The Economic Value of Groundwater Irrigation for Food Security Under Climate Change: Implication of Representative Concentration Pathway Climate Scenarios

Sustainable management of groundwater resources to support food security under the potential effects of climate change is an emerging area of research and particularly relevant in the context of Small Island Developing States. Employing three regional downscaled Representative Connection Pathway (RCP 2.6, RCP4.5, and RCP 8.5) emission scenarios that have been linked to an economic evaluation framework, the potential impact of climate change on groundwater scarcity, economic value of groundwater irrigation, food security, and farming livelihoods is investigated. A nonlinear hydro-economic framework, which integrates groundwater hydrology, climate data, land use, economics and institutions, has been applied for the island of Barbados. Results indicate that climate change would intensify the dependency on groundwater irrigation overtime, modulated by climate intensity. The strength of climate change will boost the marginal value of groundwater irrigation, as food price will scale up, presenting negative impacts on food security and reducing farming livelihoods. The climate change would also result in higher cost of producing foods resulting from increased cost of pumping, mainly driven by the effect of meeting abstraction needs for domestic and municipal consumption. Our primary results show that for a small island, sustaining groundwater resources will be a challenging objective to achieve under severe climate change.     

泾惠渠灌区地下水资源演变与农田生态安全

通过对泾惠渠灌区地下水形成机理及其演变态势的分析,认为气候条件变化、地质条件变化以及人类活动的负面影响是导致灌区地下水资源量衰减的主要原因,其中人类活动(地表水引水灌溉、地下水开采等)的影响作用最为突出。同时也指出了灌区水资源衰减所引发的农田生态安全问题,地下水资源的衰减已经影响到灌区的可持续发展。从灌溉水量的大小、时间分配以及地下水开采量几个方面讨论了灌区水资源调控方式,指出只有合理联合使用地表水和地下水、涵养地下水源,才能实现灌区水资源的可持续开发利用,确保灌区农业供水安全,维护灌区农田生态环境良性循环。     

黄河流域最小保有灌溉需水量预测

从粮食安全角度提出了最小保有灌溉需水量的概念及预测方法,建立了区域灌溉需水量对干旱的响应关系,预测了黄河流域及流域外引黄地区2020年不同干旱条件下的最小保有灌溉需水量。结果表明:黄河流域及流域外引黄地区最小保有灌溉面积为371.3万hm~2,占全部有效灌溉面积的42.3%;不同干旱等级的最小保有灌溉需水量为187.0亿~239.0亿m~3;随着干旱等级由轻旱到特旱,最小保有灌溉需水量分别较无旱情况增大5%、11%、19%和28%。     

Water Use Efficiency and Productivity of the Irrigation Districts in Southern Alberta

The data envelopment analysis (DEA) model was used to estimate the technical efficiency (TE) scores, the Malmquist total factor productivity (TFP) indices, and their implicit input shadow shares for 12 irrigation districts in Southern Alberta using data for the period 2008–12. The main purpose was to establish benchmarks so that future increases in conservation, efficiency and total factor productivity of water use (major goals of Alberta’s Water for Life strategy) can be assessed. Results of an input-oriented DEA model indicated that the irrigation districts were, on average, 84.3 % technically efficient in their input use, primarily the net water diverted. The output-oriented model indicated that the irrigation districts, alternatively, could expand their total irrigated areas by 58.3 % with the current level of input use. Over the period 2008–12, the year-to-year mean Malmquist TFP for the irrigation districts of Southern Alberta was estimated to be 0.98 %. Net water diverted was identified as the most important contributing input (76 %) to the TFP change. The second and third contributing factors were pivot irrigation technology (6 %) and precipitation (5 %).     

Major Trends in Groundwater Development: Opportunities for Public-Private Partnership?

Provision of sufficient water of good quality under growing water demands and increasing climate variability will be one of the main concerns for water managers in the coming decades. It is generally accepted that an integrated approach is required in which resource development options and demand management go hand in hand to provide a management structure with balances between immediate demand from different user groups and the short- and long-term environmental functions of our global water resources. Groundwater plays an important role in achieving this goal provided that its interaction with surface water is fully recognized and its function is fully integrated in land and water planning. The success of integrated water resources management will also benefit from a broader partnership in planning, development and management of our water resources. The focal role of central government is gradually complemented with a growing responsibility of lower levels in the public sector and broader partnerships with the private sector. This paper describes the comparative characteristics of groundwater and its functions in integrated water resources management. Some major trends are discussed in the use of aquifers for enhancing the role of groundwater to cope with increasing water demands and changes in climate variability: the use of brackish groundwater; and the enhancement of recharge and subsurface storage and the ability of aquifers to ameliorate water quality. These potential developments offer good opportunities to enhance the role of the private sector under the regulatory control of the government. These options are particularly important for the Middle East and North Africa region as coping strategies to alleviate the present water scarcity.     

