Drawdown Of Groundwater Level Research Articles

An uncertain agent-based model for socio-ecological simulation of groundwater use in irrigation: A case study of Lake Urmia Basin, Iran

Socio-ecological systems include diverse resources of complexity involving complicated interactions, feedback, dynamic behavior patterns, heterogeneity in agents’ characteristics and behaviors, as well as system uncertainties. Agent-based modeling is introduced as a tool to simulate different levels of stakeholders and interactions, including individual, group, and institutional agents in complex socio-ecological systems. In the present study, an agent-based model was developed to explore sustainable solutions in uncertain conditions for groundwater restoration of a critical aquifer in the Lake Urmia Basin, Iran. Different projects for aquifer restoration such as wells monitoring, license adjustment, and modern irrigation development were implemented in the developed framework. The results showed that it is possible to alleviate the negative balance of the aquifer in case of necessary coordination in the projects implementation. So that during the simulation period, while increasing the total annual net income of the cultivation by €1.3 million (about 7%), the groundwater level drawdown can be compensated by about 5 m (about 50% of the decline over the past 30 years). Results of sensitivity analysis on the risk-taking behavior of farmer agents showed that it has a more significant impact on the total income than groundwater level. In the risk-seeking society conditions, a 10% increase of total annual net income is expected in the early years of simulation. The framework is used to learn about the influences of agents’ objectives, characteristics, and behaviors on the system variability. Systematic analysis in such a framework provides a better understanding of system structures to support decision-making under uncertainty in a participatory process.

Death time estimation of water heritages in Gonabad Plain, Iran

A Qanat is a hydraulic structure for the extraction of the groundwater using only gravity force without need to apply external force through pumping. The deepest and oldest Qanats in the world are located in the Gonabad Plain in the Razavi Khorasan Province, east of Iran. Qanats have been the most important approach for groundwater extraction and survive in arid region such as the study area for thousands of years, but they are disappearing because of climate and human factors. In the present research, descending trends of flow rate of four historical Qanats (i.e., Rahn, Baidokht, Kheshuie and Qasabeh) of the Gonabad Plain have been studied and analyzed using discharge values of the Qanats over the last 33 years. Effective factors on discharge values of these Qanats have also been discussed. The analysis indicated that the amount of precipitation in the study area and its mountains has decreased significantly since 2000. Moreover, because of drinking demand and traditional agriculture consumptions, the amount of annual groundwater extraction through deep wells has increased since 1960 and its amount reached 12 million cubic meters. As the groundwater drawdown increases, the water-bearing zone of the Qanats will decrease and the Qanats will dry gradually. The annual groundwater level drawdown in the Gonabad Plain is 0.1 m per year. The discharges of the different Qanats in the Gonabad Plain have been dropped from 38 to 9 L/s during the last 33 years. The results indicated that the discharge reduction of the Qanats is 4–14 L/s due to one meter groundwater level drawdown. As the groundwater drawdown continues with the current rate in the Gonabad Plain, these valuable water heritages will perish over 9–157 next years for the aforementioned Qanats. To prevent the destruction of the Qanats, it is suggested to reduce 7.2 MCM of groundwater extracted through wells by optimal use of water and prevent the development of agriculture and industries that need water in the Gonabad Plain.

Pattern and degree of groundwater recharge from river leakage in a karst canyon area under intensive mine dewatering

