An Initial Inventory and Indexation of Groundwater Mega-Depletion Cases

The state of groundwater systems worldwide is presently not well defined, and in particular there is little context for agencies responsible for managing water resources to evaluate occurrences of groundwater depletion against other cases globally. In this study, an initial inventory of groundwater depletion problems is compiled and ranked to identify the world’s most critical cases, i.e. situations of groundwater mega-depletion. The ranking is based on an indexed approach that considers overdraft, drawdown and subsidence, plus the importance of the resources in terms of population-dependency and rates of extraction. The five most highly ranked depleted aquifers of the world include the shallow aquifers of the Hai River Plain (China), the Altiplano region (Spain), the Mexico Basin (Mexico), the Huang River basin (China) and the California Central Valley (USA). An abridged account of modelling to assess drawdown is described for the Hai River Plain, revealing that despite recharge in the order of 13,000 GL/yr, an overdraft of about 8,000 GL/yr is occurring to support the vast population of the region. This has led to up to 100 m of drawdown in places and reports of subsidence of several metres. The Hai River situation demonstrates that falling water levels may not act to alleviate pumping stresses; a symptom of unchecked extraction and an exemplary illustration of the tragedy of the commons. The causal factors leading to mega-depletion are varying across the globe and each mega-depletion case contains unique elements, although population appears to be an important factor.     

Irrigation development and environmental degradation in developing countries — a dynamic model of investment decisions and policy options

In the wake of increased environmental and sustainability concerns associated with agricultural development, developing countries are faced with the dilemma of choice between the short-run technological gains and the long-run environmental conservation. A dynamic investment decision model is developed to optimize the use of scarce public investment funds in the magagement of irrigation water supply, depth to water table and soil salinity. Four major classes of investments with different impacts on the hydrological balance within the Indus basin are considered: (a) expansion of the surface irrigation network, (b) public drainage projects, (c) tax and subsidy policies designed to influence the rate of private groundwater exploitation and (d) investment in improving the efficiency of the existing canal system by reducing conveyance losses. The crop area lost due to water logging and salt accumulation is treated as a damage cost of increasing the application of surface irrigation water. The resulting optimality conditions from the model are used to assess the development and operation of public drainage projects. The model results are compared for areas underlain by fresh and saline groundwater. The model is also used to analyze recent policy debate which has focused on the use of incentives such as subsidized credit, energy subsidies, and electrical grid expansion to accomplish the transfer of tubewell operation from the public to the private sector. Optimal switching conditions for such transfers are derived. The results show that a private farmer's optimal decision will diverge more from the societal optimal decision as more externalities from surface irrigation are accounted for.     

Challenges and Prospects of Sustainable Groundwater Management in the Indus Basin,Pakistan

In Pakistan, on-demand availability of groundwater has transformed the concept of low and uncertain crop yields into more assured crop production. Increased crop yields has resulted in food security and improved rural livelihoods. However, this growth has also led to problems of overdraft, falling water tables and degradation of groundwater quality, and yields generally remain well below potential levels. Over the last three decades, Pakistan has tried several direct and indirect management strategies for groundwater management. However the success has been limited. This paper argues that techno-institutional approaches such as introducing water rights, direct or indirect pricing and permit systems are fraught with difficulties in Pakistan due to its high population density and multitude of tiny users. Therefore there is a need to develop frameworks and management tools that are best suited to Pakistani needs. Pakistan should follow both supply and demand management approaches. For demand management, adoption of water conservation technologies, revision of existing cropping patterns and exploration of alternate water resources should be encouraged. For supply management, implementation of the groundwater regulatory frameworks developed by Provincial Irrigation and Drainage Authorities (PIDAs) and introduction of institutional reforms to enhance effective coordination between different organizations responsible for the management of groundwater resources should be given priority.     

