Operational water balance in irrigation districts

In pressure irrigation-water distribution networks, applied water volume is usually controlled opening a valve during a calculated time interval, and assuming constant flow rate. In general, pressure regulating devices for controlling the discharged flow rate by irrigation units are needed due to the variability of pressure conditions.

RWUE4: Responding to Climate in the Central Queensland Irrigation Sector

Increasing the productivity of irrigation water use and reducing energy use in rural irrigation within the Central Highlands and Dawson-Callide irrigation districts.

Optimization of water procurement decisions in an irrigation district: the role of option contracts

Water supply instability is one of the main risks faced by irrigation districts and farmers. Water procurement decision optimisation is essential in order to increase supply reliability and reduce costs. Water markets, such as spot purchases or water supply option contracts, can make this decision process more flexible. We analyse the potential interest in an option contract for an irrigation district that has access to several water sources. We apply a stochastic recursive mathematical programming model to simulate the water procurement decisions of an irrigation district?s board operating in a context of water supply uncertainty in south-eastern Spain. We analyse what role different option contracts could play in securing its water supply. Results suggest that the irrigation district would be willing to accept the proposed option contract in most cases subject to realistic values of the option contract financial terms. Of nine different water sources, desalination and the option contract are the main substitutes, where the use of either depends on the contract parameters. The contract premium and optioned volume are the variables that have a greater impact on the irrigation district?s decisions. Key words: Segura Basin, stochastic recursive programming, water markets, water supply option contract, water supply risk.

Summary of irrigation-district statutes of western states /

"January, 1931."

Barriers to Temporary Inter‐District Water Transfers in the Yakima River Basin: Irrigation District Perspective

Water marketing, or mechanisms to acquire and redistribute water such as temporary water transfers, can represent a valuable response to drought for irrigation districts. The Department of Ecology, the US Bureau of Reclamation, and a workgroup composed of members from various entities collaborated to develop the Yakima River Basin Integrated Water Resource Management Plan (Integrated Plan) to better manage water resources and address ecosystem issues in the Yakima River Basin. The Integrated Plan addresses water marketing but it does not provide specifics on how barriers to inter‐district water transfers will be eliminated. This study asks irrigation district managers in the Yakima River basin about the factors they consider when deciding whether to engage in a temporary inter‐district water transfer or not. Results show that institutional barriers are the most common barrier to inter‐district water transfers. This topic requires further research on fallowing and irrigation district behavior in relation to the other water supply efforts outlined in the Integrated Plan. Finally, the water market in the Yakima basin can benefit from education and outreach to senior water rights holders, shortening the time frame to process expedited transfers, and documentation from irrigation districts reporting denial reasons for temporary inter‐district water transfers.

Software for calculation of reservoir active capacity with the sequent-peak algorithm

It is presented a software developed with Delphi programming language to compute the reservoir's annual regulated active storage, based on the sequent-peak algorithm. Mathematical models used for that purpose generally require extended hydrological series. Usually, the analysis of those series is performed with spreadsheets or graphical representations. Based on that, it was developed a software for calculation of reservoir active capacity. An example calculation is shown by 30-years (from 1977 to 2009) monthly mean flow historical data, from Corrente River, located at São Francisco River Basin, Brazil. As an additional tool, an interface was developed to manage water resources, helping to manipulate data and to point out information that it would be of interest to the user. Moreover, with that interface irrigation districts where water consumption is higher can be analyzed as a function of specific seasonal water demands situations. From a practical application, it is possible to conclude that the program provides the calculation originally proposed. It was designed to keep information organized and retrievable at any time, and to show simulation on seasonal water demands throughout the year, contributing with the elements of study concerning reservoir projects. This program, with its functionality, is an important tool for decision making in the water resources management.

