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1.
A steady-state groundwater flow model (MODFLOW) was used to study lake and groundwater interactions in a complex rift volcanic catchment. It also was used to assess the effects of water pumping from wells, and of variable recharge rates associated with climate and lake level changes, on the dynamics of the volcanic aquifers surrounding Lake Awassa. The model simulations were made after first developing a reasonable conceptual model, on the basis of conventional hydrogeological mapping, pumping test and hydrometeorological data analyses, and from ancillary information obtained from hydrochemical and isotope techniques. The model results indicated that the lakes and Rift aquifers are fed by large groundwater inputs that originate in the highlands. The lakes and rivers have important roles in recharging the aquifers in some locations. Lake Awassa receives a major groundwater inflow from its southern and eastern shorelines, while substantial water leakage from the lake occurs along the northern shoreline. The annual groundwater outflow from the catchment is estimated to 52.5 × 106 m3. Scenario analyses revealed that increasing the current pumping rate from wells by fourfold will substantially reduce the groundwater level substantially, although the regional flow pattern would remain the same. There appears to be no immediate danger to the Rift aquatic environment from the current water pumping rate. Drying the small Lake Shalo and associated swamps, however, will cause a large change in the water balance of the larger Lake Awassa. Slight changes in groundwater recharge can cause large differences in groundwater levels for most of the Rift caldera floor far from the lake shores. This study provides a reasonable foundation for developing detailed transient predictive models, which can then readily be used as a decision support tool for development and implementation of sustainable water resources practices.  相似文献   

2.
Optimizing Safe Yield Policy Implementation   总被引:1,自引:1,他引:0  
The presented method enhances groundwater-mandated safe yield management. It is useful for settings that prevent sustained yield or integrated management. To protect hydraulically connected surface water rights, the Utah government’s Cache Valley groundwater management plan proposes that total pumping increase not exceed 84,431 m3/day. To determine how best to spatially distribute additional allowable pumping, stakeholders quantified limits defining acceptable impacts on selected water resource indicators. A new simulation–optimization (S–O) algorithm used these limits while computing optimal spatially distributed perennial yield or safe yield groundwater pumping extraction strategies. The limits prevent unacceptable decreases in: head and net flow between aquifer and surface waters (rivers, surface/subsurface drains, springs, lakes). The optimization objective function maximizes weighted pumping to provide water for 18 growing municipalities. For 16 perennial yield scenarios, computed optimal pumping increases differ in protectiveness toward senior water rights, and range from 16% to 103% of the state plan-proposed increase. Implementing a protective strategy would achieve 90% of the storage changes needed to reach equilibrium within 23 years. Indicator potentiometric heads would reach equilibrium within 10–40 years. At equilibrium, an optimal Cache Valley perennial yield strategy acceptably minimizes net annual non-pumping discharges. By comparison, multi-period 20-year transient groundwater mining optimizations allow more pumping in early years. Pumping then must decline to satisfy seepage and head constraints through year 20. Adverse seepage impact would increase for years thereafter. For situations governed by safe or perennial yield policy, equilibrium-based (steady-state) optimization is very useful. It effectively develops optimal perennial yield strategies.  相似文献   

3.
High level of groundwater in urban areas may cause major problems in construction and mining projects. One effective solution is to implement drainage wells to lower the water table into the desired level through an appropriate pumping strategy. In this paper, placement and capacity of the dewatering wells are optimized by minimizing the total costs of a groundwater lowering system (GLS) through a simulation-optimization approach. For this purpose, MODFLOW, the groundwater simulation software, is coupled with the Firefly Optimization Algorithm (FOA) to find the optimal solution. The proposed FOA-MODFLOW model is tested in an urban area in east southern part of Iran, Kerman city’s ancient Mosque region. Results show that the obtained cost-effective design noticeably outperforms the consulting engineers’ proposal in terms of both the number of drilled wells and the associated costs with justifiable constraints. Optimal strategy satisfies the constraints by suggesting construction of two wells with totally pumping rate of 5503 m3/day while the water table is dropped 1.5 m with a ground subsidence less than 80 mm in the region. Additionally, an investigation on the value of various design parameters emphasizes on the sensitivity of the solutions to the permissible groundwater level and the well’s maximum pumping rates among the others.  相似文献   

