WATERSHED DEGRADATION OVER TIME
Trends over time in watershed degradation in urban source watersheds, median cropland and rangeland coverage, as well as population density i.
Over the past century, the median population density in source watersheds has increase five-fold and the proportion of source watershed converted to cropland has doubled while pastureland has more than tripled. In the absence of robust watershed management, the problem will grow more severe in the coming years, with cropland projected to increase ten percent and fertilizer use fifty-eight percent by 2030.Access Study
i. McDonald et al, 2016, Estimating watershed degradation over the last century and its impact on water-treatment costs for the world’s large cities, Proceedings of the National Academy of Sciences (PNAS), 113 ( 32), 9117–9122.