Decadal Changes in River Channel Water Storage Variation from Multi-Remote Sensed Data

Abstract:

Rivers are one of the most important ways for human societies to interact with their surface water resources. Channel Water Storage (CWS) variation derived from altimeter height and Landsat width data present a new way to understand surface water resources both quantitatively and spatially. Global Climate change and direct human interaction are certain to have an effect on how rivers store their water, but the nature and extent of this change is poorly understood, particularly in basins without traditional gage networks. Here we present an analysis the change in amplitude of the CWS cycle from 26 of the world’s largest rivers over 25 years of observation. Our preliminary results find that ~27% of study rivers show trends of increases in CWS variation (max 26.4% increase on Amazon), indicating more drought and flood periods. However, ~65% show decreases in CWS variation (max 44% reduction on the Congo), indicating more moderate conditions. Two study rives showed no notable change (Yukon and St Lawrence). Three Northern rivers (above 40° N) show increased CWS variation, while two show very little change, and three show decreasing trends. High Northern latitude (primarily Arctic) rivers have been shown to have increased, more modulated discharge as glaciers and permafrost thaw at increasing rates. It is expected that this will be followed by a tapering as glacier mass is reduced. These three groups could be showing the later, mid and early stages of this process. The Brahmaputra River shows a 15.3% reduction in its CWS amplitude while the Ganges showed a 26% increase. The proximity and similarity of these basins points to management efforts being responsible for modulation of the signal. We will further explore man-made impacts on the CWS signal wherever possible in our study rivers.