4.
Ecological water use (EWU) is urgent in need in the lower reaches of Tarim River in China. Estimation of water amount for EWU is depending on some parameters and modeling. EWU is mainly consists of two parts in no runoff area in the basin, i.e. total water amount for restoration groundwater table and total stand water amount of the all river courses. The former is including water amount for restoration of groundwater table, lateral discharge and evaporation of water surface. The estimated values are 8.18 × 108 m3, 0.68 × 108 m3/a and 0.132 × 108 m3/a respectively. Based on the groundwater depth rising 4.0 meters requiring 5 years, the total water amount for restoration groundwater table is 2.448 × 108 m3/a. The latter, i.e., total stand water amount is 1.992 × 108 m3/a. However, the development of water management measures could alleviate the issue and lead to sustainable EWU in the lower reaches of Tarim River.  相似文献   

5.
This work demonstrates significant vertical variability in the chemical composition of groundwater (Cl −  from 150 to 550 mg/L, NO3-{\rm{NO}}_{3}^{-} from 3 to 70 mg/L, trichloroethene from 350 to 55,000 μg/L and CrTotal from 3 to 2,900 μg/L) along a 130 m thick vertical section passing through two subaquifers of the Costal Plain aquifer of Israel. Water samples were obtained by multilevel sampler under natural gradient flow conditions from a monitoring well which penetrates the entire aquifer. The vertical chemical variability detected at a single point in time in this well was found to be similar to the range of concentrations detected for Cl −  in pumping wells located over an area of about 1,000 km2 in the same aquifer. Similarly, vertical variations in NO3-{\rm{NO}}_{3}^{-} concentration in the single monitoring well represent more than 50% of the total variation in nitrate levels in pumping wells sampled across the entire aquifer. These results graphically illustrate that data from pumping wells, which extract unknown mixtures of groundwater from different depths, cannot provide adequate information about groundwater quality for management purposes.  相似文献   

6.
This paper determines the aquifer transmissivity and storage coefficient from timedrawdown data of pumping tests using a siphon well including a main pumped well along with ten brach pumped wells (deaired wells). The pumping data was analyzed by the Cooper-Jacob graphical method. The computed transmissivity and storage coefficient are 435.8 m2/day and 6.54 × 10-4 with pumping rates of 432 m3/day. Distances from the pumped wells to the observation well ranges from 225 to 268 m. The pumping tests from this siphon well (No. 38), one of the siphon wells in the Nansalum Pump Field, Tainan, Taiwan, were started at 10:40 a.m. on 19 March, 1992 and continued for 1534 min and then were shut simultaneously for water recovery. Groundwater withdrawals were pumped from the uppermost confined aquifer in the pump field.The siphon well is used to continuously provide a sufficient yield for pumping tests and irrigation, and is used when the pumped level and aquifer coefficients for more distant observation wells are to be measured and computed. These may not be achieved in less transmissive aquifers when a single pumped well is used. The siphon well can become a single pumped well in case the ten brach pumped wells (or deaired wells) are not used.  相似文献   

7.
Low stream flows in the Fenton River, part of a hydrogeological setting characterized by glacial stratified drift, forces the University of Connecticut to frequently reduce groundwater withdrawals during the months of June–October. The objective of this study was to investigate stream/aquifer interactions in such a hydrogeologic system in order to increase water withdrawals while minimizing adverse impacts to in-stream flow. A groundwater flow model was developed using MODFLOW to investigate the influence of well location and pumping timing on in-stream flow in the vicinity of the water supply wells. The numerical model comprised detailed geophysical data and decadal hydrologic data (2000–2009) to assess well placement, rest periods and cyclical pumping. The relocation of a water supply well up to 228 m from the river had a positive but minimal improvement to stream flows (<2.83 L/s). When the well field was shut off for more than 45 days, stream flows returned to the no pumping condition with only slight impact at 30 days, whereas a 30 day rest period gave 4 weeks of dampened pumping influence on stream flows. A management scenario of 1 week cyclical pumping between two water supply wells following a 45 day rest period can allow for current restriction thresholds to be reduced by 28.3 L/s with minimal impact to stream flows (7.36 L/s) and would allow additional water to be pumped for all years in which there was a demand for water.  相似文献   

