Browsing by Author "Weatherhead, E. K."
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Item Open Access 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 proItem Open Access Assessing performance of small-scale pumped irrigation systems in Sub-Saharan Africa: evidence from a systematic review(Wiley, 2016-03-16) Kamwamba-Mtethiwa, Jean; Weatherhead, E. K.; Knox, Jerry W.Small-scale irrigation (SSI) has significant potential to increase crop productivity in Sub Saharan Africa (SSA). Pumped irrigation systems are one of the technologies increasingly being used by smallholder farmers. The aim of this study was to systematically review evidence on the performance of SSI pumped systems, including motorized, treadle, rope and washer, solar and wind pumps. The study revealed a lack of standardization and use of a wide range of indicators to assess performance. Most evidence related to motorized pumps, these studies confirmed mixed levels of performance; studies relating to other types of pumped system mostly reported a positive impact, although the method of assessment used was critical. Studies reporting positive impacts tended to be those that used socio-economic based factors such as yield and profitability, whereas studies reporting mixed performance tended to be those that relied more on technically based indicators such as pumping and irrigation system efficiency. The analysis highlights the sensitivity of interpreting findings from different studies, and how caution should be exercised when comparing performance within and between different types of irrigation system. The implications for supporting policy development and identifying future research gaps are discussed.Item Open Access Assessing spectral similarities between rainfed and irrigated croplands in a humid environment for irrigated land mapping(IP Publishing, 2014-06-01) Shamal, S. A. M.; Weatherhead, E. K.Deriving accurate spatial assessments of the distribution of irrigated crops has become more important in recent years for water resource planning, particularly where irrigation water resources are constrained. However, this is easier in arid climates than in humid areas such as eastern England. The challenges in using alternative vegetation indices derived from remote sensing to discriminate between irrigated and rainfed crops in a humid climate are described, focusing on potato (Solanum tuberosum L.), the most important irrigated crop in England. Three techniques were evaluated: (a) temporal profile comparisons using the Normalized Difference Vegetation Index (NDVI); (b) cluster analysis combining the NDVI and the Normalized Difference Water Index (NDWI); and (c) identifying differences in chlorophyll content using green and near infrared bands. However, the study confirmed that the spectral signatures of irrigated and rainfed potato in England during a typical summer are very similar, presumably due to frequent rainfall events which reduce differences in water stress and chlorophyll content. The implications for using remote sensing to estimate irrigated areas in humid climates are discussed.Item Open Access Assessing the financial and environmental impacts of precision irrigation in a humid climate(Czech Academy of Agricultural Sciences, 2019-03-29) El Chami, D.; Knox, Jerry W.; Daccache, Andre; Weatherhead, E. K.Precision agriculture is increasingly used where in-field spatial variability exists; however, the benefits of its use in humid climates are less apparent. This paper reports on a cost-benefit assessment of precision irrigation with variable rate technique (VRI) versus conventional irrigation, both compared to rainfed production, using a travelling hose-reel irrigator fitted with a boom on onions in eastern England. Selected environmental outcomes including water savings and CO2e emissions are evaluated. The modelled precision irrigation system, which responds to soil variability, generates better environmental outcomes than the conventional system in terms of water savings and reduced CO2e emissions (22.6% and 23.0% lower, respectively). There is also an increase in the ‘added value’ of the irrigation water used (£3.02/m3 versus £2.36/m3). Although precision irrigation leads to significant financial benefits from water and energy savings, these alone do not justify the additional equipment investment costs. However, any changes in yield or quality benefits, equipment costs or greater soil variability than on this site would make investment in precision irrigation more viable.Item Open Access Assuring the microbiological quality of water used to irrigate salad crops: an assessment of the options available(2004-03-02T00:00:00Z) Tyrrel, Sean F.; Knox, Jerry W.; Burton, C. H.; Weatherhead, E. K.- Headline. Although no evidence to link the irrigation of salads to disease outbreaks in the UK has been found, the industry should be seen to be taking the issue of irrigation water quality seriously. The strategy should be to take proactive measures to pre-empt the adoption of unnecessarily cautious standards within grower protocols. - Background and expected deliverables. Concerns have been expressed by some of the major supermarkets that salad vegetables may become contaminated with pathogens as a result of crop irrigation using poor quality water sources. As salads are likely to be eaten raw and will have received a minimal level of processing there are fears that consumers may be put at risk if irrigation water quality is not controlled. To assure product quality and to protect consumer confidence, some supermarkets may set stringent irrigation water quality standards in future grower