The price of soil erosion : an economic evaluation of soil conservation and watershed development

Soil erosion by water is the principal cause of land degradation, and a major constraint to agricultural development in developing countries. In semi-arid zones measures have to be taken to reduce on-site soil, water and nutrient losses and in sub-humid mountainous zones the focus should also be on reducing sedimentation of reservoirs and on other downstream effects. Soil conservation and watershed development activities and projects are hard to evaluate, since neither their effects nor their beneficiaries can be easily detected. Methods are developed to identify potential participants and to assess on-site and downstream effects of conservation measures, by using water and nutrient balances and yield response functions. In the evaluation of these projects cost-benefit analysis (CBA) and multi-criteria analysis (MCA) can complement each other. The efficiency of the projects can be conveniently assessed with CBA, when the effects can be quantified and valued. And MCA can be used to assess scores on non-monetary attributes of the efficiency, equity and conservation criteria, and to show how conflicting objectives of different actors affect the scores.