Seasonal and Decadal Groundwater Changes in African Sedimentary Aquifers Estimated Using GRACE Products and LSMs
Seasonal and Decadal Groundwater Changes in African Sedimentary Aquifers Estimated Using GRACE Products and LSMs
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DOI：
10.3390/rs10060904
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发表时间：
2018-06
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影响因子：
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通讯作者：
H. Bonsor;M. Shamsudduha;B. Marchant;A. Macdonald;R. Taylor
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作者：
H. Bonsor;M. Shamsudduha;B. Marchant;A. Macdonald;R. Taylor
增加地下水抽取量对非洲的经济发展和实现许多可持续发展目标至关重要。然而，由于缺乏现场监测，关于地下水长期或季节性趋势的资料很少。在这里，我们使用了三种产品的GRACE数据，（空间研究中心陆地解决方案（CSR），喷气推进实验室的全球Mascon解决方案）（JPL-MSCN）和国家空间研究中心/大地测量空间解决方案研究小组（GRGS）），研究12个非洲沉积含水层的陆地水储存变化，研究陆地水储存与降雨之间的关系，利用4种陆面模型（CLM2.0、维克、MOSAIC和NOAH）估算地下水储量变化。我们发现，从2002年到2016年，任何非洲盆地的地下水储量都没有明显的持续长期下降趋势，但是，在Iullemmeden和塞内加尔盆地分别确定了约1 km 3/年和1.5 km 3/年的地下水持续上升趋势，以及与降雨模式相关的几个盆地ΔTWS的长期变化。GRACE显示，除刚果、北喀拉哈里和塞内加尔盆地外，每个盆地的离散季节性ΔTWS响应为±1-5 cm/年，这些盆地显示出较大的季节性ΔTWS，相当于约。±11-20 cm/年。ΔTWS的不同季节响应提供了关于地下水的有用信息，包括确定许多半干旱和干旱盆地5至9个月的降雨累积期，以及萨赫勒和南部非洲含水层对类似降雨的ΔTWS响应差异，这可能反映了土地覆盖的差异。通过GRACE ΔTWS与LSM输出相结合估算的季节性ΔGWS与不同流域地下水补给的现场测量结果不一致，突出了进一步发展LSM补给过程的代表性的必要性以及通过测压进行更多现场观测的必要性。
Increased groundwater abstraction is important to the economic development of Africa and to achieving many of the Sustainable Development Goals. However, there is little information on long-term or seasonal groundwater trends due to a lack of in situ monitoring. Here, we used GRACE data from three products (the Centre for Space Research land solution (CSR), the Jet Propulsion Laboratory’s Global Mascon solution (JPL-MSCN), and the Centre National D’etudes Spatiales / Groupe de Recherches de Geodesie Spatiale solution (GRGS)), to examine terrestrial water storage (TWS) changes in 12 African sedimentary aquifers, to examine relationships between TWS and rainfall , and estimate groundwater storage (GWS) changes using four Land Surface Models (LSMs) (Community Land Model (CLM2.0), the Variable Infiltration Capacity model (VIC), the Mosaic model (MOSAIC) and the Noah model (NOAH)). We find that there are no substantial continuous long-term decreasing trends in groundwater storage from 2002 to 2016 in any of the African basins, however, consistent rising groundwater trends amounting to ~1 km3/year and 1.5 km3/year are identified in the Iullemmeden and Senegal basins, respectively, and longer term variations in ΔTWS in several basins associated with rainfall patterns. Discrete seasonal ΔTWS responses of ±1–5 cm/year are indicated by GRACE for each of the basins, with the exception of the Congo, North Kalahari, and Senegal basins, which display larger seasonal ΔTWS equivalent to approx. ±11–20 cm/year. The different seasonal responses in ΔTWS provide useful information about groundwater, including the identification of 5 to 9 month accumulation periods of rainfall in many semi-arid and arid basins as well as differences in ΔTWS responses between Sahelian and southern African aquifers to similar rainfall, likely reflecting differences in landcover. Seasonal ΔGWS estimated by combining GRACE ΔTWS with LSM outputs compare inconsistently to available in situ measurements of groundwater recharge from different basins, highlighting the need to further develop the representation of the recharge process in LSMs and the need for more in situ observations from piezometry.