Evaluation Of Groundwater Resources Research Articles

Review: Approaches to groundwater exploration and resource evaluation in the crystalline basement aquifers of Zimbabwe

Assessment of the groundwater potential of crystalline basement aquifers is challenging. These systems can be highly spatially variable, as indicated by the drilling of numerous dry boreholes and seasonal variation in discharge rates. This paper reviews methodologies applied for the evaluation of groundwater occurrence and yield estimation in the crystalline basement aquifers of Zimbabwe. These aquifers underlie much of the country and are described in terms of low yield owing to low recharge potential in the semiarid climate. In such regions, exploitable groundwater forms a strategic supply of potable water used to meet the socio-economic needs of the local population. Case studies are used to show how remote sensing and geophysical methods are integrated to improve borehole success rates in the basement aquifers of Zimbabwe. Potential threats to groundwater resources and quality within crystalline basement aquifers are discussed. It can be concluded that major issues remain to be addressed if sustainable use of the water resources of crystalline basement aquifers in Zimbabwe is to be achieved, especially with respect to borehole-siting approaches and prevention of groundwater contamination. The key recommendation is to address the paucity of primary groundwater monitoring data within the crystalline basement aquifers at the national level, thereby creating a technical groundwater management framework.

Evaluation of national and regional groundwater resources under climate change scenarios using a GIS-based water budget procedure

The present study investigates the impact of climate change on the availability of groundwater resources in Italy and in Campania region (Southern Italy). A 20-year average from 1996 to 2015 of annual water budget components (namely total precipitation, actual evapotranspiration, surface runoff and aquifer recharge) has been evaluated over a 1-km resolution grid and have been projected considering four climate change scenarios (from the Fifth Assessment Report of the United Nations Intergovernmental Panel on Climate Change) and three different future 20-year time periods (2020–2039, 2040–2059 and 2080–2099). The groundwater balance has been carried out on a yearly basis using the “Nationwide GIS-based regular gridded hydrological water budget” procedure, which has been developed by the Italian National Institute for Environmental Protection and Research (ISPRA). The different scenarios of groundwater resources have been compared and matched to the 20-year average of latest historical values related to the period 1996–2015, leading to interesting considerations about the future depletion of groundwater resources. Nationwide results have been compared with those of Campania region, in order to underline the significant differences of climate change impact on groundwater resources at local scale, especially in a typical Mediterranean climate where groundwater resources represent the main source of water for human needs.

Simulation evaluation of groundwater resources in southeastern Bosten Lake based on GMS

Bosten Lake is located in Yanqi Basin of Xinjiang. A working area in the southeast of China is influenced by the regulation of Bosten Lake, and the transitional zone of climate in the north and south of Xinjiang, forming a climate of large evaporation, dry and little rain, and groundwater is a very important fresh water resource. In order to find out the composition of groundwater resources in the working area, the groundwater steady flow model is established by using the data of borehole, well, pumping test and so on, and the groundwater resources in this area are evaluated. The groundwater exploitation mode in the simulated area is evaluated. The results show that: the exploitable groundwater resources in the simulated area is about 22.045 million m3/a. Changing the mode of agricultural water use under the existing groundwater equilibrium condition can effectively reduce the waste of groundwater resources.

Integrated geospatial, geostatistical, and remote-sensing approach to estimate groundwater level in North-western India

The depletion of groundwater resources in Northwest India has been extensively studied. The top priority to meet the scarcity of water for irrigation, industrial and domestic purposes is supplemented by groundwater. Geostatistical modelling approach is considered to be beneficial tool for the assessment, evaluation, monitoring, and management of groundwater resources. This study is an attempt to analyze the spatio-temporal variability of groundwater level in semi-arid region of Panipat district, Haryana, India using kriging technique to fill the data gaps. Ordinary kriging was found optimal for the interpolation of groundwater levels. The results revealed that there was not much seasonal variation and also the groundwater flow direction remained almost constant in the study area during the assessment period. Spatial variability analysis showed significant variation in groundwater level and further depicted that the study area had undergone more or less decline in groundwater over the period of time. To validate the observations and results geo spatial and remote sensing techniques including normalised difference vegetation index and impervious surface relationships were worked out. It was further co-related with the rainfall data and the canal network existing in Panipat region. The integrated approach substantiated the observed results with the ground reality and helped in better understanding of the causes of declining groundwater trend in central part of Panipat.

