Soil losses in the State of Rondônia, Brazil

ABSTRACT: In the state of Rondônia, deforestation, and inadequate soil use and management have intensified the water erosion process, causing degradation of agricultural land. Modeling is a tool that can assist in the adoption of targeted and effective measures for soil and water conservation in the region. In this context, the objective of the research was to model soil losses due to water erosion in the state of Rondônia using the Revised Universal Soil Loss Equation (RUSLE). The parameters related to rain erosivity, relief, erodibility, and soil cover, as well as the conservation practices of the state of Rondônia, were considered. The modeling steps were performed with the aid of the Geographic Information System. Results were validated with data of total sediments transported with water discharge. The estimated total soil loss was about 605 million tons per year, corresponding to an average loss of 22.50 Mg ha-1 year-1. In 19% of the state, the erosion rate was higher than the soil loss tolerance(T), and these areas should be prioritized for adopting measures to mitigate the erosion process. The RUSLE underestimated the generation of sediments at 0.56 Mg ha-1 year-1, which corresponds to an error of 18.60%. Results obtained can assist in the development of different soil use and management scenarios and provide options for policymakers to encourage soil conservation in the state of Rondônia.

摘要：在朗多尼亚州，森林砍伐、不合理的土地利用与管理加剧了水力侵蚀过程，导致农用地退化。建模是辅助该区域采取精准有效水土保持措施的重要工具。在此背景下，本研究采用修正通用土壤流失方程（Revised Universal Soil Loss Equation, RUSLE），针对朗多尼亚州的水力侵蚀土壤流失量开展建模研究。研究纳入了与降雨侵蚀力、地形、土壤可蚀性、土壤覆盖度以及朗多尼亚州水土保持措施相关的各类参数，建模过程借助地理信息系统（Geographic Information System, GIS）完成。以径流输沙总量数据对模型结果进行验证后，结果显示：模拟得到的年土壤流失总量约为6.05亿吨，对应平均流失强度为22.50 兆克·公顷⁻¹·年⁻¹（即22.50吨·公顷⁻¹·年⁻¹）；该州19%的区域侵蚀速率超过了土壤允许流失量（T），此类区域应优先采取措施以减缓侵蚀过程。修正通用土壤流失方程对产沙量的估算偏低0.56 兆克·公顷⁻¹·年⁻¹，相对误差达18.60%。本研究结果可为构建多样化土地利用与管理情景提供支撑，同时可为政策制定者制定朗多尼亚州水土保持激励政策提供参考依据。