Solarizing groundwater irrigation in India: a growing debate

Abstract

India is on a path to reduce its carbon emission intensity with a major thrust on increasing the grid-connected solar photovoltaic capacity. However, the carbon footprint in agriculture is on the rise. Heavy subsidies for electricity and diesel to pump groundwater for irrigated agriculture, combined with lack of regulations on water withdrawal, are resulting in both groundwater over-exploitation and increased carbon emissions. Some researchers and practitioners have suggested large-scale promotion of solar pumps for well irrigation as a way to make agricultural growth carbon-neutral and groundwater use in farming sustainable. This article examines whether solar pumps for groundwater irrigation are technically feasible and economically viable in India.     

A groundwater perspective on the river basin management plan for central Portugal - developing a methodology to assess the potential impact of N fertilizers on groundwater bodies

The Water Framework Directive establishes that the river basin management plans must have a summary of the pressures and impacts of human activities, such as agriculture, on the chemical and quantitative status of groundwater bodies. In order to identify those areas where a potential impact from agricultural activities on groundwater bodies exists, but currently lacking groundwater monitoring data, a methodology was developed that combines the use of gross nitrogen balance values with the results of a specific vulnerability assessment index. A farm management efficiency parameter is added, to identify the factors that contribute to nitrogen use efficiency and to assess the near-future scenarios. This methodology allows the identification of significant pressures that may be responsible for a groundwater body failing good status where there is no representative monitoring network.     

Agricultural Water Use in Turkey

Abstract

Agriculture is the largest user of water in Turkey with 75 percent of the total consumption. Turkey has developed 50 percent of total irrigable land so far. Water is a limiting factor for agriculture throughout much of Turkey. The amount and distribution of precipitation is quite uneven. Turkey, like many countries today, faces challenges in efficiently developing and managing its agricultural water resources while trying to protect water quality and the environment. However, Turkey has some difficulties and problems on water use for agriculture. Current institutional framework and legal regulation, monitoring and evaluation activities are investigated, and agricultural water use and irrigation development are studied. Problems with the lack of data on environmental effects of irrigation and water pricing are underlined. Evaluation of the current situation ends in the conclusion that Turkey needs a comprehensive monitoring and evaluation system both at basin and scheme level, and rehabilitation of irrigation systems for efficient water use in agriculture.     

Drivers of groundwater use and technical efficiency of groundwater,canal water,and conjunctive use in Pakistan’s Indus Basin Irrigation System

Abstract

This paper explores the major determinants of heavy reliance on groundwater and the extent to which conjunctive use of ground and surface water affects the production efficiency of Pakistan’s irrigators. The results show that the major drivers of groundwater use in Pakistan’s agriculture are the variability and uncertainty associated with surface water delivery and that any effort to address the groundwater–energy nexus challenge should first consider fixing the problems associated with surface water supplies. The findings also suggest that having access to groundwater does not directly translate into improvements in technical efficiency of production.     

Trends and perceptions of rural household groundwater use and the implications for smallholder agriculture in rain-fed Southern Laos

In Laos, the extent of rural groundwater use is largely unknown. This paper presents results of a study conducted in Champasak province, Southern Laos, to examine rural household attitudes to groundwater use and management; and to gauge farmer perceptions of the opportunities/constraints of increased groundwater use for smallholder agriculture. Significant differences in groundwater use, total cash income and perceived groundwater quality were found. Further agricultural expansion was constrained by insufficient labour and the limited area of individual landholdings, not by the limited groundwater supply, which was the preferred source to fulfil increased demands for domestic/agricultural use. There were no groundwater regulations.     

Quantitative Assessment of Agricultural Practices on Farmland Evapotranspiration Using EddyCovariance Method and Numerical Modelling