Most lead-zinc (Pb-Zn) deposits in southwestern China located in karst canyon areas are faced with difficulties to identify the connection between surface water and groundwater. Hydrological dynamics monitoring, tracer injection test, and riverbed dredging test were applied to discuss the contribution of river leakage to the mining area under intensive mine dewatering. The water level of surface water (~887 m asl), pore groundwater (~886 m asl), and karst groundwater (882–886 m asl) decreased in turn in the Maoping Pb-Zn deposit, which suggested the Luoze River as a losing stream. The groundwater temperature dynamics did not respond to rainfall events. Karst groundwater presented a peak delay and amplitude decay when compared with the overlying pore groundwater. Lower electrical conductivity (40–70 μS/cm) was generated due to cation exchange process during vertical infiltration. It could be concluded firstly that pore groundwater ran horizontally and rapidly according to the synchronous response within an hour of groundwater level in the upstream and downstream boreholes to riverbed dredging test. Secondly, pore groundwater could supply the underlying karst groundwater vertically and slowly, which caused an increase of groundwater level lasting for one week during the dredging test until the recovery of decreasing trend in the dry season. Finally, the injected tracer cost more than seven months to eliminate, indicating a slow velocity around 0.01 m/d in the karst aquifer. Overall, it could be proved that surface water could be an indirect and limited water-filling source for the karst groundwater in the mining area under the control of the riverbed sediment structure. Despite the significant groundwater level drawdown caused by intensive mine dewatering, the mining area would not be threatened by the possible river leakage, and the river ecological system would not be reshaped greatly due to the weak interaction process between surface water and groundwater.

An Optimal Socialist Cooperative Game Theory Model in Agricultural Sector (Case Study: Dezful-Andimeshk Plain)

The increase in exploitation from aquifers in an unbalanced way to meet the growing demands of agriculture has led to a decrease in the groundwater levels and as a result, an increase in the cumulative groundwater-reservoir deficit. In the long run, this will also reduce profits from agriculture due to declining water table levels and rising water extraction costs. In this article, is proposed the application of a socialist cooperative game for propensity to cooperate and improve agriculture's cumulative net benefit and stimulate the balanced use of groundwater. The purpose of this approach is to prevent groundwater level drawdown and compensate for part of the groundwater-reservoir deficit in the Dezful-Andimeshk plain, southwest of Iran. In this study, the consumer behavior, as one of the main factors in groundwater resources management has been investigated. This method has been derived from the socialist cooperative game theory, taking the consumer as an effective factor on water table drawdown, and envisioned in the form of an eco-socialism model. Results revealed that maximum water table drawdown will be reduced by 21%, and as a result, 16 million cubic meters (MCM) of groundwater reservoir deficit will be compensated and the net benefit from agricultural activities will also increase by 26%.

F-MOPSO/Div: an improved extreme-point-based multi-objective PSO algorithm applied to a socio-economic-environmental conjunctive water use problem.

In this paper, a new version of the multi-objective particle swarm optimizer named the Diversity-enhanced fuzzy multi-objective particle swarm optimization (f-MOPSO/Div) algorithm is proposed. This algorithm is an improved version of our recently proposed f-MOPSO. In the proposed algorithm, a new characteristic of the particles in the objective space, which we named the "extremity," is also evaluated, along with the Pareto dominance, to appoint proper guides for the particles in the search space. Three improvements are applied to the f-MOPSO to mitigate its shortcomings, generating f-MOPSO/Div: (1) selecting the global best solution based on the diversity of the extreme solutions, (2) impeding the particles to be trapped in the local optima using a mutation scheme based on the dynamic probability, and (3) removing the pre-optimization process. To validate f-MOPSO/Div, it was compared with some other popular multi-objective algorithms on 14 standard low- and high-dimensional test problem suites. After the comparative results indicated the outperformance of the proposal, the f-MOPSO/Div was applied to solve an optimal conjunctive water use management problem, in a semi-arid study area in west-central Iran, over a 13-year long-term planning period with two main objectives: (1) maximizing the aquifer sustainability as an environmental goal, and (2) maximizing the crop yields as a socio-economic goal. As the results suggest, the cumulative groundwater level drawdown is considerably decreased over the whole planning period to make the aquifer sustainable, while the water productivity is held at a desirable level, demonstrating the superiority of the f-MOPSO/Div when also applied to solve a large-scale real-world optimization problem.