冀中山前平原农灌用水与地下水承载力适应性状况

针对冀中太行山前平原浅层地下水严重超采与农林灌溉用水之间关系问题,应用地学的模数理念、水量均衡理论方法和MapGIS空间特征分析技术,建立了农灌用水与地下水承载力之间适应性状况评价方法及指标体系,以0.49km2剖分单元精度识别了冀中山前平原农林灌溉用水强度及其与浅层地下水可采资源量之间适应性状况。结果表明,冀中山前平原农林灌溉导致的"极严重不适应"或"严重不适应"状态是浅层地下水超采的主要原因,其中小麦等夏粮作物灌溉用水主导了这些农灌区地下水超采,蔬菜作物和耗水型果林灌溉开采对地下水的影响呈显著增加趋势,应重视这种非理性加剧影响因素。     

Agricultural water and energy management in Tajikistan: a new opportunity

ABSTRACT

Agricultural water use in Tajikistan is largely based on mechanized irrigation pumps. The farming community cannot afford the cost of the energy used for pumping, resulting in large debts to the service provider. We propose limiting pumping facilities for five years in exchange for energy export to neighbouring countries. The energy export could cover the annual pumping expenditures, pay off agricultural debt and partly rehabilitate the irrigation network. We suggest three scenarios with different pumping energy reductions, and the relevant technical parameters of the set-aside scheme are assessed.     

Policy Options to Improve Water Allocation Efficiency: Analysis on Egypt and Morocco

Abstract

Because of political risk, economic feasibility, and cultural concerns, it has been a great challenge for economists to provide palatable remedies to governments to promote water allocation efficiency. Considering the limitation of water pricing to irrigation water, this research addresses questions of which strategic policy alternatives to water pricing might improve irrigation water allocation efficiency. An empirical framework is provided to compare irrigation policies for allocating scarce water to agricultural production in Egypt and Morocco. Partial-equilibrium agricultural sector models specific to Egypt and Morocco were employed for policy tests. Consumer and producer surplus from agricultural based commodities is maximized subject to various resources, technical, and policy constraints. Positive Mathematical Programming (PMP) was used to calibrate the model. Water pricing policy, water complementary input factor tax policy, and output tax policy are tested using these two agricultural sector models. Results suggest that effective policy depends on the social, economic, and environmental contexts of specific regions. For countries like Egypt where most agricultural land is irrigated, taxes on Nitrogen (N) fertilizer and energy and output tax on water-intensive and low profit crop production may be more effective than others. For the Moroccan case, taxation on crop inputs and outputs not only affect water use in the public irrigation sector, but also private irrigation sector and rain-fed as a whole. Water pricing and output tax policies are better suited and effective than water complementary input factor taxation. Findings from Morocco might be generalized to other countries with similar irrigation characteristics and diversity in irrigated (public and private) and rain-fed land. The results for both countries demonstrate that some of the strategic irrigation policies can work towards directing cropping decisions to less water intensive crops and also generating revenues for governments in situations where governments choose not to price water.     

Simulation-Optimization Modelling for Sustainable Groundwater Management in a Coastal Basin of Orissa, India

The Balasore coastal groundwater basin of Orissa in eastern India is under a serious threat of overdraft and seawater intrusion. Two optimization models were developed in this study for the efficient utilization of water resources in Balasore basin during non-monsoon periods: (a) a non-linear hydraulic management model for optimal pumpage, and (b) a linear optimization model for optimal cropping pattern in integration with a calibrated and validated groundwater flow simulation model. Based on the simulation-optimization modeling results, optimal pumping schedules, cropping patterns, and corresponding groundwater conditions are presented for three scenarios viz., wet, normal and dry years. It was found that optimal pumping schedules and corresponding cropping patterns differed significantly under the three scenarios, and the groundwater levels improved significantly under the optimal hydraulic conditions compared to the existing condition. In dry years, the groundwater levels under the present pumping pattern and the optimal pumpage indicated that the non-monsoon pumpage should not exceed the optimal pumpage in the absence of remedial measures in the basin. It is concluded that in order to ensure sustainable groundwater utilization in the basin, the optimal cropping pattern and pumping schedule should be adopted by the farmers.     

Do policy and institutional factors explain the low levels of smallholder groundwater use in Sub-Saharan Africa?

This article examines the policy and institutional constraints on smallholder adoption of groundwater irrigation practices in Sub-Saharan Africa. The analysis departs from the unilateral focus on the promotion of technologies and probes not only the issues of groundwater governance but also those policies related to other enabling factors such as access to credit, energy and agricultural pricing policies and land-tenure security. The paper argues that the region may be missing an opportunity by not ensuring at least neutral policy towards agricultural groundwater development and addressing other constraints which hold back not only agricultural groundwater use but smallholder agriculture development in general.     

