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• This work estimates water and light use efficiency in garlic based on ground data. • The model integrates series of satellite vegetation indices in crop growth models. • The normalization of these efficiencies for the atmospheric conditions is analyzed. • Additional analysis are the use of cold temperature stress on the noted models. • The results are promising for the operative estimation of garlic biomass production. The objective of this paper was to determine the water use efficiency (WUE) and light use efficiency (LUE) values of garlic (Allium sativum L.) and to analyze the normalization of these efficiencies for the atmospheric conditions. We analyzed the use of daily reference evapotranspiration (ETo) and the vapor pressure deficit (VPD) for these purposes. WUE and LUE were valued based on the experimental measurements of dry biomass production and the estimation of transpiration and radiation interception based on time series of Remote Sensing satellite images. The experimental data were obtained in two commercial fields each planted with a different variety of garlic (var. morado and var. spring) growing in different weather conditions in the province of Albacete (in the south-east of Spain). The correlation between the accumulated values of biomass and the estimated values of crop transpiration and radiation absorption resulted in strong linear relationships. The slope of these correlations resulted in values of WUE and LUE, WUE = 5.51 g m−2 mm−1 and LUE = 2.26 g·MJ−1 for both analyzed varieties. The results demonstrated that the inclusion of temperature stress coefficient is required when the WUE and LUE parameters are normalized using the ETo and the VPD variables. However, atmospheric normalization did not conclusively improve results in this study. Results obtained in this paper provided empirical evidence regarding the feasibility of estimating biomass production in garlic based on the same physiological principles used for other crops. [ABSTRACT FROM AUTHOR]

Highlights • Farmers' preferences toward irrigation water supply reliability (WSR) are analyzed. • A discrete choice experiment (DCE) is used with stochastic variables for WSR. • Three classes of farmers are identified according to their WTP for improved WSR. • They show no, low, and high WTP, with several factors explaining class belonging. • The results can assist the design of more efficient water management instruments. Abstract In irrigated agricultural systems, a major source of uncertainty relates to water supply, as it significantly affects farm income. This paper investigates farmers' utility changes associated with shifts in the probability density function of water supply leading to a higher water supply reliability (higher mean and lower variance in annual water allotments). A choice experiment relying on a mean-variance approach is applied to the case study of an irrigation district of the Guadalquivir River Basin (southern Spain). To our knowledge, this is the first study using parameters of these probability density functions of water supply as choice experiment attributes to value water supply reliability. Results show that there are different types of farmers according to their willingness to pay (WTP) for improvements in water supply reliability, with some willing to pay nothing (47.8%) while others have a relatively low (28.0%) or high (24.2%) WTP. A range of factors influencing farmers' preferences toward water supply reliability are revealed, with those related to risk exposure to water availability being of special importance. The results can be used to assist the design of more efficient policy instruments to improve water supply reliability in Mediterranean and semi-arid climate regions. [ABSTRACT FROM AUTHOR]

Highlights • Satellite images have been utilized to estimate crop coefficients. • The estimated and the theoretical crop coefficients have been compared. • The comparison was made among field plots, municipalities and irrigation districts. • A set of water use efficiency indicators have been calculated. Abstract Irrigation in the Duero river basin accounts for 75% of total water resources. Nevertheless, irrigation in this area is paramount to maintain agricultural production. Within this context, this paper is aimed at assessing the water use efficiency (WUE), for the major crop (corn), among four irrigation districts (IDs) from 2014 to 2017. Since the WUE indicators base upon crop water requirements, these were calculated by estimating the reference evapotranspiration and the local crop coefficients Kc. First, they were estimated by satellite images and then, compared with the recommendation from the Regional Irrigation Advisory Service. Finally, the gross irrigation requirements were compared with the irrigation supply. WUE indicators varied among IDs depending upon the hydrologic year, the water available for irrigation (superficial and subsurface water), and the corn sowing date. Usually, the IDs performed deficit irrigation in the dry years, and either full irrigation or over irrigation in the wet years. The rainfall only fulfilled less than 10% of corn requirements. Small differences in Kc were observed within municipalities (in each ID) and/or among IDs. The pattern of the Kc fitted curves varied among IDs and was affected by sowing dates. Although, the local Kc values were close to the general coefficients recommended by the Irrigation Advisory Service, they affected the determination of gross irrigation requirements which were significant different among IDs. Moreover, it was observed that the FAO recommendation for the duration of the corn growth stages fitted better the estimated Kc than the one from the Advisory Center. The gross irrigation requirements were similar among IDs and years, varying between 6476 and 7646 m3/ha. The local Kc estimation could help irrigation managers to adapt the irrigation supply to the actual corn needs. [ABSTRACT FROM AUTHOR]

