Cost-Effectiveness of Water Conservation Measures: A Multi-level Analysis with Policy Implications

Groundwater in Spain, as in other arid or semiarid countries worldwide, has been intensely used for the expansion of irrigated agriculture. This booming development has induced a remarkable socioeconomic development in many rural areas but has produced far-reaching environmental problems. In the Spanish Western La Mancha Aquifer, the excessive, and sometimes illegal, water abstraction for irrigation agriculture has resulted in the Aquifer’s overexploitation and has been responsible of the degradation of the associated wetlands “Tablas de Daimiel”, an internationally reputed, Ramsarnominated aquatic ecosystem. To undertake this analysis, a mathematical programming model has been developed to simulate farmers’ behaviour and their responses to different water policy scenarios. Specifically, the policy simulations selected are: alternative water pricing schemes (uniform volumetric and block-rate water tariffs), water use quota systems and water rights market. Results show that controlling illegal water mining is a necessary condition but it is not sufficient to recover the aquifer. Consequently, other measures will be necessary for an effective water management in this area. Among these, the block-rate water pricing scheme seems the most cost-effective system to reach the goal of aquifer sustainability but will entail important income losses in several farms. Therefore, we cannot conclude that a unique water conservation policy instrument will be the best overall solution for all types of holdings that will respond to efficiency as well as to equity considerations. It seems reasonable to make a combination of the tools proposed, even including additional measures that promote an environmental protection and develop sustainable agricultural systems.Environmental degradation, water policies, cost-effectiveness analysis, Resource /Energy Economics and Policy,

INTEGRATED ECONOMIC-HYDROLOGIC ANALYSIS OF POLICY RESPONSES TO PROMOTE SUSTAINABLE WATER USE UNDER CHANGING CLIMATIC CONDITIONS

Resource /Energy Economics and Policy,

Prevention of sulfate-induced thaumasite attack: thermodynamic modeling in BaCO3-blended cement

Thaumasite, an expansive salt, remains stable over a wide range of compositions in the CaO-SiO2-Al2O3-CaCO3-CaSO4-H2O system. Despite its slow formation, it constitutes a risk for the integrity of underground structures such as foundations and tunnels that are in contact with sulfate-containing soil or groundwater. Sulfate-resistant Portland cements, which pursuant to the existing legislation are manufactured with clinker containing 0-5% of C3A, prevent ettringite- but not thaumasite-mediated concrete deterioration. The present study used thermodynamic modeling to explore the viability of a new type of BaCO3-blended Portland cement able to resist thaumasite formation. The results of sulfate attack (44 wt% Na2SO4 solution), simulated with the GEMS geochemical code in cements with 5 or 20% BaCO3, or 2.5, 5, 10 or 20% CaCO3 at 8 ºC, showed that less thaumasite precipitated and at higher sulfate/cement ratios in the presence than in the absence of Ba. Particularly at the higher replacement ratio, Ba proved to be able to immobilise sulfates in the medium via the precipitation of BaSO4, a highly insoluble salt, and hamper the precipitation of thaumasite. The study also showed that a higher BaCO3 content in the system hindered thaumasite formation even in the presence of greater amounts of carbonates. At 5% BaCO3, thaumasite started to precipitate after 53 g of Na2SO4 were added per 100 g of cement, while at 20%, the sulfate content threshold was higher, at 70 g per 100 g of cement, and smaller quantities of the salt formed

Fases termodinámicamente estables en el sistema cerrado CaO-SiO2-Al2O3-CaSO4-H2O a 25 ºC. Aplicación a sistemas cementantes

