根据有关台站的水文气象观测资料及"九五"国家科技重点攻关项目"96－912"专题有关成果，对甘肃省河西内陆干旱区地表水、地下水资源的数量、分布特征与变化规律及相互转化关系进行了分析和研究。结果表明，内陆干旱地区的地表径流主要形成于中、高山区，散失于山前平原和沙漠。径流的补给来源主要为大气降水、冰雪融水和地下水。降水量及其时空分布对水资源的形成有着重要的影响。这里降水、河川径流与地下水转化关系十分明显。内陆干旱地区水资源最主要的特征就是从山区到平原地表水与地下水在不同地质地貌单元间的相互转化，并且由径流源区的山区到河流下游的平原，不同区域、不同地段地表水与地下水的转化关系及地下水的流动模式亦不相同：即由降水与冰雪融水下渗所形成的山区地下水绝大部分以基流形式排泄，形成地表径流进入盆地；而河流在进入盆地或平原区流经透水性极强的山前冲、洪积平原后又大量渗漏补给地下水，山前冲、洪积扇平原的地下水沿地形坡降向冲积平原运动至冲积扇缘地带后，由于含水层土壤颗粒变细，导水性减弱，形成地下水溢出带，地下水沿沟壑呈泉水大量溢出地表，汇集成泉沟进入河流而转化成为地表水。在冲、洪积扇以下的冲积平原上，潜水含水层土壤颗粒细，地下水埋藏浅，径流水平流动缓慢，地下水以垂向水量交替为主。在自然状态下，冲积平原下游直到尾闾湖；洪水季节（洪水季节外，河川径流量很小甚至没有）河流泻洪通过河道补给地下水，余水进入尾闾湖。正是水量不大的河水及其所转化形成的地下水维系着西北内陆干旱地河流下游地区的绿州的存在和这里十分脆弱的生态环境。这些地表水与地下水之间的转化过程的这种特征直接影响本地区水资源的开发利用模式。目前，在上游地区大规模发展经济、开发水资源的情况下，随着地表径流利用率的不断提高和地下水得到的补给减少，许多地方泉水量减少甚至枯竭，原来的泉灌区被迫变为井灌区。冲积平原下游即使在洪水季节也很难接受上游地表径流的补给，造成地下水位持续下降，植被死亡，土壤荒漠化。因此，内陆干旱区的水资源开发利用必须从整个流域的角度出发进行统一的合理的规划，总结不同类型地区水资源开发利用过程中的经验教训，逐步建立不同类型最优化的水资源利用模式，这将对今后干旱区的水资源开发利用具有重要的意义。

The quantities, the distributing characteristics, the variation law and the mutual transformation relationship of surface water resources and ground water resources in the Hexi inland arid region of Gansu Province are analyzed on the basis of the hydrological and meteorological measured data at the concerned hydrometric stations and weather stations, and the related research achievements of National Science and Technology Tackle Key Problem Item (project 96-912). The results show that the surface runoff mainly are formed in the middle and the high mountainous area in the inland arid areas and dissipate in the pediment plain and desert.  The supply of runoff mainly is atmosphere precipitation, ice and snow melting water and ground water. The quantity and temporal and spatial distribution of precipitation possess quite important effect to water resources forming in the region. There the mutual transforming relationship between surface water resources and ground water resources is quite clear. The most primary characteristic of water resources in inland arid region just is the mutual transformation between the river runoff and the ground water in the different geology and physiognomy cells from the mountainous area to plain area. The transforming relationship among surface water resources, ground water resources and the flowing mode are dissimilar in the different regions from the runoff forming situated the mountainous area to the lower reaches situated plain and desert, that is, the most of the mountainous area ground water formed by ice and snow melting water and precipitation is excreted in the form of the base runoff and entered into the basin in the form of the surface runoff.  Surface runoff largely supplies groundwater again after rivers enter into the basin or the pediment plain which penetrating power are quite strong.  Ground water in the basin or the pediment alluvial and diluvial plain largely overflow from the surface and inflow into river to transform as river runoff again after they flow from the pediment plain to the edge zones of pediment fan s along terrain and slope.  The flow of runoff is slow and the movement of groundwater basically is vertical in alluvial plain below the pediment alluvial and diluvial fans. Under nature, river rushes down flood and supplies groundwater by river ways, and that the residual river runoff flows into the sink lakes from lower reaches of the wash plain to the sink lakes in the flood season. The rivers runoff is little even none during non-flood season. It is the small quantity rivers runoff and the groundwater formed by it that maintain the oasis of the lower reaches area of rivers in the inland arid regions in the northwest China and quite flimsy zoology environment here. The characteristic of the transformation processes between surface water and ground water affects directly the water resources development of the regions. At present, the quantity of output spring is being decreased even has dried up because of developing economy and developing water resources on a large scale in the upriver areas. The former spring irrigation areas have had to be changed well irrigation areas along with the utilization rate of surface water being improved continually and the supply of ground water being decreased continually.  The ground water in lower reaches of rivers in the alluvial plain is difficult to be supplied with surface runoff from the upriver areas even in the flood season, which lead to the continual descent of ground water level, the death of the vegetation and the desolation of the land. So the development and the utilization of the water resources should possess a uniform and rational layout in the inland arid regions. Summarizing the experiences of the various areas and working up the optimization water resources utilizing mode of the various areas will possess a quite important meaning on the development and utilization of water resources in the inland arid region for the future.