Browsing by Author "Rodriguez Diaz, J. A."

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    Assessing optimum irrigation water use: additional agricultural and non- agricultural sectors. Environment Agency Science Report - SC040008/SR1
    (2008-04-01T00:00:00Z) Knox, Jerry W.; Weatherhead, E. K.; Rodriguez Diaz, J. A.
    The Water Act (2003) and its preceding legislation requires the Environment Agency to assess and justify authorisations for irrigation abstraction, whether for agricultural, horticultural, amenity, sports turf or other use. A previous study, Optimum use of water for industry and agriculture (W6-056), has provided a framework for assessing the ‘optimum’ or ‘reasonable’ needs of a wide range of crops. In this study, water use was analysed for a range of other agricultural and non-agricultural sectors dependent on irrigation, but not included in the W6-056 study. These include some sectors where new authorisations for trickle will be required, as well as for existing and new spray irrigation abstractions. The sectors considered include golf courses, racecourses, turf production, frost protection, horticultural nursery stock, pot plant and bedding plant production and glasshouse pro
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    Climate change impacts on water for irrigated horticulture in the Vale of Evesham. Final Report
    (Cranfield University/Environment Agency, 2007-02-19) Knox, Jerry W.; Rodriguez Diaz, J. A.; Weatherhead, E. K.; Khan, K.
    This project has undertaken a scoping review and assessment of the impacts of climate change on irrigated horticulture in the Vale of Evesham, an area of intense irrigated production located within the Environment Agency’s Warwickshire Avon CAMS Catchment. The research was based on a combination of methodologies including desk-based review of published and grey literature, computer agroclimatic and water balance modelling, GIS mapping, meetings with key informants and a stakeholder workshop. Future climate datasets were derived from the latest UK Climate Impacts Programme (UKICIP02) climatology, using selected emission scenarios for the 2020s, 2050s and 2080s. These scenarios were then used to model and map the future agroclimatic conditions under which agriculture might operate and the consequent impacts on irrigation need (depths of water applied) and volumetric demand. This was complimented by a postal survey to abstractors and a stakeholder workshop, to identify, review and assess farmer adaptation options and responses. The key findings arising from the research, implications for water resource management and recommendations for further work are summarised below. Using a geographical information system (GIS), a series of agroclimate maps have been produced, for the baseline and selected UKCIP02 scenario. The maps show major changes in agroclimate within the catchment over the next 50 years. The driest agroclimate zones are currently located around Worcester, Evesham, Tewkesbury and Gloucester, corresponding to areas where horticultural production and irrigation demand are most concentrated. By the 2020s, all agroclimate zones are predicted to increase in aridity. By the 2050s the entire catchment is predicted to have a drier agroclimate than is currently experienced anywhere in the driest parts of the catchment. This will have major impacts on the pattern of land use and irrigation water demand. Cont/d.
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    A comparative assessment of trickle and spray irrigation:  Science Report - SC040008/SR3, Environment Agency
    (2007-06-01T00:00:00Z) Knox, Jerry W.; Weatherhead, E. K.; Rodriguez Diaz, J. A.
    Recent research (Assessing optimum irrigation water use: additional agricultural and nonagricultural sectors SC040008/SR1) complements existing guidelines (W6- 056) for the Environment Agency to assess and set the ‘optimum’ or ‘reasonable’ irrigation needs for an abstraction licence, across a wide range of agricultural, horticultural, amenity and sports turf sectors. For those abstractors with time-limited licences, demonstrating efficient use of water is one of three tests required by the Environment Agency for successful licence renewal. However, the definition of efficiency under UK conditions of supplemental irrigation has been the subject of widespread debate between academics, the regulator, industry and individual abstractors. To improve our understanding of efficiency, and particularly the differences between overhead (spray) and micro (trickle) irrigation, this report offers a comparative study of the efficiency of water use with these contrasting irrigation
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    Modelling impacts of precision irrigation on crop yield and in-field water management
    (Elsevier, 2017-08-29) González Perea, R.; Daccache, Andre; Rodriguez Diaz, J. A.; Camacho Poyato, E.; Knox, Jerry W.
