scholarly journals Constructing a 3D geological model from geophysical data for groundwater modelling and management in the Kribi-Campo sedimentary sub-basin, Cameroon

2020 ◽  
Vol 15 (1) ◽  
pp. 105-119 ◽  
Author(s):  
Gah-Muti Salvanus Yevalla ◽  
Biyong Bi Mback Emmanuel Blaise ◽  
Rodrigue Ebonji Seth ◽  
Étienne Totcha Beka ◽  
Tabod Charles Tabod
Keyword(s):  
Positive Impact ◽  
Groundwater Resources ◽  
Current Model ◽  
System Structure ◽  
Geological Model ◽  
Infrastructure Development ◽  
Visual Modflow ◽  
Hydrogeological Model ◽  
Aquifer System ◽  
3D Geological Model

Abstract Groundwater resources along the coast of Cameroon (Kribi–Campo Sub-Basin) are under siege from point and non-point pollution sources, climate change, urbanization and infrastructure development. This situation is made worse by the absence of a water management and development strategy. Managing and monitoring the area's water resources requires an understanding of the groundwater systems, and thus a thorough understanding of the geology. In this study, a 3D geological model was built from electro-seismic data and the structure of the area's aquifer system developed. The aquifer system structure was transferred into Visual MODFLOW Flex and then used to develop a typical hydrogeological model, which will help the management and monitoring of the area's groundwater resources. As more geological data become available, the current model can be updated easily by editing and recomputing. This work is expected to have a positive impact quite quickly on the provision of potable water and on public health.

Evaluation of Shallow Groundwater Quantity in Harbin by Numerical Modeling

2011 ◽  
Vol 255-260 ◽  
pp. 2745-2750
Author(s):  
Chang Lei Dai ◽  
Zhi Jun Li ◽  
Shao Min Du ◽  
Chun He Liu
Keyword(s):  
Numerical Modeling ◽  
Groundwater Modeling ◽  
Groundwater Resources ◽  
Shallow Groundwater ◽  
System Structure ◽  
Shallow Aquifer ◽  
Hydrogeological Model ◽  
Aquifer System ◽  
Structure Boundary ◽  
Groundwater Quantity

In order to complete the geological survey of Harbin, it is necessary to understand the regime and law of groundwater in Harbin with the method of groundwater numerical modeling which requires the evaluation of groundwater resources quantity as a basic and critical step. Based on the analysis of hydrogeological conditions of the shallow aquifer in Harbin which includes the characteristics of aquifer system structure, boundary conditions, groundwater regime and recharge and discharge, a conceptual hydrogeological model has been built up with GMS (Groundwater Modeling System). With the numerical simulation model transferred by the conceptual model, the total amounts of renewable groundwater resources under different precipitation frequencies have been calculated. The result not only illustrates that the shallow aquifer in Harbin has certain potential in development and utilization but also provides some reference for managing a highly precise groundwater quantity evaluation by groundwater numerical modeling techniques.

scholarly journals Solutions for groundwater flow with sloping stream boundary: analytical, numerical and experimental models

2017 ◽  
Vol 49 (4) ◽  
pp. 1120-1130 ◽  
Author(s):  
Uğur Boyraz ◽  
Cevza Melek Kazezyılmaz-Alhan
Keyword(s):  
Surface Water ◽  
Groundwater Flow ◽  
Laboratory Experiments ◽  
Groundwater Resources ◽  
Experimental Models ◽  
Flow Equation ◽  
Visual Modflow ◽  
Aquifer System ◽  
Aquifer Characteristics ◽  
Made In

Abstract Protecting groundwater resources plays an important role in watershed management. For this purpose, studies on groundwater flow dynamics incorporating surface water–groundwater interactions have been conducted including analytical, numerical, and experimental models. In this research, a stream–aquifer system was considered to understand the physical behavior of surface water–groundwater interactions. Interactions in a stream–aquifer system were incorporated into the mathematical modeling by defining the stream head as a boundary condition for the groundwater flow equation. This boundary was chosen as a sloping stream boundary, which is an approach in representing the natural conditions of the stream and may be used to define continuous interactions between stream and aquifer. A semi-analytical solution for transient 2D groundwater flow was developed for the considered problem. Isotropic, homogeneous, and finite aquifer assumptions were made in order to define the aquifer characteristics. Then, a series of laboratory experiments was conducted to simulate this stream–aquifer system. Finally, a numerical model was developed by using Visual MODFLOW to verify analytical and experimental results. Numerical results matched with both analytical solutions and the experimental observations.