Infiltración y erosión

Esta monografía se enmarca en el manejo de los recursos hídricos en grandes redes de riego. En ella se describe el caso del río Mendoza, en la provincia homónima, el que fuera regulado en el año 2002. Este río nace en la Cordillera de los Andes, y presenta un importante arrastre de sólidos en suspensión, los que actualmente son retenidos en gran medida por el embalse Potrerillos. Las “aguas claras" que se erogan del embalse producen problemas erosivos, los que a su vez estarían ocasionando una mayor infiltración en los canales, y con ello un incremento en la recarga de acuíferos en ciertas zonas, así como problemas derivados del ascenso de la freática en otras. Se citan procesos ocurridos en otros distritos de riego frente a la regulación de los ríos, para concluir que el del río Mendoza es un caso susceptible de sufrir ciertos per-juicios, ya señalados en la Manifestación General de Impacto Ambiental del embalse Potrerillos, los que actualmente se están presentando en la red de riego. A partir de los estudios de sedimentología en el río Mendoza, se hace un análisis técnico de los fenómenos asociados al cambio de las características físicas del agua. Luego se describen los procesos erosivos, de acuerdo con la hidráulica clásica. Se define la Eficiencia de conducción (Ec), la infiltración en canales y su importancia en distintos distritos de riego, para luego mencionar los estudios realizados en el área del río Mendoza. Se analiza el desarrollo espacial que ha tenido el oasis, la escasa programación que tuvo su traza y la antigüedad de la misma. La descripción de los suelos permite concluir acerca de la importancia de su estructura y del papel que juegan las porciones finas, aún en minoría, que integran las distintas clases texturales con respecto a la Ec. Se describen los criterios con que se distribuye el agua en Mendoza, analizándose los caudales distribuidos actualmente, para relacionarlos con los niveles freáticos. Se mencionan además distintas acciones encaradas por la provincia para mitigar los efectos de las aguas claras. El análisis de los métodos utilizados para medir la Ec, permite apreciar el estado de la ciencia al respecto. Un análisis de las ventajas y de las desventajas de los distintos métodos, y de los resultados que con ellos se obtienen, permite concluir que el método de entradas y salidas es el que mejor se adapta en Mendoza, incluyendo además aspectos metodológicos de la medición. También se concluye en que la Ec. está insuficientemente evaluada; las fracciones finas de los suelos en muchos casos gravitan más que la textura frente a la Ec; por ello, se considera que el estudio de la Ec en las distintas áreas de manejo es necesario para entender los procesos de revenición y recarga de acuíferos, y que las pérdidas administrativas pueden gravitar más que la Ec. Se recomienda continuar con los trabajos de evaluación de Ec, al ser necesarios para todas las actividades en la cuenca; se desaconseja en este río el ajuste de modelos de predicción de Ec; las características de los suelos obligan a interpretar y aplicar con criterio la bibliografía internacional, pero aún así no se pueden hacer generalizaciones acerca de de la Ec en Mendoza.

Metodología para la determinación de la evapotranspiración integrada y la capacidad de canales en una zona de riego

La capacidad de la red de canales en un sistema de riego depende de satisfacer la demanda hídrica máxima de los cultivos. Los métodos para determinar la capacidad del canal requieren de la estimación de la variable agronómica: evapotranspiración de los cultivos. En grandes áreas de riego, con un padrón diversificado de cultivos, diferentes fechas de siembra y varios ciclos agrícolas no existe un procedimiento integrado para estimar esta variable agronómica, lo cual genera incertidumbre al ser requerida en los métodos. En este trabajo se desarrolla una propuesta para estimar dicha variable para grandes zonas de riego. La propuesta inicia con el cálculo de la evapotranspiración de los cultivos por fecha de siembra, y termina con la obtención de una curva general integral para un año agrícola, encontrándose la variable evapotranspiración de una zona de riego (ETzr). Esta metodología se aplicó para el canal principal del módulo de riego Santa Rosa, Distrito de Riego 075, Sinaloa, México en que la ETzr resultó de 4,1 mm d-1. Por los resultados se concluye la veracidad de la propuesta en determinar la evapotranspiración para el cálculo en la capacidad del canal.