protocols. Product quality is of paramount importance to growers, processors, retailers and consumers alike. However, the salad growing industry advocates a proportionate, science-based approach to the development of grower protocols rather than the adoption of an excessively precautionary principle. The aim of this project was to generate the baseline information needed by the industry to respond in a positive way to the concerns of retailers. The findings should help to inform the decisions and actions necessary to demonstrate and assure the quality of these products. The work should also support and contribute to the broader commercial objectives of the HDC regarding the efficient use of water. - Summary of the project and main conclusions. The following research tasks were undertaken in pursuit of the project’s aim. 1 A review of literature relating to the microbiological quality of irrigation water and of salad crops. 2 A survey of current UK irrigated salad production to assess current usage and underlying trends. 3 An evaluation of the technological and economic feasibility of on-farm water treatment options. 4 An analysis and discussion of the data collected and development of recommendations for the industry. The main conclusions of this work are: Irrigation water is one of many potential sources of contamination of salads. No published direct evidence has been found to link the irrigation of salads to disease outbreaks in the UK. However, there is a clear potential for this to occur. Published laboratory trials have shown that pathogens associated with poor quality irrigation water may survive on lettuce until harvest. Epidemiological investigations (not from UK) have indicated a link between disease and poor quality irrigation water. On occasions, some UK salad crops are probably irrigated with water of a lower microbiological standard than that recommended for comparable uses (e.g. reuse of wastewater for irrigation and bathing). The actual extent to which this occurs should be quantified and reviewed. The lack of guidance on irrigation water quality is a deterrent to proper water quality monitoring as most growers are unsure how they should respond to the data that is generated. This situation should be corrected as a matter of priority. It is reported that some of the multiple retailers in the UK favour a standard for irrigation water close to that which would meet the requirements for drinking water (i.e. absence or infrequent presence of E. coli in 100 ml water). Our review of standards suggests that this may be an unnecessarily cautious and expensive option. A grower faced with doubts about water quality appears to have four options: Demonstrate existing water is of adequate quality; Treat existing water; Change water source; Relocate crop. A site specific water resources study should be undertaken before assuming that treatment is necessary. Where water quality cannot be assured by management or sourcing strategies, treatment technologies may be considered. Of the many options, three technologies are likely to be suitable: ultra-violet (U/V) treatment, thermal treatment, and sand filters. U/V is considered to be attractive when taking all of the factors into account. Thermal treatment is the most rigorous and reliable. With heat recovery, such treatment could be viable in some cases. Sand filters offer the most farmer-friendly solution but these systems offer less assurance of water quality. - Financial benefits. There are no direct financial benefits to be gained by growers from this work. It may be prudent for growers to take proactive measures to improve monitoring procedures to pre-empt the adoption of unnecessarily cautious (and costly) standards in future grower protocols. - Action points for growers. There is likely to be increasing scrutiny of the microbiological quality of irrigation water. It is advised that growers review their monitoring strategy as a matter of priority. Regular sampling of water sources, at least monthly during the irrigation season, for faecal indicator bacteria would be a good start. The development of such a dataset would aid future decisions regarding the acceptability of particular sources.Item Open Access CCDeW: Climate Change and Demand for Water.(2003-02-01T00:00:00Z) Downing, T. E.; Butterfield, R. E.; Edmonds, B.; Knox, Jerry W.; Moss, S.; Piper, B. S.; Weatherhead, E. K.The Climate Change and Demand for Water Revisited project (CCDeW) revisits and updates the benchmark study by Herrington (1996) and takes advantage of new data sets, regional coverage of demand projections and new methodologies for climate impact assessment. Domestic demand, industrial and commercial water use and irrigated agriculture and horticulture are included in the CCDeW study. Leakage was excluded from the CCDeW study. This report presents the outcome of an extensive UK research programme concerning: demand forecasting; demand management; sensitivity of demand to climatic variations; and sources of risk and uncertainty. While the CCDeW study focuses on demand, climate change uncertainties feed into supply side and demand estimates of water requirements. Therefore, the report’s conclusions should be seen as one element in the dynamic management of the supply/demand balance over the course of the next twenty years and beyond (see Section 9). Clearly, the extent to which water consumption will be influenced by climate change depends upon the sensitivity of different sectors to specific aspects of climate change as well as potential behavioural and regulatory changes, in part related to different socio-economic and climatic futureItem Open Access Climate