and it was notsuitable for long-term direct irrigation. Therefore, establistment of irrigation technology system on drip irrigationunder mulch&irrigation and drainage mode can greatly contribute to reasonable utilization of medium salinitygroundwater resources in Tarim Basin.