Comparative Analysis of the Vulnerable Period of Groundwater Level Drawdown

This study selected groundwater level as the factor to represent the changes in groundwater resources and developed an evaluation method for the management of monthly groundwater level considering the temporal variability with the target of 9 sub-basins located in the Namwon. For the evaluation of vulnerable period in the groundwater level considering the influence of rainfall on the underground aquifer, the following methods were used: applying effective rainfall amount based on the application of rainfall data, and using rainfall data with the notion of critical infiltration, among which vulnerable periods were compared for evaluations. A standard was developed for evaluating groundwater level; the weighting values were determined by using the entropy method, and the vulnerability period of groundwater resources of each sub-basin was evaluated via multiple decision-making methods. The methods developed in this study are expected to make grounds for building measures for the effective spatiotemporal management of groundwater resources.

Analysis of groundwater and river stage fluctuations and their relationship with water use and climate variation effects on Alto Grande watershed, Northeastern Brazil

Sustainable use of water resources on the behavior of groundwater table and surface water level variations, especially in phreatic sedimentary aquifers, where a strong interaction between stream flow and groundwater normally takes place. In the present study, precipitation, water level fluctuation, river flow and pivot installation data from an important agricultural frontier with an increasing water use for irrigated agriculture and a downward precipitation trend were compared with surface and water level fluctuation monitoring data. The main purpose was to assess possible impacts on the aquifers and to analyze the variation in groundwater table and surface water levels due to long-term downward precipitation trend (climate variation effects) and increasing water demand (irrigation). A growing number of central pivots installed for irrigation are withdrawing water from the Urucuia Aquifer System (UAS) in western Bahia State, Northeastern Brazil, one of the leading agricultural frontiers of the world. Field surveys provided hydrogeological aspects that led to the construction of a hydrogeological conceptual model. Monitoring groundwater and surface water through Brazilian Geological Survey's Integrated Groundwater Monitoring Network (RIMAS-CPRM), satellite images and Hydrological Information System (HidroWeb-ANA) network formed the databases for the study. This data was compared with rainfall data and evolution of irrigated areas captured by satellite image analysis. Results indicate that reduction of rainfall volumes from 1990 to 2018 in the headwaters of Alto Grande basin, due to cyclic droughts, and an increase in surface and groundwater exploitation due to flourishing agribusiness activity has caused a considerable groundwater level drawdown. The drawdown of up to 6.63 m points to the need of strong management actions, which should provide a long-term sustainable use of water resources (superficial and underground) within Alto Grande watershed. This study is part of the actions undertaken to provide the scientific and technical basis to secure the availability of water and a sustainable agricultural activity, since an important part of the Cerrado, the Brazilian savanna ecosystem, and considerable proportion of São Francisco river flow, lies in the study area.

Inverse modeling of saturated-unsaturated flow in site-scale fractured rocks using the continuum approach: A case study at Baihetan dam site, Southwest China

Modeling saturated-unsaturated flow in fractured rock formations remains a challenging issue due to the difficulties in properly calibrating the unsaturated flow properties for fractured rocks. On the basis of the continuum approach, this study uses inverse modeling to determine the unsaturated hydraulic parameters of fractured rocks, loose sediments, and geologic structures in a large-scale slope under difficult hydrogeologic conditions at the Baihetan dam site, Southwest China. The saturated hydraulic conductivities were determined a priori by packer tests. Field data, including time-series of groundwater level observations and available discharge measurements, is used. A combined procedure of orthogonal design, finite element forward analysis, artificial neural network, and genetic algorithm is adopted for the inverse analysis with high computational efficiency. The numerical results well reproduce the typical features of multiple water tables and wedge-shaped unsaturated zones controlled by gently-sloping tuff zones of low vertical permeability, showing 46–65% of groundwater flowing subhorizontally along each tuff zone and the remaining 35–54% infiltrating vertically and recharging deeper layers. The drastic drawdown of groundwater level after 10-year site characterization is also reproduced. The calculated discharge and water tables agree reasonably well with field observations, indicating that the estimated parameters are representative of the unsaturated hydraulic properties at the site. This work provides an efficient and effective methodology for seeking an optimal solution in large-scale inverse modeling of saturated-unsaturated flow, and further manifests the feasibility of the continuum approach in predicting unsaturated flow in site-scale fractured rock formations.