Evaluation of Groundwater Resources in Response to Agricultural Management Scenarios in the Central Valley, California

AbstractDependence on groundwater throughout the Central Valley of California has resulted in severe and unsustainable groundwater depletion. In this research, we used the Central Valley hydrologic...

Estimation of Sandstone Permeability with SEM Images Based on Fractal Theory

Permeability is one of the key parameters for quantitatively evaluating groundwater resources and accurately predicting the rates of water inflows into coal mines. This paper presents an efficient method to estimate the macroscopic permeability by using the scanning electron microscopy (SEM) images. A correlation between the microscopic features of sandstone porosity and the macropermeability is approached by an image identification technique. Firstly, the gray images were transformed into the binary images by using the histogram of the entropy method. Then, the Green and Euler distance methods were applied to calculate the length and area of the pores, and the fractal parameters were estimated according to the slit island method. Based on the theory of microscopic seepage flow, the seepage coefficient and permeability were calculated by fractal parameters. Typical water-bearing sandstone samples in the Kailuan coal field area in North China were selected to demonstrate the methodology. SEM microscopic images of nine groups of sandstone samples collected at different depths (from the outcrop to the deep mines) were analyzed. Based on the theoretical model of micropore structures and the fractal theory, the permeabilities were estimated. The results provide insights for understanding the hydraulic properties of the sandstone.

Assessment of groundwater recharge processes through karst vadose zone by cave percolation monitoring

AbstractRecharge processes of karst aquifers are difficult to assess given their strong heterogeneity and the poorly known effect of vadose zone on infiltration. However, recharge assessment is crucial for the evaluation of groundwater resources. Moreover, the vulnerability of karst aquifers depends on vadose zone behaviour because it is the place where most contamination takes place. In this work, an in situ experimental approach was performed to identify and quantify flow and storage processes occurring in karst vadose zone. Cave percolation monitoring and dye tracing were used to investigate unsaturated zone hydrological processes. Two flow components (diffuse and quick) were identified and, respectively, account for 66% and 34% of the recharge. Quickflow was found to be the result of bypass phenomenon in vadose zone related to water saturation. We identify the role of epikarst as a shunting area, most of the storage in the vadose zone occurring via the diffuse flow component in low permeability zones. Relationship between rainfall intensity and transit velocity was demonstrated, with 5 times higher velocities for the quick recharge mode than the diffuse mode. Modelling approach with KarstMod software allowed to simulate the hybrid recharge through vadose zone and shows promising chances to properly assess the recharge processes in karst aquifer based on simple physical models.

Using DEM and GIS for evaluation of groundwater resources in relation to landforms in the Maharlou-Bakhtegan watershed, Fars province, Iran

Abstract The study of groundwater resources in relation to topography is important. Clearly, in different topography, depth of the water level is different. Therefore, the aim of this study is the determination of the relationship between landform classes with compound topographic index (CTI) and depth of the water for the Maharlou-Bakhtegan watershed, Fars Province, Iran. In order to evaluate the depth of the water for the study area, CTI and geomorphology (landforms) were derived from a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). The results of landform classes extracted using topographic position index (TPI) showed that the largest landform is open slope, while the smallest are plains. It was found that CTI and depth of the water values are high in plain classes, while they are low in local ridges. High depth of the water were found to be mostly confined to the pit regions in the plain landform, because groundwater recharge occurs in the zones where standing water remains for sufficient long period of time and has favourable condition for recharge.

