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Abstract: Availability of fresh water is one of the elementary conditions for life on Earth, however, water is a limited resource, which is now under an unprecedented pressure by global population growth, climate change and demand from several economic sectors such as tourism, industry, and agriculture. In particular, irrigated agriculture is one of the major water-consuming sectors. The aforementioned issues justify the need for a sustainable and rational use of water in irrigated crops, which motivates the implementation of new precise automatic irrigation technologies based on control theory. In this paper, we introduce the main concepts of control theory, how can it be applied to irrigation and a literature review of automatic irrigation control systems over the last decade. In addition, we present our latest developments in this field. In particular, we present some promising preliminary experimental results of four different control strategies applied to fruit trees in southern Spain to show the potential of the application of control techniques to irrigation. [Copyright &y& Elsevier]

Abstract: Although spate irrigation systems are risk-prone, they can be an important component for livelihood security in semi-arid areas. Spate uses water (flood water), which upstream users often do not require, as rainfall during these periods is more than sufficient. The use of this flood water for spate irrigation is therefore a good opportunity to convert water with a low opportunity cost to high value water. As more rivers are closing, due to socio-economic and climate changes, spate irrigation may become increasingly relevant in semi-arid areas. Spate irrigation systems pose institutional and technical challenges: collective action is challenged by complex upstream–downstream interactions between users within the system, and the high labour demands for regular reconstruction of temporary diversion weirs and intake structures. This paper describes a spate irrigation system in Makanya village, Tanzania that emerged in response to increased upstream water use. We use three of the four dimensions (hydrological, hydraulic and sociological) of spate irrigation proposed by to assess the Makanya spate irrigation system. The Makanya spate irrigation system has an organisational structure that is similar to the canal irrigation (furrow) committees located upstream, and effectively deals with the institutional demands of managing water in spate irrigation systems. Water allocation is reminiscent to the water sharing arrangements existing in the full irrigation system, which previously was in place at the site and in the high- and midlands of the Makanya catchment and therefore set this system apart from the traditional spate irrigation practice elsewhere. Technically, a major challenge is the reconstruction of the head works after each flood. Another aspect is the changes in the river bed. Flash floods carry sediments that deposit on the fields, raising the elevation of the irrigated land every year and making it increasingly difficult for the river water to enter the plots. Improving system efficiency through modernisation of the diversion and distribution structures in this case is not feasible due to the huge amounts of sediments delivered to the system each year. Instead investments in conjunctive use of groundwater could be the solution because it involves a relatively small intervention, minimises the physical disturbance of the system, and therefore is likely to respect the existing locally developed water management arrangements. [Copyright &y& Elsevier]

Abstract: In the North China Plain (NCP), while irrigation using groundwater has maintained a high-level crop productivity of the wheat–maize double cropping systems, it has resulted in rapid depletion of groundwater table. For more efficient and sustainable utilization of the limited water resources, improved understanding of how crop productivity and water balance components respond to climate variations and irrigation is essential. This paper investigates such responses using a modelling approach. The farming systems model APSIM (Agricultural Production Systems Simulator) was first calibrated and validated using 3 years of experimental data. The validated model was then applied to simulate crop yield and field water balance of the wheat–maize rotation in the NCP. Simulated dryland crop yield ranged from 0 to 4.5tha−1 for wheat and 0 to 5.0tha−1 for maize. Increasing irrigation amount led to increased crop yield, but irrigation required to obtain maximum water productivity (WP) was much less than that required to obtain maximum crop yield. To meet crop water demand, a wide range of irrigation water supply would be needed due to the inter-annual climate variations. The range was simulated to be 140–420mm for wheat, and 0–170mm for maize. Such levels of irrigation applications could potentially lead to about 1.5myear−1 decline in groundwater table when other sources of groundwater recharge were not considered. To achieve maximum WP, one, two and three irrigations (i.e., 70, 150 and 200mmseason−1) were recommended for wheat in wet, medium and dry seasons, respectively. For maize, one irrigation and two irrigations (i.e., 60 and 110mmseason−1) were recommended in medium and dry seasons, while no irrigation was needed in wet season. [Copyright &y& Elsevier]

Abstract: This article gives a brief review of the development and current situation in global irrigation, and looks at the drivers affecting irrigation performance, development and modernization. The article concludes that the options for new developments are limited, and that future investment will need to be more precisely targeted to specific niches in different agroecological and economic contexts. The paper notes the powerful implications of global climatic change on irrigation through changes in hydrology and water supply that, in conjunction with (1) continued demand for cheap food to satisfy continuously growing populations and changing dietary preferences (projected to 2050) and (2) increasing competition for high reliability water from higher value economic sectors, indicate irrigation performance and the productivity of agricultural water use must further improve, and are also likely to become more targeted at higher value enterprises. Improving management, through better institutions and better technology will require constant adaptation and finessing, with no silver bullets currently on the horizon. [Copyright &y& Elsevier]

Abstract: This study aims at adopting modeling tools focusing multi-scale problem solving in basins with irrigation water uses. Multi-scaling may help conflict solving since an approach to the scale close to that where conflicts occur is more appropriate for understanding and dealing with related problems. It mainly applies to rural basins where competition among agricultural and non-agricultural uses is high during periods when water availability is scarce. The approach refers to the field scale modeling relative to agricultural demand considering soils, crops and crop patterns, cropping techniques, environment factors, irrigation practices and restrictions to water use (ISAREG model), and basin scale water resource planning models including non-agricultural uses—urban, domestic, industrial, recreational and other uses (SAGBAH model). Analyses of scenarios require then a multi-scale approach. It results a tool that produces a distributed spatial analysis of the agricultural demand, while non-agricultural uses refer to sub-basins. Simplicity in model operation is aimed. The model operates interactively, sharing results from the sub-models, in order to obtain the information required to define strategies for crop irrigation management and to assess impacts on the non-agricultural users, and to generate rules for water allocation in the basin. The multi-scale analyses allows to improve knowledge on the processes relative to water use, to understand spatial and temporal variations, to simulate with historical data and for different scenarios, including those that may result from climate change. Furthermore, the software system works in a semi-automatic way allowing the user to interact along all computations steps, particularly relative to the interaction among scales. Selected results are included in this paper. [Copyright &y& Elsevier]

• Low and narrow level of adoption. Most of farmers not implementing technologies. • Farmer's, farm, and water community characteristics affect irrigation adoption. • Relative abundance of the resource discourages the adoption of technologies. • Irrigating the whole farm produces the largest negative effect on adoption. This paper examines the adoption of irrigation technologies and the underlying diversity in terms of intensity of adoption in 2 irrigated valleys in Central Chile. Results show a low and narrow range of adoption, with only 30 % of farmers adopting technologies. Through a Latent Class Analysis, 2 types of farmers were identified, a small group comprising moderate to intensive users, and a second one consisting of the majority of farmers mostly constrained in natural capital. Furthermore, the econometric analysis indicates that education, diversification, continuous access to water, and perception of water reliability increase the adoption. Conversely, higher water-land ratios, presence of community reservoirs, and earthen canals reduce the uptake. Overall, the dominance of fruit and horticulture production, access to agricultural credits, and full irrigation of the farm are the main drivers of adoption. The latter is a critical factor, indicating a relative abundance of water resources, which, alongside contextual characteristics, discourages farmers from implementing technologies. The low adoption rate, as well as the hindering factors, will challenge public and private organizations to design and implement policies aiming to improve water reliability and management. To generate incentives and increase awareness on the scarcity of the resource in the light of the predicted reductions in water availability because of climate change will be crucial as well. [ABSTRACT FROM AUTHOR]