This paper analyses the impacts and water policy implications of an increase of perennial crops on irrigation water requirements and on the vulnerability of the agricultural system to climatic events in the case of the Guadalquivir River basin. As indicated by the EU Water Framework Directive (WFD), the characterisation of a river basin requires information on the major economic drivers and pressures at river basin scale. Guadalquivir River basin (southern Spain) can be considered a representative Mediterranean case study that has faced basin closure and continues the trend towards increased crop intensification and greater water-use efficiency. Our result shows an increased vulnerability to drought and water scarcity in the basin due to the expansion of irrigated perennial crops and a decrease of RIS (relative irrigation supply) from 0.70 to 0.56 in the period 2000–2021, thereby forcing farmers to adopt deficit irrigation techniques. The potential increase in the frequency of droughts and the growth of irrigation water requirements (IWR) due to higher temperatures, raise the vulnerability of the system to extreme climate events. Such findings can be employed to support the efficient allocation of water resources in order to improve water policy through its adaptation to increasing risks related to droughts and water scarcity. • The evolution of irrigated area in Guadalquivir River basin is characterised by an increasing share of perennial crops. • IWR have increased continuously due to changes in crop patterns (intensification). • Since IWR exceed availability, the irrigation system applies deficit irrigation as a response, with a decreasing RIS. [ABSTRACT FROM AUTHOR]

Over recent decades, groundwater-fed irrigation has sustained the social and economic development of La Mancha, Spain. Without much initial regulation and control, groundwater resources and aquifer levels decreased dramatically, threatening agriculture and also highly valuable groundwater-dependant wetland ecosystems. This paper presents as a historical analysis of the different policy tools used to manage and regulate groundwater abstraction in the Western Mancha Aquifer after Spain approved its 1985 Water Law. It analyses the panoply of control and management instruments laid out by the state to counter the resource depletion trend, demonstrating the necessity by regulatory bodies to complement soft incentives (carrots) with the threat of sanctions and groundwater access limitations (sticks). As this case study shows however, each policy modality has its legal and practical loopholes which can be negotiated and exploited by groundwater users to their own advantage. Improvements in groundwater levels starting in 2010 seem to be linked to aquifer recharge following an unprecedented wet cycle rather than the effectiveness of the policy tools. [ABSTRACT FROM AUTHOR]

The realization of buyback welfare enhancing opportunities is conditioned to the ability of government agencies to place bids consistent with the shadow price of irrigators. However, methods used to inform buyback programmes to date either rely on ex-post trading data that is not readily available in most regions worldwide; or compensate projected foregone income, and thus ignore the effects that buyback may have on other relevant attributes determining utility. This paper uses revealed preference methods to elicit the parameters of a multi-attribute objective function that mimics the observed behavior of irrigators in the overexploited Segura River Basin in SE Spain. Objective functions are used in a series of simulations in which water allocation is progressively constrained to ex-ante reveal the shadow price of water using two alternative compensation measures: i) the foregone income, a proxy of the shadow price typically used in the literature; and ii) the compensating variation that addresses foregone utility. Results show a relevant gap between the two methods For example, restoring the balance in the basin through purchase tenders would demand an investment of million 2400+ EUR (9.6+ EUR m −3 ) attending to the foregone income method, and million 950+ EUR (3.8+ EUR m −3 ) (−60.3%) with the foregone utility method. [ABSTRACT FROM AUTHOR]

Concerns about hydrological drought risk and irrigation water supply reliability have grown in recent years due to the increasing demand for water for irrigation and other uses, and the decline in water availability due to climate change. Hydrological drought insurance hedging against water supply gaps can be a key instrument for adapting irrigated agriculture to this new scenario, since it improves the resilience of the irrigation sector, which is having to cope with increasing uncertainty and vulnerability. The objective of this paper is to assess farmers' willingness to pay (WTP) for index-based hydrological drought insurance under different policy designs, considering several different amounts of insured capital, insurance deductibles, and contract terms. To that end, it uses a discrete choice experiment as the valuation method and the Sector BXII irrigation district (southern Spain) as a case study. The results show that farmers would be willing to pay for the proposed hydrological drought insurance, stating a higher preference for policy designs with lower amounts of insured capital, lower deductibles, and shorter contract terms. Moreover, the results also show the existence of heterogeneity among farmers' preferences, depending on their socio-economic characteristics. Finally, we compare the distribution of farmers' WTP for different policy design options of the proposed insurance with the commercial premium estimated using actuarial analysis. The comparison confirms that only the options with lower levels of insured capital present a mean WTP below the commercial premium, while the rest of the policy design options would need to be subsidized like other agricultural insurance schemes to make them attractive to most farmers. • Farmers are willing to pay for hydrological drought insurance. • Farmers prefer policies with low levels of insured capital, low deductibles, and short contract terms. • WTP is heterogeneous depending on farmers' socio-economic characteristics. • Only policy designs with low levels of insured capital are currently commercially viable. • Once the new drought insurance is implemented, it will become more attractive for farmers. [ABSTRACT FROM AUTHOR]

