三峡库区柑桔林水土保持效益分析

Soil Conservation Benefit Analysis for Citrus Orchard in the Reservoir Basin of Three Gorges

对三峡库区2种不同建园方式的柑桔林，从建园开始连续9年定位观测柑桔林水土流失情况，结果表明，梯田柑桔林径流系数在0．047～0.153之间，径流含沙量在425—2170g／m^3之间，侵蚀模数在9．37-116．67g／m^2之间。25°坡地柑桔林径流系数在0．079—0．378之间，径流含沙量在500—5050g／m^3之间，侵蚀模数在48.29～1962．04g／m^2之间。在建国初期4年内，25°坡地柑桔林径流系数、径流含沙量和侵蚀模数急剧下降，径流系数由0．378下降到0．103，径流含沙量由5050g／m^3下降到350g／m^3，侵蚀模数由1962．04g／m^2下降到131．42g／m^2。4年后，覆盖度的增加有效的抵消了坡度对水土流失的影响，柑桔林覆盖度达到0．82，径流系数，径流含沙量和侵蚀模数分别为0．103～0．253，350～3404g／m^3、14．71～148．4g／m^2，表现出较好的水土保持效益。

Since the orchard establishment, uninterrupted located monitoring has been conducted for nine years on the two citrus orchards with different establishment methods in the reservoir basin of the Three Gorges. The result of monitoring indicates that the values of the runoff coefficient, the runoff sediment concentration and the erosion modulus in the terracing citrus orchard are between 0.047 - 0. 153,425 - 2170 g/m^3 and 9.37 - 116.67 g/m^2, respectively. While in the 25° sloping citrus orchard, the values are between 0.079 - 0.378, 500 - 5050 g/m^3 and 48.29 - 1962.04 g/m^2, respectively. During the first four years initially from the orchard establishment, the values of runoff coefficient, the runoff sedi- ment concentration and the erosion modulus fell sharply, from 0.378, 5050 g/m^3 and 1962.04 g/m^2 respectively, down to 0. 103, 350 g/m^3 and 131.42 g/m^2, respectively. After four years, the increase of the coverage effectively offset the impact of slope to the soil erosion, that is, when the coverage of citrus orchard reached 0.82, the values of the runoff coefficient, the runoff sediment concentration and the erosion modulus are between 0. 103 - 0. 253, 350 - 3404 g/m^3 and 14.71 - 148.4 g/m^2 respectively, appearing the better soil conservation benefit.