Wetland Depletion Assessment in Marine Local Government Areas of Rivers State

Wetlands are considered to be one of the most productive yet disappearing ecosystems, providing critical ecological, social (livelihood, water supply, floods regulation) and economic services. But once depleted these vital supporting functions are lost or diminished to a great degree. The prime aim of this paper is therefore to provide cost-effective, accurate and spatially-explicit information that supports appropriate policy decisions and actual wetland conservation in the Marine LGAs of Rivers State, Nigeria.
Three specific questions were addressed: (i) Spatial identification and delineation of wetlands in the LGAs based on Landsat-7 images from 2004–2024 in ≥5-year period; (ii) Quantification of the variation of their spatial extent and depletion rate; and (iii)Examination of the spatio-temporal variation of land use/land cover (LULC). Preprocessed multi-temporal Landsat-7 imageries were spectral-enhanced using indices (NDVI, NDWI), digested with DEM, classified into wetlands and non-wetlands based on threshold technique and changes were spatio-temporally quantified through image differencing; while status, distribution and dynamics of LULC were analyzed. Classifications schemes for the selected LULC categories; built-up, vegetation, water bodies and bare earth were derived according to the nature of the area, spectral characteristics of Landsat-7 image and their potential roles in the hydrological and Ecological functioning of the wetlands. These schemes were respectively rooted on indices, boundaries, spectral characteristics, and extent of the variables. The maximum likelihood supervised classification was consecutively employed on the focused area for the multi-temporal datasets image-sets for the years (2004, 2009, 2014, 2019 and 2024) to ensure homogeneity in classification and accordingly, consistency in change detection accuracy.
The temporal prevalence of wetland extent in years (2004, 2009, 2014 and 2024) indicated gain of +153% just before the onset of observed decline within the period (2014–2024) by ≈51%, which explained the trend of increase in exploitation of wetlands in the last decade. The classification of LGAs landsat images revealed a significant gain in built-up lands area between the two endpoints (2004 and 2024) from 1000km² to 3420Km² (341% increase), which is indicative of a significant increase in anthropogenic intervention. A significant loss was observed between 2004 and 2009 (N=−61%), before a recovery period with a gain of 37% in 2019, followed by an accelerated depletion with a loss in area of −73% in 2024 (N=−73%). Intermedium-year variations were affected by the clouds ratio and scanning errors of Landsat 7 visible bands, which induced inaccuracies in imagery classification. Nonetheless, these findings did also report a relative stability in water body surface areas in the study area. This was countered with fluctuations in bare lands with a magnitude of −99%, from 651 km ²in 2004 to 6 km ²in 2024 as well as a continuous increase in urbanized lands from 1000 km2 in 2004 to 3420 Km ²in 2024. It was concluded that the loss in the values of 2004 exhibited wetlands dynamic could be tackled to ensure sustainable development if immediate actions are taken. These could include setting up GIS-based monitoring and controlling framework, establishing effective regulations on land uses & implementation, and providing participatorily active role for local communities & authorities in wetland conservation.

Assessment , Wetland , monitoring

1. Adekola, O., & Mitchell, G. (2011). The Niger Delta wetlands: Threats to ecosystem services, their importance to dependent communities and possible management measures. International Journal of Biodiversity Science, Ecosystem Services & Management, 7(1), 50–75 [Google Scholar] [Crossref]

2. Amnesty International. (2011). The true tragedy: Delays in the cleanup of oil spills in the Niger Delta. Retrieved May 5, 2025 from https://www.amnesty.org [Google Scholar] [Crossref]

3. Cowardin, L. M., Carter, V., Golet, F. C., & LaRoe, E. T. (1979). Classification of wetlands and deepwater habitats of the United States (FWS/OBS-79/31). U.S. Fish and Wildlife Service. [Google Scholar] [Crossref]

4. Food and Agriculture Organization. (2022). The state of food and agriculture 2022. FAO. [Google Scholar] [Crossref]

5. IPCC. (2023). Climate Change 2023: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. Retrieved May 8, 2025 from https://www.ipcc.ch/report/ar6/wg2/ [Google Scholar] [Crossref]

6. National Population Commission. (2006). Population and housing census of the Federal Republic of Nigeria: Priority tables. [Google Scholar] [Crossref]

7. Niger Delta Budget Monitoring Group. (2021). Communiqué adopted at the end of the fiscal governance roundtable. Retrieved April 4, 2026, from https://www.nigerdeltabudget.org/communiques/ [Google Scholar] [Crossref]

8. Nigeria Meteorological Agency (NiMET). (2021). Annual rainfall and climate data for Rivers State, Nigeria. [Google Scholar] [Crossref]

9. Nigeria Meteorological Agency (NiMET). (2022). Annual climate report on Rivers State: Temperature and humidity patterns. [Google Scholar] [Crossref]

10. Nwankwoala, H. O., Amadi, A. N., Oborie, E., & Ushie, F. A. (2013). Hydrochemical factors and correlation analysis in groundwater quality in Yenagoa, Bayelsa State, Nigeria. Applied Ecology and Environmental Sciences, 2(4), 100–105. Retrieved February 14, 2026 from https://doi.org/10.12691/aees-2-4-3 [Google Scholar] [Crossref]

11. Obi, A., Udo, J., & Eze, C. (2021). Wetland degradation and conservation in the Niger Delta region of Nigeria. Journal of Environmental Management, 288, 112404. https://doi.org/10.1016/j.jenvman.2021.112404 [Google Scholar] [Crossref]

12. Obiefuna, J., Nwilo, P. C., Atagbaza, A. O., & Okolie, C. J. (2023). Spatial changes in the wetlands of Lagos/Lekki Lagoons of Lagos, Nigeria. Journal of Sustainable Development, 6(7), 123–134. Retrieved June 15, 2025 from https://doi.org/10.5539/jsd.v6n7p123 [Google Scholar] [Crossref]

13. Wala, C., Ugbomeh, A. P., Green, A. F., & Anaero-Nweke, G. N. (2023). Evaluation of the perceived ecosystem services provided by selected sites: The Imo River, Rivers State, Nigeria. Journal of Global Ecology and Environment, 18(1), 23–31. Retrieved 24th March, 2026 from https://doi.org/10.56557/jogee/2023/v18i18253 [Google Scholar] [Crossref]

14. Udom, P., Okon, E., & Etim, F. (2022). Riverine and coastal wetlands of Rivers State, Nigeria: Distribution, ecological significance, and threats. Wetlands Ecology and Management, 30(5), 1127–1142. Retrieved July 11, 2025 from https://doi.org/10.1007/s11273-022-09850-x [Google Scholar] [Crossref]

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