Groundwater Depletion in the Jordan Highlands: Can Pricing Policies Regulate Irrigation Water Use?

Jordan is one of the countries with the scarcest water resources in the world. The aquifers of the Lower Jordan River Basin, a region of prime importance for the country, are exploited well beyond their sustainable rate. In 1997, Jordan’s officials designed a new water strategy, with emphasis on demand-management instruments. Water pricing policies, and notably the bylaw no. 85 of 2002, were deemed to assist in controlling agricultural groundwater abstraction with the ambitious task of taking the abstraction rate close to the annual recharge. While much hope has been placed in such strategies, this paper argues that substantial increases in volumetric charges would not result in major water savings but would further decrease the income from low-value or extensive crops. A shift towards high-value crops would raise water productivity but would also entail a transfer of wealth to the government and to wealthier entrepreneurs. It is therefore essential that negative incentives be accompanied by positive measures offering attractive alternatives (market opportunities, subsidies for modernization, technical advice, etc.) and exit options with compensation. Prices are unlikely to enable regulation of groundwater abstraction and significant reduction will only be achieved through policies that reduce the number of wells in use, such as buying out of wells.     

Optimum Abstraction of Groundwater for Sustaining Groundwater Level and Reducing Irrigation Cost

Adaptation to increasing irrigation cost due to declination of groundwater level is a major challenge in groundwater dependent irrigated region. The objective of this study is to estimate the optimum abstraction of groundwater for irrigation for sustainable management of groundwater resources in Northwest Bangladesh. A data-driven model using a support vector machine (SVM) has been developed to estimate the optimum abstraction of groundwater for irrigation and a multiple-linear regression (MLR)-based model has been developed to estimate the reduction of the irrigation cost due to the elevation of the groundwater level. The application of the SVM model revealed that the groundwater level in the area can be kept within the suction lift of a shallow tube-well by reducing pre-monsoon groundwater-dependent irrigated agriculture by 40%. Adaptive measures, such as reducing the overuse of water for irrigation and rescheduling harvesting, can keep the minimum level of groundwater within the reach of shallow tube-wells by reducing only 10% of groundwater-based irrigated agriculture. The elevation of the groundwater level through those adaptive measures can reduce the irrigation cost by 2.07 × 10³ Bangladesh Taka (BDT) per hectare in Northwest Bangladesh, where the crop production cost is increasing due to the decline of the groundwater level. It is expected that the study would help in policy planning for the sustainable management of groundwater resources in the region.     

全球地下水形势:机会与挑战(一)

目前,全球地下水形势非常严峻,采大于补的地区越来越多。一般来讲,地下水使用涉及3个方面的问题:由过度抽取引起的水损耗问题;主要由排水不当和利用不充分所引起的水渗透和盐渍化问题;由农业、工业及其它人类活动所造成的水污染问题。     

Irrigation, Productivity and Poverty Linkages in Irrigation Systems in Java, Indonesia

This paper analyzes irrigation-poverty linkages, and determines how and to what extent irrigation contributes to poverty alleviation, and whether there are any spatial patterns in poverty in irrigation systems. It also identifies conditions under which irrigation has greater anti-poverty impacts. The analysis is based on primary data collected during the 2000--2001 agricultural year, from four selected irrigation systems and rainfed areas in Java. The results indicate that irrigation has significant poverty reducing impacts. Poverty varies across irrigation systems and across locations within the systems. In general, crop productivity is relatively higher and poverty is lower in middle parts of the systems compared to head and tail parts. Further, locational differences in poverty are more pronounced in larger systems where locational inequities in water distribution and productivity differences are also high. Crop productivity, the size of landholdings and location of households are important determinants of poverty, in addition to demographic factors such as family size. The smaller the systems with well managed infrastructure, relatively equitable water distribution and diversified cropping patterns supported with market infrastructure, the greater the poverty reducing impacts of irrigation. Overall, the study findings suggest that improving the performance of irrigation systems by enhancing land and water productivity, diversifying cropping patterns and improving water distribution across locations would help reduce poverty in presently low productivity-high poverty parts of the systems.     