scholarly journals Depletion of groundwater resources under rapid urbanisation in Africa: recent and future trends in the Nairobi Aquifer System, Kenya

2020 ◽  
Vol 28 (8) ◽  
pp. 2635-2656
Author(s):  
Samson Oiro ◽  
Jean-Christophe Comte ◽  
Chris Soulsby ◽  
Alan MacDonald ◽  
Canute Mwakamba
Keyword(s):  
Negative Impact ◽  
Groundwater Resources ◽  
Climatic Data ◽  
Groundwater Abstraction ◽  
Management Scenarios ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Future Evolution ◽  
Level Data ◽  
Groundwater Assessment

AbstractThe Nairobi volcano-sedimentary regional aquifer system (NAS) of Kenya hosts >6 M people, including 4.7 M people in the city of Nairobi. This work combines analysis of multi-decadal in-situ water-level data with numerical groundwater modelling to provide an assessment of the past and likely future evolution of Nairobi’s groundwater resources. Since the mid-1970s, groundwater abstraction has increased 10-fold at a rate similar to urban population growth, groundwater levels have declined at a median rate of 6 m/decade underneath Nairobi since 1950, whilst built-up areas have increased by 70% since 2000. Despite the absence of significant trends in climatic data since the 1970s, more recently, drought conditions have resulted in increased applications for borehole licences. Based on a new conceptual understanding of the NAS (including insights from geophysics and stable isotopes), numerical simulations provide further quantitative estimates of the accelerating negative impact of abstraction and capture the historical groundwater levels quite well. Analysis suggests a groundwater-level decline of 4 m on average over the entire aquifer area and up to 46 m below Nairobi, net groundwater storage loss of 1.5 billion m3 and 9% river baseflow reduction since 1950. Given current practices and trajectories, these figures are predicted to increase six-fold by 2120. Modelled future management scenarios suggest that future groundwater abstraction required to meet Nairobi projected water demand is unsustainable and that the regional anthropogenically-driven depletion trend can be partially mitigated through conjunctive water use. The presented approach can inform groundwater assessment for other major African cities undergoing similar rapid groundwater development.

scholarly journals Seismically induced changes in groundwater levels and temperatures following the ML5.8 (ML5.1) Gyeongju earthquake in South Korea

2021 ◽  
Author(s):  
Soo-Hyoung Lee ◽  
Jae Min Lee ◽  
Sang-Ho Moon ◽  
Kyoochul Ha ◽  
Yongcheol Kim ◽  
...  
Keyword(s):  
South Korea ◽  
Groundwater Level ◽  
Seismic Waves ◽  
Groundwater Resources ◽  
Fluid Pressure ◽  
Water Levels ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Gyeongju Earthquake

AbstractHydrogeological responses to earthquakes such as changes in groundwater level, temperature, and chemistry, have been observed for several decades. This study examines behavior associated with ML 5.8 and ML 5.1 earthquakes that occurred on 12 September 2016 near Gyeongju, a city located on the southeast coast of the Korean peninsula. The ML 5.8 event stands as the largest recorded earthquake in South Korea since the advent of modern recording systems. There was considerable damage associated with the earthquakes and many aftershocks. Records from monitoring wells located about 135 km west of the epicenter displayed various patterns of change in both water level and temperature. There were transient-type, step-like-type (up and down), and persistent-type (rise and fall) changes in water levels. The water temperature changes were of transient, shift-change, and tendency-change types. Transient changes in the groundwater level and temperature were particularly well developed in monitoring wells installed along a major boundary fault that bisected the study area. These changes were interpreted as representing an aquifer system deformed by seismic waves. The various patterns in groundwater level and temperature, therefore, suggested that seismic waves impacted the fractured units through the reactivation of fractures, joints, and microcracks, which resulted from a pulse in fluid pressure. This study points to the value of long-term monitoring efforts, which in this case were able to provide detailed information needed to manage the groundwater resources in areas potentially affected by further earthquakes.

scholarly journals Study on 3D Geological Model of Highway Tunnels Modeling Method

2010 ◽  
Vol 02 (01) ◽  
pp. 6-10
Author(s):  
Kun ZHENG ◽  
Fang ZHOU ◽  
Pei LIU ◽  
Peng KAN
Keyword(s):  
Modeling Method ◽  
Geological Model ◽  
3D Geological Model

scholarly journals Simulation of Regional Karst Aquifer System and Assessment of Groundwater Resources in Manatí-Vega Baja, Puerto Rico

