Kalu Ikechukwu, Ndehedehe Christopher E, Ferreira Vagner G, Janardhanan Sreekanth, Currell Matthew, Kennard Mark J
School of Environment and Science, Griffith University, Nathan, QLD, 4111, Australia.
Australian Rivers Institute, Griffith University, Nathan, QLD, 4111, Australia.
Sci Rep. 2024 May 2;14(1):10113. doi: 10.1038/s41598-024-60366-2.
The coarse spatial resolution of the Gravity Recovery and Climate Experiment (GRACE) dataset has limited its application in local water resource management and accounting. Despite efforts to improve GRACE spatial resolution, achieving high resolution downscaled grids that correspond to local hydrological behaviour and patterns is still limited. To overcome this issue, we propose a novel statistical downscaling approach to improve the spatial resolution of GRACE-terrestrial water storage changes (ΔTWS) using precipitation, evapotranspiration (ET), and runoff data from the Australian Water Outlook. These water budget components drive changes in the GRACE water column in much of the global land area. Here, the GRACE dataset is downscaled from the original resolution of 1.0° × 1.0° to 0.05° × 0.05° over a large hydro-geologic basin in northern Australia (the Cambrian Limestone Aquifer-CLA), capturing sub- grid heterogeneity in ΔTWS of the region. The downscaled results are validated using data from 12 in-situ groundwater monitoring stations and water budget estimates of the CLA's land water storage changes from April 2002 to June 2017. The change in water storage over time (ds/dt) estimated from the water budget model was weakly correlated (r = 0.34) with the downscaled GRACE ΔTWS. The weak relationship was attributed to the possible uncertainties inherent in the ET datasets used in the water budget, particularly during the summer months. Our proposed methodology provides an opportunity to improve freshwater reporting using GRACE and enhances the feasibility of downscaling efforts for other hydrological data to strengthen local-scale applications.
重力恢复与气候实验（GRACE）数据集粗糙的空间分辨率限制了其在当地水资源管理与核算中的应用。尽管人们努力提高GRACE的空间分辨率，但要获得与当地水文行为和模式相对应的高分辨率降尺度网格仍存在局限性。为克服这一问题，我们提出了一种新颖的统计降尺度方法，利用来自《澳大利亚水资源展望》的降水、蒸散（ET）和径流数据来提高GRACE陆地水储量变化（ΔTWS）的空间分辨率。在全球大部分陆地区域，这些水分收支组成部分驱动着GRACE水柱的变化。在此，GRACE数据集在澳大利亚北部一个大型水文地质盆地（寒武纪石灰岩含水层 - CLA）上从原始的1.0°×1.0°分辨率降尺度到0.05°×0.05°，捕捉该区域ΔTWS中的亚网格异质性。利用12个现场地下水监测站的数据以及2002年4月至2017年6月期间CLA陆地水储量变化的水分收支估算值对降尺度结果进行了验证。从水分收支模型估算的随时间的储水量变化（ds/dt）与降尺度后的GRACE ΔTWS弱相关（r = 0.34）。这种弱关系归因于水分收支中使用的ET数据集可能存在的不确定性，特别是在夏季月份。我们提出的方法为利用GRACE改进淡水报告提供了机会，并增强了对其他水文数据进行降尺度以加强局部尺度应用的可行性。