Generally, in most pressure irrigation systems and particularly in irrigation systems of golf courses, an efficient management of water and energy use is required. Through an efficient management of these resources the excessive consumptions are controlled and a savings in exploitation costs could be achieved. One of the tools that allow controlling and identifying the water and energy consumption is the use of management and automation indicators. With the employ of these tools, several parameters that affect in the efficiency of water and energy use of pumping systems, water network configuration, automation and the associated energy systems could be controlled. In this paper the methodology and implementation of several water, energy and automation indicators and their productivity adapted to four golf courses in south-east Spain are shown. For this purpose, some data of a developed study among 2008 and 2011 in the irrigation systems of these golf courses and their influence in the improvement of the efficiency in the water and energy use are presented. This combined methodology is particularly suitable for comparing the irrigation systems of several golf courses. Moreover, by using these indicators with automation and remote control devices for water and energy management in such irrigation systems, it is possible to reduce and control associated costs. The results demonstrate that automation is a low-cost investment (with a maximum of 2% of the total costs) compared to the large benefits and advantages. For this study, the maximum values of the automation cost per controlled water volume and energy were 0.2007 €·m −3 and 0.2233 €·kWh −1 , respectively. The percentage of automation cost in the total cost is around 1.5 percent. [ABSTRACT FROM AUTHOR]

This paper assesses the feasibility and robustness of an index-based insurance scheme against hydrological droughts under climate change. To this end, we develop a grand ensemble that samples both modeling and scenario uncertainty in the estimation of the insurance risk premium, so to reveal potential unfavorable surprises and minimize regret in the design of the proposed insurance scheme. The grand ensemble combines four microeconomic models and seven GAMLSS models, which are run for three alternative climate change scenarios: stationary climate/no climate change, RCP 2.6, and RCP 8.5. Methods are illustrated with an application to the Cega River Sub-basin (CRS) in central Spain. Results indicate that for a conventional deductible of 30%, the proposed index-based insurance scheme would be actuarially feasible and affordable under all models for the stationary climate scenario (i.e., robust). For climate change scenarios RCP 2.6 and 8.5 and a 30% deductible, the suggested index-based insurance would be actuarially feasible under most models, albeit some outliers point towards potential unfavorable surprises. Lower deductibles decrease feasibility, particularly for deductibles <10%. • For a deductible of 30% and stationary climate, the proposed index-based insurance is actuarially feasible under all models. • Under climate change (RCPs 2.6, 8.5), the insurance is feasible for all deductibles and the median model (except PMAUP WGP). [ABSTRACT FROM AUTHOR]

Abstract: This paper re-visits the concept of water efficiency applied to Spanish agriculture and assesses how this technical concept is sometimes lost in translation when applied at different spatial scales. The paper traces the historical dominance of irrigated agriculture in Spanish water policy. It analyses the water efficiency concept at the macro level, by evaluating recent national policy initiatives and public investment programmes over the last decade to modernise irrigation, which anticipated large water savings. “Water efficiency” is then framed in its socio-political context, by looking at debates and discussions over the past, current and future role of irrigation, key evaluation criteria and objectives for large scale irrigation modernisation plans, what are the links to water rights and allocation, benefits and beneficiaries from water savings and important unanticipated consequences and co-benefits in modernisation, and the reform of agricultural policies. Finally it identifies the central role played at national, European and global levels by agricultural (and energy) policies as key external drivers for the long term viability of modern irrigation on social, environmental and economic-productivity terms. [Copyright &y& Elsevier]

• New index-based insurance to cover irrigation water supply gaps is proved to be technically feasible. • Although the proposal is tailored to Spain, its main features can also be implemented worldwide. • An innovative actuarial analysis based on a stochastic hydrological model is implemented. • Simulation results show irrigation in southern Spain is expected to become more vulnerable to droughts. • New water management rules mean that the proposed insurance scheme has relatively high premiums. In Mediterranean-climate regions, irrigated agriculture is especially vulnerable to the risk of hydrological drought, and irrigators are particularly concerned about the negative effects of water supply failures. This paper proposes a new index-based drought insurance scheme to cover the risk of water supply failures in irrigated agriculture that overcomes the problems currently hindering the development of this kind of insurance, especially those related to arbitrariness in annual water allotments decision-making. Although the proposal is tailored to Spain, it can be easily adapted to other countries or regions because its main features can also be implemented worldwide. The scheme proposed is a promising instrument to help irrigators manage the risk related to hydrological droughts since it has been proved to be technically feasible. The main contribution of this paper is the innovative actuarial analysis implemented, which is aimed at calculating fair premiums. Considering that recent changes in the institutional framework (new demands, new storage capacity, and revised basin and drought management plans) make historical records unsuitable for this purpose, the actuarial analysis applied is based on a stochastic hydrological model able to simulate future hydrological situations under updated settings. Simulation results have shown that irrigated agriculture in southern Spain is expected to be more vulnerable to hydrological droughts. In fact, incidence rates are likely to increase because of the new institutional framework, leading to relatively high fair premiums. Only by implementing high ordinary deductibles can the hypothetical cost of commercial premiums be affordable for irrigators, accounting for less than 10% of their current variable costs. [ABSTRACT FROM AUTHOR]

