渭干河—库车河三角洲绿洲灌区水盐均衡特征分析

依据实地考察实测资料,分析渭干河-库车河灌区的水量平衡、盐量平衡、引水和排水矿化度的变化特征、排盐效率及排水的主要盐分离子.结果显示: (1) 受灌区上游大型水库的调蓄作用,灌区引入地表水的年际变化不大,年内引水出现双峰,排灌比例在8.79%～18.65%,引水利用量为22.53～30.05亿m~3,主要用于农业灌溉用水,农田园林耗水量占总耗水量的75.26%. (2) 随着灌排系统的完善,渭干河-库车河灌区整体处于脱盐过程,年均脱盐量为86.64万t,灌区非盐化土地面积扩大,盐渍化土地面积缩小,灌区内耕地的土壤含盐量减少.(3) 由于大型水库的调蓄作用,灌区引入地表水的矿化度年变幅也较小,1993～1996年平均为0.38 g/L,1997～2001年平均为0.42 g/L,在年内洪水期水量大,矿化度相应偏小.年均排盐量为99.77～275.40万t,排水量和排盐量总体变化趋势相一致,呈略微上升趋势.排水盐分离子中,阴离子主要以Cl~-为主,其次是SO_4~(2-);阳离子主要以Na~+为主,Mg~(2+)出现的机会较小.保持灌区水盐持续均衡所需达到的水量排引比为0.09:1.

Analysis of characteristics of water-salt balance in Weigan-Kuqa River irrigation district

Based on the field work data, this paper analyses the water balance, salt balance, the variability of di-version and discharge water mineralization degree, desalt capacity and the main drainage salt ions in the Weigan - Kuqa River irrigation district. The results show that (1) Affected by the storage of large-scale reservoir upstream in the irriga-tion areas, the diversion of surface water has little annual change in the irrigation district, and it appears a split-blip. The ratio of irrigation and drainage is 8.79% ～ 18.65%. The use of water introduction is 22.53 × 10~8 m~3 ～ 30.05 × 10~8 m~3, and it was mainly used for agricultural irrigation water, and 75.26% of the consumption is used for farmland and garden. (2) With the improvement of irrigation and drainage system, the Weigan - Kuqa River irrigation district is being in a desalting process. The average annual desalination capacity is 86.64 × 10~4 t. The area of non- salinized land is expanded, while the salinized area reduced, and the salinity in the cultivated soil is reduced in the irrigation. (3) Because of the storage of the large reservoir, the amplitude of the diversion surface-water salinity is also getting smaller in the irri-gation district. It has an average of 0.38g/L from 1993 to 1996,while the average is 0.42 g/L from 1997 to 2001. Dur-ing the flood period, the water is abundant and the mineralization degree is smaller. The average annual amount of drainage salt is 99.77 × 10~4 t ～ 275.40 × 10~4 t,and the drainage salt and water displacement are overall in a micro-rising trend. The main anion of the salt ions is C1~- in the drainage, and followed by SO_4~(2-). The cation is mainly Na~+, while Mg~(2+) has a smaller chance to appear. To maintain the necessary balance of water-salt in the irrigation district, the ratio of discharge and diversion water is 0.09:1.