Qiemo Oasis Space Time Variation And Its Environmental Effects

Arid area oasis formed by a long-standing history that it has been raisinggeneration after generation over the past thousands ofyears,But with the increase ofthe oasis population, rapid economic development, the environment of the arid area isconstantly changing. To sum up, constant expansion of oasis outward is driven by ahighly human development. Under the background of arid area oasis of limitedresources and deteriorated ecological environment, Oasis area expansion has twopossible outcomes: Firstly, When the oasis expansion is kept within certain limits, ithas a constructive role which will consolidate systematic functions of the oasis toprovide a comfortable living environment and sufficient space for production andmore social and economic wealth for the human in arid areas. Secondly, as a fragilesystem of the arid area, it is not that the oasis scale the bigger the better, there is athreshold in the Oasis system, when the oasis expansion exceeds its threshold, theytend to play a destructive role that there will be some serious ecological problemwhich can not be restored (salinization, desertification, soil erosion, white pollution offarmland, etc.) that may make the Oasis fragile to lose stability and collapse.Therefore, studying spatial expansion process of the oasis has a very importantstrategic meaning, to understand the characteristics and scale of the Oasis systemexpansion and to explore whether there is a new "transition" which is correspond withdevelopment of productive forces that may improve human understanding of the oasisand its development law, scientific implementation of its development and planning,effective long-term organization, appropriate selection of development model foroasis system and correct guidance to the development.In this article, Typing theory and Gray model theory are applied as a theoreticalguidance, on the base of the spatial structure characteristics and spatial expansionprocess of the oasis, understand its expansion characteristics, explore the correlation between arable land and oasis area expansion, and then, establish further assessmentto evaluate ecological environment, and eventually predict the changes of the oasisarea in the next20years. Therefore, this article divided into three parts: study onexpansion process of the oasis based on the spatial data (RS/GIS); The second part:studies of ecological and environmental problems on the base of oasis expansion. Asfor theoretical research, this paper focused on typing development law of cultivatedland, the main research achievements are as blow: Typing theory is the essential oneto explainreclamation, expansion and evolution processes of cultivated oasis land in avery powerful and effective way. Cultivated Oasis land expansion is an irregular andcomplicated process, so we used the Typing theory to reveal stability and complexityof the cultivated oasis land better. Cultivated land is the most fundamental and mostimportant elements that its stability and complexity on spatial expansion process havea direct impact on the operational state of oasis system and its developmentcharacteristics in the future.In this thesis, based on the theoretical studies, at the same time, on the base ofspecific research area s natural environment and its spatial information andexploitation of RS/GIS technology, enriched the process and feature of oasisexpansion. Above all,in this paper, by using remote sensing image and map of landuse in different periods as a data source, by means of remote sensing and geographicinformation system technology, discusses the distribution pattern and dynamicchanging process of the Qarqan Oasis over the past40years. Results showed that, inaccordance with Qarqan Oasis expansion rate, spatial expansion process of the oasisis divided into two stages: from1970to2000, it is an oasis-making stage, that it wasoccurred with rapid growth of population, the continuous development of productiveforces and expansion of cultivated area. In this period, expansion scale of the oasis isincreasing, by the time of2000, whole oasis which can be developed has almost beenexploited. From2000to2011, it is an oasis urbanization and industrialization stage that was occurred with the rapid development of social productivity levels. Secondly,studies of natural and socio-economic driving force of the oasis expansion showedthat: Expansion rate of cultivated area slowed down and urbanization processaccelerated, the oasis area in2011has expanded to1102.18km2. Main natural factorsthat affect expansion of oasis area include variation of temperature, climate and waterresources. Principal component analysis on the socio-economic factors shows thatchanges in cultivated land, population and GDP growth is the main factors invariation of oasis area.Continuous expansion of cultivated land coupled with human's unreasonableand large-scale irrigation, resulted in large scale of land salinization in low-lying oasisareas and desertion of partial farmland, and because of great quantity of drainedAlkali-salt caused many ecological and environmental problems, such as death ofnatural vegetation, desertification, soil erosion and white pollution. According to theanalysis, we can know that, over the past40years, expansion of Qarqan oasis andeco-environmental problems are mainly caused by high intensity of human activities.Therefore, development of Qarqan oasis must be adjusted to the structure ofagriculture and animal husbandry, reasonable exploitation of water resources, raiseawareness of humans, maintain natural vegetation etc, only in these ways, can theprocess of external desertification and internal salinization of the oasis be inhibited,and there by, can the sustainable and healthy development of Qarqan oasis bepromoted.