An example of integration between en economic and an hydrologic model in the framework of water resource management problems

Growing scarcity, increasing demand and bad management of water resources are causing weighty competition for water and consequently managers are facing more and more pressure in an attempt to satisfy users? requirement. In many regions agriculture is one of the most important users at river basin scale since it concentrates high volumes of water consumption during relatively short periods (irrigation season), with a significant economic, social and environmental impact. The interdisciplinary characteristics of related water resources problems require, as established in the Water Framework Directive 2000/60/EC, an integrated and participative approach to water management and assigns an essential role to economic analysis as a decision support tool. For this reason, a methodology is developed to analyse the economic and environmental implications of water resource management under different scenarios, with a focus on the agricultural sector. This research integrates both economic and hydrologic components in modelling, defining scenarios of water resource management with the goal of preventing critical situations, such as droughts. The model follows the Positive Mathematical Programming (PMP) approach, an innovative methodology successfully used for agricultural policy analysis in the last decade and also applied in several analyses regarding water use in agriculture. This approach has, among others, the very important capability of perfectly calibrating the baseline scenario using a very limited database. However one important disadvantage is its limited capacity to simulate activities non-observed during the reference period but which could be adopted if the scenario changed. To overcome this problem the classical methodology is extended in order to simulate a more realistic farmers? response to new agricultural policies or modified water availability. In this way an economic model has been developed to reproduce the farmers? behaviour within two irrigation districts in the Tiber High Valley. This economic model is then integrated with SIMBAT, an hydrologic model developed for the Tiber basin which allows to simulate the balance between the water volumes available at the Montedoglio dam and the water volumes required by the various irrigation users.

Criterios para el dimensionamiento de redes de riego robustas frente a cambios en la alternativa de cultivos

En los años 50 y 60 del siglo XX se produjo en Europa un cambio en la concepción de los sistemas de riego, en los cuales se pasó del regadío por superficie al presurizado y con ello del riego por turnos al riego a la demanda. Las ventajas de este nuevo sistema de riego dieron lugar a una gran expansión de las redes colectivas de riego a presión, especialmente en los países del arco mediterráneo y del Sur de Europa (Francia, España, Italia, Portugal y Grecia). Desde entonces el riego presurizado a la demanda ha tenido una evolución permanente, en la que han mejorado los equipos y las técnicas de aplicación del riego, siempre con una clara orientación hacía el incremento de la productividad. Esta evolución unida a los vaivenes de los mercados, al abaratamiento de los transportes y la globalización, y a las subvenciones agrícolas, ha propiciado que las alternativas de cultivos previstas hayan sufrido cambios. El cambio de la alternativa de cultivos hacia otros más exigentes desde el punto de vista de las necesidades hídricas tiene como consecuencia el aumento de los consumos, circunstancia para cual debe estar capacitada la red. Otros fenómenos como el cambio climático, de amplio interés a día de hoy, presentan algunos escenarios en lo que se prevé un incremento de las temperaturas que unido a una reducción en las precipitaciones, supondría también que se elevarían las necesidades de riego de los cultivos. Todas estas circunstancias deben ser contempladas en la redacción de los proyectos de transformación de nuevas zonas regables y en los de modernización de las existentes. Las redes de riego deben estar dimensionadas para poder atender dichos incrementos de consumo. La fortaleza de la red para atender variaciones en las demandas de agua se convierte por tanto en una premisa del proyecto. Dicha fortaleza se puede conseguir de formas diferentes y a costos distintos, puesto que en el proceso de dimensionamiento estadístico de los caudales circulantes en punta de campaña intervienen muchas variables y parámetros de riego. En la presente tesis doctoral se analiza en detalle el estado del arte en la materia, se efectúa un análisis de la función específica y la influencia en el cálculo de cada uno de los parámetros, se establece un procedimiento de actuación que optimice el dimensionamiento de la red colectiva para que ésta disponga de la robustez necesaria para hacer frente a incrementos potenciales de consumo de agua sobre la previsiones de base del proyecto y se establecen los criterios, rangos y combinaciones de parámetros que permiten dotar a la red de la fortaleza necesaria de la manera más eficiente posible. During the 1950s and 1960s the design of irrigation systems in Europe underwent change. Traditional surface irrigation was replaced by pressure irrigation, with the delivery method shifting from a scheduled type to an on-demand one. The advantages obtained with this new system led to a significant development of on-demand pressurised irrigation districts, especially in the Southern countries (France, Greece, Italy, Portugal and Spain). On-demand pressurised irrigation has since evolved in a continuous manner in which, with the purpose of gaining productivity, on-farm equipment and automation instruments have seen improvements. Such developments, along with market fluctuations, reductions in transport costs, globalisation and the influence of agricultural subsidies, have resulted in changes in the crop pattern. The farming of new crops may require more water and the consumption may become greater. In addition to this, other phenomena, such as the frequently-debated effects of climate change, reveal scenarios in which an increase in temperatures and the accompanying reductions in rainfall are expected. One consequence of this would be an increase in irrigation requirements and subsequent impact on irrigation networks. All such circumstances should be taken into account in both the design of new irrigation districts and the upgrading of the existing ones. Irrigation networks should be of a size that allows them to meet increases in consumption. The robustness of the network, defined as its capacity to absorb increments in water requirements, becomes a key point to be taken into account in the design phase. Given that there are several parameters that influence the calculus of design flows, such robustness may be obtained in different ways and at varying costs. In the context of this, the thesis reviews the state of the art, analyses the role and influence of each parameter, establishes a procedure for checking the design and robustness of on-demand irrigation networks, and sets design criteria for selecting the most effective range and combination of parameters that provide the network with such robustness.

