Comparing Rainfall Use Efficiency Trends with Expert Judgments for Nation-Wide Land Degradation Assessments: The Case of Senegal

Abstract

This study compares the results of two nationwide land degradation assessments for Senegal. The first approach is based on expert judgments, the second on trend analyses of Rainfall Use Efficiency (RUE). The comparison yields some interpretable results for extreme negative RUE slope values with maximum degrees of land degradation as indicated by experts, yet, overall, the correlation between both approaches proves to be low and without clear sign. As RUE trend analysis suffers from several inherent methodological problems and expert judgments are found to be consistent we consider expert opinions as the preferable option for a nation-wide land degradation assessment in Senegal. Yet, we argue that methodological improvements would increase the explanatory power of the expert approach and consolidate its position in a policy making framework.