    Precision irrigation technologies are being widely promoted to resolve challenges regarding improving crop productivity under conditions of increasing water scarcity. In this paper, the development of an integrated modelling approach involving the coupling of a water application model with a biophysical crop simulation model (Aquacrop) to evaluate the in-field impacts of precision irrigation on crop yield and soil water management is described. The approach allows for a comparison between conventional irrigation management practices against a range of alternate so-called ‘precision irrigation’ strategies (including variable rate irrigation, VRI). It also provides a valuable framework to evaluate the agronomic (yield), water resource (irrigation use and water efficiency), energy (consumption, costs, footprint) and environmental (nitrate leaching, drainage) impacts under contrasting irrigation management scenarios. The approach offers scope for including feedback loops to help define appropriate irrigation management zones and refine application depths accordingly for scheduling irrigation. The methodology was applied to a case study in eastern England to demonstrate the utility of the framework and the impacts of precision irrigation in a humid climate on a high-value field crop (onions). For the case study, the simulations showed how VRI is a potentially useful approach for irrigation management even in a humid environment to save water and reduce deep percolation losses (drainage). It also helped to increase crop yield due to improved control of soil water in the root zone, especially during a dry season.
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    A preliminary assessment of climate change impacts on sugarcane in Swaziland
    (Elsevier Science B.V., Amsterdam., 2010-02-01T00:00:00Z) Knox, Jerry W.; Rodriguez Diaz, J. A.; Nixon, D. J.; Mkhwanazi, M.
    The spatial and temporal impacts of climate change on irrigation water requirements and yield for sugarcane grown in Swaziland have been assessed, by combining the outputs from a general circulation model (HadCM3), a sugarcane crop growth model and a GIS. The CANEGRO model (embedded with the DSSAT program) was used to simulate the baseline and future cane net annual irrigation water requirements (IRnet) and yield (t ha-1) using a reference site and selected emissions scenario (SRES A2 and B2) for the 2050s (including CO2-fertilisation effects). The simulated baseline yields were validated against field data from 1980-1997. An aridity index was defined and used to correlate agroclimate variability against irrigation need to estimate the baseline and future irrigation water demand (volumetric). To produce a unit weight of sucrose equivalent to current optimum levels of production, future irrigation needs were predicted to increase by 20-22%. With CO2-fertilisation, the impacts of climate change are offset by higher crop yields, such that IRnet is predicted to increase by 9%. The study showed that with climate change, the current peak capacity of existing irrigation schemes could fail to meet the predicted increases in irrigation demand in nearly 50% of years assuming unconstrained water availability.
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    Water and energy footprint of irrigated agriculture in the Mediterranean region
    (IOP Publishing, 2014-12-15) Daccache, Andre; Ciurana, J. S.; Rodriguez Diaz, J. A.; Knox, Jerry W.
    Irrigated agriculture constitutes the largest consumer of freshwater in the Mediterranean region and provides a major source of income and employment for rural livelihoods. However, increasing droughts and water scarcity have highlighted concerns regarding the environmental sustainability of agriculture in the region. An integrated assessment combining a gridded water balance model with a geodatabase and GIS has been developed and used to assess the water demand and energy footprint of irrigated production in the region. Modelled outputs were linked with crop yield and water resources data to estimate water (m3 kg−1) and energy (CO2 kg−1) productivity and identify vulnerable areas or 'hotspots'. For a selected key crops in the region, irrigation accounts for 61 km3 yr−1 of water abstraction and 1.78 Gt CO2 emissions yr−1, with most emissions from sunflower (73 kg CO2/t) and cotton (60 kg CO2/t) production. Wheat is a major strategic crop in the region and was estimated to have a water productivity of 1000 t Mm−3 and emissions of 31 kg CO2/t. Irrigation modernization would save around 8 km3 of water but would correspondingly increase CO2 emissions by around +135%. Shifting from rain-fed to irrigated production would increase irrigation demand to 166 km3 yr−1 (+137%) whilst CO2 emissions would rise by +270%. The study has major policy implications for understanding the water–energy–food nexus in the region and the trade-offs between strategies to save water, reduce CO2 emissions and/or intensify food production.