8.
Groundwater has always been considered to be a readily available source of water for domestic, agricultural and industrial use. The last decades, the lack of policymaking for the utilization of groundwater, has led to overexploitation in many areas. The cooperation of a wide range of scientists such as mathematicians, engineers, computer scientists, environmentalists and economists – operation researchers, have led to the design and construction of commercial computer programs concerned on water management and specifically on the optimal distribution of limited water resources using groundwater management models. These combined models, via simulation and optimization algorithms, result in one optimal solution through operations research and mathematical programming methods. The groundwater management models are based on the method of space superposition or the combination of space and time superposition for steady and unsteady state problems, respectively. In the present study, an algorithm is presented, which minimizes the dimension of the response matrix, concerning on two assumptions: the first is the added fixed cost which represents the water supply pumping well and the second is the removal of time superposition. The study area is a transboundary phreatic aquifer in Northern Greece, in the area of Eidomeni, a small Hellenic village just on the borderline with FYROM. The aquifer has a total area of 10,84 km2, 26 operating – pumping wells, which the 9 of them consist control points of the hydraulic head. The number of the management periods is 12 months.  相似文献   

9.
In this paper, a groundwater resources management problem has been studied, namely pumping cost minimization for any number and layout of wells. Steady state flow in infinite and semi-infinite confined aquifers, to which the method of images applies, has been considered. It has been proved analytically that when pumping cost is minimized, hydraulic head is the same at all wells. Based on this proof, an analytical calculation procedure of the respective optimal distribution of the required total flow rate to the individual wells is also presented.  相似文献   

10.
Remote sensing (RS) and geographic information system (GIS) are promising tools for efficient planning and management of vital groundwater resources, especially in data-scarce developing nations. In this study, a standard methodology is proposed to delineate groundwater potential zones using integrated RS, GIS and multi-criteria decision making (MCDM) techniques. The developed methodology is demonstrated by a case study in Udaipur district of Rajasthan, western India. Initially, ten thematic layers, viz., topographic elevation, land slope, geomorphology, geology, soil, pre- and post-monsoon groundwater depths, annual net recharge, annual rainfall, and proximity to surface water bodies were considered in this study. These thematic layers were scrutinized by principal component analysis technique to select influential layers for groundwater prospecting. Selected seven thematic layers and their features were assigned suitable weights on the Saaty’s scale according to their relative importance in groundwater occurrence. The assigned weights of the thematic layers and their features were then normalized by using AHP (analytic hierarchy process) MCDM technique and eigenvector method. Finally, the selected thematic maps were integrated by weighted linear combination method in a GIS environment to generate a groundwater potential map. Thus, four groundwater potential zones were identified and demarcated in the study area, viz., ‘good’, ‘moderate’, ‘poor’ and ‘very poor’ based on groundwater potential index values. The area falling in the ‘good’ zone is about 2,113 km2 (17% of the total study area), which encompasses major portions of Sarada, Salumber, Girwa, Dhariawad, and Mavli blocks of the study area. The northeast and southwest portions along with some scattered patches fall in the ‘moderate’ zone, which encompasses an area of 3,710 km2 (about 29%). The ‘poor’ zone is dominant in the study area which covers an area of 4,599 km2 (36% of the total area). The western portion and parts of eastern and southeast portions of the study area are characterized as having ‘very poor’ groundwater potential, and this zone covers an area of 2,273 km2 (18%). Moreover, in the ‘good’ zone, the mean annually exploitable groundwater reserve is estimated at 0.026 million cubic metres per km2 (MCM/km2), whereas it is 0.024 MCM/km2 in the ‘moderate’ zone, 0.018 MCM/km2 in the ‘poor’ zone, and 0.013 MCM/km2 in the ‘very poor’ zone. The groundwater potential map was finally verified using the well yield data of 39 pumping wells, and the result was found satisfactory.  相似文献   

