Research Spatial Coupling On Settlement And Water-soil Resource Based On The Irrigation

Heihe River Basin is the second largest inland river basins in arid northwestChina, Zhangye City in Heihe River Basin is the main part and the essence of region.Arid inland basin lies in the water,the core area is an oasis. The actual unit of the useof "water" is "irrigation district", instead of oasis overall. We can also say that it is acomplex interdependence Irrigation District, after spatial integration, which formingthe modern oasis. under the strongly control and guidance of artificial irrigation canalsystem, the amount of canal water supply determines the size of the irrigated area(irrigated land), while the size of the irrigated land determine the carrying capacity ofthe population, so there is a high degree of interdependence and symbiosis among thewater-soil-human systems.The paper extracted residential patches land area and irrigated patches land areafrom the database of "Second Land Survey" of Zhangye to characterize of"settlement" and "land", and extracted the properties data of irrigation canal and waterresources from the database of Zhangye "Irrigation Management Annual Report" tocharacterize of "water resources". It adopted thinking method from the part to thewhole, first of all,started from the three categories of typical irrigation district byintegrated using spatial autocorrelation model, interpreted the pattern of spatialorganization between the water-soil-the settlement, and then zoom to27largeirrigation district in Zhangye, further visits the spatial organization of the pattern ofoverall irrigation between water-soil-settlement, at last, it applicated coupling modeland coordination degree model to analyze the coupling relationship and harmoniousrelations between irrigation water-soil-settlement.The results showed that:(1)From the view of three typical irrigation district: Xinba irrigation area (oasisedge irrigation) is profound impacted by the inflow direction and level of assurance,the canal was a typical fan-shaped radiation characteristic, canal， irrigated land andsettlements outward from the main canal,hot spots gradually transformed into a coldspot region, which show that the upstream region effects downstream water use with acertain degree of "deprivation",the canal control and guide irrigated distributionsignificantly. Pingchuan Irrigation District (the hillside independent irrigation) is effected by the movement of the main stream of Heihe River, the main canal spreadparallelly with Heihe River, settlements, irrigated performance core (the Heihe andcoastal main canal)-the external characteristics, scilicet transition from Heihe coast tothe peripheral, settlements, irrigated and canal system gradually change from hot tocold spots, the performance of a strongly basic role for Heihe Coas t main canal ofpopulation and water resources. Yingke Irrigation District (typical belly of irrigationin oasis) canal was a typical grid mesh characteristics, due to the complex multi-levelallocation of water resources between each irrigation, leading that it also exists acomplex series and parallel relationship inside the irrigation district, since water rich,high level of assurance, the control action of canal for irrigated land and settlements islower than the other two types of irrigation district on the contrary.(2)Speaking from the view of overall Irrigation of Zhangye: canal and irrigatedMoran index is greater than0, but the vast majority of canal and irrigated land variesbetween0.1-0.4, indicating a degree of uniformity in the spatial distribution. From thecanal, irrigated land and settlements Moran Index, canal system (4.783507)> irrigatedland(4.350581)> the settlements (2.006427), that is, the relevance of the canal isstronger than irrigated land, and more stronger than settlements, in the three, thecorrelation between the canal and irrigated is closer than others. Irrigation canal,irrigated land and settlements Moran index showed good coupling in typical oasis.But in oasis edge of the irrigation area and along the mountain independe nt irrigation,canal, irrigated land and settlements Moran index showed a strong contrast.whichshow that there are significant inconsistencies in the spatial distribution ofwater-soil-settlements. In Zhangye irrigation, there is a significant difference for thedegree of aggregation of the population and water resources between the core area ofoasis irrigation and the border irrigation area, the typical oasis irrigation and thehillside between the independent irrigation. Oasis core heart showed significantspatial aggregation characteristics, the edge of the area and hillside irrigation areinfluence by water security and regional conditions, the density distribution of waterresources and population is low.(3)All of irrigation units in Zhangye, the average of coupling degree aboutsettlements and water, soil resource is0.714for the high level of coupling stage. But the spatial differences are significant, water-soil-human high strength coupling region(coupling value of0.8or more) mainly distributed in the part of the core oasis;water-soil-human in the run-in phase(coupling value between0.5to0.8)are mainly locatedin the core area of the economy or the administrative center of theenclave;moderate-intensity coupling areas(coupling value between0.5to0.3)mainlydistributed along the mountain irrigation and the edge of irrigation;low intensitycoupling region of (degree of coupling value of0.3or less) distributed in the moreindependence Sunan irrigation.So it is visible that the basic characterization of water-soil-human coupling is that the belly of irrigation district is higher than the edge ofthe oasis in irrigation area, the united irrigation district is higher than the independentirrigation district.(4)The spatial distribution characteristics about water-soil-human system ofthe degree of coordination and coupling is essentially similar, but slightly different inZhangye irrigation unit, highly coordinated areas (the coordination value above0.5)only4which is Liyuan River Irrigation District, West Jun irrigation,Yingke irrigationarea, Dachuma irrigation, moderate coordinated region (coordinate value between0.3and0.5) in the tour-shaped distribution in the core area of the oasis, the spatial extentconsistent with a high degree of coupling region; low-moderate coordinated regions(coordinate values between0.14and0.3) are distributed around the moderatecoordination area; the low coordinated area (coordinate value below0.14) is a widerange, mainly in the Qilian Mountains hillside irrigation and the edge of the oasisirrigation.(5)Accordingly, the27irrigation district of Zhangye can be divided into thewater-soil-human resources harmonious,namely high coupling high coordinationareas; water-soil-human resources run-in area, namely high coupling low harmoniousregion; water-soil-human resources antagonistic area, namely middle coupling lowharmonious region; water-soil-human resources low coupling region, low couplingand harmonious region.