Thesis
Modeling the potential impacts of climate change on surface and groundwater resources in the Niger Delta part of Nigeria
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2020
- Thesis identifier
- T15855
- Person Identifier (Local)
- 201654955
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Climate change impact studies are challenging in developing countries due to the paucity of climatological datasets resulting from insufficient monitoring stations, and constraint in human and computational resources. The Niger Delta region is one of the most vulnerable and densely populated regions in Nigeria, which presents special challenges for water resource policy and management due to climate change and anthropogenic activities, especially with an increase in water demands. Flooding events are recorded annually in settlements along River Niger and its tributaries, inundating many towns, displacing people from their homes and polluting the surface and groundwater resources. As the surface and groundwater resources are two interconnected components of one single resource, any negative impacts on one will inevitably affect the quantity or quality of the other component. The increase in intense stress on the groundwater from shallow coastal plain sand aquifers as the significant source of water resources for domestic, industrial and agricultural purposes in the area. This study, therefore, presents a novel approach for climate change impact assessment on surface and groundwater resources in developing countries.;The first stage of this study assessed the performance of three widely used daily gridded precipitation (prcp), maximum and minimum temperature (Tmax and Tmin) datasets from the Climatic Research Unit (CRU), Princeton University Global Meteorological Forcing (PGF) and Climate Forecast System Reanalysis (CFSR) datasets available over the Niger Delta part of Nigeria against the observed station datasets to select the best datasets that can serve as a possible replacement to the observed datasets. Symmetrical uncertainty (SU) filter was employed together with the selected hydro-climatological datasets to assess the performance of 26 Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation model (GCM)outputs. The selection was made according to their capability to simulate observed daily precipitation (prcp), maximum and minimum temperature (Tmax and Tmin) over the historical period 1980-2005 (Baseline periods) in the Niger Delta region. The selected GCMs were used for climate change predictions and impacts assessment over the period 2020s (2010-2039), 2050s (2040-2069) and 2080s (2070-2099), under Representative Concentration Pathway (RCP) 4.5 and 8.5. Standardized precipitation index (SPI) of 1-month and 12-month time steps were used for extreme event assessment. SWAT (Soil and Water Assessment Tool) model was used to analyse the effects of climate change on the hydrologic processes of the Niger River Basin (NRB)in Nigeria. The hydrostratigraphy of the Niger Delta shallow coastal aquifers was characterised coupled with the simulated aquifer recharge and evapotranspiration deduced from Global Climate Model (GCM) simulations under two Representative concentration pathways (RCP4.5 and RCP8.5) to develop a transient groundwater flow model to investigate the potential impacts of climate change and increased groundwater abstraction on the coastal plain sand aquifer over the periods 2010 to 2099.;Results of the hydro-climatological study revealed that the CRU datasets performed better in most of the statistical assessments conducted. The symmetrical uncertainty filter revealed the four top-ranked GCMs, namely ACCESS1.3, MIROCESM, MIROC-ESM-CHM, and NorESM1-M as the best set of GCMs to form an ensemble for the Spatio-temporal climate projection over the study area. The selected GCM ensemble predicted an increase in the mean annual precipitation in the range of 0.26% to 3.57% under RCP4.5, and 0.7% to 4.94% under RCP 8.5 by the end of the century as compared to the base period. The study also revealed an increase in maximum temperature in the range of 0 to 0.4 °C under RCP4.5 and 1.25-1.79 °C under RCP8.5 during the periods 2080s. Minimum temperature also revealed a significant increase of 0 to 0.52 °C under RCP4.5 and between 1.38-2.02 °C under RCP8.5, which indicates that there might be the occurrence of extreme events in the Niger Delta due to climate change. The 1-month and 12-month SPI under both RCPs predict incidences of extreme wet cycle across all the study locations, especially during the 2080s. The mean annual streamflow was also predicted to increase from 21% to 48% at the Onitsha gauging station under both emission scenarios. Results of hydrostratigraphic studies revealed that the system was more complicated than previously reported. A unit of silty sand was observed in the western part of the basin, which thins out leaving the eastern part of the basin as an unconfined aquifer underlain by multiple thin beds of the sand aquifer and a layered sand aquifer, which holds freshwater occurring in the northern parts of the basin. Transient groundwater flow model simulations of Port-Harcourt metropolis predicted the maximum change in groundwater budget and levels when abstraction was increased by 50% under RCP 8.5 resulting to a decrease in groundwater levels by 1 m around the coast to 7 m towards the northern part of the study area. This further cause a change in the aquifer storage to decrease by 325,000 m3/day and groundwater levels to decrease from a range of 1 to 27 m, respectively.;The findings in this study shows that interconnected surface water-groundwater modelling of climate change impacts is critical as predicted change in the surface flow and water levels will affect the regional groundwater budget of the aquifer. The findings from this study shows that understanding climate changes impacts on both surface and groundwater resources is crucial for the water resources management of any region. Associating climate scenarios, hydrologic modeling and numerical groundwater modeling of aquifers provides useful insight into the future hydrogeological systems interactions, which can be used to envisage measurements of adaptation and protection of the water resources. For the coastal aquifer of Niger Delta, the study shows that the risk of contamination of this system by rivers is high. It is recommended that end-users should reflect on the results of this study during IWRM planning to preserve the long-term exploitation of this aquifer, and as part of the sustainable management of the local and national water resources.
- Advisor / supervisor
- White, Chris J.
- Kalin, Robert M.
- Resource Type
- DOI
- Date Created
- 2020
- Former identifier
- 9912981390702996
- Embargo Note
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