Estimation of sustainable safe yield of wells using analytical and numerical models in the northern Wadi Araba Basin, southern Jordan

Sustainable yield is defined as the amount of groundwater abstraction that can be maintained for an indefinite time without causing unacceptable environmental, economic and social consequences. It is usually determined by monitoring the water-table depth, without the need for costly pumping exercises and subsequent deterioration of the groundwater and ecological environment. Groundwater numerical modelling provides an effective way to determine the yield by analysing the responding water levels to various pumping scenarios. In this study, the natural flow system and flow with pumping scenarios were simulated using FEFLOW for the fractured-rock aquifer in Table Mountain Group, South Africa. Results for different pumping rates show the distinct impact of groundwater abstraction on hydraulic head, which indicates that long-term abstraction slowly increases the well drawdown, but it would stabilize at a level that is dependent on pumping rate and induced recharge. To estimate the aquifer sustainable yield, a relationship between simulated drawdown and pumping rate was established, namely an exponential function with parameters that may change value between sites. This empirical relation, derived from this site-specific study, provides an option for informed decision-making. The issue of how to sustainably abstract groundwater might rely on a compromise between the groundwater user and the governmental authority.

The fundamental challenge for managing groundwater resources in arid and semiarid lands is evaluating the response of aquifers to future short-term and long-term abstractions. This technical knowledge is then used as the basis for water-policy and management decisions. For example, groundwater pumping may be restricted to quantities that are considered sustainable, recognizing that sustainable or safe yields are, in practice, values that are difficult to quantify. Information is, therefore, needed on the impacts of various pumping rates and well distributions on aquifer water budgets, surface water resources, and sensitive environments. In the case of non-renewable groundwater resources, a strategy of planned depletion may be employed, in which case information is needed on the likely rate of future declines in aquifer water levels under different pumping scenarios and on various water resource replacement strategies (e.g., managed aquifer recharge) that may be required to meet future human and natural system requirements. Numerical groundwater modeling is a standard tool for making groundwater resource assessments and projections.

Water, perhaps more than any natural resource, is the universal nexus between development and human existence thus, society is apprehensive about future availability. Potable groundwater is an important component of the total water resource and unlike most other extractable resources can be renewable. As a consequence, it is possible to develop a groundwater source that will last indefinitely—a highly desirable societal outcome. Groundwater, however, is a shared resource in which usage by one party may be highly beneficial to that party but harmful to others and/or to the long-term viability of the resource. Thus, to prevent the “Tragedy of the Commons,” societal management is necessary with the term “sustainability” having been proposed for this role. Sustainability was first used in the 1970s in defining an economic steady state lasting over hundreds of years. In 1987, however, the Brundtland Commission (United Nations 1987) popularized the term in the larger environmental sense. They defined sustainability as, “the ability to meet the needs of the present generation without compromising the ability of future generations to meet their needs.” Or more generally, circumvention of the depletion of a natural resource in order to continue an ecological balance. Groundwater sustainability has been proposed for groundwater management of this concept, yet as shown below that this concept does not capture the reality of most groundwater development! Sustainability in groundwater development is frequently interpreted as withdrawal from a basin not exceeding natural recharge. This is the “safe yield” concept that has been challenged by Bredehoeft et al. (1982); who referred to this concept as a “myth” as it significantly underestimates the potential steady-state yield from a developed aquifer system! In the expansion of the seminal 1940 publication by C. V. Theis, it was quantitively demonstrated that developed groundwater originates from expansion of the cone of depression that has the potential to capture additional water from rejected recharge, induced infiltration from adjacent surface water, as well as capturing water that would have been naturally discharged. If extraction is balanced by these sources, a new dynamic steady-state equilibrium is achieved referred to as “sustained yield” and the volume extracted is greater than that for “safe yield” of the same system. Sustained yield, however, neglects the impact on other interconnected water resources of the larger hydrologic cycle in which change in one part impacts the others and thus, may have cultural or legal implications. Implicitly imbedded in the word groundwater is the perception of quality. That is, “groundwater” suggests potable or agriculturally useful quality, and if not, it is usually specified with a modifier such as saline, brackish, brine, contaminated, toxic, and so on. Hence the concept of quality is inextricably incorporated in the expression of sustainability and the societal value of groundwater includes both quantity and quality aspects. It is obvious that a system could be in dynamic equilibrium (sustained yield) in terms of water balance but owing to change in quality with time (geogenic or anthropogenic) might make the water unusable for the intended purpose. Similarly, it is possible to envision a system in which the water quality remains unchanged while the withdrawals are increased beyond “sustained yield.” Thus, it is clear that most groundwater developments are unlikely to attain sustainability and the term should be discontinued for use as a goal in groundwater management. What is necessary is a word or concept that incorporates both quantity and quality; the philosophical problem, however, is that quantity is a thing (mass, volume, time, etc.), whereas quality is functional utility of an object or its usefulness. Perhaps “groundwater robustness” or “groundwater durability” is a more suitable term. Maybe a word from the Klingon language would be better, who knows. I will let the reader decide, but let us lose the word “sustainability”!