11.
民勤绿洲是西北内陆河流域地下水超采严重、地下水漏斗突显、生态环境恶化的典型区域,寻找有利于地下水漏斗抑制和生态修复的调控方式是地下水管理亟待解决的首要问题。基于2011—2012年观测数据,采用GIS和FEFLOW软件,构建民勤绿洲潜水非稳定流模型,模拟分析不同关井限采方案对地下水漏斗和植被的影响。结果表明:(1)缩减地下水开采量能有效减缓地下水位下降,修复地下水漏斗,改善生态环境;(2)减少单井抽水量和关闭一定数量机井相结合缩减地下水开采量的方式,对于修复区域地下水漏斗,抬升绿洲边缘地区地下水位,增加植被存活面积较为有效;(3)目前已实施的关井方法有利于防治绿洲荒漠化,而相同比例关井方法对于区域地下水漏斗修复效果更明显,生态环境和社会效益更佳。研究成果可为当地地下水调控和管理提供参考。  相似文献   

12.
To support the development of protective water resources management strategies, a 3D hydrodynamic model was applied to the Little Manatee River (LMR) to evaluate the effects of reducing river flow and drought on the Estuarine Residence Time (ERT). ERT is an important indicator for estuarine environmental quality. The Little Manatee River is a small tidal river estuary with a yearly mean gaged freshwater inflow of 4.8 m3/s. The hydrodynamic model was calibrated and verified by using two continuous data sets for a six month period. Model simulations were conducted for 17 river inflow scenarios. Among the flow scenarios, 13 scenarios were within a flow range from 0.26 m3/s to 10 m3/s total freshwater inflow. A regression equation (R 2 = 0.98) fitted by a power-law function was derived from analysis of the hydrodynamic modeling results to correlate model predicted ERT to total river inflow, though ERT can be predicted from gaged freshwater inflow as well. The study indicates that the estuarine residence time reaches 53.3 days under an extreme drought condition of 0.26 m3/s total inflow. When river inflow falls below the critical flow (4 m3/s or less), further flow reductions can cause the substantial increases of ERT by a factor of 2 to 10 times. This suggests that the management of flow reductions is particularly critical when total river flows are 4 m3/s or less if adverse impacts to the water quality and ecological characteristics of the Little Manatee River are to be avoided.  相似文献   

13.

Evolving optimal management strategies are essential for the sustainable development of water resources. A coupled simulation-optimization model that links the simulation and optimization models internally through a response matrix approach is developed for the conjunctive use of groundwater and surface water in meeting irrigation water demand and municipal water supply, while ensuring groundwater sustainability and maintaining environmental flow in river. It incorporates the stream-aquifer interactions, and the aquifer response matrix is generated from a numerical groundwater model. The optimization model is solved by using MATLAB. The developed model has been applied to the Hormat-Golina valley alluvial stream-aquifer system, Ethiopia, and the optimal pumping schedules were obtained for the existing 43 wells under two different scenarios representing with and without restrictions on stream flow depletion, and satisfying the physical, operational and managerial constraints arising due to hydrological configuration, sustainability and ecological services. The study reveals that the total annual optimal pumping is reduced by 19.75?% due to restrictions on stream flow depletion. It is observed that the groundwater pumping from the aquifer has a significant effect on the stream flow depletion and the optimal conjunctive water use plays a great role in preventing groundwater depletion caused by the extensive pumping for various purposes. The groundwater contribution in optimal conjunctive water use is very high having a value of 92?% because of limited capacity of canal. The findings would be useful to the planners and decision makers for ensuring long-term water sustainability.

