Economic and environmental effects of land use on water yield and sediment: A case study in Colombia

Abstract

Scope and Method of Study: This dissertation covers a set of watershed management problems faced by social planers in the eastern part of the province of Antioquia, (Colombia). This dissertation aims to shed light on the sustainable management practices in the Rionegro watershed of Antioquia by approaching different alternatives of land use and their economic and environmental effects on water yield and soil erosion. Natural forestry, shifting cultivation, and agroforestry are analyzed according to the physical, climatic, and economic characteristics of the watershed.

Findings and Conclusions: Using the Erosion Productivity Impact Calculator (EPIC) model, different simulations were performed in order to estimate the environmental effects of three main activities: natural forest, shifting cultivation, and agroforestry in terms of erosion, runoff, and organic carbon. Soil classes and different slopes were considered for simulating the environmental effects of land use. From the outcomes of EPIC, a linear programming model was developed to maximize the net present value of revenues derived from the agricultural activities. Erosion, runoff, labor, and land constraints were defined to estimate the model. Shifting cultivation appears to be the most erosive land practice. The less erosive land practice is natural forest followed by agroforestry. The dissertation recommends the implementation of an incentive system in order to encourage subsistence farmers to convert their lands from shifting cultivation to agroforestry.