Water reuse is a strategic priority for Water Authorities in Europe to reduce the pressure on water resources, although implementation is lagging behind expectations due to financial, administrative and social acceptance concerns. In this context, there is a special interest to identify in which specific Wastewater Treatment Plants it would be interesting to add a Water Regeneration Plant, taking account of potential existing clients in the vicinity and the implied costs and benefits. This paper proposes a method to quantify the infrastructure and operation costs of project implementation and the benefits of the additional water offer. An algorithm designs the distribution network, allowing for a quick cost analysis. The method is applied in the Upper Guadiana in Central Spain, where irrigation led to the overexploitation of the local aquifers and the subsequent restrictions on water use. Taking account of the existing Wastewater Treatment Plants, candidate reuse projects are classified according to their benefit/cost ratio, showing large differences according to the location and potential use of the regenerated water. The analysis allows for a quick assessment of the costs and benefits implied in different reuse projects and scenarios, providing science-based evidence to support water policy decisions. [Display omitted] • A Cost and Benefit Analysis assesses the viability of potential water reuse projects. • An irrigation water distribution network is generated automatically to support cost calculation. • The analysis allows to create multiple scenarios of reuse policies. • Project viability is determined by location and profitability of irrigated crops. [ABSTRACT FROM AUTHOR]

The transfer of successful water market governance between international settings is increasingly attractive to policy makers under globalization. This paper tests lesson-drawing approaches to water market governance transfers using data from Spain and the Murray-Darling Basin, Australia. Spain is the blueprint country for water market adoption in Europe, while Australia is often presented as a world leader in innovative water market arrangements. A preliminary comparative analysis framework linking water market governance principles to observed institutional arrangements and outcomes is provided. Finally, some key lessons, problems and policy transfer potential to stimulate and enhance Spanish water markets from lesson-drawing approaches are drawn, with an emphasis on adaptive capacity as an institutional performance metric. We find that Spain's current water governance institutions and arrangements offer a solid platform for marketing reform, where some key adaptive capacity constraints are able to be addressed. The lessons drawn from this study highlight those areas of change which, while challenging, can be achieved in our view. • Lesson drawing methods offer a novel way to assess adaptive capacity in policy settings. • Australia's water markets provide a case study for comparing Spain's readiness for water market adoption. • Current institutional strengths and weaknesses are identified via the analysis. • Future adaptive capacity evaluation offers useful insights for water governors and policy-makers. [ABSTRACT FROM AUTHOR]

This paper examines the effectiveness of reforming water rights regimes in the agricultural sector by replacing allocation procedures based on the proportional rule with the implementation of a priority rule that establishes security-differentiated water rights. The main objective is to assess whether this change improves the economic efficiency of water allocation at the irrigation district level, particularly during cyclical scarcity events. To this end, a Positive Mathematical Programming model is built to simulate the performance of the proposed reform in an irrigation district in southern Spain. The results show that the efficiency gains brought about by this change are very small, which casts doubt on its ability to improve water-use efficiency in the agricultural sector at the local level (i.e., irrigation district) under current local climate and water availability conditions. In any case, further research is needed to assess the suitability of this change in allocations rules at basin scale with greater farm heterogeneity, especially given the likelihood of more frequent, more intense droughts due to climate change. • A priority-based water rationing system is assessed at the irrigation district level. • The implementation of the new rationing system yields only small efficiency gains. • Efficiency increases could be banished considering actual transaction costs. • Spot water markets are a more suitable policy instrument to cope with droughts. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines irrigation water management in the Genil-Cabra Irrigation District of the Province of Cordoba (southern Spain) using three irrigation indicators: relative irrigation supply (RIS), relative water supply (RWS), and relative rainfall supply (RRS). The three indicators are calculated both globally and by grouping the data according to crop type, irrigation method, soil texture, and plot size. Then, it is possible to determine the influence that each individual factor has on irrigation management and take subsequent measures to improve irrigation performance. All of the information regarding agronomic and hydraulic variables has been included in a geographical information system (GIS) to facilitate data management. The results show that irrigation is deficit given that the mean value of the RIS indicator is relatively low, around 0.60. However, the RWS indicator achieves higher mean values, normally above 0.80, indicating that evaporation demand can be met throughout the crop development cycle. The RRS indicator shows less variability with mean values around 0.40. This indicator, together with the RWS indicator permits the evapotranspiration fraction covered by rainfall to be determined. The mean values of the calculated indicators are very useful for gaining a better understanding of irrigator behavior and general irrigation trends, although the study sample is still insufficient to characterize a large irrigation area as a whole. [Copyright &y& Elsevier]