Sustainable management of groundwater resources is essential for sound groundwater development, especially in sensitive salt-affected areas. In Northeast Thailand, the Central Huai Luang Basin, underlain by rock salt, is the source of groundwater and soil salinity. The future sustainable groundwater development yield was assessed under the plausible uncertainty of hydrogeological and projected climate scenarios that could impact the groundwater system. The SEAWAT and HELP3 models were used to simulate groundwater system. The four alternative scenarios of hydrogeological conceptual models were formulated to determine the impact on groundwater system and sustainable groundwater yield. In addition, impacts of projected climate conditions on each alternative model were explored. The results indicate that variable depths and thicknesses of rock salt layers have a higher impact on groundwater salinity distribution and sustainable yield estimations than model boundary conditions. Groundwater salinity, shallow water table areas, and sustainable yield projections vary substantially depending on the possible conceptual model scenarios. It is clear that the variable hydrogeological models affect groundwater sustainable yields.

This paper presents the results of water balance study and aquifer simulation modeling for preliminary estimation of the recharge rate and sustainable yield for the semi arid Barind Tract region of Bangladesh. The outcomes of the study are likely to be useful for planning purposes. It is found from detailed water balance study for the area that natural recharge rates in the Barind Tract vary widely year to year. It may have resulted from the method used for the calculation. If the considered time interval had been smaller than the monthly rainfall, the results could have been different. Aquifer Simulation Modeling (ASM) for the Barind aquifer is used to estimate long-term sustainable yield of the groundwater considering limiting drawdown from the standpoint of economic pumping cost. In managing a groundwater basin efficiently and effectively, evaluation of the maximum annual groundwater yield of the basin that can be withdrawn and used without producing any undesirable effect is one of the most important issues. In investigating such recharge rate, introduction of certain terms such as sustainable yield and safe yield has been accompanied. Development of this area involves proper utilization of this vast land, which is possible only through ensured irrigation for agriculture. The Government of Bangladesh has a plan to develop irrigation facilities by optimum utilization of available ground and surface water. It is believed that the groundwater table is lowering rapidly and the whole region is in an acute state of deforestation. Indiscriminate groundwater development may accelerate deforestation trend. In this context estimation of actual natural recharge rate to the aquifer and determination of sustainable yield will assist in proper management and planning of environmentally viable abstraction schemes. It is revealed from the study that the sustainable yield of ground water (204 mm/y) is somewhat higher than the long-term annual average recharge (152.7 mm) to the groundwater reservoir. The reason behind this is that the rivers within and around the Barind Tract might have played the role of influent rivers.

Pumping tests carried out in three highly tectonized Mediterranean areas, which share similar climate conditions, were used to characterize hard-rock aquifers and examine the issue of the sustainable yield of wells. On the basis of the identified drawdown trends and hydraulic parameters, pumping scenarios were simulated through different methods. The results show that the long-term trend in the drawdown and the initial thickness of the aquifer constrain the sustainable yield of a well. In the worst cases examined, namely those related to an aquifer with a barrier boundary and a delayed response of the aquifer, the sustainable well yield is 1–2 L s −1 . These well discharge values are significant when compared with those found in other regions of the world, and may be related to the dense network of the discontinuities which characterizes the sites.

