民勤盆地地下水水位下降特征与可持续利用评价

Characteristic of Groundwater Drawdown and its Sustainable Development Countermeasure in Minqin Basin

在水文地质调查的基础上,以地下水化学与同位素为基础数据,研究了民勤盆地地下水组成的基本特征,自然演变规律和人类活动影响下的变化过程。地下水δ18O较现代降水值低-3.5‰左右,表明民勤盆地地下水均为地质时期封存或入渗补给年代久远的古水,现代农业灌溉地下水是不可再生资源,大规模超采地下水导致地下水水位形成漏斗形曲面下降。作者以水量平衡理论为依据建立了估算地下水储量与农业经济规模灌溉可开采储量的"漏斗"模型,经计算绿洲浅层、深层地下水可开采静储量632亿m3;绿洲浅层地下水淡水农业生产经济资源可开采总量为110亿m3;按照目前开采速率,维持目前产业经济规模极限时间约为16 7a。因此,必须实施农业种植业经济向农业畜牧业、草业经济发展,以及产业调整期经济平稳过渡。

The study has been taken up to understand the groundwater evolution process and potential for future sustainability by use of the hydrogeological survey and geochemical technology. The depletion -3.50‰ in (δ^(18)O) of groundwater than that in the modern precipitation shows that the groundwater was recharged in colder paleao-environment. The economy development upstream in the Wuwei basin is at the cost of destroying the groundwater and ecology in the Minqin basin, the downstreams of the Shiyang river basin. The Minqin basin has been experiencing over-exploitation of groundwater resources due to the lack of water resources and its rational planning measure, and thus groundwater recharge is decreasing, water level are reducing and the water quality is getting worse. A funnel model was developed based on the water balance to calculate the groundwater storage and the potential permitted extraction for future sustainability. The result shows that the groundwater storage is about 63.2 billion cubic meter and the resources is unrenewable and the economy resources can be sustained less than 17 years regarded the development scale at the present time. From now on,we must consider the Shiyang river basin as a whole and make reasonable arrangements for the whole area,combine utilization of surface water and groundwater resources,and improve effective utilization rate of water resources. Especially, it is important to start a new economic style from crop planting to stockbreeding and grass planting.