While low cost eddy covariance (EC) techniques based on the open-path laser analyzers have been widely used, they are not very accurate and are restricted to use in non-rainy days. As an alternative, and relevant to promoting precision agriculture where water availability is proving key, the application of the EC technique based on closed-path QCLAS-EC Analyzer is described, in a study of cabbage farmland evapotranspiration (ET). This study uses the advantages of the closed-path EC method to quantitatively assess the impact of agricultural activities on farmland ET and compared with RZWQM2 (Root Zone Water Quality Model) model. The cumulative ET is shown to have increased by 1.5–3.6 mm over ten-days after planting, and decreased by 3.5–8.1 mm over 10 days, following harvesting. While irrigation contributed to ET, the cumulative ten-day ET increase is between 0.6–2.3 mm which is significantly lower than the effects due to planting and harvesting. The RZWQM2 model was used to quantify the effects of four agricultural practices. Simulation of ET attained R² and RMSE as 0.79 and 0.013 mm/d, respectively. In addition, the RZWQM2 model successfully simulated groundwater levels, Leaf area index, and crop height (R² values of 0.71, 0.98 and 0.97, respectively). The RZWQM2 model simulates the effects of planting, harvesting, and irrigation on ET, indicating the same directional changes of magnitude with measured data. The results provide a comprehensive and direct study based on the closed-path EC method and RZWQM2 model to assess the impact of multiple agricultural activities on farmland ET and to improve precision agriculture.

     

Application of Genetic Algorithms and Artificial Neural Networks in Conjunctive Use of Surface and Groundwater Resources

Abstract

In this paper, a methodology for conjunctive use of surface and groundwater resources is developed using the combination of the Genetic Algorithms (GAs) and the Artificial Neural Networks (ANN). Water supply to agricultural demands, reduction of pumping costs and control of groundwater table fluctuations are considered in the objective function of the model. In the proposed model, the results of MODFLOW groundwater simulation model are used to train an ANN. The ANN as groundwater response functions is then linked to the GA based optimization model to develop the monthly conjunctive use operating policies. The model is applied to the surface and groundwater allocation for irrigation purposes in the southern part of Tehran. A new ANN is also trained and checked for developing the real-time conjunctive use operating rules.

The results show the significance of an integrated approach to surface and groundwater allocation in the study area. A simulation of the optimal policies shows that the cumulative groundwater table variation can be reduced to less than 4 meters from the current devastating condition. The results also show that the proposed model can effectively reduce the run time of the conjunctive use models through the composition of a GA-based optimization and a ANN-based simulation model.     

Methodology for Quantifying Groundwater Abstractions for Agriculture via Remote Sensing and GIS

Among the difficulties and uncertainties that arise when determining water balance is the calculation of groundwater abstraction. This factor is particularly important in aquifers whose extension and heavy agricultural use make direct quantification methods unfeasible (i.e. flow meters and power consumption data). This study presents a method of quantifying groundwater abstractions for irrigation based on the analysis of multitemporal and multispectral satellite images. The process begins with a highly detailed classification of irrigated crops; these data are entered in a Geographic Information System, overlain with a correct estimate of the irrigation requirements of the crop, and corrected in accordance with the agricultural practices of the area. The results reveal the spatial and temporal distribution of the groundwater volume abstracted and used for agriculture. This methodology has been applied in the Mancha Oriental Hydrogeological System (Spain, 7,260 km²), where abstractions for agriculture comprise more than 90% of the hydrological resources consumed. In this context, accuracies of over 95% have been obtained with a cost sixty times lower than that of traditional methods.     

Improving Wheat Productivity in Pakistan: Econometric Analysis Using Panel Data from Chaj in the Upper Indus Basin

Abstract

Increasing water scarcity, degradation of land and water resources, continuing low agricultural productivity, and increasing populations are posing the largest ever challenges for development of agricultural economies in many developing countries including Pakistan. Using panel data from irrigated settings in Chaj sub-basin of the Indus basin in Pakistani Punjab, we attempt to: (a) analyze the causes of low productivity; (b) disentangle factors (both land, water and other factors) contributing to productivity variations; and (c) identify limits and opportunities for narrowing productivity gaps and increasing overall wheat production, with a view to enhance food security for the poor. The results of the study indicate that locational inequities in distribution of canal water, use of groundwater of varying quality, differences in use of seed varieties, and other inputs lead to significant variations in wheat productivity. Key implications are that large gains in wheat productivity are possible by (a) improving the production environment at the tail-end through integrated water management practices; (b) adjusting the mix of canal and groundwater use; and (c) using technological interventions to improve the adoption of modern wheat varieties and dissemination of knowledge on planting dates and timings and application rates of inputs, especially water and fertilizer. Not only such interventions are economically, financially, and environmentally desirable, they are also pro-poor. What is needed is a strong political will and commitment.     