The Pros and Cons of Encouraging Shallow Groundwater Use through Controlled Drainage in a Salt-Impacted Irrigation Area

Encouraging shallow groundwater use through water table management or controlled drainage in irrigated areas can relief crop water stress under water shortage condition. But substituting fresh irrigation water with saline groundwater may speed up salinity buildup in the crop root zone, and consequently increase water use for salt leaching. With a proposed analytical model, this paper presents a case study demonstrating the effect of encouraging shallow groundwater use through controlled drainage on salt and water management in a semi-arid irrigation area in northwestern China. Based on the average rainfall condition, the model assumes that salt accumulates in the crop root zone due to irrigation and shallow groundwater use; till the average soil salinity reaches the crop tolerance level, leaching irrigation is performed and the drainage outlet is lowered to discharge the salt-laden leaching water. For the relatively salt tolerant crop–cotton in the study area, the predicted leaching cycle was as long as 751 days using the fresh water (with salinity of 0.5 g/L) irrigation only; it was shortened to 268 days when the water table depth was controlled at 2 m and 23% of the crop water requirement was contributed from the saline groundwater (with salinity of 4.43 g/L). The predicted leaching cycle was 140 days when the water table depth was controlled at 1.5 m and groundwater contribution was 41% of the crop water requirement; it was shortened to 119 days when the water table depth was controlled at 1.2 m and the groundwater contribution was 67% of the crop water requirements. So the benefit from encouraged shallow groundwater use through controlled drainage is obtained at the expense of shortened leaching cycle; but the shallow groundwater use by crops consists of a significant portion of crop water requirements, and the leaching cycle remains long enough to provide a time window for scheduled leaching in the off season of irrigation. Weighing the pros and cons of the encouraged shallow groundwater use may help plan irrigation and drainage practices to achieve higher water use efficiency in saline agricultural areas.     

Pond and Irrigation Model (PIM): a Tool for Simultaneously Evaluating Pond Water Availability and Crop Irrigation Demand

Agricultural ponds are an important alternative source of water for crop irrigation to conserve surface and ground water resources. In recent years more such ponds have been constructed in Mississippi and around the world. There is currently, however, a lack of a tool to simultaneously estimate crop irrigation demand and pond water availability. In this study, a Pond-Irrigation Model (PIM) was developed to meet this need using STELLA (Structural Thinking, Experiential Learning Laboratory with Animation) software. PIM simulated crop land and agricultural pond hydrological processes such as surface runoff, soil drainage, and evapotranspiration as well as crop irrigation demand and pond water availability. More importantly, PIM was able to decide when to conduct crop irrigation based on management allowable depletion (MAD) root zone soil water content and to determine optimal ratios of agricultural pond size to crop land with sufficient pond water available for crop irrigation. As a case demonstration, the model was applied to concomitantly estimate row crops (i.e., corn, cotton, and soybeans) water irrigation demand and pond water availability in a farm located at East-central Mississippi. Simulations revealed that corn used more soil water for growth than soybeans, whereas soybeans needed more irrigation water than corn and occurred due to less rainwater available for soybeans growth. We also found that there was one time for corn, zero time for cotton, and two times for soybeans when the pond water level was drawn to near zero for irrigation from 2005 to 2014. PIM developed in this study is a useful tool for estimating crop irrigation demand and pond water availability simultaneously.     

Mapping of Conjunctive Water Use Productivity Pattern in an Irrigation Command Using Temporal IRS WiFS Data

Irrigated agriculture in many areas of the world is currently being practiced from multiple water sources such as precipitation, canal, wetlands, ground aquifer, etc. This study highlights the use of high temporal remote sensing data [IRS-1D; Wide Field Sensor (WiFS), 188-m resolution] to assess conjunctive water use pattern and its productivity in the 6 Main Canal command of Damodar Irrigation Project West Bengal, India. In this command three sources of water (canal water, groundwater and wetland) were used for the rice growing system during the summer season. A multi-date (ten dates, two bands) image stack was prepared. Using this image stack and an unsupervised classification (Fuzzy k-means) backed by space–time spiral curve (ST-SCs) technique, canal release and wetlands information was used to prepare irrigated classes (canal, groundwater or wetlands) map for summer 2000. ST-SCs have been used to analyze temporal WiFS data to continuously monitor class dynamics over time and space and to determine class separability (different types of irrigated-classes) at various time periods within the season. Results showed that the area under agriculture, non-agriculture and water were 81%, 18.5% and 0.5%, of the total area respectively. While, groundwater, canal water and wetland irrigated rice were 67.6%, 25.6% and 6.8%, respectively out of the total agriculture area. Classification results found to have more than 89.3% overall accuracy for broad land cover, while sub-classes of rice i.e. irrigated classes found have reasonably good accuracy of 85.7%. A productivity index (LAI/water-requirement) was also developed. Productivity index was high for the wetland and groundwater irrigated rice as compared to the rice irrigated through canal water. These results were weighed against the observed yield data.     

