Study On The Eco-geological Environmental Carrying Capacity Of Qushui - Sangri Area In Tibet

Eco-geological environmental carrying capacity composed of geological environment, ecological environment and socio-economic environment is an indicator, and it is also an important basis of land resources development model. The study area is located in the active zone of geological structure in Tibetan Plateau, and is the main region of watershed of the Yarlung Zangbo River, the Lhasa River, and the Nyang Qu. The valleys are the main developing region in the study area, the relationship among the abundant resources, fragile environment and increasing human activities is becoming more complex. It is value to study the coupling effect between time and space, and construct harmonious developing relationship among resource, environment and human.Qushui to Sangri area in Tibet is selected as study area, weather, topography, geology, geochemical, geophysical, remote sensing data are systemicly collected, and the remote sensing technology, geographic information system technology, and mathematical statistics method are used, the effect of eco-geological environmental space differentiation and time succession is selected as the study principal line, then the eco-geological environmental carrying capacity of systems, subsystems and the factors are assessed and analyzed. The main work as follows: studied the climatic change principle; mined the geological environmental characteristic information; interpreted the vegetation covering and land use in 1988, 2000, and 2009, and study the evolution law from 1988 to 2009, especially revealed the environmental evolution law by studying the desertification and lakes; discussed the evolution mechanism of soil and the surface water from 1993 to 2009; constructed the assessment index of eco-geological environmental carrying capacity, and got four levels regions of carrying capacity excellent, good, moderate, and poor; designed land resources development model.Research results are as follows:(1)Many times geological events and evolution of long geological history laid the foundation of the diversity of land resources and vulnerability of ecological geological environment, added with the increasing human activities, the regional vulnerability differentiation becomes more serious, and lead to the abnormal fluctuations of soil, surface water ,and mining groundwater.(2)Some weather index presented periodicity shock and adaptive adjustment from 1991 to 2007; Temperature rose accompany by shocks; the precipitation reached the maximum value about 2000, and then returned to the level of the early 1990s; Relative humidity reduced gently, its extremum appeared later than the precipitation, and its changes cycle longer than the precipitation; the average wind speed in the northern and eastern changed more frequently and greaterly than in the south and west; The maximum wind speed mostly is the north wind.(3)The area of high and low vegetation coverage which showed as the dumbbell structure features occupied the main body, leads to ecological environmental evolution appeared constant strong or weak which is difficult to control. From 1988 to 2009, vegetation coverage shifted slowly to the adjacent levels, the most increasing is vegetation coverage70% to 80%, and the most decreasing is vegetation coverage10% to 20%, the vegetation coverage evolution is coincide with the dumbbell structure features.(4)Land use evolved at landscape and patches levels. Because of the increasing intensity of human activity, the boundary of each land types occurred different degree of deformation. Desertification at relative low altitude and lakes at relative high altitude simultaneously changed which was highly consistent with the regional climate change; all of this shows that environmental change in the horizontal and vertical spatial scales is consistent. In the northern Brahmaputra bank and the eastern Lhasa River bank, the area and thickness of the desertification are great, from 1988 to 2009; the desertification remained deteriorating, in some region, sand even spread through the ridge and linked into one piece. From 1988 to 2009, the change rate of lake area is -9.14%, the maximum value is the region of elevation from 5100m to 5200m, the minimum value is the region of elevation less than 5000m; the average change value of lake perimeter is -4.47%, the maximum value is the region of elevation 5100m to 5200m, while the minimum value is the region of elevation 5200m to 5300m.(5)The excellent and good levels eco-geological environmental carrying capacity distributes a ring form along the border of the key research areas, the poor level region of carrying capacity distributes at relative high altitude, and the medium level region formed the main division is located in the transition zone of the excellent, the good, and the poor regions. The area of excellent level carrying capacity is least, and surrounded by other levels, there is a large number of human activities, although the geological environment is stable, but Socio-economic environment influence on ecological is increasing, thus the excellent level regions face an increased eco-geological risk. The good level region is the protective shell of the excellent level region, there is more and more human activities transferred from the excellent level region, thus there is also face some extent increased eco-geological risk. The medium level region where there is a number of animal husbandry and mining development activities, the geological environment and ecological environment is less stable, human activities need to be controlled, then environmental balance can be maintained. In the poor level region, the intensity of human activities is gradually increasing, and it would spread its adverse effects to other regions, so it is important to protect environment and reduce disturbance.