title: USLE-Based Assessment of Soil Erosion by Water in the Nyabarongo River Catchment, Rwanda.
abstract: Soil erosion has become a serious problem in recent decades due to unhalted trends of unsustainable land use practices. Assessment of soil erosion is a prominent tool in planning and conservation of soil and water resource ecosystems. The Universal Soil Loss Equation (USLE) was applied to Nyabarongo River Catchment that drains about 8413.75 km² (33%) of the total Rwanda coverage and a small part of the Southern Uganda (about 64.50 km²) using Geographic Information Systems (GIS) and Remote Sensing technologies. The estimated total annual actual soil loss was approximately estimated at 409 million tons with a mean erosion rate of 490 t·ha(-1)·y(-1) (i.e., 32.67 mm·y(-1)). The cropland that occupied 74.85% of the total catchment presented a mean erosion rate of 618 t·ha(-1)·y(-1) (i.e., 41.20 mm·y(-1)) and was responsible for 95.8% of total annual soil loss. Emergency soil erosion control is required with a priority accorded to cropland area of 173,244 ha, which is extremely exposed to actual soil erosion rate of 2222 t·ha(-1)·y(-1) (i.e., 148.13 mm·y(-1)) and contributed to 96.2% of the total extreme soil loss in the catchment. According to this study, terracing cultivation method could reduce the current erosion rate in cropland areas by about 78%. Therefore, the present study suggests the catchment management by constructing check dams, terracing, agroforestry and reforestation of highly exposed areas as suitable measures for erosion and water pollution control within the Nyabarongo River Catchment and in other regions facing the same problems.
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. fidelekaramage@yahoo.com.|University of Chinese Academy of Sciences, Beijing 100049, China. fidelekaramage@yahoo.com.|Faculty of Environmental Studies, University of Lay Adventists of Kigali (UNILAK), P.O. 6392, Kigali, Rwanda. fidelekaramage@yahoo.com.
authors.forename: Fidele
authors.initials: F
authors.lastname: Karamage
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. zc@ms.xjb.ac.cn.|School of Resources Environment Science and Engineering, Hubei University of Science and Technology, Xianning 437000, China. zc@ms.xjb.ac.cn.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. kayiranga2020@yahoo.co.uk.|University of Chinese Academy of Sciences, Beijing 100049, China. kayiranga2020@yahoo.co.uk.|Faculty of Environmental Studies, University of Lay Adventists of Kigali (UNILAK), P.O. 6392, Kigali, Rwanda. kayiranga2020@yahoo.co.uk.
authors.forename: Alphonse
authors.initials: A
authors.lastname: Kayiranga
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. shaohua@ms.xjb.ac.cn.|University of Chinese Academy of Sciences, Beijing 100049, China. shaohua@ms.xjb.ac.cn.
authors.forename: Hua
authors.initials: H
authors.lastname: Shao
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. sun@163.com.|University of Chinese Academy of Sciences, Beijing 100049, China. sun@163.com.
authors.forename: Xia
authors.initials: X
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. davfelix@yahoo.fr.|University of Chinese Academy of Sciences, Beijing 100049, China. davfelix@yahoo.fr.|Faculty of Environmental Studies, University of Lay Adventists of Kigali (UNILAK), P.O. 6392, Kigali, Rwanda. davfelix@yahoo.fr.
authors.forename: Felix
authors.initials: F
authors.lastname: Ndayisaba
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. lameknahayo@gmail.com.|University of Chinese Academy of Sciences, Beijing 100049, China. lameknahayo@gmail.com.|Faculty of Environmental Studies, University of Lay Adventists of Kigali (UNILAK), P.O. 6392, Kigali, Rwanda. lameknahayo@gmail.com.
authors.forename: Lamek
authors.initials: L
authors.lastname: Nahayo
authors.affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. mupenzic@gmail.com.|University of Chinese Academy of Sciences, Beijing 100049, China. mupenzic@gmail.com.|Faculty of Environmental Studies, University of Lay Adventists of Kigali (UNILAK), P.O. 6392, Kigali, Rwanda. mupenzic@gmail.com.
authors.forename: Christophe
authors.initials: C
authors.lastname: Mupenzi
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. tianguangjin@bnu.edu.cn.
authors.forename: Guangjin
authors.initials: G
authors.lastname: Tian
mesh_terms: D003247:Conservation of Natural Resources; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D040362:Geographic Information Systems; D058998:Remote Sensing Technology; D012432:Rwanda; D012987:Soil; D014454:Uganda; D014872:Water Movements
chemical_list: D012987:Soil
keywords: GIS; Nyabarongo River Catchment; Rwanda; USLE; cropland; land-cover and land-use; remote sensing; soil erosion; water pollution