Analyses of groundwater storage change using GRACE satellite data in the Usutu-Mhlatuze drainage region, north-eastern South Africa

Ramjeawon, Manish; Demlie, Molla; Toucher, Michele

doi:10.1016/j.ejrh.2022.101118

Cited by 11 publications

(7 citation statements)

References 26 publications

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“…Temperature (Tmp) and precipitation (Pre) are the most widely studied and important meteorological factors. Previous studies also showed that Tmp and Pre have significant effects on the variation in GWS [23,50].…”

Section: Temperature and Precipitationmentioning

confidence: 81%

Spatiotemporal Variation Characteristics of Groundwater Storage and Its Driving Factors and Ecological Effects in Tibetan Plateau

Ren,

Gao,

Qian

et al. 2023

Remote Sensing

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Known as the “Asian Water Tower”, the Tibetan Plateau (TP) is a rich water resource and serves an important ecological function. Climate change may cause changes to the water cycle, and these changes may affect the alpine vegetation growth. However, the variation characteristics of groundwater storage (GWS) and its driving factors and associated ecological effects in the TP are poorly understood. In this study, terrestrial water storage changes retrieved by GRACE (Gravity Recovery and Climate Experiment) were combined with GLDAS (Global Land Data Assimilation System) to estimate the GWS changes in the TP. The temporal and spatial variation characteristics of GWS were identified using linear regression and the modified Mann–Kendall (MMK) test, respectively. The analyses showed that the GWS of the TP decreased at an average rate of −0.89 mm/a from January 2003 to December 2021, but since January 2016, it gradually recovered at a rate of 1.47 mm/a. This shows that the GWS in the eastern and northern parts of the TP is decreasing, while the GWS in the western and southern parts is increasing. The influence of climate change on GWS in time and space was determined using the correlation analysis method. Decreased precipitation and permafrost degradation caused by increasing temperatures will lead to a decrease in GWS. On the other hand, rising temperatures may result in an increase in GWS in regions where glaciers are distributed. In this study, the ecological effects were represented by the relationship between GWS and vegetation change. A decline in GWS means that the vegetation will not receive enough water, leading to a decrease in the NDVI and the eventual degradation of grassland to sand, desert, or other kinds of unused land on the TP. On the other hand, an increase in GWS would promote vegetation restoration. The results of this study offer a new opportunity to reveal the groundwater changes in a cryosphere region and to assess the impact of changes in hydrological conditions on ecology.

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Section: Temperature and Precipitationmentioning

confidence: 81%

Spatiotemporal Variation Characteristics of Groundwater Storage and Its Driving Factors and Ecological Effects in Tibetan Plateau

Ren,

Gao,

Qian

et al. 2023

Remote Sensing

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“…Ouma et al (2015) investigated interannual GW variability in the Nzoia River Basin in Kenya and found strong correlation with drought periods and ENSO years. In the very south of Africa, Ramjeawon et al (2022) derived GW storage anomalies from GRACE and the GLDAS land surface model and validated them with in situ GW observations. They found similar trends and significant correlations with uncertainties arising from the resolution mismatch and limited number of boreholes.…”

Section: Examples Of Groundwater Storage Evolution Over the African C...mentioning

confidence: 90%

The Role of Space-Based Observations for Groundwater Resource Monitoring over Africa

et al. 2023

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Africa is particularly vulnerable to climate change impacts, which threatens food security, ecosystem protection and restoration initiatives, and fresh water resources availability and quality. Groundwater largely contributes to the mitigation of climate change effects by offering short- to long-term transient water storage. However, groundwater storage remains extremely difficult to monitor. In this paper, we review the strengths and weaknesses of satellite remote sensing techniques for addressing groundwater quantity issues with a focus on GRACE space gravimetry, as well as concepts to combine satellite observations with numerical models and ground observations. One particular focus is the quantification of changes in groundwater resources in the different climatic regions of Africa and the discussion of possible climatic and anthropogenic drivers. We include a thorough literature review on studies that use satellite observations for groundwater research in Africa. Finally, we identify gaps in research and possible future directions for employing satellite remote sensing to groundwater monitoring and management on the African continent. Article Highlights Overview on the distribution and characteristics of African groundwater resources including future projections Combination of satellite and in situ observations with numerical models allows us to obtain a synoptic view of groundwater-related processes Summary of current concepts and achievements of satellite remote sensing-based groundwater monitoring and decision making over Africa

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“…For smaller areas below the footprint of GRACE (100,000 km 2 ), the application of GRACE has been validated to estimate groundwater storage changes (Biancamaria et al, 2019;Ouma et al, 2015;Liesch and Ohmer, 2016;Rahimzadegan and Entezari, 2019;Ramjeawon et al, 2022). The direct comparison between a single GRACE grid with in situ data has been used in previous studies (Yin et al, 2020;Neves et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…These two approaches are derived from in-situ and remote sensing data, respectively. Although it is generally recommended to use the GRACE products for regional scales (>100,000 km 2 ), some recent studies have showed satisfactory results, in which GRACE was applied with a smaller scale or partial grid (Hachborn et al, 2017;Liesch and Ohmer, 2016;Neves et al, 2020;Ramjeawon et al, 2022). Therefore, the specific objectives of this study are as follows:…”

Section: Introductionmentioning

confidence: 99%

Groundwater Recharge Estimation Using In-Situ and Grace Observations in the Eastern Region of the United Arab Emirates

et al. 2022

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Analyses of groundwater storage change using GRACE satellite data in the Usutu-Mhlatuze drainage region, north-eastern South Africa

Cited by 11 publications

References 26 publications

Spatiotemporal Variation Characteristics of Groundwater Storage and Its Driving Factors and Ecological Effects in Tibetan Plateau

Spatiotemporal Variation Characteristics of Groundwater Storage and Its Driving Factors and Ecological Effects in Tibetan Plateau

The Role of Space-Based Observations for Groundwater Resource Monitoring over Africa

Groundwater Recharge Estimation Using In-Situ and Grace Observations in the Eastern Region of the United Arab Emirates

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