Abstract
The water budget equation describes the exchange of water between the land, ocean and atmosphere. Being able to adequately close the water budget gives confidence in our ability to model and/or observe the spatiotemporal variations in the water cycle and its components. Due to advances in observation techniques, satellite sensors, and modelling, a number of data products are available that represent the components of water budget both in space and time. Despite these advances, closure of the water budget at global scale has been elusive.In this study, first we attempt to close the global water budget using precipitation, evapotranspiration, and runoff data at the catchment scale. We use a large number of state-of-the-art datasets to estimate water storage changes. These estimates are then compared to terrestrial water storage (TWS) changes as measured by the GRACE satellite mission. We investigated 189 river basins covering more than 90 % of the continental land area. Secondly, we developed an optimization framework using the water balance equation to reconstruct TWS time-series from 1981 to the start of the GRACE mission. The results were then compared with state-of-the-art TWS reconstructions.
We found that TWS changes obtained from the water balance equation were more accurate than the long-term mean of GRACE time-series in 99 % of the basins examined, and better than the monthly mean in 62% of the basins. By analyzing different combinations of the datasets that make up the water balance, we identified data products that performed well in certain
regions. Although our TWS reconstruction was comparable with existing ones, we observed large uncertainties between reconstructions. This shows that a better understanding of underlying trends in datasets is needed, especially for the last decades, to improve our understanding of the spatiotemporal variations in TWS.
Date of Award | 25 Jan 2022 |
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Original language | English |
Awarding Institution |
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Supervisor | Jonathan L Bamber (Supervisor) & Bramha Vishwakarma (Supervisor) |
Keywords
- water balance equation
- terrestrial water storage
- water cycle