El objetivo de este trabajo es estudiar econométricamente las relaciones agregadas entre disponibilidades hídricas y producción de regadío, haciendo uso de datos correspondientes a la Región de Murcia. Se cuantifican las elasticidades a corto y largo plazo que relacionan estas variables, se descomponen los efectos de las oscilaciones hídricas entre un impacto sobre la superficie regada y otro de ésta sobre la producción y se estudian y comparan los efectos diferenciales sobre el VAB y sobre la Producción Final agrícolas. Las estimaciones de los parámetros a largo plazo indican que una elasticidad unitaria del VAB agrícola con respecto a las aportaciones hídricas para regadío -tal como a veces se ha supuesto en el análisis coste-beneficio de nuevas infraestructuras hidráulicas- puede constituir una aproximación aceptable (...)

El objetivo del proyecto GESMO (Gestión integral del acuífero 08.29 Mancha Oriental) financiado por el gobierno español, consiste en desarrollar nuevas herramientas para la evaluación y el seguimiento de las políticas del agua. Dichas herramientas deben ser capaces de adecuar la explotación de recursos a la reserva sostenible, aplicándolo al acuífero 08.29 de la Mancha Oriental, España. Como parte del proyecto GESMO se ha desarrollado un sistema de soporte a la decisión (DSS), que integra dos sistemas distintos en una aplicación informática. Uno de ellos consiste en un modelo hidrogeológico que simula la cuenca del río Júcar y su acuífero asociado. El otro es un sistema econométrico capaz de predecir la evolución del mapa regional de cultivos, el rendimiento de las cosechas y sus precios, todo ello encaminado al cálculo del producto regional bruto de los cultivos. Este artículo describe principalmente el sistema económico del DSS, formado por un conjunto de modelos econométricos. Los más importantes para el DSS son los que se utilizan para la asignación de cultivos. La aproximación seguida para su especificación se propone como una solución provisional al problema de la estimación de respuestas probables de los agricultores en un período postcuota, basándose en la información proporcionada por el periodo pre-cuota. Se incluyen también en este artículo una breve descripción de la estructura completa del DSS y un ejemplo de una de sus posibles aplicaciones. | The objective of the Spanish government-funded project GESMO (Gestión integral del acuífero 08.29 Mancha Oriental), is to develop new tools for the evaluation and monitoring of water policies. These tools have to be capable of matching resource exploitation with reserve sustainability, applied to aquifer 08.29 in the Eastern Mancha, Spain. A decision support system (DSS), was developed as part of the GESMO project, that integrates two different systems within one computer application. One, an hydrogeological model, simulates the River Júcar basin and its associated aquifer. The other, an econometric system, is capable of predicting the evolution of regional crop maps, crop yields and crop prices, thus allowing the determination of the regional gross product of crops. This paper describes mainly the economic system of the DSS, a set of econometric models. Those used for crop allocations are the most important for the DSS. The approach followed for the specification of the DSS is proposed as a provisional method based on information from the pre-quota period to estimate likely responses of farmers in a post-quota period. A brief description of the overall structure of the DSS and an example of one of its possible applications are also included in the paper.

"... Based on a global model of supply and demand for food and water, this report shows that if current water policies continue, farmers will indeed find it difficult to meet the world’s food needs. Hardest hit will be the world’s poorest people. The results from the model used in this report also show the consequences of changing the course of water policy. Further inattention to water-related investments and policies will produce a severe water crisis, which will lead in turn to a food crisis. A commitment to sustainable use of water, through appropriate policies and investments, however, will lead to a more water- and food-secure world. Water may be a scarce resource, but humans have developed many ways of using it more efficiently — that is, getting more from each unit of water. But water-saving policies, practices, and technologies are of no help if they are not used. Inappropriate incentives and institutions often hinder effective use of water. This report spells out the future results of our current choices." -- Authors' Introduction | Non-PR | IFPRI1; Environment and Natural Resource Management

IFPRI1; Environment and Natural Resource Management | "... Based on a global model of supply and demand for food and water, this report shows that if current water policies continue, farmers will indeed find it difficult to meet the world’s food needs. Hardest hit will be the world’s poorest people. The results from the model used in this report also show the consequences of changing the course of water policy. Further inattention to water-related investments and policies will produce a severe water crisis, which will lead in turn to a food crisis. A commitment to sustainable use of water, through appropriate policies and investments, however, will lead to a more water- and food-secure world. Water may be a scarce resource, but humans have developed many ways of using it more efficiently — that is, getting more from each unit of water. But water-saving policies, practices, and technologies are of no help if they are not used. Inappropriate incentives and institutions often hinder effective use of water. This report spells out the future results of our current choices." -- Authors' Introduction | Policy Report | Non-PR

IFPRI1; Environment and Natural Resource Management | Rosegrant Mark W., 'Panorama global del agua hasta el ano 2025 cómo impedir una crisis inminente', , IFPRI, 2004