Water scarcity and climate change impact and vulnerability in irrigated agriculture in Mediterranean river basins

Actualmente, la escasez de agua constituye un importante problema en muchos lugares del mundo. El crecimiento de la población, la creciente necesidad de alimentos, el desarrollo socio-económico y el cambio climático ejercen una importante y cada vez mayor presión sobre los recursos hídricos, a la que muchos países van a tener que enfrentarse en los próximos anos. La región Mediterránea es una de las regiones del mundo de mayor escasez de recursos hídricos, y es además una de las zonas más vulnerables al cambio climático. La mayoría de estudios sobre cambio climático prevén mayores temperaturas y una disminución de las precipitaciones, y una creciente escasez de agua debida a la disminución de recursos disponibles y al aumento de las demandas de riego. En el contexto actual de desarrollo de políticas se demanda cada vez más una mayor consideración del cambio climático en el marco de las políticas sectoriales. Sin embargo, los estudios enfocados a un solo sector no reflejan las múltiples dimensiones del los efectos del cambio climático. Numerosos estudios científicos han demostrado que el cambio climático es un fenómeno de naturaleza multi-dimensional y cuyos efectos se transmiten a múltiples escalas. Por tanto, es necesaria la producción de estudios y herramientas de análisis capaces de reflejar todas estas dimensiones y que contribuyan a la elaboración de políticas robustas en un contexto de cambio climático. Esta investigación pretende aportar una visión global de la problemática de la escasez de agua y los impactos, la vulnerabilidad y la adaptación al cambio climático en el contexto de la región mediterránea. La investigación presenta un marco integrado de modelización que se va ampliando progresivamente en un proceso secuencial y multi-escalar en el que en cada etapa se incorpora una nueva dimensión. La investigación consta de cuatro etapas que se abordan a lo largo de cuatro capítulos. En primer lugar, se estudia la vulnerabilidad económica de las explotaciones de regadío del Medio Guadiana, en España. Para ello, se utiliza un modelo de programación matemática en combinación con un modelo econométrico. A continuación, en la segunda etapa, se utiliza un modelo hidro-económico que incluye un modelo de cultivo para analizar los procesos que tienen lugar a escala de cultivo, explotación y cuenca teniendo en cuenta distintas escalas geográficas y de toma de decisiones. Esta herramienta permite el análisis de escenarios de cambio climático y la evaluación de posibles medidas de adaptación. La tercera fase consiste en el análisis de las barreras que dificultan la aplicación de procesos de adaptación para lo cual se analizan las redes socio-institucionales en la cuenca. Finalmente, la cuarta etapa aporta una visión sobre la escasez de agua y el cambio climático a escala nacional y regional mediante el estudio de distintos escenarios de futuro plausibles y los posibles efectos de las políticas en la escasez de agua. Para este análisis se utiliza un modelo econométrico de datos de panel para la región mediterránea y un modelo hidro-económico que se aplica a los casos de estudio de España y Jordania. Los resultados del estudio ponen de relieve la importancia de considerar múltiples escalas y múltiples dimensiones en el estudio de la gestión de los recursos hídricos y la adaptación al cambio climático en los contextos mediterráneos de escasez de agua estudiados. Los resultados muestran que los impactos del cambio climático en la cuenca del Guadiana y en el conjunto de España pueden comprometer la sostenibilidad del regadío y de los ecosistemas. El análisis a escala de cuenca hidrográfica resalta la importancia de las interacciones entre los distintos usuarios del agua y en concreto entre distintas comunidades de regantes, así como la necesidad de fortalecer el papel de las instituciones y de fomentar la creación de una visión común en la cuenca para facilitar la aplicación de los procesos de adaptación. Asimismo, los resultados de este trabajo evidencian también la capacidad y el papel fundamental de las políticas para lograr un desarrollo