One of the chief causes of cement and concrete deterioration is the loss of durability prompted by sulphate attack. The existing standards call for long test periods (2- 12 months). Thermodynamic modelling is a particularly appropriate technique for studying systems that only reach equilibrium in the long term. Used in the present study to establish the fields of thermodynamic stability for the phases in the CaO-SiO2-Al2O3-CaSO4-H2O system at 25 ºC. According to the model, gypsum is stable at sulphate ion concentrations of 1.23e-2 mol/kg and over, while ettringite exhibits stability at concentrations ranging from 7.64e-6 to 1.54e-2 mol/kg. Ettringite is compatible with all system phases except SH and gypsum only with ettringite, the C-S-H gels, AH3 and SH. None of the calcium aluminates or silicoaluminates in the system is compatible with gypsum: in its presence, they all decompose to cement deteriorating ettringite. Finally, the model revealed that the maximum sulphate concentration at which C-S-H gel is stable is slightly higher in systems with than without Al2O3.Uno de los principales problemas asociados al deterioro de cementos y hormigones es la pérdida de durabilidad por ataque de sulfatos. La normativa existente requiere largos tiempos de ensayo (2-12 meses). La modelización termodinámica es una técnica particularmente adecuada para el estudio de sistemas que alcanzan el equilibrio en tiempos largos. Aplicando esta metodología se han establecido los campos de estabilidad termodinámica de las fases del sistema CaO-SiO2-Al2O3-CaSO4-H2O a 25 ºC. El yeso es estable a partir de la [SO42-] = 1,23e-2 mol/kg, y la ettringita es estable en un rango de [SO42-] = 7,64e-6 -1,54e-2 mol/kg. La ettringita es compatible con todas las fases del sistema excepto con SH y el yeso sólo con la ettringita, los geles C-S-H, el AH3 y el SH. Ninguno de los aluminatos o silicoaluminatos cálcicos son compatibles con el yeso, en su presencia se descomponen dando etringita. Finalmente, la máxima [SO42-] en la que es estable el gel C-S-H es ligeramente superior en sistemas que contienen Al2O3 con respecto a los que no lo poseen

Prevention of sulfate-induced thaumasite attack: thermodynamic modelling in BaCO3-blended cement

Comunicación presentada en el International Congress on Materials and Structural Stability (CMSS 2013), celebrado en Rabat del 26 al 30 de noviembre de 2013.Thaumasite, an expansive salt, remains stable over a wide range of compositions in the CaO-SiO2-Al2O3-CaCO3-CaSO4-H2O system. Despite its slow formation, it constitutes a risk for the integrity of underground structures such as foundations and tunnels that are in contact with sulfate-containing soil or groundwater. Sulfate-resistant Portland cements, which pursuant to the existing legislation are manufactured with clinker containing 0-5 % of C3A, prevent ettringite- but not thaumasite-mediated concrete deterioration. The present study used thermodynamic modeling to explore the viability of a new type of BaCO3-blended Portland cement able to resist thaumasite formation. The results of sulfate attack (44 wt% Na2SO4 solution), simulated with the GEMS geochemical code in cements with 5 or 20 % BaCO3, or 2.5, 5, 10 or 20% CaCO3 at 8 ºC, showed that less thaumasite precipitated and at higher sulfate/cement ratios in the presence than in the absence of Ba. Particularly at the higher replacement ratio, Ba proved to be able to immobilise sulfates in the medium via the precipitation of BaSO4, a highly insoluble salt, and hamper the precipitation of thaumasite. The study also showed that a higher BaCO3 content in the system hindered thaumasite formation even in the presence of greater amounts of carbonates. At 5 % BaCO3, thaumasite started to precipitate after 53 g of Na2SO4 were added per 100 g of cement, while at 20 %, the sulfate content threshold was higher, at 70 g per 100 g of cement, and smaller quantities of the salt formed.Funding from the Spanish Ministry of Education and Science (Project CONSOLIDER CSD2007-00058) and the Regional Government of Madrid (Geomaterials Programme) is gratefully acknowledged.Peer Reviewe

Reactividad y aptitud a la cocción de crudos de cemento con elevados contenidos en manganeso

It has been verified that high manganese content in raw mixes causes alters the mineralogical composition of clinkers. New phases like 2 CaO.Mn02 and Ca2AIMnO5 are developed and C3A formation can be inhibited. Manganese is a flux similar to iron in the traditional raw mixes. The presence of manganese will modify the expressions of the lime saturation factor (LSF), silica modulus (Ms) and aluminum modulus (Mf). This has as consequence an increase of the proportion of interstitial phase in the obtained clinkers.Se ha comprobado que contenidos elevados de manganeso en el crudo provoca una modificación significativa en la composición mineralógica del clinker. Se desarrollan las fases no tradicionales 2 CaO.Mn02 y Ca2AIMnO5 , y se puede llegar, incluso, a inhibir la formación de alumínate tricálcico. El manganeso tiene un comportamiento fundente muy similar al jugado por el hierro en los crudos tradicionales, por lo que la incorporación de óxidos de manganeso al crudo produce una alteración significativa en los módulos tradicionales (LSF, Ms y Mf). Esto tiene como consecuencia inmediata un gran incremento en la proporción de fase intersticial en los clínkeres producidos

Assessment of Socio-Economic and Climate Change Effects on Water Resources and Agriculture in Southern and Eastern Mediterranean countries. MEDPRO Technical Paper No. 28/March 2013