Abstract: Regulated deficit irrigation (RDI) strategy using saline reclaimed water is becoming a frequent practice under semiarid Mediterranean climatic conditions in the southeastern region of Spain. There is a concern that the long-term use of this strategy will affect the production sustainability of the agricultural soils. This paper evaluates the field consequences of this strategy on the accumulation of salts within the plant root zone. Full and regulated deficit surface drip deficit irrigation was combined with fresh water (EC 1dSm−1) and saline (EC 3dSm−1) tertiary reclaimed water to irrigate adult mandarin trees over a 3-year period. The control treatment received 100% of the crop evapotranspiration “ETc” and the RDI treatment received 50% of ETc during the 2nd stage of fruit growth. Soil water content was monitored every other week within the soil wetted volume under the emitter. Gravimetric soil samples were collected from 3 depths and at 3 distances to the emitter, twice a year: at the end of irrigation season and at the conclusion of RDI period. Soluble salts, electrical conductivity and sodium adsorption ratio were determined in the saturated paste extract. The results show how the RDI strategy intensifies the development of salinity gradient away from the emitter even when using good quality water. The combination of RDI with saline reclaimed water produced transient saline-sodic conditions at the outer superficial limits of the wetted bulb under the emitter. The appearance of such adverse conditions is alarming and would threaten the sustainability of agricultural soils. Therefore soil water deficit should be avoided whenever saline reclaimed water is in use for irrigation. [Copyright &y& Elsevier]

Abstract: This paper describes the calibration (year 2005) and validation (year 2003) processes for the simulation of an onion crop (Himalaya cultivar) in a two-year field test under deficit irrigation conditions in Castilla-La Mancha (Spain) using the MOPECO model. Results show that MOPECO is suitable for simulating the yield versus total water use under the climatic and soil conditions in this study (RMSE=7462kgha−1, and relative error=10.1%, between observed and simulated yields). Growing-degree-days (GDD) for the whole growth cycle is around 2283.4°C, while the crop coefficient (K c: 0.65, 1.20, and 0.75) and calibrated crop yield response (K y: 0.45, 0.8, and 0.2) values for the growth stages proposed by FAO are similar to those presented in the literature. The electrical conductivity of the irrigation water in the area (0.85dSm−1) can be neglected when simulating the yield response of onion to water (over-estimations up to 7% without considering the effect of salinity). Under the current harvest sale price scenarios (0.12€kg−1 if onions are sold after harvest and up to 0.20€kg−1 if onions are stored to sell at a higher price later), this crop is one of the most profitable in the area, reaching a gross margin between 1750 and 2620€ha−1, respectively, for an average yield (70,000kgha−1). Even though optimized regulated deficit irrigation (ORDI) may slightly increase yield by 3–7%, the gross margin may significantly raise up to 30% compared with an irrigation strategy where the stress levels remain constant during the whole growth cycle. Hence, for medium and high water deficit conditions it is of interest to guarantee nascence and to favor the bulb formation stage as much as possible. For low and medium-low water deficit scenarios, nascence and establishment are guaranteed, and the model assigns more water to vegetative development than to ripening. [Copyright &y& Elsevier]

Abstract: It is recognised that the hydrological and erosion processes in watersheds are very much conditioned by the (inter)action of a number of variables. This paper covers a 15-year period of studying those factors that have a major influence on the sediment yield and transport during individual hydrological events in a small Mediterranean agricultural watershed. Multivariate statistical techniques such as cluster analysis and principal component analysis were applied for the interpretation of datasets. In addition, the relationships between suspended sediment concentration and discharge (hysteretic loops) were also analysed. The hydrological response of the studied watershed is mainly controlled by the antecedent condition of the flow. Most of the runoff and sediment are generated during the wet season when vegetation cover is scant and saturation overland flow occurs promptly as a response to almost any rainfall events. In contrast, during the dry seasons even if high-intensity rainfalls normally occur, very scant runoffs are, however recorded, at the exit of the watershed. Most of the eroded sediment seems to come from riparian areas. The discharge registered at the watershed outlet up to 1h prior to the flood is a very good surrogate for antecedent soil moisture. [Copyright &y& Elsevier]