Hydrogeological conceptual model of large and complex sedimentary aquifer systems – Central Kalahari Basin

Successful groundwater resources evaluation and management is nowadays typically undertaken using distributed numerical groundwater flow models. Such models largely rely on hydrogeological conceptual models. The conceptual models summarize hydrogeological knowledge of an area to be modelled and thereby providing a framework for numerical model design. In this study, an efficient data integration method for developing hydrogeological conceptual model of the large and hydrogeologically-complex, Central Kalahari Basin (CKB) aquifer system, was undertaken. In that process, suitability of 3-D geological modelling with RockWorks code in iterative combination with standard GIS (ArcGIS) was tested. As a result, six hydrostratigraphic units were identified, their heads and related flow system interdependencies evaluated and hydraulic properties attached. A characteristic feature of the CKB is a thick unsaturated Kalahari Sand Unit (KSU), that restricts the erratic recharge input to <1 mm yr−1 in the centre to about 5–10 mm yr−1 in the eastern fringe. The analysis of the spatial distribution of topological surfaces of the hydrostratigraphic units and hydraulic heads of the aquifers, allowed to identify three flow systems of the three aquifers, Lebung, Ecca and Ghanzi, all three having similar radially-concentric regional groundwater flow patterns directed towards discharge area of Makgadikgadi Pans. That pattern similarity is likely due to various hydraulic interconnections, direct or through aquitard leakages, and also due to the presence of the overlying unconfined, surficial KSU, hydraulically connected with all the three aquifers, redistributing recharge into them. The proposed 3-D geological modelling with RockWorks, turned to be vital and efficient in developing hydrogeological conceptual model of a large and complex multi-layered aquifer systems. Its strength is in simplicity of operation, in conjunctive, iterative use with other software such as standard GIS and in flexibility to interface with numerical groundwater model. As a result of conceptual modelling, fully 3-d, 6 layer numerical model, with shallow, variably-saturated, unconfined layer is finally recommended as a transition from conceptual into numerical model of the CKB.

Comprehensive evaluation of groundwater resources based on DPSIR conceptual framework

In order to manage integrated groundwater resources in the plains with high dependence on the ground water resources, it seems to be essential to take into account the economic, social, and environmental dimensions in management and planning of water resources, based on DPSIR (driving forces-pressures-states-impacts-responses) framework. Kuhdasht plain located in Iran is one of such settlements in which human activities have led to irreversible destruction of groundwater resources during the last two decades. A case study is performed to properly investigate the causes of groundwater resources degradation in Kuhdasht plain and optimize measures for the sustainable groundwater resources management by the DPSIR approach. The results showed that the key driving forces influencing groundwater resources have been the population growth, the increased cultivated surface area, the cropping pattern change, the changes in industrial water consumption pattern and per capita water consumption, the natural resources destruction, and climate variability. The main pressures on groundwater resources of the study region have been extensive groundwater overdraft, decreased aquifer recharge caused by reduced precipitation, vegetation cover destruction, and land use change. Based on the results, the aquifer exhibits a negative balance for 1989–2008 period as well as a 7-m decline in the aquifer’s water table, and land subsidence of 0.012–0.31 m. On the other hand, the results indicate that despite the agricultural sector has exerted the highest stress on the Kuhdasht aquifer, this sector has had the lowest economic efficiency with little contribution to employment creation.

Investigation and Evaluation of Groundwater Resources of Juxian

The investigation and evaluation of groundwater resources refers to the analysis of groundwater quantity, quality, spatial-temporal property and exploitation status. Based on the collected data and field investigation, the groundwater resources in plain and hilly area of Juxian were calculated by replenishment method, discharge method and comprehensive infiltration coefficient method, and the groundwater quality was analyzed and evaluated. The conclusions are as follows: (1) The amount of groundwater resources is 224.940 million m3/a, including 89.585 million m3/a of plain area and 142.523 million m3/a of hilly area respectively. (2) The allowable yield of groundwater is about 162.948 million m3/a, in which the amounts in the plain area and the hilly area are 74 .585million m3/a and 88.363 million m3/a, respectively. (3) The pH value of groundwater ranges from 6.5∼7.5 and the degree of mineralization of groundwater was lower than 1 g/L at most. In addition, the total hardness varies from 150 mg/L to 450 mg/L in plain area and 300 mg/L to 550 mg/L in hilly area, respectively. The investigation and evaluation of groundwater resources was of great significance in ensuring the sustainable development of groundwater resources, establishing the scheme of groundwater resources exploitation and utilization.

