8th National Water Conference organized by National Water Resources Institute, Kaduna in collaboration with Ogun-Osun River Basin Authority, Abeokuta, Ogun State COMBATING WATER RESOURCES CHALLENGES IN NIGERIA THROUGH GROUNDWATER FLOW MODELLING (original) (raw)
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Modelling of Groundwater Flow in Ibeji Lekki Local Government Area of Lagos State Nigeria
International Journal of Innovative Science and Research Technology , 2021
This study created a groundwater flow model using Groundwater Modeling System (GMS) software integrated with MODFLOW to create a steady-state groundwater flow model for the Ibeju Lekki Local Government Area of Lagos State. Aquifer parameters (hydraulic conductivity, transmissibility), groundwater recharge data (rainfall/climate, recharge rate), topography, and a hydrogeological map were acquired from both public and commercial organisations. The contour of the head solution demonstrates that the groundwater flow of the research region flows from the northeast , where the value of the head is high, to the south, where it also declines.The head expresses the potential energy of the groundwater per unit weight and thereby influences the direction of the groundwater flow.
GROUNDWATER MODELLING WITH LIMITED DATA: A CASE STUDY OF YOBE RIVER BASIN, NORTH EAST NIGERIA
An exploratory numerical groundwater model of a shallow aquifer interacting with a river in a semi-arid zone was developed using MODFLOW. The model simulated field data adequately as well as the physical processes presented in its conceptual framework. The conceptualization of the aquifer to exist under both confined and unconfined conditions can be adequately described in the model. Water balance from the model shows that river to aquifer flow dominates aquifer recharge processes, and its magnitude is limited not only by relative head difference, but also by the transmissivity and hydraulic gradient of the aquifer.
Groundwater development in Nsukka area is hampered by the incessant failure of boreholes drilled at the eastern boundary of a thick regional sandstone aquifer estimated at over 100km 2 in areal extent.The flow systems were investigated using mathematical models based on the solution of the Laplace equation for steady state flow from flow net and functional analysis. Well data from over forty boreholes were used. The aquifer hydraulic parameters used in the models include hydraulic heads (H),transmissivity (T),hydraulic conductivity (K) and flow gradient(i).Three areas of the flow system have been identified in this work; areas of origin in the groundwater divide in the east associated with high heads that attain a maximum of 328m with gradient values of 1/200 or less ,the through flow or transfer areas of Nsukka plateau with head values generally less than 300m and gradient values of 1/150 or less, and the discharge or termination areas in the west and northwest where heads are 230m or less. The modeled parameters provide baseline data for drilling and design of boreholes and a clear understanding of the flow process.
Numerical groundwater flow modeling of the Coastal Plain Sand aquifer, Akwa Ibom State, SE Nigeria
Akwa Ibom State is located in the Niger delta region of Nigeria. The coastal plain sand aquifer, which underlies the area, is the major source of potable water for domestic, agricultural, and industrial use. The increase in demand for water has led to an increased exploitation of the aquifer in the last few years. Hence it is essential to quantify the amount of exploitable water in the aquifer. To achieve this goal, a regional numerical groundwater flow model using MODFLOW was calibrated under steady-state conditions to determine the aquifer's hydraulic conductivity (K) and the recharge characteristics of the area. The hydraulic conductivity and recharge values from the pilot points calibration ranged from 1 to 75 m/d and 5.89 × 10 −6 m 3 /d to1.23 × 10 −4 m 3 /d. The calculations of the model showed that the average recharge rate amounts 0.40l/s/km 2 or 12.60 mm/year. The estimated recharge suggests a high groundwater potential for the area. This is the first time that such a study has been carried out in the area, and it will serve as an important basis for future groundwater management and simulation of transient groundwater flow modeling in Akwa Ibom State.
Journal of Water Resource and Protection, 2016
This study examined the hydrological modeling of aquifers and their ground water potentials for the purposes of water resources planning and management. This was done using the electrical resistivity method employing the schlumberger electrode configuration at randomly selected stations to obtain the thicknesses and resistivities of each layer and depth to the presumably conglomeratic sand stone and its resistivity. Findings showed that the top soil layer resistivity values vary from 59.3 to 248.4 ohm-m and thickness of 0.6 to 3.9 m. The second layer has resistivity values ranging from 45.0 to 743.5 ohm-m and a thickness range of 1.5 to 13.8 m. The wet sand is characterized by resistivity values ranging from 144.8 to 1930.2 ohm-m and a thickness range of 3.8 to 65.8 m. The conglomeratic sand/sand stone has resistivity values ranging from 55.8 to 7719.8 ohm-m. The depth to this bottom layer varies from 6.6 to 89.5 m. Findings indicate that the entire profile is a sedimentary formation represented by lithological units of sand and clayey sand which make for a good groundwater potentials. However, the groundwater potential zones of the study area in terms of transmisivity revealed four distinct classes representing "very good" (Mgbuosimini, Rumuigbo, Okporo, Rumuomasi and Rumuodara), "good" (Alakahia, Rumuodomaya, Oginigba and Rumuola), "moderate" (Aluu, Rumuekeni, Rumuokoro, Rumuobiakani and Rumueme), and "low" (Ogbogoro, Ozuoba, Akpajio, Elelenwo, Eliozu, Rumuepirikon, Rumuokwuta, Rumuebekwe and Rumurolu) groundwater potential in the area. Well logging should therefore be incorporated in borehole development process for safe and sustainable yield of groundwater in Obio/Akpor. V. E. Weli et al.