RESPONSES OF SHALLOW GROUNDWATER SYSTEM TO DIFFERENT WATER-SAVING PRACTICES IN TYPICAL IRRIGATION AREA IN NORTHWEST CHINA

The Jinghui Canal Irrigation District (JCID) is a highly productive agricultural area of Shaanxi province, China. Because of severe water scarcity, implementing water-saving renovation practices for agricultural sustainability is necessary. To determine the influence of different water saving practises on the shallow groundwater system in the JCID, ArcGIS and Processing MODFLOW are used to simulate changes in shallow groundwater in the irrigated farmland in this area. The results show that field water-saving measures can reduce 18.5%-33.4% of well irrigation water, and the control effect on groundwater level drawdown is prominent. The shallow groundwater level s declining rate in some areas is increased, owing to the adjustment of the agricultural planting structure. Moreover, the spatiotemporal distributions of water and soil resources do not reasonably match, which offsets the active impact of water-saving renovation in the mitigation of falling groundwater tables. The groundwater s annual average decline rate has increased from 0.535 m year-1 during 1981-1997 to 0.734 m year-1 during 2000-2014. The groundwater cone of depression shows a continuous expanding tendency. The area in which the groundwater depth is larger than 13 m has increased from 358.56 km2 in September 1997 to 612.92 km2 in September 2014. However, successful agricultural water-saving renovation requires a practical feasibility of water-saving projects, in addition to an appropriate planting structure, strong bearing capacity of farmers, water-saving propaganda, and policy implementation of agricultural subsidy and water resource management.

Numerical Simulation of Groundwater Flow of Emergency Water Source in Nanchang City

The source of water supply in Nanchang City is relatively single, and the safety of urban water supply is difficult to guarantee. According to the hydrogeological conditions of the study area, a threedimensional visualization numerical model of groundwater system was established. After the model identification and verification, combined with the target of emergency water supply in Nanchang city, the emergency exploitation of groundwater in Youkou emergency water source was simulated by using the model under different emergency exploitation schemes, respectively. The prediction results show that compared with scheme I and scheme II, scheme III is most suitable for the requirements of well layout, which has the advantages with the minimum drawdown of groundwater level, and the maximum exploitation. For scheme III, under the conditions that the dewatered aquifers are no more than 1/2 and 2/3 of the original aquifer, the emergency exploitation of 36.55×104m3/d and 49.45×104m3/d can be provided, which could meet the emergency water demands of 54.9% and 74.3% of the local residents, respectively.

Excessive groundwater inflow during TBM tunneling in limestone formation

A sudden increase of groundwater inflow of 670 tons a day was experienced during tunneling in a limestone formation at around 53 m below the ground surface. The limestone cavities were expected to be located at 5–10 m or more above the tunnel crown in geotechnical exploration. However, limestone cavity network was encountered at the tunnel depth, and large groundwater inflow was experienced. Because of the excessive groundwater inflow into the tunnel, the groundwater level dropped to GL-32 m from the original level of GL-16 m, and consequently maximum of 23 mm of ground settlement and damage of adjacent structures took place. In this study the change of groundwater regime during tunneling in limestone area containing cavity network was analyzed through 3-dimensional numerical analysis, and the mechanism of groundwater level drawdown followed by ground subsidence was analyzed by comparing measurements and numerical analysis results. And also the analytical solution for determining the range of cutoff grouting was proposed to minimize groundwater inflow during excavation in a fractured zone.