Conceptual site model (CSM) development is a foundational step for numerical groundwater model construction. Tools for reviewing and combining disparate data to develop a CSM have been furthered through software that efficiently integrates multiple data streams, especially when a large amount of information is available at complex sites. Three‐dimensional (3D) interfaces for data visualization and geological modeling are becoming commonly used to compile data, support development of a robust CSM, and create effective visuals that enable project stakeholders to understand site complexity. This article describes a 3D interface workflow applied to a geological and numerical groundwater modeling case study where numerical modeling (i.e., MODFLOW family of codes) was used to assess remedy effectiveness. Specifically, the numerical model was used to overview an in situ solidification (ISS) application, where soil mixing will be conducted with cement, for possible adverse effects to an existing groundwater treatment system. 3D geological modeling allowed for the existing numerical groundwater flow model to be reconstructed to include previously overlooked data on buried infrastructure, which led to a detailed depiction of high‐permeability channels and a more accurate representation of site conditions. Modeling showed that the ISS remedy would not adversely impact the existing groundwater treatment system. Integration of existing data within a 3D interface led to hydrogeological insights that would have been difficult to obtain from two‐dimensional visualization of information, improved numerical modeling efficiency, and informed site remedy decisions. Additionally, the 3D interface created effective visuals that increased internal and external project team conceptual understanding.

A critical review of groundwater budget myth, safe yield and sustainability

Determining the yield of a production well remains one of the main problems in hydrogeological studies. Starting from the results of a 3-year-long monitoring of a continuously exploited well functioning at constant head (i.e., at a variable discharge rate), a new pumping style has been examined using numerical models. The objective is to control the impact of pumping on the aquifer in accordance with the principle of sustainability. Different models were developed in a transient state and were calibrated using discharge data of the well during the recession periods. Successively, the trends of the residual outflow from the aquifer system with the well operating at variable discharge and at constant discharge were simulated. The results indicate that the ratio of the volume of water pumped from the well to the volume of residual outflow is a significant indicator of the sustainability of groundwater withdrawals. Modeling confirms that a constant discharge rate can be derived from the information gained through a preliminary production phase of a well at constant head. This approach appears to be particularly useful when the problem is determining the sustainable yield of a single well from aquifers with low hydraulic diffusivity.

The main target of this research paper was to the hydrogeological assessment of the groundwater resources to irrigate 600 ha of irrigable agricultural lands, distributed along the Dead Sea–Aqaba Highway in Umm, Methla, Wadi Musa, Qa’ Saideen and Rahma, southern Jordan. Therefore, a comprehensive groundwater study was commenced by drilling eight new wells which can be used to supply irrigable areas with the existing groundwater that would be enriched by the yield of three proposed recharge dams on Wadi Musa, Wadi Abu-Burqa, and Wadi Rahma. The evaluation of the pumping test data of the drilled was carried out using the standard methods of pumping test interpretation. This was based on the available water table measurements at well locations and knowledge of water flow in the general. The sustainable yield of each well was calculated based on the pumping test parameters. The obtained results indicate that pumping out of Beer Mathkor wells should not exceed 1,100 m3/day in the case of continuous pumping and 8,700 m3/day in the case of intermittent pumping. Since the water table did not significantly change with small changes in pumping (it took eightfolds of magnitude increase in pumping from approximately 1,100 to 8,700 m3/day to show a significant drop in the water table equivalent to about 5.5 MCM per year from the aquifer.