2015 ◽  
Vol 07 (12) ◽  
pp. 909-922 ◽  
Author(s):  
Balati Maihemuti ◽  
Reza Ghasemizadeh ◽  
Xue Yu ◽  
Ingrid Padilla ◽  
Akram N. Alshawabkeh
Keyword(s):  
Puerto Rico ◽  
Groundwater Resources ◽  
Karst Aquifer ◽  
Aquifer System ◽  
Karst Aquifer System ◽  
Vega Baja

scholarly journals Towards a national 3D geological model of Denmark

2016 ◽  
Vol 35 ◽  
pp. 27-30
Author(s):  
Peter B.E. Sandersen ◽  
Thomas Vangkilde-Pedersen ◽  
Flemming Jørgensen ◽  
Richard Thomsen ◽  
Jørgen Tulstrup ◽  
...  
Keyword(s):  
Subsurface Layer ◽  
Geological Model ◽  
Technical Standards ◽  
Near Surface ◽  
Subsurface Geology ◽  
3D Geological Model ◽  
Combining Data ◽  
National Model ◽  
Surface Geology ◽  
2D To 3D

As part of its strategy, the Geological Survey of Denmark and Greenland (GEUS) is to develop a national, digital 3D geological model of Denmark that can act as a publicly accessible database representing the current, overall interpretation of the subsurface geology. A national model should be under constant development, focusing on meeting the current demands from society. The constant improvements in computer capacity and software capabilities have led to a growing demand for advanced geological models and 3D maps that meet the current technical standards (Berg et al. 2011). As a consequence, the users expect solutions to still more complicated and sophisticated problems related to the subsurface. GEUS has a long tradition of making 2D maps of subsurface layer boundaries and near-surface geology (Fredericia & Gravesen 2014), but in the change from 2D to 3D and when combining data in new ways, new geological knowledge is gained and new challenges of both technical and organisational character will arise. The purpose of this paper is to present the strategy for the national 3D geological model of Denmark and the planned activities for the years ahead. The paper will also reflect on some of the challenges related to making and maintaining a nationwide 3D model. Initially, the model will only include the Danish onshore areas, with the Danish offshore areas and Greenland to be added later using a similar general setup.

scholarly journals A partially-coupled hydro-mechanical analysis of the Bengal Aquifer System under hydrological loading

2018 ◽  
Author(s):  
Nicholas D. Woodman ◽  
William G. Burgess ◽  
Kazi Matin Ahmed ◽  
Anwar Zahid
Keyword(s):  
Mechanical Load ◽  
Groundwater Resources ◽  
Ground Surface ◽  
Coupled Model ◽  
Hydraulic Head ◽  
Water Levels ◽  
Elastic Model ◽  
Surface Boundary ◽  
Aquifer System ◽  
Terrestrial Water

Abstract. The coupled poro-mechanical behaviour of geologic-fluid systems is fundamental to numerous processes in structural geology, seismology and geotechnics but is frequently overlooked in hydrogeology. Substantial poro-mechanical influences on groundwater head have recently been highlighted in the Bengal Aquifer System, however, driven by terrestrial water loading across the Ganges-Brahmaputra-Meghna floodplains. Groundwater management in this strategically important fluvio-deltaic aquifer, the largest in south Asia, requires a coupled hydro-mechanical approach which acknowledges poro-elasticity. We present a simple partially-coupled, one-dimensional poro-elastic model of the Bengal Aquifer System, and explore the poro-mechanical responses of the aquifer to surface boundary conditions representing hydraulic head and mechanical load under three modes of terrestrial water variation. The characteristic responses, shown as amplitude and phase of hydraulic head in depth profile and of ground surface deflection, demonstrate (i) the limits to using water levels in piezometers to indicate groundwater recharge, as conventionally applied in groundwater resources management; (ii) the conditions under which piezometer water levels respond primarily to changes in the mass of terrestrial water storage, as applied in geological weighing lysimetry; (iii) the relationship of ground surface vertical deflection to changes in groundwater storage; and (iv) errors of attribution that could result from ignoring the poroelastic behaviour of the aquifer. These concepts are illustrated through application of the partially-coupled model to interpret multi-level piezometer data at two sites in southern Bangladesh. There is a need for further research into the coupled responses of the aquifer due to more complex forms of surface loading, particularly from rivers.

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