Application of GRACE to the estimation of groundwater storage change in a data‐poor region: A case study of Ngadda catchment in the Lake Chad Basin

Skaskevych, A.; Lee, Jejung; Jung, Hahn Chul; Bolten, J. D.; David, John L.; Policelli, F.; Goni, Ibrahim Baba; Favreau, Guillaume; San, Soma; Ichoku, Charles

doi:10.1002/hyp.13613

Cited by 20 publications

(7 citation statements)

References 77 publications

(110 reference statements)

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“…This implies that the coarse spatial resolution of GRACE is problematic for monitoring groundwater resources for small areas. A recent study by Skaskevych et al [86] assessed the feasibility of GRACE-based estimation of groundwater storage change in the Ngadda catchment in the Lake Chad Basin and demonstrated that GRACE-based modelling is a cost-effective method to monitor groundwater changes. While important insights have been gained from using this sensor, the coarse resolution limits its application over finer spatial scales.…”

Section: Remote Sensing Products For Drought and Climate Variability mentioning

confidence: 99%

Impacts of Climate Variability and Drought on Surface Water Resources in Sub-Saharan Africa Using Remote Sensing: A Review

et al. 2020

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Climate variability and recurrent droughts have caused remarkable strain on water resources in most regions across the globe, with the arid and semi-arid areas being the hardest hit. The impacts have been notable on surface water resources, which are already under threat from massive abstractions due to increased demand, as well as poor conservation and unsustainable land management practices. Drought and climate variability, as well as their associated impacts on water resources, have gained increased attention in recent decades as nations seek to enhance mitigation and adaptation mechanisms. Although the use of satellite technologies has, of late, gained prominence in generating timely and spatially explicit information on drought and climate variability impacts across different regions, they are somewhat hampered by difficulties in detecting drought evolution due to its complex nature, varying scales, the magnitude of its occurrence, and inherent data gaps. Currently, a number of studies have been conducted to monitor and assess the impacts of climate variability and droughts on water resources in sub-Saharan Africa using different remotely sensed and in-situ datasets. This study therefore provides a detailed overview of the progress made in tracking droughts using remote sensing, including its relevance in monitoring climate variability and hydrological drought impacts on surface water resources in sub-Saharan Africa. The paper further discusses traditional and remote sensing methods of monitoring climate variability, hydrological drought, and water resources, tracking their application and key challenges, with a particular emphasis on sub-Saharan Africa. Additionally, characteristics and limitations of various remote sensors, as well as drought and surface water indices, namely, the Standardized Precipitation Index (SPI), Palmer Drought Severity Index (PDSI), Normalized Difference Vegetation (NDVI), Vegetation Condition Index (VCI), and Water Requirement Satisfaction Index (WRSI), Normalized Difference Water Index (NDWI), Modified Normalized Difference Water Index (MNDWI), Land Surface Water Index (LSWI+5), Modified Normalized Difference Water Index (MNDWI+5), Automated Water Extraction Index (shadow) (AWEIsh), and Automated Water Extraction Index (non-shadow) (AWEInsh), and their relevance in climate variability and drought monitoring are discussed. Additionally, key scientific research strides and knowledge gaps for further investigations are highlighted. While progress has been made in advancing the application of remote sensing in water resources, this review indicates the need for further studies on assessing drought and climate variability impacts on water resources, especially in the context of climate change and increased water demand. The results from this study suggests that Landsat-8 and Sentinel-2 satellite data are likely to be best suited to monitor climate variability, hydrological drought, and surface water bodies, due to their availability at relatively low cost, impressive spectral, spatial, and temporal characteristics. The most effective drought and water indices are SPI, PDSI, NDVI, VCI, NDWI, MNDWI, MNDWI+5, AWEIsh, and AWEInsh. Overall, the findings of this study emphasize the increasing role and potential of remote sensing in generating spatially explicit information on drought and climate variability impacts on surface water resources. However, there is a need for future studies to consider spatial data integration techniques, radar data, precipitation, cloud computing, and machine learning or artificial intelligence (AI) techniques to improve on understanding climate and drought impacts on water resources across various scales.