Groundwater, possibly of fossil origin, is used for water supply in some arid regions where the replenishment of groundwater by precipitation is low. Numerical modelling is a helpful tool in the assessment of groundwater resources and analysis of future exploitation scenarios. To quantify the groundwater resources of the East Owienat area in the southwest of the Western Desert, Egypt, the present study assesses the groundwater resources management of the Nubian aquifer. Groundwater withdrawals have increased in this area, resulting in a disturbance of the aquifer’s natural equilibrium, and the large-scale and ongoing depletion of this critical water reserve. Negative impacts, such as a decline in water levels and increase in salinity, have been experienced. The methodology includes application of numerical groundwater modelling in steady and transient states under different measured and abstraction scenarios. The numerical simulation model developed was applied to assess the responses of the Nubian aquifer water level under different pumping scenarios during the next 30 years. Groundwater management scenarios are evaluated to find an optimal management solution to satisfy future needs. Based on analysis of three different development schemes that were formulated to predict the future response of the aquifer under long-term water stress, a gradual increase in groundwater pumping to 150% of present levels should be adopted for protection and better management of the aquifer. Similar techniques could be used to improve groundwater management in other parts of the country, as well as other similar arid regions.Editor D. Koutsoyiannis; Associate editor X. ChenCitation El Alfy, M., 2014. Numerical groundwater modelling as an effective tool for management of water resources in arid areas. Hydrolological Sciences Journal, 59 (6), 1259–1274. http://dx.doi.org/10.1080/02626667.2013.836278

The Wadi Araba Basin is a desert area in which finding water represents a real challenge. One potential source for the abstraction of groundwater is a sandstone aquifer which is partly covered by alluvial sediments distributed along the Wadi Araba Valley. The study analyses the impacts of abstraction and climate changes on groundwater quantity. It also aims to define a safe yield for the groundwater resources and to locate new wellfields in hydrogeological areas that will minimize high drawdown. Numerical modelling (MODFLOW NWT version) was applied in order to develop a regional groundwater flow model for the Wadi Araba Basin. The modelling area covers 6268 km2 (the Wadi Araba Basin on the Jordanian side). The cell sizes in horizontal directions are 500 m, and there are four layers in a vertical direction represented by the main aquifers and aquitards of the hydrogeological system (alluvial aquifer, A7/B2 carbonate aquifer, A1-A6 marly aquitard and Kb/Ram sandstone aquifer). Results of the modelling show that renewable groundwater resources stand at around 20 million cubic meters per year (MCM/year). According to the most pessimistic predictive scenario, the water table might decrease by 60 m by 2050, with the most optimistic scenario putting that figure at 24 m. Five new wellfield locations are proposed (four in the central part and one in the northern part of the Wadi Araba Valley). According to the model, the opening of new wellfields in these optimal locations, and the closing of some old wells where relatively large drawdowns were recorded, revealed that a more sustainable abstraction of groundwater could be achieved.

This paper aims to contribute to understanding the importance of four factors on the determination of sustainable yields: (i) aquifer properties; (ii) temporal distribution of recharge; (iii) temporal distribution of groundwater pumping; and (iv) spatial distribution of pumping wells. It is important to comprehend how the present‐day and future vulnerability of groundwater systems to pumping activities depend on these critical factors and what the risks are of considering sustainable yield as a fixed percentage of mean annual recharge (MAR). A numerical model of the Querença–Silves aquifer in Portugal is used to develop hypothetical scenarios with which these factors are studied. Results demonstrate the aquifer properties, particularly the storage coefficient, have an important role in determining the resilience of an aquifer and therefore to which degree it is dependent on the spatial and temporal distribution of abstraction and recharge, as well as the occurrence of extreme events. Sustainable yields are determined for the developed scenarios based on specific criteria rather than a fraction of MAR. Under simplified current recharge and abstraction conditions, the sustainable yield was determined at approximately 73% of MAR or 76 million m3. When considering a concentration of rainfall in time, as predicted by climate scenarios for the region, sustainable yield could drop to ca 70% of MAR. However, a more even distribution of pumping volumes throughout the year could increase this value. The location of the pumping wells is seen to affect the distribution of hydraulic heads in the aquifer, albeit without significant changes in sustainable yield. Copyright © 2011 John Wiley & Sons, Ltd.

