Spatio-Temporal Mapping and Analysis of Surface-Water Dynamics in Kopa Dam, Niger State, Nigeria, Using Sentinel-2 Level-2A and GIS Techniques
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Abstract
Surface-water extent provides a spatial measure of reservoir condition and supports water-resource monitoring where field observations are limited. This study assessed the spatio-temporal dynamics of surface water in Kopa Dam, Niger State, Nigeria, from January 2022 to January 2026 using Sentinel-2 Level-2A imagery and the Modified Normalized Difference Water Index (MNDWI). One image was selected for January of each year to maintain seasonal consistency. MNDWI was calculated using the green band (B03) and shortwave infrared band (B11), with B11 resampled to 10 m. Water and non-water reference points were used to determine image-specific thresholds of −0.01, −0.01, −0.18, −0.01, and −0.25 for 2022, 2023, 2024, 2025, and 2026, respectively. Binary water masks were generated and refined using the Majority Filter. Mapped water areas were 3.3097, 3.2929, 4.4854, 3.7591, and 4.2103 km² for 2022–2026, respectively. The largest increase occurred between 2023 and 2024 (+36.21%), while the largest decline occurred between 2024 and 2025 (−16.19%). Overall, water area increased by 0.9006 km² (27.21%) between 2022 and 2026. The linear time-series model indicated a positive tendency (R² = 0.4523). Spatial transition analysis identified 95.46 ha of water gain, 5.64 ha of water loss, 325.31 ha of persistent water, and 85.63 ha of stable non-water. The findings indicate substantial annual fluctuations rather than a uniform directional change and demonstrate the usefulness of Sentinel-2 and MNDWI for reproducible reservoir monitoring. Continued application with field water-level observations and bathymetric surveys is recommended for improved reservoir management.
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Copyright (c) 2026 Musa Abdulmumin, Abubakar Sunusi, Dauda Waziri Abdullahi, Abubakar Zalkiflu Idris (Author)
This work is licensed under a Creative Commons Attribution 4.0 International License.
European Space Agency. (2026). Sentinel-2 facts and figures.
Frichi, B., Ibrahim, M., & Abubakar, T. (2023). Assessment of trend of surface water in Kiri Dam, Adamawa State, Nigeria. Nigerian Journal of Environmental Sciences and Technology, 7(1), 142–153. https://doi.org/10.36263/nijest.2023.01.0405
International Organization for Migration. (2024). Nigeria flood situation report: Niger State (13 September 2024). Displacement Tracking Matrix.
Ji, L., Zhang, L., & Wylie, B. K. (2009). Analysis of dynamic thresholds for the normalized difference water index. Photogrammetric Engineering & Remote Sensing, 75(11), 1307–1317. https://doi.org/10.14358/PERS.75.11.1307 USGS record and article information DOI: https://doi.org/10.14358/PERS.75.11.1307
Ngebe, S., Malunda, K. B., & du Plessis, A. (2022). Utility of geospatial techniques in estimating dam water levels: Insights from the Katrivier Dam. Water SA, 48(2), 151–160. https://doi.org/10.17159/wsa/2022.v48.i2.3890 DOI: https://doi.org/10.17159/wsa/2022.v48.i2.3890
Ogilvie, A., Fall, C. S., Bodian, A., Martin, D., Bruckmann, L., Dia, D., Leye, I., Ndiaye, P. M., Soro, D. D., Danumah, J. H., Bader, J.-C., & Poussin, J.-C. (2025). Surface water and flood-based agricultural systems: Mapping and modelling long-term variability in the Senegal river floodplain. Agricultural Water Management, 308, 109254. https://doi.org/10.1016/j.agwat.2024.109254 DOI: https://doi.org/10.1016/j.agwat.2024.109254
Olaniyi, O. E., Komolafe, I., Ajayi, S. R., Aderonmu, E. A., & Adeola, A. J. (2023). Performance evaluation of Landsat 8 and Sentinel 2A for surface water area mapping at a local scale: A case study of Ise Forest Reserve, Nigeria. World Environmental Conservation Conference, 396–404
Pekel, J.-F., Cottam, A., Gorelick, N., & Belward, A. S. (2016). High-resolution mapping of global surface water and its long-term changes. Nature, 540, 418–422. https://doi.org/10.1038/nature20584 DOI: https://doi.org/10.1038/nature20584
Reis, L. G. D. M., Souza, W. D. O., Ribeiro Neto, A., Fragoso Jr, C. R., Ruiz-Armenteros, A. M., Cabral, J. J. D. S. P., & Montenegro, S. M. G. L. (2021). Uncertainties involved in the use of thresholds for the detection of water bodies in multitemporal analysis from landsat-8 and sentinel-2 images. Sensors, 21(22), 7494. DOI: https://doi.org/10.3390/s21227494
Samaila-Ija, H. A., Ajayi, O. G., Zitta, N., Odumosu, J. O., Kuta, A. A., Adesina, E. A., & Ibrahim, P. (2014). Bathymetric survey and volumetric analysis for sustainable management: Case study of Suleja Dam, Niger State, Nigeria. Journal of Environment and Earth Science, 4(18), 24–32.
Tesfaye, M., & Breuer, L. (2024). Performance of water indices for large-scale water resources monitoring using Sentinel-2 data in Ethiopia. Environmental Monitoring and Assessment, 196, 467. https://doi.org/10.1007/s10661-024-12630-1 DOI: https://doi.org/10.1007/s10661-024-12630-1
Umar, J. J., Adenle, A. A., Asonibare, O. F., & Nwobi, N. O. (2026). Peri-urban flood risk mapping and exposure analysis in Niger State, Nigeria: A geospatial assessment for monitoring and actions. Discover Hazards, 2, 30. https://doi.org/10.1007/s44475-026-00037-0 DOI: https://doi.org/10.1007/s44475-026-00037-0
Xu, H. (2006). Modification of normalized difference water index (NDWI) to enhance open water features in remotely sensed imagery. International Journal of Remote Sensing, 27(14), 3025–3033. https://doi.org/10.1080/01431160600589179 DOI: https://doi.org/10.1080/01431160600589179
Yeboah, E., Mensah, A. O. K. N., Madjanor, J. T., Anaba, C. I., Antwi, A. V., Adjei, B. A., Afele, I. K., Blagogie, L., Rathnayaka, D. M. S. K., Liyanage, P., & Sarfo, I. (2026). Surface water monitoring in Ghana: Evaluating spectral water indices across diverse aquatic environments. Ecological Frontiers, 46(4), 1517–1525. https://doi.org/10.1016/j.ecofro.2026.02.008 DOI: https://doi.org/10.1016/j.ecofro.2026.02.008
Zeng, F., Song, C., Cao, Z., Xue, K., Lu, S., Chen, T., & Liu, K. (2023). Monitoring inland water via Sentinel satellite constellation: A review and perspective. ISPRS Journal of Photogrammetry and Remote Sensing, 204, 340–361. https://doi.org/10.1016/j.isprsjprs.2023.09.011 DOI: https://doi.org/10.1016/j.isprsjprs.2023.09.011
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