Study On Groundwater Spatiotemporal Distribution Law And Its Entironmental Effects In Hotan Oasis

Water is a key factor to Hotan oasis. Study on groundwater spatiotemporal distribution law and its entironmental effects in Hotan oasis could provide scientific basis for agricultural irrigation and amelioration of saline alkali land, give references for ground water rational exploitation and utilization and management in Hotan area. Besides, it is of great theoretical and practical significance to ecological environment protection and sustainable development of Hotan oasis. In this thesis, groundwater depth series was simulated and predicted with grey self-memory model, groundwater spatial distribution law was obtained by Kriging method and entironmental effects of groundwater spatiotemporal distribution law was studied accordingly. The main research findings were as follows:1) Groundwater depth of monitoring well GW9 was simulated and predicted by grey differential equation combined with self-memory theory, the results show that this model has the merits of simplicity and practicality, and it could improve the simulation and prediction precision.2) Evaporation, temperature and air speed, especially the evaporation, were the main meteorological affecting factors to Hotan oasis groundwater depth. Besides, water temperature, humidity and precipitation were also necessary affecting factors, but their effects were relatively low.3) Procedures of several Kriging arithmetic and its associated variograms parameter fitting were written and tested. The results show estimation precision was relatively higher, especially in the ideal plane and ideal curved surface where the error was dramatically low; the precision became somewhat lower when random number was involved. It suggested that Kriging method could dig the spatial correlation information sufficiently.4) Spatial interpolation models of elevation, groundwater depth and groundwater chemicalconstituents contents in Hotan oasis were established, and the corresponding contour maps were protracted with Surfer software.5) Groundwater depth of 1999 and 2004 was relatively deeper in the southern part than the northern part of Hotan oasis, deeper in the western part than the eastern part, groundwater depth along the banks of the two rivers was also relatively shallower. Hotan groundwater depth, which was deeper in south and shallower in north, was in accordance with its terrain. Groundwater depth of 2004 was deeper than that of 1999.6) Distribution trend of 1999 and 2004 groundwater chemical constituents were as follows. pH value and total hardness were higher in north, lower in south, and gradually gone lower from west to east. Calcium ion content was higher in south, lower in north, higher next to the two rivers, lower in the area of Moyu county and Luopu county that far away from the two rivers. Total hardness was higher in north, low in south, and gradually gone higher from west to east. HCO3 ? content and total alkalinity were higher in north, lower in south, and gradually gone higher from west to east except the bank area of the two rivers where was lower. Besides, all the groundwater chemical constituents'contents of 2004 were higher than that of 1999.