The alluvial–fluvial drainage system in the Wadi Araba, southern Jordan, incised into Cambrian clastic sedimentary and felsic igneous rocks giving rise to a disseminated Cu–(Mn) mineralization of diagenetic and epigenetic origin along the southern branch of the Dead Sea Transform Fault (=DSTF). During the Late Pleistocene and Holocene, the primary Cu sulfides were replaced by secondary minerals giving rise to hypogene to supergene encrustations, bearing Cu silicates, Cu carbonates, Cu oxychlorides and cupriferous vanadates. They occur in fissures, coat walls and developed even-rim/meniscus and blocky cements in the arenites near the surface. The first generation cement has been interpreted in terms of freshwater vadose hydraulic conditions, while the second-generation blocky cement of chrysocolla and malachite evolved as late cement. The Cu–Si–C fluid system within the Wadi Araba drainage system is the on-shore or subaerial facies of a regressive lacustrine regime called the “Lake Lisan Stage”, a precursor of the present-day Dead Sea. Radiocarbon dating (younger than 27,740 ± 1,570 years), oxygen-isotope-based temperature determination (hot brine-related mineralization at 60–80 °C, climate-driven mineralization at 25–30 °C) and thermodynamical calculations let to the subdivision of this secondary Cu mineralization into four stages, whose chemical and mineralogical composition was controlled by the variation of the anion complexes of silica and carbonate and the chlorine contents. The acidity of the pore water positively correlates with the degree of oxidation. The highest aridity and most intensive evaporation deduced from the thermodynamical calculations were achieved during stage 3, which is coeval with late Lake Lisan. Geogene processes causing Cu-enriched encrustations overlap with man-made manganiferous slags. The smelter feed has been derived mainly from Cu ore which developed during Late Pleistocene in the region.

Groundwater quality is an important factor that determines its usage for drinking and irrigational use. This study was carried out along the quaternary alluvial aquifer which extends along Wadi Araba groundwater basins, in southern Jordan. Chemical and physical parameters were measured and analyzed for thirty-seven groundwater samples collected from twenty-one wells in the study area during two periods in the year 2019; the spring season (April–May) was represented by fourteen samples and the autumn season (August–September) represented by twenty-three samples were collected to determine its suitability for drinking and irrigational purposes. The groundwater in the study area is generally of low alkalinity with an average pH value of less than 8 for both spring and autumn seasons. The water of the area is excessively mineralized due to salinity, and the increase in water salinity of the southern Wadi Araba basin is less expressed than in the northern part. The hydrochemical characterization shows that most wells of the study area are characterized by HCO3–Ca–Mg and HCO3–SO4–Ca–Mg types in the eastern escarpments of Wadi Araba (i.e., recharge area) and Cl–SO4–Na and Cl–Na types in the discharge area. There is no substantial change in the hydrochemical composition during the two seasons. Based on the Piper diagram, most of the groundwater samples (91.8%) belong to class “E” as “earth alkaline water with increased portions of alkalis with prevailing sulfate and chloride.” The Durov diagram reveals that most groundwater samples (62.2%) lay in the water genesis “field 6” which indicates that the water may be related to the reverse ion exchange of Na–Cl. The chemical composition of the water samples was compared with the drinking water standards of the World Health Organization and the Jordanian Standard. Groundwater from this area was not suitable to be a source for direct drinking based on total hardness and total dissolved solids. The dominant cation is sodium, while the dominant anion is chloride. The calculations of saturation indices for the two sampling campaigns for different minerals showed negative values of (SI) for carbonates minerals (anhydrite, gypsum, sylvite, and halite). This suggests that the groundwater in the alluvial aquifer is undersaturated with respect to these minerals in most of the study area. This is indicative of the fact that these minerals are undergoing the process of dissolution. The mineral saturation indices suggest that the dominating hydrochemical processes were dissolutions of evaporite minerals (halite and gypsum), carbonate minerals (such as calcite, dolomite, and rhodochrosite), the manganese oxide minerals (such as jarosite-K, hausmannite, pyrochroite, and pyrolusite) and reverse ion exchange.