A national-level land degradation risk monitoring system identified an important grazing area in central northern Namibia as an area at risk of environmental change. A time series analysis of primary indicators used for this monitoring system for the period 1971-2001 shows that increase in livestock pressure and high rainfall variability are potential threats. The study presented here compares these national-level results with those obtained by interviewing local farmers about their perceptions of past and present states of the environment in the grazing area. Keywords: semi-arid, local knowledge, rainfall variability, water supply, grazing, land management.