The negative impact of subsidies on the adoption of drip irrigation in India: evidence from Madhya Pradesh

Abstract

Drip irrigation in India has expanded slowly. One reason cited is the high capital costs facing the smallholder-dominated agricultural sector. Governments have provided capital subsidies in response. This study finds that, rather than improving access to drip, the subsidy system holds the technology back, because its technical requirements, highly bureaucratic processes and pricing incentives turn many drip providers into rent-seeking agents rather than service providers to farmers, leading to price increases of 40% or more. If capital costs are truly the constraint on drip expansion in India, alternative models to address them are available.     

Rational Pricing of Water as an Instrument of Improving Water Use Efficiency in the Agricultural Sector: A Case Study in Gujarat,India

The agricultural sector in India accounts for over 85% of the total water used for various purposes in the country. However, the efficiency of water use in agriculture is very low, approximately 40% for surface irrigation and 60% for groundwater irrigation. Part of the reason for the low efficiency is the highly subsidized price of irrigation water that encourages the excessive application of water to crops. This paper is based on a case study conducted in the command area of a public irrigation canal in the state of Gujarat, India. It attempts to explore the role of the rational pricing of canal irrigation water in motivating farmers to use water judiciously and thereby enhance the water use efficiency in irrigated agriculture. The paper contends that farmers are sensitive to an increase in irrigation water charges, but unless the administered price is increased to the level that would prevail in a free market, it will not have its intended effect on irrigators.     

Positive externalities of irrigation from the Sardar Sarovar Project for farm production and domestic water supply

A detailed study was conducted in six districts of Gujarat, India, in gravity- and lift-irrigated commands of the Sardar Sarovar Project to assess the direct and indirect benefits of canal irrigation. Benefits such as savings in the cost of energy used to pump groundwater for irrigation, reduction in well failures, and increased income of well irrigators from farming (crops and dairy) were remarkable. Groundwater augmented by recharge from gravity irrigation resulted in large economic returns to the well irrigators in the command areas and reduced the cost of domestic water supply in villages and towns (through improved yield of agro-wells and drinking-water wells, respectively). Canal irrigation also raised wages for workers, through enhanced agricultural labour demand along with appreciation of land markets.     

三江平原地下水循环演化特征

对三江平原20世纪50—60年代、70—80年代和90年代至今的地下水资源量进行了调查对比,结果表明:低山丘陵区和平原区主要接受大气降水的补给,平原区还接受丘陵区的地下水侧向流补给及河水补给,排泄在早期以蒸发为主,后期以人工开采为主;三江平原地下水循环演化是从20世纪70—80年代开始发生负均衡变化的,而在农业经济发展的90年代负均衡更加显著,形成了一些地下水超采区。     

太阳能光伏提水灌溉技术应用

可再生新能源的开发利用是实现绿色和可持续发展的重要途径,因而受到全世界广泛关注,太阳能光伏提水灌溉也是备受关注的研究和应用领域之一。在我国西部偏远缺乏电力供应的地区,通常情况下日照时间长,太阳能资源比较丰富。这些地区也是水资源紧缺和生态严重退化的地区。因此,在我国西部地区发展太阳能提水和节水灌溉不但可以充分利用分布广泛的绿色能源,有效解决能源短缺的问题,发展节水、节能、高效的灌溉牧草和农业,具有良好的社会和经济效益,还可以保护人类赖以生存的生态环境。本文结合所承担的项目研究及推广成果,总结了太阳能光伏提水技术及应用效果。     

昆明盆地地下水超采区水资源评价

随着经济快速发展,昆明盆地淡水资源供需矛盾日益加剧,部分地区地下水超采严重。为合理开发、利用与保护地下水资源,根据地下水位动态变化以及其引发问题等因素评价了昆明盆地地下水超采情况,并划定了超采区域。评价结果表明至2010年底,昆明盆地地下水总超采区面积为128 km²,属于中型超采区,且各超采区均为禁采区。同时提出了治理超采区的措施和建议,可为区域地下水资源的科学管理提供技术支撑。     

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.     