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。     

Groundwater in Water Resources Planning: Conjunctive Use

ABSTRACT

Many water resources planning specialists underrate or overlook groundwater resources. In many cases, the reasons which are usually expressed belie a lack of confidence in their potential and in the ability of today's technology to predict their behavior. The area occupied by aquifers and the fact that they account for 30% of stream discharges, are strong arguments in favor of utilizinggroundwater resources. Likewise, with present groundwater evaluation techniques and the availability of models and simulation methods, the impact of long-term groundwater exploitation can be evaluated with as great a degree of accuracy as the methods used for surface water. Very often groundwater resources are economically more favorable than surface water; however, in regions where water resources are scarce, the problem should not be one of competition but collaboration. The correct approach is the conjunctive use of surface and groundwater resources. Through conjunctive use additional water resources can be obtained, additional means of water storage, distribution and treatment can be made available, as well as achieving greater efficiency in water resources system management.     

湖南省农业灌溉设施现状及发展对策探讨

湖南是一个农业大省,50余年来全省的农业灌溉设施建设取得了较大成就,但由于长期的封闭管理与技术落后等原因,湖南水利产业尚未形成良性运行机制,水利行业自身实力不强,农业灌溉设施的硬件与软件还不能适用全省社会、经济发展的需要。文章建议发展节水农业技术、调整农业种植结构、健全灌溉管理制度以及制定节水政策与完善水利法规体系,使水利设施能更好地为农业发展服务。     

Challenges and Opportunities in GRACE-Based Groundwater Storage Assessment and Management: An Example from Yemen

Sustainable management of groundwater resources is often hampered by information asymmetries between abstracters and managers. At the same time, developments in satellite remote sensing, particularly estimates of groundwater storage using the Gravity Recovery And Climate Experiment (GRACE), have dramatically improved water resource assessment. This study examines the potential for GRACE-based assessment of groundwater resources in the context of the persistent challenges of water management in Yemen, which suffers from acute groundwater depletion and water scarcity. By comparing GRACE estimates of groundwater storage change to observed well measurements in Yemen, this study indicates that GRACE can complement institutional water management reform by providing better water resources information, especially in combination with socioeconomic data visualized in a Geographic Information System (GIS). However, the case of Yemen also indicates that commonly accepted principles of water management must be adapted to harness the potential of GRACE-based groundwater storage assessment.     

全球地下水形势:机会与挑战(二)

在南亚和非洲的一些地区,地下水灌溉为改善穷人生活提供了一个很大的机会。然而,在其它地方地下水的损耗和污染对人类生产和生活构成了一种威胁,如沿海海水入侵地下水蓄水层。目前,地下水消耗和由此导致的相关问题是当今世界在水问题上所面临的最令人头疼的挑战之一,这是由地下水资源量和对其需求的空间不平衡造成的。     

全球地下水形势:机会与挑战(三)

随着地下水的不断消耗及其有害后果的发生,世界上许多国家采取各种各样的措施以减轻乃至扭转这种状况。其中,最常见的办法有两种,一是利用地表水进行补给,二是利用雨水进行补给。实践证明,这两种办法收效显著。     

山西省地下水机井普查状况及其对策建议

通过对山西省地下水机井的普查,了解了山西省地下水资源开发现状,机井普查的数据也说明了机井超量开釆地下水带来的资源、环境、生态及管理问题,针对这些问题提出了相应的对策措施。     

全球地下水形势:机会与挑战(四)

为了应对地下水缺乏危机,从资源开发向资源管理转变势在必行。而加强地下水资源管理,至少包括4项重要内容:水资源数据系统和水资源计划,需求方的管理,补给方的管理和流域环境的地下水管理。