Vertical Electrical Sounding Survey for Groundwater Exploration for Rural Water Supply in Parts of Ketu South in the Volta Region of Ghana

Hydrogeological investigations and geophysical surveys are important methods in many subsurface characterization studies. This work examines the importance of geophysical surveys in the construction and development of boreholes to provide portable drinking water to rural communities. The paper discusses the interpretation of subsurface features that can be used to assist in the evaluation of groundwater resources in a typical rural area. Lack of infrastructure in these areas is a constraint on borehole drilling due to limited subsurface data availability. Vertical Electrical Sounding (VES) stations were established to investigate the subsurface geology and aquifer potentials in the study area. VES technique was performed by measuring the resistivity change with depth. The resistivitymeasurements were conducted using ABEM SAS 100C Terrameter by using Schlumberger electrode configuration. The hydrogeological information obtained by the methods discussed in this paper can be used as estimates of the depth of groundwater, aquifer geology, and recharge and discharge zones. The objective of the study was to provide guidelines with sufficient data and information to evaluate borehole options and future borehole drilling and development campaigns in typical rural settings.

Delineation of groundwater potential zones using remote sensing, GIS, and AHP technique in Tehran–Karaj plain, Iran

Evaluation of groundwater resources in dry areas without enough data is a challenging task in many parts of the world, including Tehran–Karaj plain in Iran, which includes Tehran, the capital city of Iran and Karaj, one of Iran’s biggest cities. Water demand due to increasing agricultural and industrial activities caused many problems in the field of water resources management. In this study, the potential of groundwater resources was evaluated using remote sensing, geographic information system (GIS), and analytic hierarchy process (AHP) for the first time. Digital Elevation Model from Shuttle Radar Topography Mission was used to generate a slope map and drainage density map. Three Landsat-8 satellite images were utilized to provide lineament density and land cover/land use maps. Geological and soil type maps were provided from the Geological Survey and Mineral Explorations of Iran (GSI). Tropical Rainfall Measuring Mission data were used to prepare average annual precipitation map. Discharge values from 102 pumping wells in the time period of 2002–2014 were used to evaluate the results. Seven data layers were prepared, and the geodatabase was made in GIS. The layers and their classes were assigned weights using AHP method. Finally, the layers were overlaid based on their weights, and the potential map of groundwater resources was generated. The area was classified into five zones with very high, high, moderate, low, and very low potentials. The zones covered 5.95, 32.90, 22.70, 10.20, and 28.25% of the study area, respectively. The results showed good agreement with the field data obtained from discharge wells.

ACQUE SOTTERRANEE: RISORSA IDRICA STRATEGICA NELLA PIANURA LOMBARDA

A proper understanding of the water cycle, and in particular of the distribution and availability of groundwater will enable to evaluate their sustainability and manage them especially in critical situations which in the future will be related to climatic change with high temperature conditions, in which more consumable water is needed. Water use in Lombardy region is an economic opportunity and related consumption are described. To satisfy water uses it is necessary to develop an integrated system for a rational management in which groundwater have an important role. In DISAT researches to evaluate groundwater resources are developed by long time. Mathematical models applied to hydrogeology are used to verify and simulate real systems and to predict future scenarios. The methodology use an integrate system from a database of wells to software which permit to reconstruct the 3D geometry of subsoil and parameterize it according to the texture distribution of the subsoil to evaluate the water storage and its availability. According to these application and coupling models it will be possible, in the future, simulate the effects of critical situations related to groundwater and to identify the best solutions.

Stratigraphic sequence map for groundwater assessment and protection of unconsolidated aquifers: A case example in the Abitibi-Témiscamingue region, Québec, Canada