sostenible y la adaptación al cambio climático es regiones de escasez de agua tales como la región mediterránea. Especialmente, este trabajo pone de manifiesto el potencial de la Directiva Marco del Agua de la Unión Europea para lograr una efectiva adaptación al cambio climático. Sin embargo, en Jordania, además de la adaptación al cambio climático, es preciso diseñar estrategias de desarrollo sostenible más ambiciosas que contribuyan a reducir el riesgo futuro de escasez de agua. ABSTRACT Water scarcity is becoming a major concern in many parts of the world. Population growth, increasing needs for food production, socio-economic development and climate change represent pressures on water resources that many countries around the world will have to deal in the coming years. The Mediterranean region is one of the most water scarce regions of the world and is considered a climate change hotspot. Most projections of climate change envisage an increase in temperatures and a decrease in precipitation and a resulting reduction in water resources availability as a consequence of both reduced water availability and increased irrigation demands. Current policy development processes require the integration of climate change concerns into sectoral policies. However, sector-oriented studies often fail to address all the dimensions of climate change implications. Climate change research in the last years has evidenced the need for more integrated studies and methodologies that are capable of addressing the multi-scale and multi-dimensional nature of climate change. This research attempts to provide a comprehensive view of water scarcity and climate change impacts, vulnerability and adaptation in Mediterranean contexts. It presents an integrated modelling framework that is progressively enlarged in a sequential multi-scale process in which a new dimension of climate change and water resources is addressed at every stage. It is comprised of four stages, each one explained in a different chapter. The first stage explores farm-level economic vulnerability in the Spanish Guadiana basin using a mathematical programming model in combination with an econometric model. Then, in a second stage, the use of a hydro-economic modelling framework that includes a crop growth model allows for the analysis of crop, farm and basin level processes taking into account different geographical and decision-making scales. This integrated tool is used for the analysis of climate change scenarios and for the assessment of potential adaptation options. The third stage includes the analysis of barriers to the effective implementation of adaptation processes based on socioinstitutional network analysis. Finally, a regional and country level perspective of water scarcity and climate change is provided focusing on different possible socio-economic development pathways and the effect of policies on future water scarcity. For this analysis, a panel-data econometric model and a hydro-economic model are applied for the analysis of the Mediterranean region and country level case studies in Spain and Jordan. The overall results of the study demonstrate the value of considering multiple scales and multiple dimensions in water management and climate change adaptation in the Mediterranean water scarce contexts analysed. Results show that climate change impacts in the Guadiana basin and in Spain may compromise the sustainability of irrigation systems and ecosystems. The analysis at the basin level highlights the prominent role of interactions between different water users and irrigation districts and the need to strengthen institutional capacity and common understanding in the basin to enhance the implementation of adaptation processes. The results of this research also illustrate the relevance of water policies in achieving sustainable development and climate change adaptation in water scarce areas such as the Mediterranean region. Specifically, the EU Water Framework Directive emerges as a powerful trigger for climate change adaptation. However, in Jordan, outreaching sustainable development strategies are required in addition to climate change adaptation to reduce future risk of water scarcity.

