Attribution of changes in hydrologic extremes to changing land cover

Changes in hydrological extremes over time are driven by the combined influence of shifts in climate patterns and changes in land cover. However, the lack of global data on changing land cover at catchment scales has hindered our understanding of the influence of land cover on streamflow distributions, and especially extremes.

Here we use a global dataset of changes in annual land cover over the past 25 years alongside climate and catchment characteristics. We develop a statistical attribution procedure to quantify the influence of changes in land cover on different quantiles of the streamflow distribution, ranging from low flows to high flows.

We consider four broad land cover classes: urban land, shrub/grassland, cropland, and tree cover, to answer the following questions:

What is the relative importance of different land cover classes in explaining the variance of hydrological extremes? How have changes in land cover contributed to the changes in flow distributions? Where are these changes the most significant?

By quantifying the effects of changing land cover on hydrological extremes, we provide some insight into the effects of future land cover scenarios on water resources, and how changes in land cover might be used as a tool to manage hydrological extremes.