Quantifying water resources at various scales is crucial for ensuring safe access to potable water for present and future generations. Fitting into this framework, this study presents a GIS-based approach aimed at allowing the evaluation of available groundwater resources within unconsolidated aquifers set in vast and heterogeneous shield regions. The approach was developed in a 19,397 km2 region located in Abitibi-Témiscamingue (Québec, Canada) where unconsolidated aquifers are set in an irregular geologic framework owing to the rugged Canadian Shield topography and to the diversity of glacial and post-glacial events that shaped the landscape. Sparse and unevenly distributed stratigraphic borehole data were used for constructing a GIS-based model representing the total overburden thickness (unconsolidated sediments covering the bedrock), as well as the thickness and extent of the fine-grained deep-water sediments (silt-clay) of the Barlow-Ojibway proglacial Lake on a 100 m × 100 m mesh at the regional scale. The study suggests a new set of functions to map drift thickness in areas of highly discontinuous drift cover, using GIS tools. These data were used jointly with surficial deposits maps in order to develop a regional-scale two-dimensional model where 15 distinct stratigraphic sequences allow representation of the architecture of unconsolidated geological units. The approach allows simplifying data representation and ensuring the consistency between various regional-scale hydrogeological maps. The data is used to produce a stratigraphic sequence map for representing the architecture of aquifer– aquitard systems at the regional scale in a manner that is intelligible to non-specialists. The map and related data are first discussed for documenting the extent and volume of regional aquifers. The stratigraphic sequence map is subsequently discussed as a tool for supporting political decision makers dealing with issues related to groundwater resource assessment, protection and sustainable development.

Development of a new model tool for evaluating groundwater resources within the Floridan Aquifer System in Southern Florida, USA

The US Army Corps of Engineers (USACE) and the South Florida Water Management District (SFWMD) are partners in an ambitious plan to restore water flows throughout the Everglades ecosystem. An important component of the restoration plan involves storing excess stormwater deep underground in the Floridan Aquifer System using aquifer, storage and recovery (ASR) wells. In order to determine the optimal ASR system and to assess environmental impacts, USACE spent over 11 years and significant resources to develop a three-dimensional groundwater model of the Floridan Aquifer System covering a large portion of the Florida peninsula. This SEAWAT model is capable of evaluating changes in aquifer pressures and density-dependent flows in the entire study area. The model has been used to evaluate the Everglades ASR system already but could also be used by water managers for other important water resources studies in Florida including water supply estimates and adaptation to climate change. As part of an effort to make the model more readily available for other important studies, this study documents and summarizes the overall development of the SEAWAT model including a discussion regarding the intensive calibration and validation efforts undertaken during model development. The paper then demonstrates the use of the model using Everglades ASR project alternatives. Lastly, the paper outlines potential future uses of the model along with its overall limitations. Supplementary online resources are also included that provide researchers with further detail regarding the model development effort beyond the scope of this summary article as well as model development databases.

Evaluation of groundwater resources for sustainable groundwater development in a semiarid river basin of India

There is a growing stress on groundwater due to increase in the frequency and intensity of droughts, and the limited availability of surface water. Therefore, proper assessment of available groundwater reserves is highly essential at a microscale (e.g., block level) to take into account spatial variability. In this paper, a methodology for the effective assessment of groundwater resources is demonstrated considering a semiarid river basin of Western India as a study area. The rainfall data of nine raingauge stations and seasonal groundwater-level data of 132 sites over the basin for 20 years (1990–2009) were used. Groundwater availability in the unconfined aquifer was evaluated at a block level in terms of ‘static groundwater reserve (SGWR)’ and ‘dynamic groundwater reserve (DGWR),’ and their spatial and temporal variabilities were analyzed. Furthermore, the status of groundwater utilization in individual blocks was explored considering the level of groundwater development (GWDL) and the trends of long-term seasonal groundwater levels. To sustain available groundwater resources on a long-term basis, the runoff potential in the study area was also evaluated. It was found that SGWR varies from 0.09 to 136.97 MCM (million cubic meters), whereas DGWR ranges from −35.85 to 156.26 MCM. During ‘normal’ years, around 43% of the study area has a SGWR in the range of 20–40 MCM and DGWR in the range of 0–50 MCM. Although the GWDL in the study area varies from about 12 to 124%, the status of groundwater development in the study area is categorized to be ‘safe.’ The analysis of runoff potential in the study area revealed that it considerably varies with time and space. About 71% of the study area is suitable for rainwater conservation during ‘wet’ years, whereas this figure reduces to 33% in ‘normal’ years. It is emphasized that regular monitoring of groundwater at a suitable spatial scale (at least block level) is necessary on long-term basis and the adoption of rainwater harvesting measures are indispensable for sustainable utilization and management of groundwater resources in semiarid regions.