change and land suitability for potato production in England and Wales: impacts and adaptation(Cambridge University Press, 2012-04-01T00:00:00Z) Daccache, Andre; Keay, Caroline A.; Jones, Robert J. A.; Weatherhead, E. K.; Stalham, M. A.; Knox, Jerry W.The viability of commercial potato production is influenced by spatial and temporal variability in soils and agroclimate, and the availability of water resources where supplemental irrigation is required. Soil characteristics and agroclimatic conditions greatly influence the cultivar choice, agronomic husbandry practices and the economics of production. Using the latest (UKCP09) scenarios of climate change for the UK, this paper describes a methodology using pedo-climatic functions and a GIS to model and map current and future land suitability for potato production in England and Wales. The outputs identify regions where rainfed production is likely to become limiting and where future irrigated production would be constrained due to shortages in water availability. The results suggest that by the 2050s, the area of land that is currently well or moderately suited for rainfed production would decline by 74 and 95% under the "most likely" climate projections for the low and high emissions scenario respectively, owing to increased droughtiness. In many areas, rainfed production would become increasingly risky. However, with supplemental irrigation, around 85% of the total arable land in central and eastern England would remain suitable for production, although most of this is in catchments where water resources are already over-licensed and/or over-abstracted; the expansion of irrigated cropping is thus likely to be constrained by water availability. The increase in volumetric water demand due to the switch from rainfed to irrigated potato cropping is likely to be much greater than the incremental increase in water demand solely on irrigated potatoes. The implications of climate change on the potato industry, the adaptation options and responses available, and the uncertainty associated with the land suitability projections, are discussed.Item Open Access Climate change and the performance of pressurized irrigation water distribution networks under mediterranean conditions: Impacts and adaptations(Ip Publishing, 2010-12-31T00:00:00Z) Daccache, Andre; Weatherhead, E. K.; Lamaddalena, N.Numerous previous studies have modelled the impact of climate change on crop water requirements and hence future water resource needs for irrigated agriculture. Fewer have considered the impacts on the performance of irrigation systems and the required engineering and managerial adaptations. This study considers the impacts and adaptations for a typical pressurized pipe irrigation system. The dry years of the baseline period (1970-90) in the southern part of Italy are expected to become the average or even wet year by the 2050s, according to HadCM3 projections. Under these conditions, the large water distribution systems designed to satisfy the baseline dry years will fail unless appropriate engineering or managerial adaptations are made. The resilience of District 8 of the Sinistra Ofanto to the possible future increase in irrigation demand has been assessed. A stochastic weather generator was used to generate future weather under the IPCC A1 and B1 emissions scenarios, taking into consideration the outputs of the HadCM3 model. A daily water balance model was used to quantify the actual and future peak water demand of the district. The reliability of each hydrant under baseline and future demand was calculated using a stochastic hydraulic model and the failure zones identified. Under the current design, the system can tolerate a peak demand discharge up to 1,500 l.s (-1), which is below the 2050s' average (1,720 l.s(-1)). Above that value, the performance of the system will fall drastically as the number of unreliable hydrants will increase. In the future, assuming the same cropping pattern, the threshold discharge (1,500 l.s(-1)) will be exceeded 80% of the time and, as an average, 20% of the system's hydrants will be failing during the peak demand periods. The adaptation options available to farmers and system managers in response to the increasing demand are discussed.Item Open Access 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.Item Open Access 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 irrigationItem Open Access Competition, conflict, and compromise: Three discourses used by irrigators in England and their implications for the co-management of water resources(Water Alternatives Association, 2015-02-01) Whaley, Luke; Weatherhead, E. K.In this paper we use discourse analysis to explore the current dynamic that exists among farmer irrigators in England, and between irrigators and water managers in order to understand the potential for co-management to develop. To do this we employ two concepts from the field of critical discursive psychology – 'interpretive repertoires' and 'subject positions' – and apply them to a qualitative analysis of 20 interviews with farmers who are members of irrigator groups and two focus group discussions with farmers thinking about forming an irrigator group. The findings reveal that the participants drew upon three interpretive repertoires when talking about the relationship between farming and water resources management, namely the 'competition', 'conflict', and 'compromise' repertoires, with the latter being the least dominant. We situate the repertoires in their wider historical context to reveal the ideological forces at play, and conclude that the relative dominance of the competition