旺达共和国山地丘陵区土壤侵蚀调查报告

Investigation Report on Soil Erosion in Mountain and Hilly Regions of Republic of Rwanda

[目的]在卢旺达山地丘陵区开展土壤侵蚀调查,分析该区土壤侵蚀特征及成因,为尼罗河上游山地丘陵区土壤侵蚀预报和水土流失防治提供科学依据。[方法]在卢旺达布设4条调查路线并选择调查点,于2019年10月17-22日对调查点土壤侵蚀特征、成因及水土保持措施等进行了调查。[结果]卢旺达多山地且以农牧业为主,土壤侵蚀主要发生在坡耕地、损毁林地、建设用地等。坡耕地以片蚀和细沟侵蚀为主。损毁林地以片蚀和细沟侵蚀为主,部分出现沟蚀;当裸露地表形成草地或幼林后均较少发生土壤侵蚀。公路边坡、开挖边坡、土路路面及边坡等在降雨及径流的作用下产生沟蚀,部分路段偶有勤侵蚀发生。梯田是该国最主要的水土保持措施,具有较好的生态和经济效益。[结论]卢旺达土壤侵蚀主要以水力侵蚀为主,重力侵蚀次之。不合理的开垦坡地、毁林,加之多山的地形,导致侵蚀较为严重,威胁当地的生态安全及粮食安全。该区缺乏水土流失监测资料,需要重视水土保持基础理论研究,加强水土流失基础数据的监测和采集,同时需要加强其水土保持措施及土地管理工作,保障卢旺达农业的可持续绿色发展。

[Objective]The field investigation of soil erosion was carried out in mountain and hilly regions of the Republic of Rwanda to analyze the characteristics and reasons of soil erosion,in order to provide basis for soil erosion prediction and control in the mountainous and hilly areas of the upper reaches of the Nile River.[Methods]Four investigation routes were selected,soil erosion characteristics and reasons,and soil and water conservation measures were investigated from October 17 to 22,2019 in Rwanda.[Results]The Republic of Rwanda is mountainous and dominated by agriculture and animal husbandry.Soil erosion mainly occurs in slope farmland,deforested land and construction land.Slope farmland is dominated by sheet erosion and ditch erosion.Destroyed land is dominated by sheet erosion and gully erosion,and part of it appears gully erosion.When grass or young forest is formed on bare ground,soil erosion is less likely to occur.Gully erosion is caused by rainfall and runoff on roadside slope,excavated slopes and dirt road surface and slopes.Gravity erosion occasionally occurs on some roadside slopes.To prevent soil erosion,terrace is the most important soil and water conservation measure with significant ecological and economic benefits.[Conclusion]Soil erosion in Rwanda is dominated by water erosion,followed by gravity erosion.Unreasonable reclamation of sloping land,deforestation,and mountainous topography have caused severe soil erosion,and threatened food security as well as the safe ecology.Rwanda lacks monitoring data on soil and water loss at present.Thus,it is urgent and necessary to attach importance to the basic theoretical research of soil and water conservation,to strength the monitoring and collection of basic data of soil and water loss,to promote the implementation of soil and water conservation measures and land management,and to ensure the sustainable and green development of agriculture in Rwanda.