Browsing by Author "Kay, M. G."
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Item Open Access The challenges of developing an irrigation strategy for UK agriculture and horticulture in 2020: industry and research priorities(CABI, 2020-10-14) Knox, Jerry W.; Kay, M. G.; Hess, Tim; Holman, Ian P.In many countries, including the UK, water resources are under intense stress with recent droughts highlighting the risks to the security of supplies for different sectors including domestic water supply, industry, agriculture (including horticulture), power generation and the environment. A changing climate with greater rainfall uncertainty, coupled with new regulations, increasing competition for water and demands for sustainable development will only exacerbate the current situation, with major supply-demand imbalances expected over the next few decades. In the UK, irrigated agriculture constitutes a volumetrically small but economically high value use of water, to maximise crop yields and quality. However, the importance of irrigation is also changing; driven by the intensification and transformation of the agricultural sector, the need to recognise water as an 'essential' use, policy incentives to increase domestic food production and an industry imperative to increase water use efficiency and ensure agricultural expansion can continue to underpin the rural economy. This review considers the key climate and water-related risks facing the agricultural and horticultural crop sectors, the various environmental, regulatory and business externalities or 'drivers for change', and the strategic priorities for action, both from industry and research perspectives.Item Open Access The Development of A mathematical Model to Predict Runoff From A micro-catchment under High Water Application Rates(Cranfield University, 1988-05) Abo-Ghobar, Hussein Mohammed Ali; Kay, M. G.Current trends in sprinkler irrigation to improve application uniformity and reduce energy requirements haste led to problems of water application and potential surface runoff, which in turn have highlighted the importance of the soil and cultivation practice in making best use of irrigation water. The objective of this study was to begin the development of a mathematical model, which will simulate the operation of current sprinkler-soil-crop system, in order to provide a means of predicting surface runoff and so provide a more effective approach to system design. A model has now been developed which will predict runoff from a small simple agricultural catchment in the form of a ridge and furrow ciltivation system. The model is based on the kinematic wave theory involving the continuity equation and the simplified momentum equation. A four-point implicit finite difference scheme is used to solve numerically the kinematic wave equations. The model (SROFF) may be used to predict the runoff at various times from a simple catchment with different slopes, water application rates and soil infiltration rate. A further development of the model was made by the introduction of the interception loss model (INCEPT) to predict the amount of water intercepted by the crop canopy during irrigation. The validity of the model was tested and supported by the results of laboratory experiments conducted on two soil samples with different infiltration rates, using three different application rates. The performance of the model was also evaluated by statistical test. There was good agreement between experiment and model results. The results indicated that this model can provide valuable information for the effective design of sprinkler systems, particularly where runoff may be a potential problem. This is particularly the case with current low pressure irrigation systems but equally the problem is common with high pressure systems when applied to soils with low infiltration rates.Item Open Access A mathematical model to predict surface runoff under sprinkler irrigation conditions(1997-06) Ghorbani, Behzad; Kay, M. G.Runoff from agricultural areas under sprinkler irrigation systems is a big problem. This is because runoff not only reduces water use efficiency (WUE), but also reduces soil fertility through depletion of fertilisers and pesticides, causes non uniformity of soil water content along the field slopes and ultimately reduces crop production and causes environmental pollution. Although sprinkler irrigation systems are usually designed so that the water application rate is less than the soil infiltration rate to avoid runoff, there are a growing number of sprinkler systems where runoff has become a serious problem. Large mobile single sprinklers (rainguns) which can irrigate large areas in a relatively short time are prone to severe runoff problems, because of the high application rates. Modern centre pivot and linear systems, which have now been designed to run at low energy saving pressures also produce high application rates and potential runoff. Most runoff problems are dealt with in the field on a trial and error basis. Being able to predict runoff under sprinkler irrigation would enable water application rate to be recommended and cultivation practices to be ‘designed’ rather than guessed on a trial and error basis in order to store surface water and avoid runoff. The objective of this study was to develop a mathematical model that can predict surface runoff from a small watershed area using sprinkler irrigation systems in either a stationary or moving condition. The objective was met in two ways: a mathematical model was developed from first principles called Overland Flow (OLF) and an existing model, KINEROS modified to EUROSEM, but designed for overland flow and soil erosion from hydrological watersheds was adapted to suit micro-catchment conditions for both stationary and moving sprinklers. Both models are based on kinematic wave theory. Both models were validated by laboratory and field experiments using stationary and moving sprinklers on simple plane and ridge and furrow cultivation practices. The validation results showed that the model predicts well the shape of the runoff hydrograph but also the key points for practical application. For example, time to start runoff, time to peak, peak flow rate, volume of runoff and time to end which are important when designing a cultivation practice in the field. The performance of the EUROSEM-KINEROS model was further evaluated by statistical techniques. There was good agreement between observed and model results. The EUROSEM-KINEROS model was also used to examine the best practical techniques to minimise the surface runoff. The application of this model to sprinkler irrigation design and management was also assessed. The evaluation results showed that the hydrograph parameters can be used to recommend water application rate, water application time and / or to design soil and water conservation structures to avoid critical situation in the field. Model validation for a moving sprinkler is recommended to be undertaken for different moving irrigators such as rainguns, centre pivot, side move systems and low energy precision application (LEPA) systems. Further investigations are also required to evaluate the use of the model to predict the effects of soil and water conservation techniques on runoff prevention for a cultivated land for different crops.