REFLECT,a Decision Support System for Harmonizing Spatial Developments with Groundwater Resources

A sustainable drinking-water supply requires durable securing of the resource. With an increase in spatial pressure, the need is increasing to prioritize measures based on the vulnerability of the resources and the impact of surrounding land use functions. This is especially challenging in the Province of Overijssel with groundwater abstraction sites in vulnerable Pleistocene sandy soils and increasing spatial pressure from both agricultural and urban areas. The governance of the groundwater abstractions in the Province of Overijssel is based on a combination of precaution and a risk-based approach. The Province has adopted REFLECT to assess the risks of spatial developments. REFLECT is a negotiation support system that gives an overview of the vulnerability of the groundwater abstractions and risks of several land use functions on the groundwater quality. REFLECT has been used to obtain the current risk scores of all drinking water abstractions in the Province and following the EU Water Framework Directive. Spatial insight of risks was used to identify and target measures reducing these risks. Moreover, REFLECT has been applied to decide on a local spatial development near an abstraction. Knowledge of the impact of land use changes on groundwater quality helped the municipality harmonizing the spatial plan with the interest of the drinking water abstraction and creating a step-forward in the protection level of the abstraction site. These applications illustrate that REFLECT is an instrument that fits well within risk-based groundwater governance which aims at safeguarding of the public water supply by harmonizing land use functions.     

Achieving water security in Nepal through unravelling the water-energy-agriculture nexus

ABSTRACT

This article investigates water security in Nepal from the perspective of the water-energy-agriculture (food) nexus, focusing on pathways to water security that originate in actions and policies related to other sectors. It identifies promoting development of Nepal’s hydropower potential to provide energy for pumping as way to improve water security in agriculture. Renewable groundwater reserves of 1.4 billion cubic meters (BCM), from an estimated available balance of 6.9 BCM, could be pumped to irrigate 613,000 ha of rainfed agricultural land in the Terai plains, with a potential direct economic gain of USD 1.1 billion annually and associated benefits including promotion of energy-based industry, food security and local employment. Governance also plays an important role in addressing water security. We conclude that a nexus-based approach is required for effective water management and governance.     

Comparing 20th Century Trends in U.S. and Global Agricultural Water and Land Use

Abstract

Globally and in the United States, agriculture is the major user not only of water but also of land. This paper compares trends in aggregate and per capita water and land use by the agricultural sector in the United States and the world during the 20^th century. It finds that although cropland use per capita has been declining in both areas since the early 1900s, agricultural water use per capita only began declining in the latter half of that century. That the increases in efficiencies of agricultural water use lagged behind the increases in the efficiency of cropland use is consistent with the fact that farmers (and farming communities) have traditionally had stronger property rights to their land than to their water. As a result, through much of the 20^th century, farmers had a greater incentive to improve the efficiency of land use than that of water use and to substitute water for land (or irrigated land for dryland) in producing crops.     

Groundwater Resources and Human Impacts in a Quaternary Intramontane Basin (L'Aquila Plain,Central Italy)

Abstract

An aquifer vulnerability study was carried out in the L'Aquila Plain of Central Italy for evaluating changes in groundwater quantity and quality induced by human activities. The L'Aquila Plain, filled with Quaternary clastic deposits, is an intramontane basin encircled by karst massifs characterized by regional groundwater, which is connected with the porous multilayer aquifer of L'Aquila Plain. The study was organized into different steps: (1) geo-lithological characterization; (2) sampling of hydrogeological data and water budget evaluation; and (3) hydrochemical and microbiological monitoring of springs and wells. The latter step made it possible to identify water-rock interaction, groundwater mixing and recharge, and to recognize the different sources of groundwater pollution. The plain aquifer, mainly recharged by the surrounding carbonate massifs, shows centripetal groundwater flowpaths. The hydrochemical features show two groundwater end-members, coming from carbonate aquifers or circulating only in the plain, with intermediate mixed groundwater. The observed ground-water pollution is negligible, but it will probably increase if the strong development of the human activities continues without groundwater protection planning.     

Groundwater Resource Use Practices and Implications for Sustainable Agricultural Development in the North China Plain: A Case Study in Ningjin County of Shandong Province,PR China

This paper addresses the critical situation of water resource exploitation for agriculture and environmental effects in Ningjin County in the North China Plain. Several negative environmental effects such as declining groundwater table levels, decline in groundwater quality, increased irrigation cost, increased soil salinity, compaction of soil, increased land subsidence and increased incidence of waterlogging have been experienced in the area, as perceived by the local farmers. This is due to overpumping of groundwater by a large number of wells clustered in small areas. The study indicates that if the current pattern of groundwater use, existing attitudes of farmers and improper implementation of policies and regulations is continued, the agricultural activities will face severe consequences and tend to be unsustainable. This warrants new strategies to improve the present situation.     

