The scale and severity of soil erosion withinthe headwaters of the Yangtze River in Yunnan Provinceare discussed. The Yangtze River rises in the westernuplands of the Qinghai-Tibet Plateau and traverses 6380km through southern and central China. The headwatersare in tectonically active and geologically unstableuplands. The basin is also generally under intensiveagricultural use, mainly for rice cultivation. Hence,erosion rates are high and of increasing concern,especially considering the construction of the ThreeGorges (Sanxia) Dam in the middle section. Sedimentationwithin the proposed reservoir could impair itsefficiencv and therefore soil conservation must be anintegral component of basin management. Soilconservation efforts in Yunnan are reviewed and thelocal-scale planned approach to soil conservation isillustrated, using Dongchuan and Xundian as case studies.An ongoing runoff plot study at Yunnan AgriculturalUniversity (Kunming) is used to evaluate theeffectiveness of various soil conservation measures.Maize (Zea mays) cropping treatments, typicallyemployed in local agronomic practices, are applied to30 erosion plots at 3 different slope angles, cultivatedboth parallel and perpendicular to the contour, thussimulating a range of agricultural conditions on arableslopes. Plot data from 1993-1996 suggest severalsuitable soil conservation measures. Erosion rates weregenerally lower on plots where contour cultivation wasused. The mean contour cultivation erosion rate was 0.69of the mean downslope orientated cultivation rate. Strawmulch and contour cultivation seem particularlysuitable soil conservation measures.
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