Mapping the spatial changes in Lake Volta using multitemporal remote sensing approach

Ghansah, Benjamin; Asare, Yaw Mensah; Tchao, Eric Tutu; Forkuo, Eric Kwabena

doi:10.1111/lre.12138

Cited by 7 publications

(7 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A global gridded dataset for the freshwater is a prerequisite for a water resources management and research [9,10,11,12,13]. In Egypt, Ghana, Malawi and Tanzania, this method has been used in the study of inland water bodies, which are inaccessible and plagued with sparse datasets [14,15,16,17]. The applicability of the satellite’s wide areal coverage, re-visits, and multiple freely accessible data channels permits researchers to carry out studies of freshwater bodies in areas where the in-situ observations are sparse.…”

Section: Introductionmentioning

confidence: 99%

Recent Surface Water Extent of Lake Chad from Multispectral Sensors and GRACE

Buma

Seo

2018

Sensors

View full text Add to dashboard Cite

Consistent observations of lakes and reservoirs that comprise the majority of surface freshwater globally are limited, especially in Africa where water bodies are exposed to unfavorable climatic conditions and human interactions. Publicly available satellite imagery has increased the ability to monitor water bodies of various sizes without much financial hassle. Landsat 7 and 8 images were used in this study to estimate area changes around Lake Chad. The Automated Water Extraction Index (AWEI), Normalized Difference Water Index (NDWI), Modified Normalized Difference Water Index (MNDWI) and Normalized Difference Vegetation Index (NDVI) were compared for the remote sensing retrieval process of surface water. Otsu threshold method was used to separate water from non-water features. With an overall accuracy of ~96% and an inter-rater agreement (kappa coefficient) of 0.91, the MNDWI was a better indicator for mapping recent area changes in Lake Chad and was used to estimate the lake’s area changes from 2003–2016. Extracted monthly areas showed an increasing trend and ranged between ~1242 km2 and 2231 km2 indicating high variability within the 13-year period, 2003–2016. In addition, we combined Landsat measurements with Total Water Storage Anomaly (TWSA) data from the Gravity Recovery and Climate Experiment (GRACE) satellites. This combination is well matched with our estimated surface area trends. This work not only demonstrates the importance of remote sensing in sparsely gauged developing countries, it also suggests the use of freely available high-quality imagery data to address existing lake crisis.

show abstract

Section: Introductionmentioning

confidence: 99%

Recent Surface Water Extent of Lake Chad from Multispectral Sensors and GRACE

Buma

Seo

2018

Sensors

View full text Add to dashboard Cite

show abstract

“…Individual time series have been created e.g. by Singh et al (2015) for Lake Mead and Aral Sea and Ni et al (2017) and Ghansah et al (2016) for Lake Volta. Regional (Zhang et al, 2014) or global investigations (Busker et al (2019); Semmelroth (2019)) show that adequate results for lake water volume are best obtained by a linear regression model with an error between 3% and 15%.…”

Section: Limitationsmentioning

confidence: 99%

RECOG RL01: Correcting GRACE total water storage estimates for global lakes/reservoirs and earthquakes

Deggim¹,

Eicker²,

Schawohl³

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. Observations of changes in terrestrial water storage obtained from the satellite mission GRACE (Gravity Recovery and Climate Experiment) have frequently been used for water cycle studies and for the improvement of hydrological models by means of calibration and data assimilation. However, due to a low spatial resolution of the gravity field models spatially localized water storage changes, such as those occurring in lakes and reservoirs, cannot properly be represented in the GRACE estimates. As surface storage changes can represent a large part of total water storage, this leads to leakage effects and results in surface water signals becoming erroneously assimilated into other water storage compartments of neighboring model grid cells. As a consequence, a simple mass balance at grid/regional scale is not sufficient to deconvolve the impact of surface water on TWS. Furthermore, non-hydrology related phenomena contained in the GRACE time series, such as the mass redistribution caused by major earthquakes, hamper the use of GRACE for hydrological studies in affected regions. In this paper, we present the first release (RL01) of the global correction product RECOG (REgional COrrections for GRACE), which accounts for both the surface water (lakes & reservoirs, RECOG-LR) and earthquake effects (RECOG-EQ). RECOG-LR is computed from forward-modelling surface water volume estimates derived from satellite altimetry and (optical) remote sensing and allows both a removal of these signals from GRACE and a re-location of the mass change to its origin within the outline of the lakes/reservoirs. The earthquake correction RECOG-EQ includes both the co-seismic and post-seismic signals of two major earthquakes with magnitudes above 9 Mw. We can show that applying the correction dataset (1) reduces the GRACE signal variability by up to 75 % around major lakes and explains a large part of GRACE seasonal variations and trends, (2) avoids the introduction of spurious trends caused by leakage signals of nearby lakes when calibrating/assimilating hydrological models with GRACE, even in neighboring river basins, and (3) enables a clearer detection of hydrological droughts in areas affected by earthquakes. A first validation of the corrected GRACE time series using GPS-derived vertical station displacements shows a consistent improvement of the fit between GRACE and GNSS after applying the correction. Data are made available as open access via the Pangea database (RECOG-LR: Deggim et al. (2020a) https://doi.org/10.1594/PANGAEA.921851; RECOG-EQ: Gerdener et al. (2020b, under revision), https://doi.pangaea.de/10.1594/PANGAEA.921923).

