Simulation Modeling for Efficient Groundwater Management in Balasore Coastal Basin,India

The Balasore coastal groundwater basin in Orissa, India is under a serious threat of overdraft and seawater intrusion. The overexploitation resulted in abandoning many shallow tubewells in the basin. The main intent of this study is the development of a 2-D groundwater flow and transport model of the basin using the Visual MODFLOW package for analyzing the aquifer response to various pumping strategies. The simulation model was calibrated and validated satisfactorily. Using the validated model, the groundwater response to five pumping scenarios under existing cropping conditions was simulated. The results of the sensitivity analysis indicated that the Balasore aquifer system is more susceptible to the river seepage, recharge from rainfall and interflow than the horizontal and vertical hydraulic conductivities and specific storage. Finally, based on the modeling results, salient management strategies are suggested for the long-term sustainability of vital groundwater resources of the Balasore groundwater basin. The most promising management strategy for the Balasore basin could be: a reduction in the pumpage from the second aquifer by 50% in the downstream region and an increase in the pumpage to 150% from the first and second aquifer at potential locations.     

西北内陆盆地地下水资源可持续利用战略分析

西北内陆盆地气候干旱,水资源缺乏,而地下水分布较广泛,开采方便,在经济建设和环境保护中具有不可替代的作用.结合水资源开发引起的生态环境问题,对地下水可持续利用战略进行了分析,强调西北内陆区地下水开发要与生态建设相协调,保证生态用水,实施科学用水.     

Field Investigations for Sustainable Groundwater Utilization in the Konan Basin

The Konan groundwater basin of Kochi Prefecture, Japan, is experiencing freshwater shortages for the past few years, particularly during the winter season. The present study aimed at analyzing the problem and exploring increased groundwater withdrawals to meet burgeoning freshwater demands in various sectors. The trend analysis of waterconsumption indicates that the groundwater demandwould increase by 43 and 52% by the years 2010 and2025, respectively, compared to 32 100 m³ d^-1 at present.The streamflow of the Monobe River reduces to a minimumin winter and it shows a decreasing trend in recentyears. The geologic investigation results indicatethat unconfined (phreatic) aquifers comprisingalluvial sand and gravel and/or diluvial silty sandand gravel are dominant, and that the northwestern andwestern portions of the basin have greater potentialfor groundwater. Groundwater flows essentially fromnorth to south into the ocean. Groundwater levelfluctuations over the basin vary appreciably in spaceand time, indicating a wide variation of naturalrecharge. Field observations confirm the hypothesisthat stream-aquifer interaction also significantlycontributes to groundwater recharge, besides therainfall infiltration. Further, the pumping testsresults demonstrate that though the aquifers arelow-yielding, enhanced groundwater withdrawals couldbe possible. The aquifer hydraulic conductivity ischaracterized as high and ranges from 65 to 804 m d^-1(mean = 229 m d^-1), thereby suggesting great aquiferheterogeneity. Finally, it is concluded that thelong-term sustainability of the scarce groundwaterresource of the Konan basin is doubtful, and that acomprehensive analysis of the groundwater system isessential prior to formulating plans for the futuregroundwater development and management.     

海河流域地下水开发利用现状与对策

从海河流域地下水开发利用现状入手,分析了近年来地下水供用水量变化趋势和平原区地下水动态情况,阐述流域地下水存在的一系列生态环境问题和管理问题,并有针对性地提出地下水管理的法律、经济、行政等多方面的对策建议。     

Optimal Crop Planning and Conjunctive Use of Water Resources in a Coastal River Basin

Due to increasing trend of intensive rice cultivation in a coastal river basin, crop planning and groundwater management areimperative for the sustainable agriculture. For effective management, two models have been developed viz. groundwater balance model and optimum cropping and groundwater management model to determine optimum cropping pattern and groundwater allocation from private and government tubewells according to different soil types (saline and non-saline), type of agriculture(rainfed and irrigated) and seasons (monsoon and winter). A groundwater balance model has been developed considering mass balance approach. The components of the groundwater balance considered are recharge from rainfall, irrigated rice and non-rice fields, base flow from rivers and seepage flow from surface drains. In the second phase, a linear programming optimization model is developed for optimal cropping and groundwater management for maximizing the economic returns. Themodels developed were applied to a portion of coastal river basin in Orissa State, India and optimal cropping pattern forvarious scenarios of river flow and groundwater availability wasobtained.     