and conflict repertoires serve as a barrier to co-management. In particular, this is because they engender low levels of trust and reinforce a power dynamic that favours individualism and opposition. At the same time, the less-dominant compromise repertoire challenges the power of the other two, providing some hope of achieving more participatory forms of water resources management in the future. To this end, we discuss how the restructuring of current agri-environment schemes and government water programmes may be used to promote the adoption and institutionalisation of the compromise repertoire in order to facilitate the emergence of co-management.Item Open Access Coping with climate change uncertainty for adaptation planning: An improved criterion for decision making under uncertainty using UKCP09(2014-03-01T00:00:00Z) Green, Michael; Weatherhead, E. K.Despite information on the benefits of climate change adaptation planning being widely available and well documented, in the UK at least relatively few real-world cases of scenario led adaptation have been documented. This limited uptake has been attributed to a variety of factors including the vast uncertainties faced, a lack of resources and potentially the absence of probabilities assigned to current climate change projections, thereby hampering conventional approaches to decision making under risk. Decision criteria for problems of uncertainty have been criticised for being too restrictive, crude, overly pessimistic, and data intensive. Furthermore, many cannot be reproduced reliably from sub-samples of the UKCP09 probabilistic dataset. This study critically compares current decision criteria for problems of uncertainty and subsequently outlines an improved criterion which overcomes some of their limitations and criticisms. This criterion, termed the GreenZ-score, is then applied to a simplified real-world problem of designing an irrigation reservoir in the UK under climate change. The criterion is designed to be simple to implement, support robust decision making and provide reproducible results from sub-samples of the UKCP09 probabilistic dataset. It is designed to accommodate a wide range of risk appetites and attitudes and thereby encourage its use by decision makers who are presently struggling to determine whether and how to adapt to future climate change and its potential impacts. Analyses using sub-samples of the complete probabilistic dataset showed that the GreenZ-score had comparable reproducibility to Laplace and improved reproducibility compared to other current decision criteria, and unlike Laplace is able to accommodate different risk attitudes. KeywordsDecision making; Adaptation; Uncertainty; UKCP09; WaSim; GreenZ-scoreItem Open Access A critical comparison of using a probabilistic weather generator versus a change factor approach: irrigation reservoir planning under climate change(IWA, 2014-03-01) Green, Michael; Weatherhead, E. K.In the UK, there is a growing interest in constructing on-farm irrigation reservoirs, however deciding the optimum reservoir capacity is not simple. There are two distinct approaches to generating the future daily weather datasets needed to calculate future irrigation need. The change factor approach perturbs the observed record using monthly change factors derived from downscaled climate models. This assumes that whilst the climate changes, the day-to-day climate variability itself is stationary. Problems may arise where the instrumental record is insufficient or particularly suspect. Alternatively, probabilistic weather generators can be used to identify options which are considered more robust to climate change uncertainty because they consider non-stationary climate variability. This paper explores the difference between using the change factor approach and a probabilistic weather generator for informing farm reservoir design at three sites in the UK. Decision outcomes obtained using the current normal practice of 80% probability of non-exceedance rule and simple economic optimisations are also compared. Decision outcomes obtained using the change factor approach and probabilistic weather generators are significantly different; whether these differences translate to real-world differences is discussed. This study also found that using the 80% probability of non-exceedance rule could potentially result in maladaptation.Item Open Access Developing a strategy to improve irrigation efficiency in a temperate climate A case study in England(Ip Publishing, 2009-12-31T00:00:00Z) Knox, Jerry W.; Weatherhead, E. K.; Diaz, J. R.; Kay, Melvyn G.Irrigation is an essential component of agricultural production in England, but the water resources required are under intense pressure due to rising competition, demands for greater environmental protection and the longer-term threats from climate change. This paper describes the development of a water strategy for agriculture to assure its future sustainability by reducing water wastage and maximizing the benefit from the water used. Three themes have been defined - working together, making best use of available water and developing a knowledge base. The approaches described have international relevance to countries where agricultural irrigation is an important component of water abstraction.Item Open Access Difficulties in using spectral properties to map irrigated areas in a temperate climate: A case study of potatoes in England(2008) Shamal, S.; Weatherhead, E. K.; Knox, Jerry W.Irrigation in England is supplemental to rainfall and only used on a small proportion of the cultivated land, notably on high value vegetable and potato