Estimating seasonal water budgets in global lakes by using multi-source remote sensing measurements

The seasonal change in lake water storage (LWSsc) reflect periodic fluctuations of the basin-scale water balance. However, the role of LWSsc in regulating the water budget at the global scale has not yet been investigated based on straight-forward observations. Quantifying LWSsc is necessary, especially under the context of global change. Available in-situ measurements of lake water levels and volumes are still scarce. Therefore, the Global Surface Water datasets of Joint Research Centre and multi-source satellite altimetry datasets through mathematical statistics methods are used in this study to address this issue. We estimate the LWSsc of 463 lakes and reservoirs worldwide with areas greater than 10 km(2), which represent nearly 64% of the total global lake area and 93% of the total lake volume capacity. Results show that the global seasonal water storage variation of these examined water bodies is 1390.91 +/- 78.91 km(3), comprising 869.44 +/- 67.35 km(3) from lakes and 521.46 +/- 41.11 km(3) from reservoirs. The relatively large estimates of LWSsc are concentrated in North American and African basins. Among the watersheds, the seasonal fluctuations of lakes in the North American Lawrence basin make up the most substantial magnitude of 10.76% of the global LWSsc. The latitudinal direction zonality of LWSsc is relatively significant. The LWSsc is concentrated between 30 degrees N and 60 degrees N in the northern hemisphere and between the equator and 30 degrees S in the southern hemisphere. Considering the geographic similarity and climatological zonality, the global LWSsc estimates are also extrapolated to other lakes without direct satellite altimetry observations on the basis of the average rate of the examined lakes distributed in the same Koppen Geiger Climate Classification zones. The LWSsc is calculated with a consequence of 488.23 +/- 14.72 km(3) for these extrapolated lakes, indicating an estimate of 1357.67 +/- 68.94 km(3) for the LWSsc of the global natural lakes (>10 km2). This initial estimation of LWSsc at a global scale will greatly help the improvement of our understanding of the seasonal behavior of lakes and reservoirs in regulating global and regional water cycles and the contribution of terrestrial water storage to sea level rise.

Automated summary

This study estimated the seasonal water storage variation of 463 lakes and reservoirs worldwide, finding that North American and African basins have relatively large seasonal water storage changes globally. The latitudinal zonality of LWSsc is significant, concentrated between 30 degrees N and 60 degrees N in the northern hemisphere and between the equator and 30 degrees S in the southern hemisphere.