A distributed monthly water balance model: formulation and application on Black Volta Basin

Recharge assessment is of critical importance for groundwater resources evaluation in arid/semiarid areas, as these have typically limited surface water resources. There are several models for water balance evaluation. One of them is WetSpass, which has the ability to simulate spatially distributed recharge, surface runoff, and evapotranspiration for seasonally averaged conditions. This paper presents a modified methodology and model, WetSpass-M, in which the seasonal resolution is downscaled to a monthly scale. A generalized runoff coefficient was introduced, enabling runoff estimation for different land-use classes. WetSpass-M has been calibrated and validated with observed streamflow records from Black Volta. Base-flow from simulated recharge was compared with base-flow derived via a digital filter applied to the observed streamflow and has shown to be in agreement. Previous studies have concluded that for this basin, small changes in rainfall could cause a large change in surface runoff, and here a similar behavior is observed for recharge rates. An advantage of the new model is that it is applicable to medium- and large-sized catchments. It is useful as an assessment tool for evaluating the response of hydrological processes to the changes in associated hydrological variables. Since monthly data for streamflow and climatic variables are widely available, this new model has the potential to be used in regions where data availability at high temporal resolution is an issue. The spatial–temporal characteristics of the model allow distributed quantification of water balance components by taking advantage of remote sensing data.

Inverse modelling of aquifer parameters in basaltic rock with the help of pumping test method using MODFLOW software

The origin and movement of groundwater are the fundamental questions that address both the temporal and spatial aspects of ground water run and water supply related issues in hydrological systems. As groundwater flows through an aquifer, its composition and temperature may variation dependent on the aquifer condition through which it flows. Thus, hydrologic investigations can also provide useful information about the subsurface geology of a region. But because such studies investigate processes that follow under the Earth's shallow, obtaining the information necessary to answer these questions is not continuously easy. Springs, which discharge groundwater table directly, afford to study subsurface hydrogeological processes.The present study of estimation of aquifer factors such as transmissivity (T) and storativity (S) are vital for the evaluation of groundwater resources. There are several methods to estimate the accurate aquifer parameters (i.e. hydrograph analysis, pumping test, etc.). In initial days, these parameters are projected either by means of in-situ test or execution test on aquifer well samples carried in the laboratory. The simultaneous information on the hydraulic behavior of the well (borehole) that provides on this method, the reservoir and the reservoir boundaries, are important for efficient aquifer and well data management and analysis. The most common in-situ test is pumping test performed on wells, which involves the measurement of the fall and increase of groundwater level with respect to time. The alteration in groundwater level (drawdown/recovery) is caused due to pumping of water from the well. Theis (1935) was first to propose method to evaluate aquifer parameters from the pumping test on a bore well in a confined aquifer. It is essential to know the transmissivity (T = Kb, where b is the aquifer thickness; pumping flow rate, Q = TW (dh/dl) flow through an aquifer) and storativity (confined aquifer: S = bSs, unconfined: S = Sy), for the characterization of the aquifer parameters in an unknown area so as to predict the rate of drawdown of the groundwater table/potentiometric surface throughout the pumping test of an aquifer. The determination of aquifer's parameters is an important basis for groundwater resources evaluation, numerical simulation, development and protection as well as scientific management. For determining aquifer's parameters, pumping test is a main method. A case study shows that these techniques have been fast speed and high correctness. The results of parameter's determination are optimized so that it has important applied value for scientific research and geology engineering preparation.

Groundwater Supply and Climate Change Management by Means of Global Atmospheric Datasets. Preliminary Results

Climate change influences hydrological cycle with a direct effect on groundwater resources, one of the most important supply sources for human consumption and irrigation. In a scenario where General Circulation Models do not represent yet a usual tool for water industry managers, potentially the use of global atmospheric datasets is of great interest for evaluating groundwater resources. In this paper data from the European Centre for Medium-Range Weather Forecasts (ECMWF) are compared to local water table measurements. With particular regard to unconfined aquifers, the good correlation between the trend of soil moisture and local water table data is pointed out. Such a promising result authorizes further insights in order to refine reliable tools for evaluating available groundwater resources in a climate change scenario.