Abstract: Water performs essential ecological functions in agroecosystems and supplies an array of hydrologic ecosystem services (HES). The nature and quantity of HES is intimately linked with the management of the territory, and the capacity of the different land uses to partition rainfall into green (evapotranspiration) and blue (runoff) freshwater flows. This paper presents an innovative method to empirically assess the underlying relationship between the use and management of Mediterranean agroecosystems, their spatial pattern of green and blue freshwater flow generation and the provision of HES. We test this approach in Sierra Norte de Sevilla, a characteristic Spanish agro-forestry system. To assess the hydrological functioning we used the spatially explicit hydrologic model BalanceMED. HES’ identification and societal valuation was done through an expert panel. The hydrologic performance and the social values ascribed to the different services were combined to identify key provisioning areas or HES hotspots. Our results show that multifunctional agroecosystems, where agrarian and forestry activities co-exist, optimize the partition and use of freshwater flows and supply the largest bundles of HES at a wide range of spatial scales. The often low profitability of these extensive activities is prompting either the intensification or the abandonment of many Mediterranean agro ecosystems. We discuss the trade-offs in HES associated with these land use trends, and we illustrate the potential options available for implementing payments for ecosystem services (PES) schemes to pursue “win–win” management solutions. [Copyright &y& Elsevier]

Abstract: Pasture productivity depends on soil hydro-physical properties, which in turn are deeply affected by livestock grazing. However, the comparative response of different soil types, and particularly gypseous soil types, to grazing has hardly been studied before. This paper compares the effect of grazing on the soil hydro-physical properties of silty gypseous (Gy) and non-gypseous (NGy) soils located in a semi-arid region (Middle Ebro Valley, NE, Spain). Two different soil managements were selected: ungrazed natural shrubland (N) and grazed shrubland (GR) soils. The gypsum, CaCO3 and organic matter content (OM), soil texture, soil bulk density (ρ b ), penetration resistance (PR), saturated sorptivity (S), hydraulic conductivity (K), and the water retention curve (WRC) for undisturbed soil samples from 1 to 10cm depth soil layer were measured. The ρ b and PR in NGy soils were significantly higher than those observed in the Gy ones. Soil compaction due to grazing treatment tended to increase ρ b and decrease the K and S values. While no differences in PR were observed in the Gy soils between grazing treatments, the PR measured in the NGy soils under GR was significantly higher than the corresponding values observed under N. Differences in K and S between GR and N treatments were only significant (p <0.05) in NGy soils, where K and S values under the N treatment were almost four times greater than the corresponding values measured under GR. Overall, no differences in the WRCs were observed between soil types and grazing treatments. While the WRCs of NGy soils were not significantly affected by the grazing treatment, Gy soils under N treatment present a significantly higher level of soil macropores than under GR treatment. The hydro-physical features of Gy soils tended to be less affected by grazing than those of the NGy soils. These results suggest that livestock grazing, in both Gy and NGy soils, has a negative effect on the physical soil properties, which should be taken into account by land managers of these semi-arid regions where silty gypseous and non-gypseous areas coexist. [Copyright &y& Elsevier]

Abstract: This paper describes a two-part methodology for managing the risk posed by water supply variability to irrigated agriculture. First, an econometric model is used to explain the variation in the production value of irrigated agriculture. The explanatory variables include an index of irrigation water availability (surface storage levels), a price index representative of the crops grown in each geographical unit, and a time variable. The model corrects for autocorrelation and it is applied to 16 representative Spanish provinces in terms of irrigated agriculture. In the second part, the fitted models are used for the economic evaluation of drought risk. Inflow variability in the hydrological system servicing each province is used to perform ex-ante evaluations of economic output for the upcoming irrigation season. The model''s error and the probability distribution functions (PDFs) of the reservoirs’ storage variations are used to generate Monte Carlo (Latin Hypercube) simulations of agricultural output 7 and 3 months prior to the irrigation season. The results of these simulations illustrate the different risk profiles of each management unit, which depend on farm productivity and on the probability distribution function of water inflow to reservoirs. The potential for ex-ante drought impact assessments is demonstrated. By complementing hydrological models, this method can assist water managers and decision makers in managing reservoirs. [Copyright &y& Elsevier]

Abstract: Groundwater in Spain, as in other arid and semiarid countries worldwide, has been widely used in the expansion of irrigated agriculture. In the Spanish Mancha Occidental aquifer, the excessive, and sometimes illegal, water abstraction for irrigation has promoted outstanding socioeconomic development in the area, but it has also resulted in exploitation of the aquifer and degradation of valuable wetlands. Water policies implemented in the region have not yet managed to restore the aquifer and face strong social opposition. This paper uses a multi-scale modeling approach to explore the environmental and socio-economic impacts of alternative water conservation measures at the farm and basin levels. It also analyzes their comparative cost-effectiveness to help policy makers identify the least costly policy option for achieving the goal of the Mancha Occidental aquifer''s sustainability. To conduct this analysis, a Mathematical Programming Model has been developed to simulate: the closing-up and taxed-legalization of unlicensed wells, uniform volumetric and block-rate water prices, water quotas, and water markets. Aggregate results show that net social costs are not substantially different across policy option, so none of the considered policy options will be clearly more cost-effective than the others. However, there are significant differences between private and public costs (at the farm and sub-basin levels), which will be critical for determining the application in practice of these policies. Results show that controlling illegal water mining (through the legalization of unlicensed wells) is necessary, but is not sufficient to recover the aquifer. Rather, effective water management in this area will require the implementation of other water management policies as well. Among them, uniform volumetric and block-rate water pricing policies will entail the lowest net social cost, but will produce important income losses in the smallest and most water-intensive farms, which might put at risk the viability of these farms and the social acceptance of the policies. Further investigations on social costs, policy enforcement capacity and public participation in water management are highly recommended. [Copyright &y& Elsevier]

