Study On The Formation And Controlling Factors Of Groundwater Resources In Quaternary Of Ali Area, Tibet

Ali area lies in the northwest of the Tibet Autonomous Region, which locates at the peak of the world ridge. The topography of Ali area is dominated by altiplano lake basin terrain, and it belongs to the extreme water-scarcity poverty backwater area. The truth of extremely water-scarcity restricting the development of local agriculture and livestock production seriously, so it is imperative for us to find out the regularities of the groundwater resource distribution. This paper began with the geological background of the uplift of Qinghai-Tibet plateau, analyzed detailedly Ali's hydrogeology condition and clarified elementarily the distribution law and controlling factors of groundwater resources in Quaternary strata of Ali area.Generally speaking, the climate of the Ali area is chilliness and desiccation, and the precipitation is exiguity whereas evaporation is so violent. As a result, the supply of groundwater is so sparsity. Owing to the influence by the several Cordilleras and southwest monsoon climate, the distribution of rainfall in this area is very asymmetric. The average annual rainfall is only 300mm along the western Himalayas and appears descend trend from southwest to northeast. The Quaternary strata are widespread in Ali area, and the water-containing nature of each deposit is different because of the difference of cause of formation, the southern is better than northern. The southern upgrowth rivers formation brought to the abundant fluvial deposit, which composed by sandstone and conglomerate, so the containing water capacity of the Quaternary strata was promoted greatly, and the south area storages abundant groundwater. The northern altiplano lake basin terrain, whose sedimentation is dominated by the siltstone and mudstone, are low porosity and feeble water-containing capacity. Based on the synthesis research of the groundwater system in Ali area, we can draw an overall conclusion that the distribution of water resource in quaternary is not well-proportioned, from southern to northern are sequence reduce, therefore the great mass of midland and northern belong to drought areas. Finally, we estimated approximatively the Quaternary groundwater reserves of each valley and the relevant proposals have been put forward.