School of Engineering, University of Newcastle, Callaghan 2308, Australia.
School of Earth and Planetary Sciences, Spatial Sciences, Curtin University, Perth 6102, Australia.
Sensors (Basel). 2021 Jun 23;21(13):4304. doi: 10.3390/s21134304.
During the period 2019-2020, Lake Victoria water levels rose at an alarming rate that has caused various problems in the region. The influence of this phenomena on surface and subsurface water resources has not yet been investigated, largely due to lack of enough in situ measurements compounded by the spatial coverage of the lake's basin, incomplete/inconsistent hydrometeorological data, and unavailable governmental data. Within the framework of joint data assimilation into a land surface model from multi-mission satellite remote sensing, this study employs the state-of-art Gravity Recovery and Climate Experiment follow-on (GRACE-FO) time-variable terrestrial water storage (TWS), newly released ERA-5 reanalysis, and satellite radar altimetry products to understand the cause of the rise of Lake Victoria on the one hand, and the associated impacts of the rise on the total water storage compartments (surface and groundwater) triggered by the extreme climatic event on the other hand. In addition, the study investigates the impacts of large-scale ocean-atmosphere indices on the water storage changes. The results indicate a considerable increase in water storage over the past two years, with multiple subsequent positive trends mainly induced by the Indian Ocean Dipole (IOD). Significant storage increase is also quantified in various water components such as surface water and water discharge, where the results show the lake's water level rose by ∼1.4 m, leading to approximately 1750 gigatonne volume increase. Multiple positive trends are observed in the past two years in the lake's water storage increase with two major events in April-May 2019 and December 2019-January 2020, with the rainfall occurring during the short rainy season of September to November (SON) having had a dominant effect on the lake's rise.
在 2019 年至 2020 年期间，维多利亚湖水位以惊人的速度上升，给该地区造成了各种问题。由于缺乏足够的现场测量数据，加上湖泊流域的空间覆盖范围、不完全/不一致的水文气象数据以及无法获得的政府数据，这一现象对地表水和地下水资源的影响尚未得到调查。在多任务卫星遥感数据联合同化到陆地表面模型的框架内，本研究利用最先进的重力恢复和气候实验后续（GRACE-FO）时变陆地水储量（TWS）、新发布的 ERA-5 再分析以及卫星雷达测高产品，一方面了解维多利亚湖水位上升的原因，另一方面了解由极端气候事件引发的上升对总储水层（地表水和地下水）的相关影响。此外，该研究还调查了大尺度海洋-大气指数对储水变化的影响。结果表明，在过去两年中，储水量有了相当大的增加，并且随后出现了多个正趋势，主要是由印度洋偶极子（IOD）引起的。还定量评估了各种水成分（如地表水和排水量）中的储水增加，结果表明，湖泊水位上升了约 1.4 米，导致体积增加了约 1750 吉吨。在过去的两年中，观察到湖泊储水增加的多个正趋势，其中两个主要事件发生在 2019 年 4 月至 5 月和 2019 年 12 月至 2020 年 1 月，发生在 9 月至 11 月（SON）短雨季的降雨对湖泊的上升产生了主导影响。
