Hydrological Effect Of Forest Vegetation And Simulation In A Semi-arid Loess Area In Western Shanxi Basin

Based on the Beichuanhe sub-basin-Tuqiao valley forest vegetation structure, canopy interception, litter layer, soil layer for quantitative analysis of hydrological processes. And 25 years Beichuanhe basin meteorological and hydrological data for trends, mutation analysis, and the valley of the spatial data and non-spatial data into the SWAT hydrologic model in a preliminary hydrological simulation results obtained are as follows:(1) Pine pure stands of different densities diameter class, height class are in line with single-mountain-shaped normal distribution, the overall growth-growth forest for the. Which stand density 1675/hm2 (Plot2) for the appropriate density; Robinia pseudoacacia stands diameter class distribution of low density, height class appear symmetrical, only the standard to 15 (1200/hm2) diameter class, height was a single peak distribution for the appropriate density, medium density and recession appear abnormal characteristics of diameter class, tree height in addition to 1600/hm2 (plot17), and the remaining stands are bimodal distribution, forest irregular; high density locust pure forest, trail-order distribution density, tree height curve sharp or asymmetry, potential interspecific competition. Other mixed forest, on the performance of irregular diameter class, but the distribution of tree height, the vertical direction to form mosaic will help cut rain hold.(2) Canopy marked effect on rainfall interception, interception of 72.5%, there are different points between locations, mainly caused by forest setting, canopy interception of an important role in preventing soil erosion, but the window of rain forest understory vegetation on, soil moisture, forest inefficient transformation is important.(3)Litter Litter accumulation volume range 2.06-9.86t/hm2, undecomposed layer of water-holding capacity than undecomposed layer, integrated water-holding capacity in the order:black locust× orientalis> larch> Locust> elm> pine> pine×locust> forest> cedar> larch×pine.The nine indicators of soil properties by factor analysis, the four common factors and factor scores obtained through:the density of Robinia pseudoacacia performance is superb (stand density 1200～1625/hm2), while the other stands in the consolidated although the poor performance score, but lower soil bulk density, loose soil in elm, cedar and other tree species are more prominent advantages. Non-dominant tree species have focused on improvement of soil physical and chemical properties. Statistics of soil nutrients and soil water prediction map for the subdivision of vegetation provide the basis for configuring and updating(4)With SWAT assisted, simulated annual runoff simulated high precision calibration period, while the validation period of simulation is ineffective. Considering the results of this model is still in the river basin simulation, Model calibration validation calibration period is -3.79% relative error, correlation coefficient of 0.91, Ens coefficient of 0.78;validation period relative error 4.82%, correlation coefficient of 0.71, Ens coefficient of 0.52, the level of the analog C class.