Abstract: The objective of this paper is to study evaporation and drift losses (EDLs) with two types of sprinklers: rotating spray plate sprinklers (RSPS) and fixed spray plate sprinklers (FSPS), both installed at two different heights (1 and 2.5m above the ground). A field test was carried out during three seasons at an irrigated plot with a centre pivot, in Albacete (Spain). The results show that EDLs were significantly higher with the FSPS placed 2.5m above the ground (FSPS 2.5) than with the RSPS placed 1m above the ground (RSPS 1). The EDLs obtained for the FSPS 2.5 combination were 8% for night irrigation events and 13.7% for daytime irrigation events. The lowest EDL values were registered with RSPS 1, ranging from 3.3 to 8.2% under night and day operation conditions, respectively. These results were obtained for an average wind speed of 1.3m/s at night and 3.5m/s during the day, and were normally below 5m/s. [Copyright &y& Elsevier]

Abstract: The objectives of this study were to determine onion water requirements with a sprinkler irrigation system, the most usual irrigation method in Spain. A weighing lysimeter was used to measure single (Kc) and dual (Kcb+Ke) crop coefficient curves and obtain the relationship between Kc-ground cover (GC) and Kcb-GC. Experimental work was carried out in 2005 at “Las Tiesas” farm, located in Albacete (Central Spain). To determine actual onion evapotranspiration (ETc), we used a weighing lysimeter with continuous electronic data recording. Daily measured ETc values obtained by the lysimeter were compared to calculated ETc values obtained through the standard FAO methodology [Allen, R.G., Pereira, L.S., Raes, D., Smith, M., 1998. Crop evapotranspiration. Guidelines for computing crop water requirements. FAO Irrig. and Drain. Paper 56. Rome, Italy]. Seasonal evapotranspiration measured in the lysimeter (893.34mm) was higher than the seasonal ETc calculated by FAO-56 method (832.90mm). The percentage of GC was found through the supervised classification technique of digital photographic images with the maximum probability algorithm [Calera, A., Martínez, C., Melia, J., 2001. A procedure for obtaining green plant cover: relation to NDVI in a case study for barley. Int. J. Remote Sensing, 22, 3357–3362]. The values derived from lysimetric measurements are Kc ini: 0.65, Kc mid: 1.20 and Kc end: 0.75, similar to values given in FAO-56. Lysimetric measurements showed that the evaporative component was high during the growing season, due to the high frequency of irrigation and the fact that the onion crop does not completely cover the ground; maximum GC was 72%. Therefore, the dual crop coefficient was calculated, which allowed differentiation between crop transpiration (basal crop coefficient, Kcb) and evaporation from the soil (evaporation coefficient, Ke). With the aim of facilitating extrapolation of the results to other areas, Kc and Kcb were linearly correlated to fractional GC. [Copyright &y& Elsevier]

Abstract: This paper reports the effects of irrigation amount and partial rootzone drying (PRD) on water relations, growth, yield and wine quality of Vitis vinifera cv. ‘Tempranillo’ during two consecutive years in a commercial vineyard with a deep, light-clay soil located in Requena, Valencia, Spain. Partial rootzone drying applied at two amounts (100% and 50% of the estimated crop evapotranspiration), was compared to conventional drip irrigation, and also to rainfed vines. Results showed that the effects of irrigation amount on yield and wine quality were different between years. In 2003 with low yield values (around 6.3tha−1) irrigation did neither affect grape production nor wine quality. However, in the following year, with much higher general yield (17tha−1), the high irrigation dose increased yield by 30% compared to rainfed vines and it also increased must total soluble solids and wine alcohol content. In both seasons, PRD did not significantly affect physiological parameters, nor growth, yield or fruit and wine quality, when compared to the same amount of water applied by conventional drip irrigation. Overall these results suggest that, under our experimental conditions, it was the irrigation amount rather than the system of application what affected vine performance, indicating the difficulties of successfully employing the PRD type of irrigation with a drip system in heavy and deep soils. [Copyright &y& Elsevier]

