Study Of Hydrologic Characteristics Of Main Forest And Hydrologic Function In Zhongxi River Valley

The forst hydrologic research in middle and upper reaches is the hot field both at home and abroad. Connected with the item of the national and natural science fund (No.30070605 ) , this thesis chosed and made research in Zhongxi river valley which located in the Guandi Mountain. We connected the outward experiment with the indoor experiment, and put to use the mathematical statistics method and the contrast method at work, this paper made a systematic study about the forest crown interception, litter water content and forest soil water content of Quercus liaotungensis, Larix principis-rupprechtii and Pinus tabulaeformis in the raining season. In the same time, we studied the situation about precipitation, amount of runoff and amount of sediment transport during 1960-2000.The results showed that the crown interception of different forest is different. and that the saturated canopy interception storage of Pinus tabulaeformis, Larix principis-rupprechtii, Quercus liaotungensis are respective 5mm. 6mm, 4.5mm, and the rate of the maxim crown interception storage are respective 21.54%, 23.54% and 17.24%. and that the litter contents of different forest are different, the litter contents of Pinus tabulaeformis, Larix principis-rupprechtii. Quercus liaotungensis are respective 18.62 t/hm2. 16.29 t/hm2, 11.06 t/hm2, which their contents of undecomposed litter are more their half-decomposed. In the same time, the water contents held by three litters are different. Their water contents are respective 5.62mm, 5.08mm, 3.73mm..Both forest soil capillary and non- capillary porosity are different, so their water contents held by soil are different. The effective water contents of Pinus tabulaeformis Larix principis-rupprechtii Quercus liaotungensis are respective 77.54mm. 81.51mm, 80.23mm.. After analyzing the hydrologic factors such as precipitation, runoff and sediment data from 1960 to 2000,the results show : the precipitation concentrated on the raining season, of which makes up 73.3%. the change of precipitation among different years is larege, which Cv is 0.26; the discharge of flow decreased while the precipitation reduced. The discharge of flow concentrated on four months(7~10), and the change among different years is large, which Cv is 0.65. The correlation coefficient between sediment contents and rainstorm/flood is larger, compared with the relationship between annual precipitation and the amount of sediment transport.