Modeling the Influence of Groundwater Exploitation on Land Subsidence Susceptibility Using Machine Learning Algorithms

Groundwater over-exploitation in arid and semiarid environments has led to many land subsidence cases. Immense economic losses incurred from land subsidence occurrences prompted many scientists to model this phenomenon. To this end, we used three machine learning models, boosted regression trees (BRTs), generalized additive model (GAM), and random forest (RF), together with four anthropological and geo-environmental predictors, to produce a spatial prediction map across land subsidence-prone area in the south of Iran. The inventory map and preparatory thematic layers were generated through extensive field surveys, using Google Earth images, local information, and organizational archives. The results revealed that the GAM significantly out-performs the BRT in terms of high goodness of fit (84.3% vs. 80.2%) and predictive power (81.6% vs. 70.1%). The RF model, as a benchmark model, showed slightly higher goodness of fit (85.45%) compared to the GAM; however, its prediction power was evidently lower than the GAM. Hence, the GAM was found as the best susceptibility model in the study area. According to the relative contribution test, the drawdown of groundwater level with 77.5% contribution was found to be the main causative predictor of land subsidence occurrence, followed by lithology (19.2%), distance from streams (2.5%), and altitude (0.8%). The results of the GAM suggest that almost 31.6% of the study area is highly susceptible zone to land subsidence occurrence, which can be of interest for further pragmatic actions.

Study on Optimal Allocation of Water Resources Based on Surrogate Model of Groundwater Numerical Simulation

The characteristics of groundwater systems are highly complex. It will take substantial computational resources and running time to optimize a groundwater numerical simulation model. In this study, in order to realize the coupling of simulation and optimization models, the improved backpropagation (BP) neural network was used as a surrogate model of a groundwater numerical simulation; the improved BP neural network was trained with the groundwater level drawdown–pumping volume data output of the simulation model. The method was applied to the water resource optimal allocation in the near future of Wenshang County, Shandong Provence of China. The results show that the water level drawdown output of the improved BP neural network model fits the results of the simulation model well, showing that the improved BP neural network can effectively be the surrogate of a groundwater numerical simulation to be embedded in an optimization model. The improved simulation and optimization technique can make full use of water resources in the whole area. Under an assurance rate of 50%, both water shortage and water shortage rate reduced to zero in the whole area. Under an assurance rate of 75%, water shortage and water shortage rate reduced to about 10% of the conventional scheme, which dramatically improves the comprehensive benefit of the whole area.

Land subsidence hazard modeling: Machine learning to identify predictors and the role of human activities

Land subsidence caused by land use change and overexploitation of groundwater is an example of mismanagement of natural resources, yet subsidence remains difficult to predict. In this study, the relationship between land subsidence features and geo-environmental factors is investigated by comparing two machine learning algorithms (MLA): maximum entropy (MaxEnt) and genetic algorithm rule-set production (GARP) algorithms in the Kashmar Region, Iran. Land subsidence features (N = 79) were mapped using field surveys. Land use, lithology, the distance from traditional groundwater abstraction systems (Qanats), from afforestation projects, from neighboring faults, and the drawdown of groundwater level (DGL) (1991–2016) were used as predictive variables. Jackknife resampling showed that DGL, distance from afforestation projects, and distance from Qanat systems are major factors influencing land subsidence, with geology and faults being less important. The GARP algorithm outperformed the MaxEnt algorithm for all performance metrics. The performance of both models, as measured by the area under the receiver-operator characteristic curve (AUROC), decreased from 88.9–94.4% to 82.5–90.3% when DGL was excluded as a predictor, though the performance of GARP was still good to excellent even without DGL. MLAs produced maps of subsidence risk with acceptable accuracy, both with and without data on groundwater drawdown, suggesting that MLAs can usefully inform efforts to manage subsidence in data-scarce regions, though the highest accuracy requires data on changes in groundwater level.