crops. However, it is a significant water user as most of the irrigated area is located in the driest part of England. The existing data on irrigated areas are based on government and industry surveys. Recently these datasets have been used with Geographic Information Systems (GIS) to produce irrigated maps, but these can only be published at catchment level due to confidentiality constraints on the datasets. To assess the possibility of using remote sensing data for mapping the irrigated area, one Landsat image for the summer 2003 was used to compare the spectral signature between irrigated and non-irrigated potato fields in the East of England. ISODATA algorithm was used to perform unsupervised classification, and 50 spectral classes were created. A ground truth dataset was then used to identify the most representative spectral class for irrigated and nonirrigated fields. The result showed that categories both fall into the same spectral class, suggesting there are no significant differences between their spectral properties. Therefore, using satellite imagery may not yet be an appropriate method or need more research for mapping irrigated area in temperate climates such as England. The summer rainfall reduces the water stress differences between irrigated and non-irrigated potato fields such that these satellite sensors cannot yet differentiate the crops.Item Open Access The economics of irrigating wheat in a humid climate - A study in the East of England(Elsevier, 2015-02-01) Weatherhead, E. K.; El Chami, D.; Knox, Jerry W.; Daccache, AndreIn the UK, wheat is the most important cultivated cereal, grown extensively as a rainfed crop. Irrigation of wheat has previously been considered uneconomic, but increases in world wheat prices and recent droughts have led to some farmers revising their views. Widespread adoption of wheat irrigation would have major implications for wheat production, the irrigation industry and water resources in regions that are already water scarce. This study investigated the financial viability of irrigating winter wheat grown on a sandy loam soil in the East of England. Long-term climate data (1961–2011) for Silsoe (Bedfordshire) was used to drive a biophysical crop model to assess irrigation water requirements and yield response. Modelling assumed a typical irrigation schedule to maximise yield and quality, and average reported wheat prices for 2007 to 2012. Irrigation costs were calculated assuming an overhead mobile hosereel–raingun system applying river water, abstracted either in summer and used directly, or abstracted in winter and stored in an on-farm reservoir. The results suggest that the yield benefit would justify supplemental irrigation by farmers who have unused irrigation equipment and unused summer water, although irrigation of higher-value field vegetable crops later in the season would normally take precedence – the Added Value of Water (AVW) usefully applied to milling winter wheat under these conditions ranged between 0.24 and 0.32 £ m−3. Investment in new irrigation schemes could also be marginally viable if unused summer river water was available for direct abstraction (AVW = 0.08 £ m−3). Investments in new farm reservoirs for irrigating wheat are currently not profitable (AVW = –0.23 £ m−3). Sensitivity analysis suggests that in the longer term, the expected increase in world wheat prices and the impacts of climate change are likely to make the financial benefits stronger, particularly in the drier catchments further east and on low moisture retentive soils, but competing demands for water would still make extensive wheat irrigation unlikely.Item Open Access Future irrigation water demand and on-farm water conservation in England(Cranfield University, 2001-02) Weatherhead, E. K.; Leeds-Harrison, Peter B.The aim of this thesis is to predict the future demand for water for irrigation of outdoor agricultural crops in England, and to assess the likely on-farm responses to potential water shortages and related legislative change. The past underlying growth in the demand for irrigation water was assessed, by regression analyses of the MAFF irrigation survey results, for each of eight crop categories and in total, using modelled irrigation need as a proxy for climate variation. The growth in total water demand was validated by comparison with the reported growth in total abstractions. These indicate an underlying growth in total irrigation water use between 1982 and 1995 of between 3% and 4% per annum, expressed as percentages of the 1995 values. The results show that irrigation has been increasingly concentrated on the more valuable crops, notably maincrop potatoes, small fruit and vegetables, and that those crops that are irrigated have been increasingly given more water. The future growth in the demand for irrigation water, for each of the eight crop categories and- in total, was modelled as the product of predicted future crop areas, proportions to be irrigated, depths of water to be applied and application efficiencies. On-farm economic modelling, macro-economic models, and expert opinion were used to predict future changes in each of these factors. A spreadsheet model was then used to calculate the future growth in irrigation water demand, for each crop category and in total, and for each Region and nationally. The same methodology has also been applied within a GIS to map the spatial variation in growth. In later work, the Foresight scenario approach has been used to consider alternative socio- economic futures. These results predict that in the short to medium term at least, the total demand for irrigation water will continue to