Groundwater Assessment at Santiago Island (Cabo Verde): A Multidisciplinary Approach to a Recurring Source of Water Supply

Groundwater resources are in many parts of the world the only source for private domestic, agricultural and public water supply. Subsurface has also become major recipient of wastewater and solid waters especially in the developing countries. Overexploitation of coastal aquifers and pollution are among the main problems related to groundwater resources assessment and management in Santiago Island (Cabo Verde). Brackish groundwater is the only available water type in the region that is being provided to numerous parts of the Island such as Praia Baixo, Montenegro, and Charco for agriculture and human supply. Solute and isotope data obtained in different groundwater systems were used in the identification of groundwater resources degradation. In order to understand the influence of the anthropogenic activities on the water quality and the main origin of the salts in groundwater, a statistical approach (Principal Components Analyses—PCA) was performed on the physico-chemical data. The results obtained indicate water–rock interaction mechanisms as the major process responsible for the groundwater quality (mainly calcium-bicarbonate type), reflecting the lithological composition of the subsurface soil. Also, anthropogenic contamination was identified, in several points of the island. Isotopic techniques (δ²H, δ¹⁸O and ³H content) combined with geochemistry provided comprehensive information on groundwater recharge, as well as on the identification of salinization mechanisms (e.g. seawater intrusion, salt dissolution, and marine aerosols) of the groundwater systems, at Santiago Island.     

泾惠渠灌区干旱时段内的地下水动态

泾惠渠灌区是陕西重要的农业生产基地,研究灌区干旱时段的地下水动态对灌区农业生产具有重要意义。通过灌区多年的降水量资料,采用Z指数法选取了灌区的典型干旱时段,然后选取灌区内的典型观测井位分析了其干旱时段内地下水动态特征。     

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.     

Exploring the future impacts of urbanization and climate change on groundwater in Arusha,Tanzania

ABSTRACT

We combine satellite imagery, urban growth modelling, groundwater modelling and hydrogeological field expeditions to estimate the potential impacts in 2050 of rapid urbanization and climate change on groundwater in Arusha, Tanzania, and by extension similar areas in Sub-Saharan Africa. Our analysis suggests that a reduction of groundwater recharge by 30–44% will cause groundwater levels to drop by up to 75 m, mainly due to increased evapotranspiration and to an expansion in paved surface. If this scenario becomes reality, we predict that wells will run dry, creating health, social and environmental risks.     

Comparative Evaluation Of Surface Water Availability,Wastewater Reuse And Desalination In Saudi Arabia

ABSRTACT

There is a growing concern in the Kingdom of Saudi Arabia to exploit water resources of acceptable quality to meet demands in domestic, industrial, and agricultural sectors. The agricultural water need, which constitutes approximately 84% of the total demand, was estimated to be 7430 million cubic meters in 1985. The annual domestic and other demands amounted to 1400 million cubic meters for 1985. Various alternative supplies to meet these demands are surface water, renewable groundwater resources, reclaimed wastewater, desalinated water, and non-renewable groundwater. Due to excessive withdrawal of water from deep aquifers, considerable drawdown has recently been noticed.

This paper reviews the existing and future trends in developing surface water resources, reclamation of waste-water from various towns and cities and its use, and the role of desalination plants in the coastal regions of the Arabian Gulf and Red Sea. These alternatives are evaluated and compared in economic terms. Cost-capacity relationships are developed for various alternatives which will be used in developing long-term plans for optimum allocation of available resources in different parts of the Kingdom.     

Impacts of agricultural policy on irrigation water demand: a case study of Saudi Arabia

Saudi Arabia's groundwater resources have been heavily over-exploited to achieve food self-sufficiency. The country enacted a new agricultural policy that discourages the cultivation of wheat and encourages that of vegetables and fruits. This has produced significant reductions in irrigation water demand as well as food self-sufficiency. This paper reviews the performance of the Saudi agricultural sector and presents four scenarios forecasting the new policy's long-term impacts on the use of water for agriculture. The findings show that the new policy does not support sustainable utilization of groundwater resources. Additional policy modifications are needed to optimize the combination of import and domestic production of agricultural products based on a sustainable water utilization strategy.