The Study On The Systems Of Karst Valley Hydrologic Geomorphological Evolution

Geomorphicgeology is a science which studies the surface landforms characteristics and its forming causes,evolution,and distribution of the internal structure.The surface of topography is in ever-changing and developing.Changes in the development of landforms are influenced by tectonic movement,foces from outside and the time three factors. Meanwhile,different geographical landscapes shapes differrent external forces.Thus the formation of surface is different,which can be divided into:glacial geomorphology,permafrost landforms,rivers and Karst landforms and so on.Karst landforms are mainly shaped by the functions of water corrosion and erosion.From the aspect of the river basin,the study of morphological changes of landforms solution can well explain the rule of changes.Because at different flow rows,the role of erosion and corrosion as well as the dominant position to shape the landscape are also different, types of combination are also different.Groundwater in Karst areas are divided into:with vertical movement,with seasonal changes,with the level of exercise,as well as four with stagnant deep water.Different river flow with four different thicknesses shapes various types of topography. Gentlely flowing river with vertical and seasonal changes are with thin changes;shallow groundwater levels which is mainly flowing-oriente are ups and downs,so the surface of landform does not feature as corrosion in plain and isolated peak,hill residues.When the river is with slides,the vertical gradient changes becoming thick,the level of exercise turns into a vertical movement.Runoff also leaks into groundwater,surface of water turns into deeper water.Surface of landform begins to appear,at the same time,swallow hole and depression as well as the Canyon,such as cluster shape landforms.It makes the same flowing water with different flow basin topography is in different ages of development.According to the characteristics of Maotiao River basin which is divided into upper,middle and lower,the study adopts the area analysis ---elevation points to determine which sections of their respective ages, meanwhile,using time series of the Hurst coefficient of runoff to analyze the evolution of basin-wide.In order to better reveal the relationship among base surface,runoff and the morphology of the basin,the average peak height trend surface and the lowest trend surface is analyzed from pespective of trend surface.It is found that peak height at the upper reaches of river are basically at the same trend surface,and the lowest trend surface topography slight gradient is in the early childhood development as well as the evolution is mainly affected by precipitation runoff impact;trend surface at the middle reaches of the highest and the lowest trend surface runoff at the direction of the relative height becomes great differences.Development in their prime geomorphology(David partial) during the run-up in space and time begins to decline,which shows that there is some surface water converting to groundwater; differences are great between two trends in lower runoff,in their adult period of landforms,since the cutting of Wujiang makesn the runoff leaking.It is found from the study watershed runoff variability is small at very early childhood,which shows that Karst development plays major role in the affect of wwater surface;with more obvious slide,deeper cutting,the river increases its variabilty when runoff enters the adult period,and there is a decrease,which demonstrates Karst develops strongly in the conversion of surface water to groundwatert.The rules of Karst basins evolution is aslo concluded through the study.