Analysis On The Developing Schemes Of Groundwater Resources Of Natural Groundwater Reservoir In Nalinggele River Alluvial-proluvial Fan

Nalinggele River is the biggest inner continental river in the Qaidam Basin, andthe alluvial-proluvial fan is the best zone of groundwater resources relatively.Tousethe alluvial-proluvial fan fully for regulation of groundwater resources willimprove supply capacity in this area and offer the reliable water resources guaranteefor the domestic, agricultural and industrial usage. Based on the analysis of theconditions of physical geography, geology and hydrogeology, the feasibility ofregarding Nalinggele River Alluvial-proluvial Fan as a natural groundwater reservoirwas studied at first. Then, the three-dimensional numerical model of groundwatertransient flow was established to determine the characteristic water surface andcharacteristic storage capacity of the groundwater reservoir. The effects of differentwater resources developing schemes were simulated and predicted. The conclusionscan be summarized as follows:1. Nalinggele River Alluvial-proluvial Fan is a natural groundwater reservoir.The aquifer of coarse gravel and sand is thick, and the hydraulic conductivity ofaquifer is large. The water is mainly phreatic water and there is a large space fordevelopment and utilization of groundwater resources. The overflow zone of thealluvial-proluvial fan is multilayered structure and composed mostly by fine particles,which is poorly permeable. The main recharge sources of the groundwater reservoir isinfiltration recharge of Nalinggele River, calculated by water-table fluctuation (WTF)method. The amount of groundwater recharge resources is6.16×108m3in current. Thedeveloping conditions of groundwater reservoir area is good, it is beneficial toutilization and storage and regulation of groundwater resources.2. The safe yield of groundwater resources is huge. The three-dimensionalnumerical model of groundwater flow was established and resolved by VisualMODFlow software. As the environment of this area is groundwater dependent, andthe growth area of the reed decreases with the increase of groundwater yield. The safe yield of groundwater resources is65×104m3/d based on the ecological limited factor.When the groundwater yield is less than65×104m3/d, the suitable growth area of reedwill be reduced slowly; if not, the suitable growth area of reed will be reduced morequickly.3. The characteristic water surface and the characteristic storage capacity of thegroundwater reservoir are determined. Using “characteristic water surface” to replace“characteristic water level”, the new index system of groundwater reservoir regulationincludes the dead water surface and the dead storage capacity, the normal watersurface and the normal storage capacity, the current water surface, the occupiedstorage capacity and the empty storage capacity. To calculate the characteristic watersurface and characteristic storage capacity of groundwater reservoir in NalinggeleRiver Alluvial-proluvial Fan by the established numeral model. The total storagecapacity is190.3×108m3, the dead storage capacity is159.4×108m3, and the normalstorage capacity is30.9×108m3.4. The water resources development and utilization schemes were simulated andanalyzed. Based on the situation of industry, agriculture and animal husbandry anddomestic water consumption, two different groundwater exploitations scenarios wereestablished, one scenario is based onthe water demand in research area, anotherscenario is based on the total demand in whole basin. According to the annual averageriver runoff (13.35×108m3/a) and historical monitoring river runoff,4schemes ofgroundwater exploitation were simulated. The results showed that the groundwaternatural discharge decreases with the increase of exploitation, which compensate theaffect of groundwater exploitation for groundwater budget. The conclusion can becarried out that the regulation ability of groundwater resources in Nalinggelealluvial-proluvial fan groundwater reservoir is very strong.