Temporal Evolution And Spatial Pattern In North China And Its Hydrological Response

Water is an extremely important factor in global environmental change. It influences the processes causing change. The human and economic consequences of changes in the water system can be very significant. Especially, for a region such as the North China where is large reduction of water from the mountains, Exploitation of underground, and dried up in many areas, are the three hard problems for the sustainable development in the basin. To solve these problems, it may be of great important to understand the process of hydrological cycle and its evolution law in the basin. Basing on the recognition and the support of geographical information system (GIS) technology, this thesis has tried to find out the evolution law of hydrological cycle and it mechanism in the region. Furthermore, the potential change of the hydrological cycle in a climate changing condition is also considered.This paper is based on the project "The knowledge Innovation Key Project of the Chinese Academy of Sciences", it involves two sections:Section A: Temporal and Spatial analysis In North ChinaThis section use the wavelet analysis spectrum analysis and Hurst coefficient to analysis the temporal evolution. Owing to the difference among the climate influences on the different regions, the water resource content in north China varies greatly. In order to study the future trend of precipitation in north China, On the partitioning of the 25 primary experimental stations into 6 representative regions, this thesis picked-up the connotative periods in different period and different scale of various regions, then put forward and analyzed the evolvement trend of precipitation several years from now on in north China. Thus this thesis is an instructive search for mastering the evolvement rule of precipitation in north China.Section B: Spatial pattern of precipitation and its hydrological responseThe distributed hydrological model based on DEM (Digital Elevation Model) is an attractive approach to study hydrological processes. In order to study the impact of the changing environment on hydrological processes, the watershed model must be performed on subbasins that represent different hydrologic response units. Take example for the raster-grid subbasins, the grid cell input module plays an important role to modeling. As the original input of rainfall-runoff modeling, the precipitation of each grid cell must be interpolated according to the limited observed data, where the studies on spatial interpolation methods become necessary. The fundamental principals and methodologies of spatial interpolation wereintroduced in this paper. In the case study of Chaobaihe River Basin in North China, various interpolation methods were applied to calculate the spatial distribution of daily rainfall. And the cross-validation method was used to examine the precision and applicability of these spatial interpolation approaches. The result indicates that the efficiency coefficient increases slightly with the increasing complexity of the interpolation. Meanwhile, the complex method spent much more time on interpolating which means the calculating efficiency decreases obviously. However, which method should be adaptive depends on the topographic and climatic traits of watersheds. In Chaobaihe river basin, GRDS (the Gradient plus Reverse Distance Squared) is the best interpolation method to obtain precipitation on each grid element.In the end this thesis had studied the responds of the precipitation in North China. We use various interpolation methods to generate the typical spatial distribution and analyses the runoff under the same condition.