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Section: Remote Sensing Products For Drought and Climate Variability mentioning

confidence: 99%

Impacts of Climate Variability and Drought on Surface Water Resources in Sub-Saharan Africa Using Remote Sensing: A Review

et al. 2020

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“…Lake Chad (LC), which was once the third-largest source of fresh water in Africa, has tremendously decreased in size, endangering the livelihoods of approximately 30 million people who rely on the lake. Agriculture, nomadic and semi-nomadic animal husbandry and fisheries are the predominant sources of income around LC [3,4]. Given such importance within the community, the routine monitoring of water quality is essential.…”

Section: Introductionmentioning

confidence: 99%

“…Given such importance within the community, the routine monitoring of water quality is essential. Unfortunately, monitoring records are lacking due to limited financial and infrastructural investments [4,5]. The possible challenges in measuring and monitoring water quality in situ for such a large area include spatial constraints, high costs, and the significant time required.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Sentinel-2 and Landsat 8 Images for Estimating Chlorophyll-a Concentrations in Lake Chad, Africa

Buma

2020

Remote Sensing

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Much effort has been applied in estimating the concentrations of chlorophyll-a (Chl a) in lakes. The optical complexity and lack of in situ data complicate estimating Chl a in such water bodies. We compared four established satellite reflectance algorithms—the two-band and three-band algorithms (2BDA, 3BDA), fluorescence line height (FLH), and normalized difference chlorophyll index (NDCI)—to estimate Chl a concentration in Lake Chad. We evaluated the performance and applicability of Landsat-8 (L8) and Sentinel-2 (S2) images with the four Chl a estimation algorithms. For accuracy, we compared the concentration levels from the four algorithms to those from Worldview-3 (WV3) images. We identified two promising algorithms that could be used alongside L8 and S2 satellite images to monitor Chl a concentrations in Lake Chad. With an averaged R2 of 0.8, the 3BDA and NDCI Chl a algorithms performed accurately with S2 and L8 images. For the S2 and L8 images, 3BDA had the highest performance when compared to the WV3 estimates. We demonstrate the usefulness of sensor images in improving water quality information for areas that are difficult to access or when conventional data are limited.

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“…These scenarios were defined based on observations reported in previous studies. For example, estimation of groundwater storage change based on in situ and remotely sensed groundwater data in the Lake Chad Basin indicated that the groundwater water storage could decrease to half of its value and even to zero due to both climate change and overexploitation of water (Skaskevych et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Decreasing Groundwater Supply Can Exacerbate Lake Warming and Trigger Algal Blooms

2021

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The physical consequences of increasing lake surface temperatures and decreasing ice cover duration include changes in evaporation rates, mixing-regime, and increasing duration or intensity of thermal stratification (Sharma et al., 2019;Wang, 2018;. Moreover, seasonal changes in the timing and duration of overturn and stratification in response to climate change, link trends of surface warming to deep water temperatures of lakes (Anderson et al., 2021). These physical changes, in turn, alter the ecological functioning of lakes, nutrient cycling (Tong et al., 2021), oxygen availability (Zhang et al., 2015), primary production (O'Reilly et al., 2003;Verburg, 2003), and aquatic food web structure (Tanentzap et al., 2020). Temperature changes can alter the rates of chemical reactions, aquatic ecosystem metabolism, biological growth rates, photosynthesis and respiration rates and can disturb ecosystem equilibrium (Carpenter et al., 2011;Woolway et al., 2016). Moreover, increased water temperature and the subsequent changes in stratification often negatively affect water quality of inland water bodies (Chang et al., 2015). In addition, lake warming is associated with an

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Application of GRACE to the estimation of groundwater storage change in a data‐poor region: A case study of Ngadda catchment in the Lake Chad Basin

Cited by 20 publications

References 77 publications

Impacts of Climate Variability and Drought on Surface Water Resources in Sub-Saharan Africa Using Remote Sensing: A Review

Impacts of Climate Variability and Drought on Surface Water Resources in Sub-Saharan Africa Using Remote Sensing: A Review

Evaluation of Sentinel-2 and Landsat 8 Images for Estimating Chlorophyll-a Concentrations in Lake Chad, Africa

Decreasing Groundwater Supply Can Exacerbate Lake Warming and Trigger Algal Blooms

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