An improved siphon drainage method for slope stabilization

The siphon drainage is an effective measure for the slope groundwater control. However, for the traditional siphon drainage, limitations such as siphon lift restriction and poor reliability in longterm service prevent it from being widely used. In this study, an improved siphon drainage method with inclined borehole penetrating the deep part of the slope is proposed to overcome the limitations suffered by the traditional method. Through experimental research, theoretical analysis and engineering practice, the reliability and capability of the proposed method are investigated. The results demonstrate that with the inclined pipe the height difference between the control point of the groundwater level and the orifice can be controlled to be less than the height of the water column corresponding to the local atmospheric pressure. As a result, deep drainage can be achieved. In addition, by controlling the diameter of siphon drainage pipe not larger than 4 mm, a plug flow can be formed in the siphon pipe, which can prevent air accumulation in the siphon process and a continuous and effective siphon drainage is achieved. Through a practical project running smoothly since September 2013, it is found that the proposed method can effectively drain the groundwater deep in the slope and the maximum drawdown of groundwater level in boreholes can reach 8.5 m with an average drainage flow of 5.5 m3/d. The practical results also illustrate that 4 mm siphon pipe can be used to realize deep slope drainage and restart siphon automatically.

The impact of well drawdowns on the mixing process of river water and groundwater and water quality in a riverside well field, Northeast China

AbstractRiverbank filtration (RBF) has been widely used throughout the world as an effective means to regulate surface water and groundwater resources and pretreat raw water for municipal water supply. The quality of the water from a riverside well field and the mixing ratios of surface water and groundwater is primarily impacted by the hydrodynamic processes in the RBF system. The RBF system is largely controlled by the water exploiting system in addition to the natural hydrologic condition of the river–aquifer system. As one of the most important design parameters of the riverside well field, the drawdown of groundwater level greatly determines the water head differences between the river water and groundwater as well as the field flow net, which subsequently impacts the mixing of river water and groundwater and water quality significantly. This study aimed to improve the understanding of the mixing process between the surface water and groundwater and estimate the impact of the RBF on the mixing ratio of surface water–groundwater and water quality quantitatively. A set of field pumping tests with various groundwater level drawdowns were carried out independently and successively at a riverside field with a single pumping well near the Songhua River in Northeast China in August 2017. During these tests, the water levels and hydrochemical parameters of the Songhua River, the adjacent aquifer, and the pumping well were monitored. The dynamic mixing process of the river water and groundwater and water quality under various drawdown conditions were analysed systematically using analytical methods. The results obtained from Dupuit method and the Mirror Image method in conjunction with the Hydrochemical Tracing method showed that the pumping water directly from the river water reached 60% ± 10% after a steady flow net was established. The larger the proportion of the pumping water captured from the river, the better quality of the pumping water was, because the quality of the river water (only limited to some water quality parameters monitored which were minority) was better than that of the groundwater. The results also showed that total Fe, TDS, total hardness, CODMn, and K+ were relatively sensitive to the changes of groundwater drawdown, and their concentrations decreased with an increase in the groundwater drawdown. It can be concluded that both the mixing ratio of the surface water and the groundwater and the water quality of the riverside well field can be regulated through adjusting the designed drawdown of the groundwater level, which is helpful for the design and the optimization of the riverside well water intake engineering.

Potential evaluation of river bank infiltration along the Second Songhuajiang River

Based on the evaluation of the suitability for river bank infiltration along the Second Songhuajiang River and the basic geologic and hydrogeological conditions of the study area, the hydrogeological conceptual model and the corresponding mathematical model are established, and the numerical model of groundwater flow based on Visual MODFLOW is formulated. The drawdown of groundwater level of 1/3 of less than the aquifer thickness is taken as the criterion. By making the predicted groundwater flow field as close as possible to the flow field under the conditions of the permissible drawdown, the allowable exploitation quantity of groundwater under the condition of RBF along the Second Songhua River is obtained. The results show that under the conditions of the current year, the exploitation intensity of groundwater resources is small. However, under the condition of exploitation near the river, the groundwater exploitation potential of each suitable area is as high as 140×104 m3/d, and the allowable exploitation of groundwater is large under the annual precipitation frequency. The interaction of groundwater-surface water will be influenced, but there will be no side effects on the ecological function of the river.

