中文摘要：

沂蒙山区是我国北方典型的土石山区，当地土壤由片麻岩、砂岩发育而来，质地疏松易流失，缺乏对泥沙侵蚀监测的长期观测数据。本研究采集了山东省沂蒙山区某一小流域的48个土样共72个样品，利用137cs示踪技术，确定该地区土壤中的137cs背景值约为1740Bqm^-2，并利用杨浩等人的土壤侵蚀定量模型，对该流域土壤侵蚀进行了初步估算。估算结果表明该地区非耕地土壤侵蚀的平均速率为2531tkm^-2a^-1，坡耕地土壤侵蚀的平均速率为6953tkm^-2a^-1。由于人类耕作活动以及地形的影响，坡耕地土壤侵蚀严重，土壤侵蚀速率在坡面上呈复杂变化。当地土壤流失严重，使得土壤涵蓄水能力下降，加剧了洪涝、干旱灾害的发生，影响当地农业的可持续发展和人们生活水平的提高。

英文摘要：

An experiment was carried out in the Yimeng Mountains, a typical earth-rocky mountainous region, in Shandong Province, China. Derived from gneiss and sandstone, the soil therein is loosen in texture and susceptible to soil erosion. Owing to lack of historical data on soil erosion and sediment transferring, it is hard to predict any medium-long term （50 a） mean soil erosion rate. The method of using 137Cs as soil tracer makes it feasible to study soil redistribution on a catchment scale. Moreover, it is reliable and time-and labor-saving. In this experiment this technique was used to study soil erosion and deposition rates in the area. A total of 72 samples were collected and tested for contents of 137Cs. Based on the findings, the background value of 137Cs of the catchment for the first time defined as 1740 Bq m^-2137Cs Soil erosion and deposition were calculated by following the soil erosion model constructed by Yang Hao. Results show that the mean soil redistribution rate of uncultivated soil is 2 530.5 t km-2a^-1and the cultivated land is 6 952.5 t km^-2a^-1 on the slope. And the soil erosion and deposition rates are influenced by human cultivated activities and the complex variability of concave and convexity on slopes. The soil in the region is severely eroded, causing decline in water retention capacity of the soil, triggering frequent floods and droughts, and eventually affecting sustainable development of the agriculture and living standard of the people in the region.