  相似文献   

14.
抽灌井设计是水源热泵系统设计中的关键环节之一,但目前对抽水量和回灌量的配置仍依据经验而行,导致运行成本较高。针对该问题,本文利用抽水和回灌现场试验资料,根据抽水井和回灌井的实际布局情况,建立了不同抽灌模式下水源热泵系统运行能耗最小的数学模型,利用遗传算法求解数学模型以实现抽灌量的优化配置。研究表明:水源热泵系统抽灌井施工完毕后,可根据水文地质条件及管道布局情况来优化配置其抽灌量,以实现低能耗运行;遗传算法具有适应性强、全局优化能力高和参数拾取方便的优点,可用于水源热泵系统抽灌量的合理调配;优化确定的以井5为抽水井、井1和井2及井4为日常回灌井、井3为备用回灌井,井5抽水量为90 m~3/h,井1、井2、井4回灌量分别为42.5 m~3/h、33.4 m~3/h、14.1 m~3/h,为生产中科学快速调度抽灌模式提供了依据。  相似文献   

15.
以塔里木河下游为研究区,以区域内9个固定监测断面为基础,依据断面内各个地下水监测井,收集了输水前和第15次输水后的地下水位数据,结合土壤饱和差计算方法,分析了第15次输水后的地下水补给量,并联系植被生长所需的合理水位探讨了地下水到达合理水位所需的水量,以期评价生态输水的阶段性效果,为调整生态输水方案提供理论参考。结果表明:(1)生态输水前地下水埋深在6~13 m之间,第15次生态输水后,地下水最大升高幅度达到8.26 m;(2)第15次生态输水后,塔里木河下游地下水补给量约为20.44亿m3;(3)为使地下水达到植被生长所需适宜水位,塔里木河下游地下水的合理需求量约为24.08亿m3。  相似文献   

16.
In arid and semiarid areas, bimodal and high rainfall leads to infrequent flood that can be extremely damaging. To reduce the impacts of persistent intra-seasonal drought and also to reduce flood damaging in arid and semiarid areas, rainwater storage is a prerequisite that keeps water far from evapotranspiration, increases groundwater level and decreases flood hazards modification to exchange between surface water and groundwater through flood spreading, dams, etc. The purpose of this paper is to delineate and explain variations in groundwater recharge and groundwater quality along an ephemeral stream that has been modified by flood spreading. Groundwater samples were collected from 14 deep wells located at different distances from flood spreading projection area (FSPA) in 1 month interval during September 2005 to September 2008. Groundwater quality was followed via Na+, K+, Ca2+, Mg2+, Cl-, Hco3- SO42-, Electrical Conductivity (EC) and pH measurements for two time periods between 2005 and 2008. The results show significant impact of flood spreading in groundwater table and groundwater salinity variation. Groundwater table decreased in all study wells, but groundwater drawdown increased by increasing the distance to FSPA (during 4 years study, 11.02 m in the well located at 20 m of FSPA versus 38.88 in the well located at 1,825 m). Also ion concentration increased in all of the wells during the study period, but the increasing ion concentration was significantly less important in FSPA closeness.  相似文献   

17.
The canal water supply, which is the only source of irrigation, in the rice-dominated cropping system of the Hirakud canal command (eastern India) is able to meet only 54 % of the irrigation demand at 90 % probability of exceedance. Hence, considering groundwater as the supplemental source of irrigation, conjunctive use management study by combined simulation-optimization modelling was undertaken in order to predict the maximum permissible groundwater pumpage from the command area. Further, optimal land and water resources allocation model was developed to determine the optimal cropping pattern for maximizing net annual return. The modelling results suggested that 2.0 and 2.3 million m3 of groundwater can be pumped from the bottom aquifer during monsoon and non-monsoon seasons, respectively, at 90 % probability of exceedance of rainfall and canal water availability (PERC). Optimal cropping patterns and pumping strategies can lead to about 51.3–12.5 % increase in net annual return from the area at 10–90 % PERC. The sensitivity analysis of the model indicates that the variation in the market price of crops has very high influence on the optimal solution followed by the cost of cultivation and cultivable area. Finally, different future scenarios of land and water use were formulated for the command area. The adoption of optimal cropping patterns and optimal pumping strategies is strongly recommended for sustainable management of available land and water resources of the canal command under hydrological uncertainties.  相似文献   

