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甘肃河西走廊石羊河流域下游民勤绿州面积390万亩占全县总面积16.32％,耕地面积107万亩,占绿州面积27.48％。由于上游大量引水,进入石羊大河的径流量己由五十年代的5.424亿立米,到六十年代为4.344亿立米,七十年代为3.226亿立米,到八十年代减少为2.299亿立米,即每隔10年减少1.042亿立米,平均每年以2％速率递减,按此推算到2010年前后石羊河有可能断流。自七十年代开始大规模地打井,累计打井1.3万眼,纯井灌溉面积达到30万亩,地下水年开采量达4.5～5亿立米,累积超采36.28亿立米,地下水位累积下降10～26米,已形成986平方公里的三个漏斗区,致使大批机井更新换代五次之多。由于地下水矿化度较高(一般在4～10g/L,最高达75.7～109.0g/L),使土层积盐严重,盐碱化的
Gansu Hexi Corridor Lower Shiyang River Basin Minqin area of 3900 acres of green area accounts for 16.32% of the total area of the county, 1070000 acres of arable land, accounting for the green area of 27.48%. Because of the large amount of diversion from the upper reaches, the runoff into the Shiyang River has risen from 542.4 million cubic meters in the 1950s to 434.4 million cubic meters in the 1960s to 322.6 million cubic meters in the 1970s to 229.9 million cubic meters in the 1980s Every 10 years to reduce the 104.2 million cubic meters, with an average annual rate of decline of 2%, according to projections that by 2010 Shiyanghe may cut off. Since the 1970s, a large number of wells have been drilled, with a total of 13,000 wells drilled. The area of pure well irrigation reached 300,000 mu. The annual groundwater exploitation amounted to 450-500 million cubic meters. The cumulative over-mining was 3.688 billion cubic meters and the cumulative groundwater level decreased by 10 ~ 26 meters, has formed a 986 square kilometers of three funnel area, resulting in a large number of wells up to five times as much. Due to the high groundwater salinity (generally 4 ~ 10g / L, up to 75.7 ~ 109.0g / L), so that salt accumulation of soil salinization