grow rapidly, and its use will become even more concentrated on the high-value crops. Growth is greatest in those areas where water resources are already most scarce. Meanwhile, water availability for agriculture is expected to be constrained or even decline because of increased environmental protection, particularly in the drier parts of the country where irrigation is concentrated. Climate change has not been modelled in this work, but under current predictions, it is likely to have a double effect, simultaneously reducing water supply and increasing water demand, and hence increasing the scarcity and value of water and the benefits of water conservation. The farmers' likely responses to the almost inevitable water shortages have been assessed by estimating the net on-farm value of the water, and comparing this to the benefits and costs of the various options for either reducing demand or increasing on-farm supply, within likely technical, legal and other constraints. The aspects considered include irrigation methods, scheduling, agronomic practices, mulches, on-farm reservoirs, water harvesting and water re- use. This analysis shows that the on-farm benefits of irrigation are generally substantially higher than the direct costs of irrigation. The benefits of conserving water are highly variable, partly because inflexible licensing restricts opportunities to reallocate water between farms. The thesis shows that on those farms where water is valuable and scarce, this will lead to on-farm investment particularly in on-farm reservoirs, more advanced technology and better scheduling. Constraints to change are discussed. Meanwhile, on farms which already have adequate water resources, there is at present little financial incentive to adopt any irrigation water conservation measures at all. The thesis concludes that both farmers and water regulators must prepare for a less certain future in which water for irrigation is scarcer and more valuable, and demand is higher and more concentrated. The opportunities for action by various groups are discussed.Item Open Access A geospatial approach to assessing microbiological water quality risks associated with irrigation abstraction(2011-06-01T00:00:00Z) Knox, Jerry W.; Tyrrel, Sean F.; Daccache, Andre; Weatherhead, E. K.All crops that are eaten raw can present a microbiological risk to consumers. Disease outbreaks in the United Kingdom and United States have illustrated that ready-to-eat crops can be a vehicle for the transmission of gastrointestinal disease. Irrigation water has been implicated as a possible source of microbiological contaminants. Over two-thirds of irrigation water applied to UK salad crops is abstracted from rivers and streams. Many of these are subject to a continuous input of faecal contamination from sewage treatment works as well as intermittent inputs from livestock and sewer overflows. In this paper, we show how geospatial techniques can help to assess the relationships between treated effluent discharges and abstractions and thus provide a new insight into local-scale assessments of irrigation water quality. The extent to which the approach can inform risk assessments and decision-making at the farm scale is demonstrated using a case-study catchment in eastern England.Item Open Access How to Climate Proof Water Sanitation Services for the Urban Poor(Cranfield University, 2010) Heath, Tom; Parker, Alison; Weatherhead, E. K.This report is based upon a 10 month project assessing the vulnerability of WSUP (Water and Sanitation for the Urban Poor) projects to climate change, converting climate change predictions into recommended adaptations. The findings are based on a literature review and field work in Kenya, Madagascar and Zambia, undertaking focus groups, stakeholder interviews and observations. This report synthesises the science of climate change, the impacts of climate change on drinking water and sanitation, how to climate proof water and sanitation services and how to adapt:Item Open Access Implementing precision irrigation in a humid climate - Recent experiences and on-going challenges(Elsevier, 2014-06-22) Daccache, Andre; Knox, Jerry W.; Weatherhead, E. K.; Daneshkhah, Alireza; Hess, TimThere is growing scientific interest in the potential role that precision irrigation (PI) can make towards improving crop productivity, and increasing water and energy efficiency in irrigated agriculture. Most progress has been made in arid and semi-arid climates for use in high value crop production where irrigation costs coupled with concerns regarding water scarcity have stimulated PI innovation and development. In temperate and humid climates where irrigation is supplemental to rainfall, PI is less developed but nevertheless offers scope to make more effective use of rainfall, help reduce the non-beneficial losses associated with irrigation (deep drainage, nitrate leaching) and provide farmers with evidence to demonstrate environmentally sustainable practices to processors and retailers. This paper reports on recent experiences in developing precision irrigation in UK field-scale agriculture, drawing on evidence from field research and modelling studies. By combining data from these sources, a critical evaluation focusing on selected technical, agronomic and engineering challenges that need to be overcome are described, including issues regarding PI scheduling, and the delineation of irrigation management zones to ensure compatibility with existing methods of overhead irrigation. The findings have relevance to other countries where irrigation is supplemental and where precision agriculture is gaining popularity.