| Abstract: | The inhomogeneous and non-flat paleotopography in a depositional landform area profoundly controls the process of modern gully evolution and shapes the structure of a gully network.However,this controlling effect of paleotopography on modern gully evolution is mostly ignored because of the difficulties in paleotopography reconstruction.In this study,loess area in China is selected as case area for its typical depositional landform area and inhomogeneous and non-flat paleotopography during the Quaternary.The paleotopography underlying loess is considered while evaluating its controlling effects on the gully evolutionary process.On the basis of the geophysical prospecting,detailed geological information,and high-resolution digital elevation model,we reconstruct the pre-Quaternary paleotopographic surface in the case area.Comparative analysis is conducted to reveal the modern gully evolution in relation to the paleotopography.Results show that the concave area of the paleotopography acts as the basement of the high-order modern gully evolution in the hilly-gully area,although this concave area can be covered and buried by the loess depositional process during the Quaternary.A significant controlling effect of paleotopography on high-order modern gully evolution can be observed in a depositional landform with a hilly-gully underlying topography,whereas a relatively weak controlling effect exists in a flat underlying topographical area because of the strong horizontal shift effect of gully formation process.Several low-order modern gullies also exist and limit the controlling effect of paleotopography.These results reveal a controlled high-order modern gully evolutionary process and a rather dynamic low-order modern gully evolutionary process in the hilly-gully area.These results also help us understand the variations in different modern gully evolution in relation to paleotopography and the different management schemes for soil conservation and ecological restoration during the gully evolutionary process. |