This study aims at assessing the socio-economic and environmental effects of different societal and human development scenarios and climate change in the water-scarce southern and eastern Mediterranean. The study develops a two-stage modelling methodology that includes an econometric analysis for the southern and eastern Mediterranean region as a whole and a detailed, integrated socioecological assessment focusing on Jordan, Syria and Morocco. The results show that water resources will be under increasing stress in future years. In spite of country differences, a future path of sustainable development is possible in the region. Water withdrawals could decrease, preserving renewable water resources and reversing the negative effects on agricultural production and rural society. This, however, requires a combination across the region of technical, managerial, economic, social and institutional changes that together foster a substantive structural change. A balanced implementation of water supply-enhancing and demand-management measures along with improved governance are key to attaining a cost-effective sustainable future in which economic growth, a population increase and trade expansion are compatible with the conservation of water resources

Integrated economic-hydrologic analysis of policy responses

Water is a vital resource, but also a critical limiting factor for economic and social development in many parts of the world. The recent rapid growth in human population and water use for social and economic development is increasing the pressure on water resources and the environment, as well as leading to growing conflicts among competing water use sectors (agriculture, urban, tourism, industry) and regions (Gleick et al., 2009; World Bank, 2006). In Spain, as in many other arid and semi-arid regions affected by drought and wide climate variability, irrigated agriculture is responsible for most consumptive water use and plays an important role in sustaining rural livelihoods (Varela-Ortega, 2007). Historically, the evolution of irrigation has been based on publicly-funded irrigation development plans that promoted economic growth and improved the socio-economic conditions of rural farmers in agrarian Spain, but increased environmental damage and led to excessive and inefficient exploitation of water resources (Garrido and Llamas, 2010; Varela-Ortega et al., 2010). Currently, water policies in Spain focus on rehabilitating and improving the efficiency of irrigation systems, and are moving from technocratic towards integrated water management strategies driven by the European Union (EU) Water Framework Directive (WFD)

Perspectives on climate change and human development in the Mediterranean agriculture

The Mediterranean region is one of the world's climate change hotspots. Future climate projections envisage dramatic implications for the agricultural and water sectors that will endanger economic development and lead to natural resources degradation and social instability

Integrated assessment of policy interventions for promoting sustainable irrigation in semi-arid environments: A hydro-economic modeling approach

Sustaining irrigated agriculture to meet food production needs while maintaining aquatic ecosystems is at the heart of many policy debates in various parts of the world, especially in arid and semi-arid areas. Researchers and practitioners are increasingly calling for integrated approaches, and policy-makers are progressively supporting the inclusion of ecological and social aspects in water management programs. This paper contributes to this policy debate by providing an integrated economic-hydrologic modeling framework that captures the socio-economic and environmental effects of various policy initiatives and climate variability. This modeling integration includes a risk-based economic optimization model and a hydrologic water management simulation model that have been specified for the Middle Guadiana basin, a vulnerable drought-prone agro-ecological area with highly regulated river systems in southwest Spain. Namely, two key water policy interventions were investigated: the implementation of minimum environmental flows (supported by the European Water Framework Directive, EU WFD), and a reduction in the legal amount of water delivered for irrigation (planned measure included in the new Guadiana River Basin Management Plan, GRBMP, still under discussion). Results indicate that current patterns of excessive water use for irrigation in the basin may put environmental flow demands at risk, jeopardizing the WFD s goal of restoring the ?good ecological status? of water bodies by 2015. Conflicts between environmental and agricultural water uses will be stressed during prolonged dry episodes, and particularly in summer low-flow periods, when there is an important increase of crop irrigation water requirements. Securing minimum stream flows would entail a substantial reduction in irrigation water use for rice cultivation, which might affect the profitability and economic viability of small rice-growing farms located upstream in the river. The new GRBMP could contribute to balance competing water demands in the basin and to increase economic water productivity, but might not be sufficient to ensure the provision of environmental flows as required by the WFD. A thoroughly revision of the basin s water use concession system for irrigation seems to be needed in order to bring the GRBMP in line with the WFD objectives. Furthermore, the study illustrates that social, economic, institutional, and technological factors, in addition to bio-physical conditions, are important issues to be considered for designing and developing water management strategies. The research initiative presented in this paper demonstrates that hydro-economic models can explicitly integrate all these issues, constituting a valuable tool that could assist policy makers for implementing sustainable irrigation policies