Abstract: Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5dSm−1) and an infiltration rate of 5.8mmday−1. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731mm (5.1mmday−1), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874mm, deep percolation was 830mm and surface runoff was 372mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2mmday−1 was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration. [Copyright &y& Elsevier]

Abstract: In the last decade irrigation districts in the Ebro Valley of Spain have started to use database applications to enhance their management operations. Such applications often put more emphasis on administrative issues than on water management issues. A new irrigation district management software called “Ador” is presented in this paper. This database application has been designed to overcome limitations identified in an analysis of the software used in the study area. Ador can be used in irrigation districts independently of the type of irrigation system (surface, sprinkler or trickle) and the type of irrigation distribution network (open channel or pressurised). It can even be used in irrigation districts combining different types of irrigation systems and different types of irrigation distribution networks. The software can be used with minimum district information. The goals are to manage detailed information about district water management and to promote better on-farm irrigation practices. Ador is currently used to enhance management of 62 irrigation districts accounting for some 173,000 hectares in the Ebro Valley. [Copyright &y& Elsevier]

Abstract: In this paper, a contribution to the design of collective pressurised irrigation networks in solid-set sprinkler-irrigated windy areas is presented. The methodology is based on guaranteeing minimum on-farm performance, using a historical hourly wind speed database and a ballistic solid-set irrigation simulation model. The proposed method was applied to the Montesnegros Irrigation District (central Ebro basin, Spain). The district irrigates an area of 3493ha using an on-demand schedule. The average wind speed in the area is 2.8ms−1. An analysis of district water records showed that farmers often reduce water demand when the wind speed is high, but their irrigation decision making is limited by the capacity of the irrigation network and by the unpredictable character of local winds. Simulations were performed for 11 irrigation seasons, 2 triangular sprinkler spacings (18m×18m and 18m×15m), and 2 sprinkler models. The percentage of monthly suitable time for irrigation was determined for four management strategies. The first one was based on a wind speed threshold (3ms−1), while the other three were based on three levels (standard, relaxed and restrictive) of two irrigation performance parameters: the Christiansen Uniformity Coefficient (CU) and the Wind Drift and Evaporation Losses (WDEL). The standard strategy classified the time as suitable for irrigation when CU≥84% and WDEL≤20%. The thresholds limits of the irrigation parameters for the relaxed strategy were CU≥80% and WDEL≤25%. Finally, the restrictive strategy used thresholds of CU≥90% and WDEL≤15%. The suitable time for the first strategy (56%) was always lower than for the standard and the relaxed strategies (with respective average values of 75 and 86%), and higher than for the restrictive strategy (30%). In order to design the collective network, the hydrant operating time was equalled to the suitable time for irrigation. The differences in the cost of the collective network plus the on-farm equipment were particularly relevant between the restrictive strategy and the other three. Differences in suitable operating time were clear between sprinkler spacings, and less evident between sprinkler models. The application of the proposed methodology may be limited by the availability of historical wind speed records and CU estimates for different combinations of sprinkler models, sprinkler spacings and wind speed. [Copyright &y& Elsevier]

• A methodology to classify irrigated areas is proposed. • The method permits to identify and map strengths and weaknesses of irrigated areas. • The application of the method to an irrigated area can support decision-making. • The method can be adapted to other areas of the world by adjusting criteria. The large diversity of irrigated agricultural areas hinders the development of social consensus and complicates decision-making about the allocation of investments for irrigation modernization. A classification of irrigated areas permits the identification and mapping of different categories and reveals the strengths and weaknesses of each category regarding specific criteria. This paper proposes a binomial (genus and species) classification methodology of irrigated areas, which was designed based on a participatory approach. Four internal properties determine the genus: type of water source, type of water energy, on-farm irrigation method and water availability. Four external properties classify the variability within each genus into species: land tenure, crop type, existence of an environmental protection figure and socio-economic level. The words used for the genus and specific name arise from the concatenation of syllables representing the state or level of each property. The method was applied to the irrigated area of the Ebro river basin in the Aragón region of Spain (ERB-Aragón). A total of 435,851 ha were classified. A large part of the irrigated land uses surface water (94 %), does not have water availability problems (80 %), is not affected by environmental protection figures (97 %), is devoted to field crops (86 %), and manifests a low (45 %) or moderate (41 %) socio-economic level. A total of 24 genera and 126 species were identified. The two most representative genera are SurGraFloVe (31 %) and SurPumPreVe (27 %), and the two main species are SurGraFloVe DisCeNoLo (19 %) and SurPumPreVe ConCeNoMo (19 %). These species received the local names of " Ribera del Ebro" and " Alto Aragonés" to facilitate policy discussions. The application of the method to the ERB-Aragón provides a privileged insight that can support policy analyses and guide institutional intervention. The proposed methodology can be adapted to other areas of the world by adjusting criteria and categories to local conditions. [ABSTRACT FROM AUTHOR]