Optimization of Irrigation Scheduling Using Soil Water Balance and Genetic Algorithms

In arid and semi-arid countries, the use of irrigation is essential to ensure agricultural production. Irrigation water use is expected to increase in the near future due to several factors such as the growing demand of food and biofuel under a probable climate change scenario. For this reason, the improvement of irrigation water use efficiency has been one of the main drivers of the upgrading process of irrigation systems in countries like Spain, where irrigation water use is around 70 % of its total water use. Pressurized networks have replaced the obsolete open-channel distribution systems and on farm irrigation systems have been also upgraded incorporating more efficient water emitters like drippers or sprinklers. Although pressurized networks have significant energy requirements, increasing operational costs. In these circumstances farmers may be unable to afford such expense if their production is devoted to low-value crops. Thus, in this work, a new approach of sustainable management of pressurized irrigation networks has been developed using multiobjective genetic algorithms. The model establishes the optimal sectoring operation during the irrigation season that maximize farmer’s profit and minimize energy cost at the pumping station whilst satisfying water demand of crops at hydrant level taking into account the soil water balance at farm scale. This methodology has been applied to a real irrigation network in Southern Spain. The results show that it is possible to reduce energy cost and improve water use efficiency simultaneously by a comprehensive irrigation management leading, in the studied case, to energy cost savings close to 15 % without significant reduction of crop yield.     

The impact of water users’ associations on the productivity of irrigated agriculture in Pakistani Punjab

This paper finds productivity-enhancing effects of watercourse-level water users’ associations for farms at the tail of a watercourse and for those that rely exclusively on groundwater – two groups that are marginalized from surface water use and more likely to rely increasingly on groundwater. Yet, heavy reliance on groundwater consumes vast energy resources and leads to environmental degradation through overdraft and groundwater salinization. Improving the management of surface water through functioning watercourse-level institutions can increase use efficiency across water, energy and land resources through increasing agricultural productivity of those now least able to access fresh surface water resources.     

Accounting for Climate Change and Drought in Implementing Sustainable Groundwater Management

Groundwater provides close to 40% of California’s overall water supply under average hydrologic conditions. It is a critical source of backup during drought when increased pumping occurs to compensate for reduced surface supplies and decreased soil moisture. The conundrum is that in regions of the state where groundwater dependence is already high and rates of recharge are low, over the long term the volume withdrawn, particularly during droughts, generally exceeds replenishment in many regions. The result is overdraft - ongoing declines in groundwater levels over the long-term. To facilitate the reduction or cessation of long-term groundwater overdraft, this paper proposes that sustainable groundwater management must include the development of a drought reserve. The reserve, ideally sourced, sited and used locally, would encompass sufficient water for use during a drought such that the increased withdrawals during a drought do not result in unrecoverable groundwater declines and concomitant negative impacts. The objective is to reduce vulnerability to the state’s periodic droughts, as opposed to mitigating seasonal variations in precipitation. This paper first summarizes the issues associated with developing drought reserves, and then examines in detail how two California groundwater management agencies approach establishing and implementing a drought reserve.     

大武口地区深层地下水超采区评价

大武口地处宁夏回族自治区北部,深层地下水是研究区主要供水水源,由于长期过量开采,形成了较大的降落漏斗,保护地下水资源形势严峻。根据历年地下水动态资料,参照全国地下水超采区评价技术大纲．对研究区域深层地下水进行超采区综合划分,结果表明研究区域均属于超采区,并提出了相应的保护和治理建议,为大武口地区地下水资源统一规划、有效管理及科学保护提供依据。     

Has water-saving irrigation recovered groundwater in the Hebei Province plains of China?

This study performed a quantitative evaluation of the impact of water-saving irrigation on the groundwater regime in the Hebei Province plains area. In this work, the change in groundwater regime and the contributions of precipitation and water-saving irrigation development were investigated. The results indicate that the groundwater overdraft has been mitigated to some extent, mainly due to changes in precipitation and the implementation of water-saving irrigation, with contributions of 64.3% and 35.7%, respectively, when considering only these two factors. Water-saving irrigation is accepted as an important means for reducing groundwater depletion, but should be used in conjunction with other measures.