An Integrated Approach to Groundwater Potential Modelling in Jos Metropolis, North Central Nigeria
International Journal of Research Publications, 2021
Groundwater resources are unevenly distributed in the crystalline basement terrain of Nigeria. Hence, the sustainable development and management of groundwater resource in such terrain requires precise quantitative assessment based on scientific principle and modern techniques. This study deals with the integrated approach of remote sensing, GIS and Analytical Hierarchy Process (AHP) in modelling groundwater potential zones within Jos, Northcentral Nigeria. Nigeria Sat - X, ASTER GDEM, topographic and geological maps of the study area are used to generate the various themes; lineaments, geology, drainage, geomorphology, surface water body and slope. Thematic weights are assign to the various layers AHP. The groundwater potential model of the area is produce by integrating the different thematic layers using Weighted Index Overlay Analysis (WIOA) in ArcGIS. Five different potential zones namely; very high, high, moderate, low and very low are determined. The groundwater potential map reveals that some parts in the northwestern, parts of the northeastern and a portion in the extreme southwestern of the study area have very low potential. Low potential is observed in the extreme northwestern, some areas in the northeast and some southwestern parts of the study area. The north central, some northwestern and northeastern as well as southern parts generally exhibits moderate potential. The high and very high groundwater potentiality of the study area is restricted to some parts in the northwest, northeast and few places in the central and southwestern part of the study area. Borehole data obtained from 127 boreholes within the study area where used to validate the groundwater potential of the study area, from which 69.29% coincided with the groundwater potential model.
ASM science journal, 2023
The main objective of groundwater modelling in Gash River Sub-basin, is to investigate the effect of hydrologic, hydrogeological parameters and stresses on hydrodynamic behavio ur through the implementation of a realistic three-dimensional groundwater flow model. Severe decline of water level due to uncontrollable heavy abstraction, exposes a water scarcity problem especially in summer seasons. The model was developed for four geological layers encompassing two aquifer zones. The improved three-dimensional visual MODFLOW Code was selected, implemented and run using WHS method to solve the finite difference equation using trail-and-error calibration procedure at Kassala Area. The transient model was successfully calibrated with acceptable results of model calibration criteria. The contour maps of the simulated heads were performed as potentiometric surface. The general flow direction of the groundwater is from southeast towards northwest part of the area and from Gash River course towards the east and west directions as detected from gradual decreasing of potential line's values in those directions, confirming the aquifer recharge from Gash River. The similarity of potentiometric surface contour maps of the two aquifers confirm the aquifers hydraulic interactions. It is found that t he increasing pumping rate caused considerable increase in drawdown as detected from pumping rate incremental scenarios. Moreover, incremental pumping rate scenarios also reflected increasing river leakage into the aquifer system due to disturbance of water balance due to water level decline. The components of water budgets were calculated and its percentage was performed for the hydrologic balance. The difference between inflow and outflow of the water balance shows a deficit in most stress periods of the model simulations. Calibration fitness was accomplished at most of the observation wells suggesting that the groundwater model is an accurate representation of the actual historic groundwater system and confirm the validity of the model to forecasting purp oses. It was found that the model is more sensitive to hydraulic conductivity and least sensitive to specific yield (Sy). Hence, precaution should be revealed for hydraulic conductivity in forecasting model usage.
American Journal of Water Resources, 2020
Hydrogeological and hydrochemical investigations were used to develop a conceptual model of the Continental Terminal (CT) aquifer functioning in the Oussouye plateau (South Senegal). Two field campaigns were carried out in June and October 2017 to measure physicochemical parameters and groundwater sampling. The geometry of the CT was established using geophysical technics (electrical methods) and the drilling logs from previous studies carried out in Oussouye region. These investigations led to build the mathematical model under the Visual modflow interface with the Modflow-2000 code developed by USGS. The results show a general trend of groundwater flow towards the Casamance River and its tributaries from piezometric mounds in the central area of the plateau which represent the potential recharge zones. Regarding chemical quality, electrical conductivity varies from 28 to 1314 µs/cm with high variance and standard deviation values reflecting variable sources, geochemical and dilution processes occurring in the plateau. The analysis of water samples shows an excellent groundwater quality. Major ions contents do not exceed WHO standards except Iron (Fe) which are relatively high in some wells. The mathematical model was calibrated in steady state. The average difference between simulated and observed head is 0.009 m and the root mean squared is less than 0.2m. Simulations under transient conditions showed that the groundwater is vulnerable to high pumping rate due to the drawdowns at the catchment wells, which can reach 7 m for 300 m 3 /d. This significant drawdown should be avoided for this type of piezometric configuration where the maximum hydraulic head is around 5 m. However, the model revealed a sustainable groundwater potential for the needs of local and neighboring populations by 200m 3 /d.
Review on Scope of Groundwater Modeling
IJSRD, 2014
We all know that the earth contains 70% of water and of 30% Land surface. But from that 70% of water 97% is saline water and we cannot use that water in our day to day life. Now a day the only source of pure water comes from the sub-surface. So that we need to improve the technique to bring out as maximum pure water as possible from the sub-surface. For that groundwater modeling is required. For this purpose many software are available which gives the idea about the lithology and movement of groundwater flow direction. In this paper we are giving the literature review on the groundwater modeling which gives brief idea about groundwater study. Groundwater is the most important source of drinking water in India. Especially it plays a vital role in the development and public health of the population in arid and semi-arid zones. Unfortunately due to injudicious and unplanned urbanization and Industrialization for the past few decades in few parts of the country, the resource is either being depleted or degraded in quality.