Groundwater quality management of a low inertia basin: Application to the San Mateo Basin,California

A two-dimensional finite element model is applied to the San Mateo Basin, California in order to investigate feasible and efficient management alternatives to enhance the basin yield and preserve the basin water quality. The model utilizes lumped approximation methods for the determination of its subsurface boundary conditions, and incorporates a variety of hydrological processes. The model solves uncoupled flow and transport equations using a nodal domain integration technique for the flow model and an integrated finite difference method for the transport model. The model incorporates the basin inputs and outputs as ocean flux, well and phreatophyte extractions, subsurface inflow, precipitation and streambed percolation. Modeling results indicate that the substained yield may be maximized by interception of ocean outflow from the basin. An improvement of about four times of the historical sustained yield was achieved. This strategy required relocation of existing wastewater recharge ponds and increasing basin extractions. In order to intercept most of the ocean outflow by increasing basin extractions, simulated subsurface seawater intrusion was observed. The water quality study indicated that the basin yield could be increased significantly by moderately relaxing the water quality criteria near the ocean.     

Mathematical Modelling for the Integrated Management of Water Resources in Hydrological Basins

Mathematical models are tools that can facilitate the instrumentation of the Integrated Water Resources Management (IWRM). The first basin models to be developed were completely hydrological; today, due to the urgent need to plan the sustainable use of water resources, new models are needed that in addition to hydrology also incorporate social, economic, legal, environmental and other aspects. The objective of this work was to identify the characteristics that mathematical basin models must have in order to satisfy the requirements of IWRM. To achieve this, the conclusions of the main international conferences on water and the environment were analyzed; these were conferences in which IWRM was promoted as a strategy to face the challenges of both sectors. IWRM considers social participation as a key element in the decision-making process; consequently, the models must be accepted and applied, and their results interpreted, by those who participate in the process even if they are not modelling experts. This requires a change of perspective in the scientific community for the development of new IWRM models, in government institutions regarding their role as water administrators, and in water stakeholders regarding their role as decision-makers. The results of the analysis indicate that models for IWRM must be accessible to non-expert users, integrate different viewpoints, representing adequately the problem to be solved, in addition be flexible and have a structure focused on practical solutions.     

Assessment of lake–groundwater interactions and anthropogenic stresses,using numerical groundwater flow model,for a Rift lake catchment in central Ethiopia

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.     

Harnessing the sun for an evergreen revolution: a study of solar-powered irrigation in Bihar,India

In 2012, the government of Bihar revived 34 non-functioning public tubewells using solar panels. The performance of 16 of these wells over 12 months was tracked and analyzed using data from tubewell operators and 240 farmers. Access to affordable irrigation from solar pumps led to a 9–10% increase in productivity of rice and wheat. Furthermore, in a severe drought, farmers could grow paddy in the entire area irrigated by solar pumps, when nearly 40% of other land was left fallow. Solar pumps can help increase crop productivity, reduce the cost of irrigation, and make agriculture more resilient to climate change.     

Comparison of IDW and Physically Based IDEW Method in Hydrological Modelling for a Large Mountainous Watershed,Northwest China

Topography and spatial patterns of landscape significantly affect spatial distribution of precipitation and, in turn, hydrological modelling, especially in high elevation, mountainous watersheds of arid regions. This study incorporates a physically based inverse distance and elevation weighted (PBIDEW) method into a distributed conceptual hydrological model, distributed large basin runoff model, and compared with an inverse distance weighted (IDW) method to assess the performances of both methods in precipitation estimation for hydrological modelling at watershed scale. The PBIDEW method considers the impacts of topography using month‐dependent parameters in its interpolation of meteorological variables while the IDW method does not. Both the IDW and the PBIDEW methods are evaluated and compared in hydrological modelling at different spatial resolutions in the upper reach of the Heihe River Watershed, Northwest China. Results show that the IDW method underestimated the areal precipitation, and the PBIDEW method produced more realistic precipitation estimations in the study area. Both methods have some limitations, the performance of the IDW method was mainly influenced by the availability of observation data, while that of the PBIDEW method was mainly influenced by the representation of topographical information. Considering more detailed information for precipitation estimates, the PBIDEW method performed better at finer spatial resolution. Overall, the PBIDEW method, using month‐dependent physical interpolation parameters, seems more suitable for precipitation estimation in hydrological simulations in data‐scarce, high elevation and topographically complex mountainous watersheds in arid area. Copyright © 2017 John Wiley & Sons, Ltd.     

Informal water markets and willingness to pay for water: a case study of the urban poor in Chennai City,India

The present study analyzes the role of informal markets in fulfilling the water requirements of poorer households in Chennai City, India. The results of a survey reveal that a significant number of poor people purchase water from informal markets and that they incur a sizeable expenditure on water purchases; some of these households are also willing to pay additional amounts for improved water supply from public sources. The results suggest that improvements in public water supply would significantly increase the welfare of the poor. The informal markets need to be regulated and monitored so that they can serve the households in a better way.