Optimal allocation of water in village irrigation systems of Sri Lanka

This PhD study examines whether water allocation becomes more productive when it is re-allocated from 'low' to 'high' efficient alternative uses in village irrigation systems (VISs) in Sri Lanka. Reservoir-based agriculture is a collective farming economic activity, which inter-sectoral allocation of water is assumed to be inefficient due to market imperfections and weak user rights. Furthermore, the available literature shows that a „head-tail syndrome. is the most common issue for intra-sectoral water management in „irrigation. agriculture. This research analyses the issue of water allocation by using primary data collected from two surveys of 460 rice farmers and 325 fish farming groups in two administrative districts in Sri Lanka. Technical efficiency estimates are undertaken for both rice farming and culture-based fisheries (CBF) production. The equi-marginal principle is applied for inter and intra-sectoral allocation of water. Welfare benefits of water re-allocation are measured through consumer surplus estimation. Based on these analyses, the overall findings of the thesis can be summarised as follows. The estimated mean technical efficiency (MTE) for rice farming is 73%. For CBF production, the estimated MTE is 33%. The technical efficiency distribution is skewed to the left for rice farming, while it skewed to the right for CBF production. The results show that technical efficiency of rice farming can be improved by formalising transferability of land ownership and, therefore, water user rights by enhancing the institutional capacity of Farmer Organisations (FOs). Other effective tools for improving technical efficiency of CBF production are strengthening group stability of CBF farmers, improving the accessibility of official consultation, and attracting independent investments. Inter-sectoral optimal allocation shows that the estimated inefficient volume of water in rice farming, which can be re-allocated for CBF production, is 32%. With the application of successive policy instruments (e.g., a community transferable quota system and promoting CBF activities), there is potential for a threefold increase in marginal value product (MVP) of total reservoir water in VISs. The existing intra-sectoral inefficient volume of water use in tail-end fields and head-end fields can potentially be removed by reducing water use by 10% and 23% respectively and re-allocating this to middle fields. This re-allocation may enable a twofold increase in MVP of water used in rice farming without reducing the existing rice output, but will require developing irrigation practices to facilitate this re-allocation. Finally, the total productivity of reservoir water can be increased by responsible village level institutions and primary level stakeholders (i.e., co-management) sharing responsibility of water management, while allowing market forces to guide the efficient re-allocation decisions. This PhD has demonstrated that instead of farmers allocating water between uses haphazardly, they can now base their decisions on efficient water use with a view to increasing water productivity. Such an approach, no doubt will enhance farmer incomes and community welfare.

VG07023 Driving better vegetable irrigation through profitable practice change

Despite recent flooding in eastern Australia, the availability/quality of irrigation water is a long-term issue for Australian vegetable growers. To survive, producers are told to implement new technologies. However, there is often little practical information investigating which improvements could make a real difference, and keep production profitable. In an Horticulture Australia Ltd three year project, scientists from the Department of Employment, Economic Development and Innovation (QLD), CSIRO, Department of Industry and Investment (NSW), and the National Centre for Engineering in Agriculture, evaluated practical irrigation improvements. We conducted experiments and case studies on farms in southern Queensland and Riverina vegetable districts, with over 100 extension events, including irrigation workshops, conferences, and field days.

