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Current procedures of water management often use simple models and parameterisation to predict demand that may fail in years with extreme climatic and hydrological conditions. The simulation platform ADEAUMIS, presented in a companion paper (), was developed to improve decision-making in strategic water management. In order to estimate irrigation demand over large areas, it includes a spatial data base and a bio-decisional model. The main variables of the data base are irrigated area, weather data and agricultural practices (crops, sowing dates, varieties and irrigation decision rules). ADEAUMIS was applied in the Baïse sector, in south-western France, in 1998 and 2000.This paper presents an evaluation of ADEAUMIS. Firstly, the operational validation was conducted. Estimated and true input variables and predicted and observed output variables of the bio-decisional model of ADEAUMIS were compared. Secondly, its credibility was evaluated by the water manager by comparing ADEAUMIS with the current decision support system (DSS) (called RIO), in order to determine if the new platform allows better decisions. The operational validation raises the problem of the quality of validation data.For the 2 years of simulation, data on water consumption and electricity use (for pumping) were used to construct the reference curve of water withdrawal during the irrigation season. This reference curve was compared to the estimations of ADEAUMIS. There was good agreement for irrigation demand over the whole region for one of the three methods used to estimate irrigated area. The quality and spatial coverage of the water withdrawal reference curve and of independent estimations of irrigated area, used as validation data, are discussed. It seems that a better fit to the reference curve could be obtained by improving the set of decision rules used to reproduce the average irrigation practice of the region, in particular the rules for starting irrigation and the rule for delaying irrigation following rainfall.ADEAUMIS was evaluated as a decision tool on a year (1998) for which RIO failed in the sense that decisions regarding water deliveries or restrictions were difficult to make. Better decisions would have been made with ADEAUMIS. This led the water manager to consider ADEAUMIS as satisfactory for strategic water management The major contribution of ADEAUMIS, compared to RIO, is the better estimation of the temporal dynamics of irrigation. This is due to the use of a crop model with current year climatic data and the representation of irrigation practices. [Copyright &y& Elsevier]

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: 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: Irrigated agriculture experienced a water supply shock during a drought in southern India in 2002–2003. In this paper, hotspots of agricultural change were mapped and put in the context of hydrology and water management. Time series of MODIS imagery taken every eight days before (2001–2002) and during (2002–2003) the supply shock were combined with agricultural census data to document changes in cropping patterns in four large irrigation projects in the downstream sections of the Krishna and Godavari River basins (total command area 18,287km2). The area cropped in rice in the four irrigated command areas decreased by 32% during the drought year, and rice production in the two districts that experienced the largest flow reductions fell below production levels of 1980. The irrigation project that showed the largest change in double cropped area (−90%) was upstream of the Krishna Delta. In the Krishna Delta, large areas changed from rice–rice to rice–gram double cropping. Historical water management contributed to the vulnerability of rice production to drought: the main reservoir in the system was drained to dead storage levels by the end of each growing season over 1968–2000, with little carryover storage. The land cover change maps suggested that the lower Krishna Basin has experienced a “hard landing” during basin closure, and revised management strategies that account for the new flow regime will be required to maintain agricultural production during droughts. [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]