Seasonal and decadal groundwater changes in African sedimentary aquifers estimated using GRACE products and LSMs

Bonsor, H.C.; Shamsudduha, M.; Marchant, B.P.; MacDonald, A.M. ORCID:; Taylor, R.G.. 2018 Seasonal and decadal groundwater changes in African sedimentary aquifers estimated using GRACE products and LSMs. Remote Sensing, 10 (6), 904.

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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 CSR, JPL-MCN and GRGS to examine Terrestrial Water Storage (TWS) changes in 12 African sedimentary aquifers, to examine relationships between TWS and rainfall from TRMM, and estimate Groundwater Storage (GWS) changes using four LSMs CLM2.0, VIC, MOSAIC and NOAH. We find that there are no substantial continuous longterm decreasing trends in groundwater storage from 2002 to 2016in 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 recharge process in LSMs and the need for more in situ observations from piezometry.

Item Type: Publication - Article
Digital Object Identifier (DOI):
ISSN: 20724292
Additional Keywords: GroundwaterBGS, Groundwater, Environmental change, Groundwater resources
Date made live: 06 Aug 2018 09:14 +0 (UTC)

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