18.
The Lebanese coast is highly subject to seawater intrusion and groundwater deterioration. The study is carried out in Byblos district (Jbeil Caza) 35 km north of Beirut. It aims to investigate the seawater intrusion, to determine the regional water balance of the region and finally to estimate the economic value of that water for agricultural use. The monitoring of the aquifer was achieved through samples from different wells chosen randomly. As for the regional water balance, it was determined with use of a GIS model. The economic evaluation was carried out, using the contingent valuation method to estimate the willingness to pay of farmers to contribute to the improvement of groundwater quality; two alternative scenarios were proposed and compared with the current situation. The annual regional water balance is positive, which means that the region is rich in water. The monitoring results show that the coastal part of the region is slightly contaminated by seawater intrusion due to the excess of pumping from the aquifer. The economic evaluation estimated that farmers would contribute by 102 US$ yr − 1 for the first proposal and 166.67 US$ yr − 1 for the second.  相似文献   

19.
With its important geographical location and status as the largest saltwater body in China, Qinghai Lake plays a vital role in the ecological environment of the northeastern part of the Qinghai-Tibet Plateau. Due to climate change and the subsequent adjustment of Qinghai Lake’s tourism policy, it is necessary to understand groundwater discharges in southeast of Qinghai lake both for ecological protection and risk prevention. This study used radium isotopes 223Ra and 224Ra to trace groundwater discharges and nutrients carried into the lake. The spatial characteristics of Ra isotopes with greater activity in the upper and bottom layers in the lake indicated that they were influenced by inputs of shallow groundwater and diffusion from sediments. The average 224Ra diffusion flux of the sediments in the Lake was 33.54 dpm m?2 d?1. Based on the 224Ra mass balance model, the discharge flux of shallow groundwater in this region was estimated to be 3.49 × 106 ~ 3.68 × 106 m3 d?1. The PO43? and SiO2 fluxes carried into the southeastern of the lake by groundwater were 1.78 × 1011 ~ 1.88 × 1011 mg/y and 2.22 × 1012 ~ 2.34 × 1012 mg/y, respectively. It is thus essential to monitor shallow groundwater discharge into Qinghai Lake for the protection of the water environment and prevention of potential ecological risks.  相似文献   

20.
A three-dimensional numerical model for flow and solute transport was used for the management of the Salalah aquifer. The model calibration procedures consisted of calibrating the aquifer system hydraulic parameters by history matching under steady and transient conditions. The history of input and output of the aquifer were reconstructed in a transient calibration from 1993 to 2005. Predictive simulation of the aquifer was carried out under transient conditions to predict the future demand of groundwater supply for the next 15 years. A baseline scenario was worked out to obtain the piezometric surface and salinity distribution for the “business as usual” conditions of the aquifer. The “business as usual” scenario was predicted and simulated for the period 2006 until 2020. The effectiveness of seven management options was proposed and assessed for comparison with the “business as usual” conditions. The established simulation model was used to predict the distribution of the piezometric surface, salinity distribution, and mass balance under the proposed scenarios for the prediction period 2006–2020. The scenarios were: (1) relocate Garziz and MAF farms far from the freshwater zone, (2) suspend the abstraction of grass production for 4 months a year, (3) changes in agricultural and irrigation system patterns, (4) establish a desalination plant, (5) combined scenario (1 + 4), (6) combined scenario (1 + 3), and (7) combining all scenarios (1 + 2 + 3 + 4). The result of the simulation shows that the best effective option in terms of aquifer groundwater levels is the fifth proposed scenario and the sixth proposed scenario is the best effective option in terms of aquifer groundwater salinity situation during the next 15 years. This project suggested the application of scenario 6 as it is environmentally sound in terms of sustainable management. A prediction has been made which shows that further actions have to be taken within the next two decades to ensure continuity of the municipal water supply. The management scenarios are examined in the case of the Salalah coastal aquifer using groundwater simulation, which can also be applied to other regions with similar conditions. The established model is considered a reasonable representation of the physical conditions of the Salalah plain aquifer, and can be used as a tool by the water and environmental authorities in the management of the groundwater in the region.  相似文献   

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