Study on groundwater abstraction by horizontal drains for minimization of saltwater upconing from below

In many places in Vietnam central region, the fresh coastal sand dune aquifers have an interface with salty water below, so upon groundwater (GW) abstraction, there is a risk of salty water upconing to the abstraction facilities. With the same abstraction rate, the horizontal drains shall significantly reduce the groundwater level (GWL) drawdown, which significantly reduces the development of saltwater upconing. The results analysis for the design of groundwater abstraction facilities in Thach Tri commune, Thach Ha district, Ha Tinh province have shown the effectiveness of the solution. For infinite distributed aquifers, the GWL drawdown in the facility area with the abstraction rate of 100m3/day by eight 4m- and 8m-long horizontal drains is from 11.7% to 16.8% lower in comparison to a vertical well, respectively, (GWL drawdown in vertical well is 0.733m, GWL drawdown in center of 4m-long horizontal drains is 0.646m and in 8m-long horizontal drains is 0.603m). For 1km x 1km aquifer bounded by no-flow boundaries, GWL drawdown in the vertical well and in the center of eight 4m-and 8m-long horizontal drains are 2.313m, 1.293m and 1.255m, respectively. This is corresponding to GWL drawdown decrease of 44.1% and 45.7% in comparison to the vertical well. The significantly reduced GWL drawdown in abstraction facilities of horizontal drains will significantly reduce the level of salty water upconing and therefore increase the time of abstraction of fresh water.ReferencesCPEO, 2010. Updated 2010 tech tree list of summary cleanup technology descriptions: Horizontal Wells. http://www.cpeo.org/techtree/ttdescript/horzwel.htmDagan, G. and Bear, J., 1968. Solving the problem of local interface upconing in a coastal aquifer by the method of small perturbations. J. Hydr. Res., 6, 15-44.Diersch,H.-J. Prochnow D. and Thiele M., 1984. Finite-element analysis of dispersion-affected saltwater upconing below a pumping well. Appl. Math. Modelling, 8, 305-312.Falkovich G., 2011. Fluid Mechanics. Cambridge University Press, 167p.Fletcher G. Driscoll, 1987. Groundwater and Wells. Published by Johnson Division, St. Paul, Minnesota 55112, USA, 1089p.Kushtanova G.G., 2015. Well test analysis. Kazan University, 31p. https://doi.org/10.15625/0866-7187/38/2/8603.Marta Faneca Sanchez, Khairul Bashar, Gijs Janssen, Gualbert Dude Essink, Marjolein Vogels, Jan Snel, Yangxiao Zhou and Roelof Stuurman, 2015. SWIBANGLA: Managing salt water intrusion impacts in coastal groundwater systems of Bangladesh. Deltares, The Netherlands UNESCO-IHE, The Netherlands Jahangirnagar University, Bangladesh, 153p. https://doi.org/10.15625/0866-7187/39/1/9231.Nguyen Ngoc Quynh, 2012. Determination of required geometric sizes of sand dunes for their stability in the Central Plains from Quang Ngai province to Binh Thuan province. Journal of Water Resources Science and Technology, 9, 2-6.Nguyen Tien Hai, Tran Nghi, Nguyen Van Bach, 2004. Formation characteristics and evolution of coastal strips of sands in Quang Binh. Journal of Geology, ISSN 0866-7381. Series A, 281, 30-40.Nguyen Van Dan, Vo Cong Nghiep, Dang Huu On, 1996. Groundwater of the North Trung Bo coastal plains. Geological Survey of Vietnam, 86p.Nguyen Xuan Truong, Nguyen The Tiep, 1998. Sea terrace in Vietnam with corresponding geological formations. Journal of Science 1. Hanoi University, 69-76.Phan Van Truong, 2015. Hydrogeochemistry characteristics and salinity of groundwater in Quaternary sediments in the coastal zone of Ha Tinh province. J. Sci. of the Earth, 37(1), 70-78. https://doi.org/10.15625/0866-7187/37/1/6557.Pieter S. Pauw Sjoerd E.A.T.M. van der Zee Anton Leijnse Gualbert H.P. Oude Essink, 2015. Saltwater Upconing Due to Cyclic Pumping by Horizontal Wells in Freshwater Lenses. J. Ground Water, 54(4), 521-531. https://doi.org/10.1111/gwat.12382.Soylu M. E., Istanbulluoglu E., Lenters J. D. and T. Wang, 2011. Quantifying the impact of groundwater depth on evapotranspiration in a semi-arid grassland region. Hydrol. Earth Syst. Sci., 15, 787-806,. www.hydrol-earth-syst-sci.net/15/787/2011/doi:10.5194/hess-15-787-2011.Truong Minh Duc, 2015. Climate change and environment in the Central coastal plain. Journal Vietnam Social Sciences, 89, 34-45.