El lenguado (Solea senegalensis) es una especie que tiene un gran interés para la acuicultura marina dado su relativo rápido crecimiento y sus grandes posibilidades de comercialización con un alto precio de venta. En el mar Mediterráneo, sin embargo, la gran variación de la temperatura del agua (14-26 grados C) parece ser el principal factor limitante para el desarrollo de empresas de engorde de lenguado, ya que la temperatura óptima de esta especie se sitúa en torno a los 19-20 grados C. No obstante, uno de los posibles sistemas de engorde que podría llevarse a cabo a medio plazo es el engorde en tanques con bombeo de agua de pozo, que podría garantizar una temperatura constante a lo largo de todo el año. En el presente trabajo se desarrolla un modelo matemático de viabilidad/rentabilidad para una explotación de engorde de lenguado en tanques en tierra bombeando agua de pozo (temperatura de 19-20 grados C), con la finalidad de estimar parámetros económicos ligados a la producción, que aún no están definidos a nivel del cultivo comercial del lenguado, tales como la carga óptima de engorde, el precio de venta del producto final, el coste del juvenil y de la dieta, estos dos últimos influidos por la mortalidad que aún puede ser muy variable en esta especie, y, finalmente, el coste de energía y suministro de oxígeno, que es importante en las instalaciones intensivas en tierra. El modelo permite analizar distintas situaciones posibles en función de las variables de cultivo no establecidas actualmente (coste de juveniles, alimentación, supervivencia, etc.) y establecer qué condiciones serían necesarias para que las explotaciones fueran rentables. | Sole (Solea senegalensis) is of great interest to marine aquaculture in the Mediterranean because of its relatively fast growth and good commercial prospects (high price). However, the wide mean annual variation in the temperature of Mediterranean sea water (14-26 deg C) is a limiting factor for the ongrowing of this species; the optimum for this process is 19-20 deg C. One of the possible mid-term solutions for ensuring a constant year-round temperature is to ongrow these fish in tanks containing pumped well water. The present work describes a mathematical model for estimating the values of economic variables associated with sole production (which to date have not been defined at the commercial level) for an onshore ongrowing plant using pumped well water at 19-20 deg C. The economic variables studied include optimum load, the sale price of the final product, the cost of juveniles and feed (these last two are influenced by mortality which is still highly variable in this species), and finally the cost of electricity and oxygen (of great importance in onshore plants). The model allows different possible situations to be analysed on the basis of still undefined variables for ongrowing (juvenile cost, feeding, survival, etc.), and establishes under which conditions sole ongrowing would be profitable.

Es importante valorar económicamente los cambios en la calidad del humedal debido a la contaminación y sus consecuencias en la pérdida del bienestar de los ciudadanos, con el fin de establecer medidas de uso racional y eficiente de los servicios ambientales que no cuentan con un mercado definido. Lo anterior por medio de un modelo econométrico que permite establecer la disminución en el valor total del humedal La Conejera a causa de los impactos que allí se generan. | It is important to value economically the changes in the quality of the wetland due to pollution and its consequences in the loss of the welfare of citizens, in order to establish rational and efficient use of environmental services that do not have a defined market. The above by means of an econometric model that allows to establish the decrease in the total value of the La Conejera wetland due to the impacts generated there.

Integrating economic and groundwater models for groundwater-management can help improve understanding of trade-offs involved between conflicting socioeconomic and biophysical objectives. However, there is significant uncertainty in most strategic decision-making situations, including in the models constructed to represent them. If not addressed, this uncertainty may be used to challenge the legitimacy of the models and decisions made using them. In this context, a preliminary uncertainty analysis was conducted of a dynamic coupled economic-groundwater model aimed at assessing groundwater extraction rules. The analysis demonstrates how a variety of uncertainties in such a model can be addressed. A number of methods are used including propagation of scenarios and bounds on parameters, multiple models, block bootstrap time-series sampling and robust linear regression for model calibration. These methods are described within the context of a theoretical uncertainty management framework, using a set of fundamental uncertainty management tasks and an uncertainty typology.

As in many places, groundwater in California (USA) is the major alternative water source for agriculture during drought, so groundwater’s availability will drive some inevitable changes in the state’s water management. Currently, agricultural, environmental, and urban uses compete for groundwater, resulting in substantial overdraft in dry years with lowering of water tables, which in turn increases pumping costs and reduces groundwater pumping capacity. In this study, SWAP (an economic model of agricultural production and water use in California) and C2VISim (the California Department of Water Resources groundwater model for California’s Central Valley) are connected. This paper examines the economic costs of pumping replacement groundwater during drought and the potential loss of pumping capacity as groundwater levels drop. A scenario of three additional drought years continuing from 2014 show lower water tables in California’s Central Valley and loss of pumping capacity. Places without access to groundwater and with uncertain surface-water deliveries during drought are the most economically vulnerable in terms of crop revenues, employment and household income. This is particularly true for Tulare Lake Basin, which relies heavily on water imported from the Sacramento-San Joaquin Delta. Remote-sensing estimates of idle agricultural land between 2012 and 2014 confirm this finding. Results also point to the potential of a portfolio approach for agriculture, in which crop mixing and conservation practices have substantial roles.