show abstract

“…Vanderpuye [39] found a linear relationship between the water level and surface area for Lake Volta. Therefore, based on the surface area reported by Ghansah et al [2], together with the water level derived from satellite altimetry measurements, we obtain the following approximate area-height relationship:…”

Section: Estimation Of Lake Area Changementioning

confidence: 99%

“…TWS is continually exchanged with the atmosphere and oceans through vertical and horizontal fluxes (precipitation, evapotranspiration, surface runoff and underground discharge) [1]. Lake storage is an important TWS component, providing moisture to the atmosphere through evaporation, serving as a climate modulator by absorbing and releasing heat [2], and providing water for agricultural irrigation, domestic and industrial consumption, and hydropower generation. Lake Volta (see Figure 1) is the world's largest man-made lake with a surface area of~8500 km 2 , formed by the construction of the Akosombo Dam in 1965.…”

Section: Introductionmentioning

confidence: 99%

“…Lake storage is an important TWS component, providing moisture to the atmosphere through evaporation, serving as a climate modulator by absorbing and releasing heat [2], and providing water for agricultural irrigation, domestic and industrial consumption, and hydropower generation. Lake Volta (see Figure 1) is the world's largest man-made lake with a surface area of~8500 km 2 , formed by the construction of the Akosombo Dam in 1965. Located completely within Ghana, Lake Volta collects discharge from the numerous rain-fed tributaries within the Volta River basin (VRB), supplies hydroelectric power to Ghana and neighboring Accurate estimation of lake water storage variation has been difficult due to lack of adequate in situ measurements on large regional scales.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Long-Term Water Storage Changes of Lake Volta from GRACE and Satellite Altimetry and Connections with Regional Climate

Chen

Wilson

et al. 2017

Remote Sensing

View full text Add to dashboard Cite

Satellite gravity data from the Gravity Recovery and Climate Experiment (GRACE) provides a quantitative measure of terrestrial water storage (TWS) change at different temporal and spatial scales. In this study, we investigate the ability of GRACE to quantitatively monitor long-term hydrological characteristics over the Lake Volta region. Principal component analysis (PCA) is employed to study temporal and spatial variability of long-term TWS changes. Long-term Lake Volta water storage change appears to be the dominant long-term TWS change signal in the Volta basin. GRACE-derived TWS changes and precipitation variations compiled by the Global Precipitation Climatology Centre (GPCC) are related both temporally and spatially, but spatial leakage attenuates the magnitude of GRACE estimates, especially at small regional scales. Using constrained forward modeling, we successfully remove leakage error in GRACE estimates. After this leakage correction, GRACE-derived Lake Volta water storage changes agree remarkably well with independent estimates from satellite altimetry at interannual and longer time scales. This demonstrates the value of GRACE estimates to monitor and quantify water storage changes in lakes, especially in relatively small regions with complicated topography.

show abstract

Mapping the spatial changes in Lake Volta using multitemporal remote sensing approach

Cited by 7 publications

References 11 publications

Recent Surface Water Extent of Lake Chad from Multispectral Sensors and GRACE

Recent Surface Water Extent of Lake Chad from Multispectral Sensors and GRACE

RECOG RL01: Correcting GRACE total water storage estimates for global lakes/reservoirs and earthquakes

Long-Term Water Storage Changes of Lake Volta from GRACE and Satellite Altimetry and Connections with Regional Climate

Contact Info

Product

Resources

About