Quantitative assessment of the impact of an inter-basin surface-water transfer project on the groundwater flow and groundwater-dependent eco-environment in an oasis in arid northwestern China

Inter-basin water transfer projects (IBWTPs) can involve basins as water donors and water receivers. In contrast to most studies on IBWTPs, which mainly impact the surface-water eco-environment, this study focuses on the impacts of an IBWTP on groundwater and its eco-environment in a water donor basin in an arid area, where surface water and groundwater are exchanged. Surface water is assumed to recharge groundwater and a groundwater numerical simulation model was constructed using MODFLOW. The model was used to quantitatively evaluate the impact of an IBWTP located in the upstream portion of Nalenggele River (the biggest river in the Qaidam basin, Northwest China). The impact involved decrease in spring flow, drawdown of groundwater, reduction in oasis area, and an increase in species replacement of oasis vegetation in the midstream and downstream of the river. Results show that the emergence sites of springs at the front of the oasis will move 2–5 km downstream, and the outflow of springs will decrease by 42 million m3/a. The maximum drawdown of groundwater level at the front of the oasis will be 3.6 m and the area across which groundwater drawdown exceeds 2.0 m will be about 59.02 km2, accounting for 2.71% of the total area of the oasis. Under such conditions, reeds will gradually be replaced by Tamarix, shrubs, and other alternative plant species. These findings have important implications for the optimization of water resource allocation and protection of the eco-environment in arid regions.

Holistic Approach to Sustainable Groundwater Management in Semi-arid Regions

Owing to rational deep understanding of intrinsic nature of groundwater as common pool and decayable resources, together with, lack of withdrawal control by local states, groundwater depletion has been incredibly under consistent withdrawal. Under these circumstances, attempts have been made by users to maximize withdrawal without considering any limitation on account of lack of reliable withdrawal pattern. In this research, sustainable management of groundwater in south western part of Tehran plain has been evaluated by coupling simulation and optimization models of cooperative and non-cooperative approaches. The MODFLOW model and the Artificial Neural Network model are used for simulation of different scenarios after calibration and validation. Then, a non-linear optimization model is used for optimal allocation of groundwater to different water users. Results indicate that users may gain more benefit in early years of withdrawal in non-cooperative approach. However, this may have an adverse effect which implies a decreasing trend in the benefit in such a way that it reaches null in long term period, as this is reflected by dramatic drawdown of groundwater level and its depletion. In cooperative approach, rate of withdrawal from aquifer is determined by considering renewable water volume, together with, groundwater table drawdown constraint. In this approach, water users may gain less benefit than non-cooperative in early years of withdrawal, however, that will offset in 50 years period by means of more benefit.