Study On Land Use/Cover Change And Land Ecological Security Based On3S Technique In Qingyang City

With the development of the research on global environmental change, scientistsfrom every country have increasingly realized that LUCC is an important part and mainreason for global environmental change; with the rapid increasing of population, quickadvancement of science, development of industrialization and urbanization, the ecologicalproblems of land have become increasingly severe, and the problem have endangered thehuman security seriously and constrained the Economic Development.Qingyang city, which lies in hilly and gully region of Loess Plateau in the middle andlower Yellow River, is a large energy industry base of China. The increased humanactivities and intensified land use, along with the dim consciousness of treasuring land,have lead to soil and water loss and frequent occurrence of geological hazards; thepollution of soil and water and the deterioration of ecological environment from petroleumexploitation have seriously threatened the land security of the region, so land ecologicalsecurity has become an urgent affair faced by Qingyang city. Most researches, however,mainly focus on the policies and regulations of social economy and other theoreticalresearches, only a few of research pay attention to geological environment problemswhich has caused geologic hazards and contamination of soil. Of curse, this is aninevitable result of little knowledge about vulnerability and changeability of environmentby human, and it also is a result of the immature research on the relationship betweengeographical environment and land security. Thus, treating geographical environment asone of the factors which are often used to evaluate land ecological security is of greatimportance to the scientific evaluation of land ecological security, whether from theperspective of practical evaluation of land ecological security or the perspective ofacademic research.With the help of the research project the eco-functional regionalization of Qingyangcity, by means of Geographic Information System(GIS),Global Positioning System(GPS)and Remote Sensing(RS) techniques, based on comprehensive analysis of geologicenvironment of Qingyang city, by using TM data of1987,1988,1990,1992,2000and2006, along with Geostatistics, GIS spatial analysis techniques and Multi-stage fuzzycomprehensive evaluation, this paper, from different perspectives, qualitatively andquantitatively analyzes the land use/cover change of the region, ecosystem service valueand the intensity of ecological risk of land; and finally, this paper comes to a objectively comprehensive index of ecological security of land by means of unified model ofecological security of land, this paper also explores the tendency and the dynamiccharacteristics of ecological security of land in Qingyang city from several spatial andtemporal scales. The conclusions are as follows:1) Based on the evolution of the prone degrees of unexpected geological hazards, thispaper divides Qingyang city into three regions: the regionalization of high, moderate andmild prone degrees of unexpected geological disasters and six subregions. By means ofthe model of the integrative evaluation of geological environment, based mainly on theinfluence of oil exploration pollution and geological hazards, along with geologicalenvironment, this paper also evaluates the city with superposition weight method, that is,based on the regionalization of oil exploration pollution and geological hazards, with thespatial analysis of computer, according to the geo-environment quality, this paper finallydivides the regions of the city into four kinds: three regions with the best geo-environmentquality, five regions with better geo-environment quality, nine regions with worsegeo-environment quality and four regions with the worst geo-environment quality.2) From1990to2006, the area of Cultivated Land, grass land, waters, anduncultivated land had reduced, but forest land and construction land increased, the ratio ofthe varied area to the studied area was15.58%; among these Geomorphological Types, thegreatest change happened in loess hilly and loss residual plain, the change rates were8.37%and7.66%perceptively. The greatest change in loess hilly was the change fromcultivated land to forestland; in loss residual plain, it was from forest land to uncultivatedland.3) From1990to2006, forest coverage had increased from43.35%to49.80%by0.38%annually; the increase amplitude of coverage rate on all kinds of land are as follows:the amplitude on bedrock in low mountain and hilly area was the highest of all, theamplitude on the Loess Plateau took the second place, Loess Low Hill Area took the third,loess hilly-gully area took the fourth, loss residual plain took the last place; ZhengningCounty had the highest coverage rate, the coverage of Huan County was the lowest one,except Zhengning County and Huan County, in other counties, the coverage firstdecreased a little then increased, Zhengning County had the highest increase amplitude,Zhenyuan County had the lowest.4)From1990to2006, after the coefficient correction, the whole value of the landeco-service decreased by28.98×108yuan, the decrease amplitude was27.02%; from1990 to2000, it decreased by44.33×108yuan, the decrease amplitude was41.33%; from2000to2006, it increased by15.35×108yuan, the increase amplitude was24.39%; the wholevalue of the land eco-service of all slope grades decreased, the decrease amplitude on theslope grade which are larger than250was the largest one. Among all the fivegeomorphological types, the value of the land eco-service in the unit area first decreasedthen increased, on the whole, the value was decreasing, the highest amplitude happened inthe bedrock in low mountain and hilly area; except Zhengning County, the value of theland eco-service of lands in all other counties all decreased a little, the highest rateshappened in Huan County.5) From1900to2006, the index of land ecological risk decreased first then increased,but on the whole, it decreased; Among all the five geomorphological types, the landecological risk of Bedrock in low mountain and hilly area and the Loess Plateau keptdecreasing, the risk of other three types reduced first then increased, on the whole, itincreased; the highest risk intensity happened in Zhenyuan County, the lowest was inHeshui County; during the whole period of researching, the land ecological risk intensityof Huachi County increased, other seven counties decreased.6)From1990to2006, the Ecological Security of Land generally increased, theincrease amplitude between2000and2006is much bigger than that between1990and2000, the Ecological Security of all the five geomorphological types improved, especiallybetween2000and2006, except loss residual plain, the index of ecological security in allother four types increased; generally, the ecological security in all the counties anddistricts improved, the Most significant improvement first happened in Zhengning County,Ning County took the second place, Huan County was the last one.