Driving better vegetable irrigation through profitable practice change

The availability and quality of irrigation water has become an issue limiting productivity in many Australian vegetable regions. Production is also under competitive pressure from supply chain forces. Producers look to new technologies, including changing irrigation infrastructure, exploring new water sources, and more complex irrigation management, to survive these stresses. Often there is little objective information investigating which improvements could improve outcomes for vegetable producers, and external communities (e.g. meeting NRM targets). This has led to investment in inappropriate technologies, and costly repetition of errors, as business independently discover the worth of technologies by personal experience. In our project, we investigated technology improvements for vegetable irrigation. Through engagement with industry and other researchers, we identified technologies most applicable to growers, particularly those that addressed priority issues. We developed analytical tools for ‘what if’ scenario testing of technologies. We conducted nine detailed experiments in the Lockyer Valley and Riverina vegetable growing districts, as well as case studies on grower properties in southern Queensland. We investigated root zone monitoring tools (FullStop™ wetting front detectors and Soil Solution Extraction Tubes - SSET), drip system layout, fertigation equipment, and altering planting arrangements. Our project team developed and validated models for broccoli, sweet corn, green beans and lettuce, and spreadsheets for evaluating economic risks associated with new technologies. We presented project outcomes at over 100 extension events, including irrigation showcases, conferences, field days, farm walks and workshops. The FullStops™ were excellent for monitoring root zone conditions (EC, nitrate levels), and managing irrigation with poor quality water. They were easier to interpret than the SSET. The SSET were simpler to install, but required wet soil to be reliable. SSET were an option for monitoring deeper soil zones, unsuitable for FullStop™ installations. Because these root zone tools require expertise, and are labour intensive, we recommend they be used to address specific problems, or as a periodic auditing strategy, not for routine monitoring. In our research, we routinely found high residual N in horticultural soils, with subsequently little crop yield response to additional nitrogen fertiliser. With improved irrigation efficiency (and less leaching), it may be timely to re-examine nitrogen budgets and recommendations for vegetable crops. Where the drip irrigation tube was located close to the crop row (i.e. within 5-8 cm), management of irrigation was easier. It improved nitrogen uptake, water use efficiency, and reduced the risk of poor crop performance through moisture stress, particularly in the early crop establishment phases. Close proximity of the drip tube to the crop row gives the producer more options for managing salty water, and more flexibility in taking risks with forecast rain. In many vegetable crops, proximate drip systems may not be cost-effective. The next best alternative is to push crop rows closer to the drip tube (leading to an asymmetric row structure). The vegetable crop models are good at predicting crop phenology (development stages, time to harvest), input use (water, fertiliser), environmental impacts (nutrient, salt movement) and total yields. The two immediate applications for the models are understanding/predicting/manipulating harvest dates and nitrogen movements in vegetable cropping systems. From the economic tools, the major influences on accumulated profit are price and yield. In doing ‘what if’ analyses, it is very important to be as accurate as possible in ascertaining what the assumed yield and price ranges are. In most vegetable production systems, lowering the required inputs (e.g. irrigation requirement, fertiliser requirement) is unlikely to have a major influence on accumulated profit. However, if a resource is constraining (e.g. available irrigation water), it is usually most profitable to maximise return per unit of that resource.

Geochemistry of fluoride rich groundwater in Kolar and Tumkur Districts of Karnataka

Groundwater is a significant water resource in India for domestic, irrigation, and industrial needs. By far the most serious natural groundwater-quality problem in India, in terms of public health, derives from high fluoride, arsenic, and iron concentrations. Hydrogeochemical investigation of fluoride contaminated groundwater samples from Kolar and Tumkur Districts in Karnataka are undertaken to understand the quality and potability of groundwater from the study area, the level of fluoride contamination, the origin and geochemical mechanisms driving the fluoride enrichment. Majority of the groundwater samples did not meet the potable water criteria as they contained excess (>1.5 mg/L) fluoride, dissolved salts (>500 mg/L) and total hardness (75-924 mg/L). Hydrogeochemical facies of the groundwater samples suggest that rock weathering and evaporation-crystallization control the groundwater composition in the study area with 50-67% of samples belonging to the Ca-HCO3 type and the remaining falling into the mixed Ca-Na-HCO3 or Ca-Mg-Cl type. The saturation index values indicated that the groundwater in the study area is oversaturated with respect to calcite and under-saturated with respect to fluorite. The deficiency of calcium ion concentration in the groundwater from calcite precipitation favors fluorite dissolution leading to excess fluoride concentration.