Irrigation Demand Management Research Articles

Assessing social acceptability of management options for harmonising irrigation with environmental concerns: A pilot study from the Murrumbidgee Valley, Australia

The flows in regulated rivers are strongly dependent on water demand by downstream water users. In irrigated catchments the river flow regimes are deliberately distorted to cater for crop demand, with significant deleterious ecological impacts. A number of opportunities exist to manipulate irrigation demand and supply to provide more natural seasonality of flows and optimise the social, environmental and economic outcomes from water use in a catchment. Possible options to achieve this goal include improved cropping mix incentives, groundwater - surface water substitution, intra and inter-seasonal water trading and harmonisation of on- and off-farm storage, distribution, application and drainage infrastructure with environmental outcomes. Each of these options will impact in some way on irrigation and wider communities. In this paper 'community' involvement in setting irrigation research agendas and evaluating water management options in the Murrumbidgee Valley, Australia is explored. A brief assessment of social acceptability, combined with hydrological and economic models, was found to be an effective approach for scoping different irrigation demand management options to improve seasonality of flows. In this study the value of articulating assessment criteria when dealing with new and potentially disruptive options for the management of irrigation demand in a catchment context is demonstrated.

Analytical optimization of demand management strategies across all urban water use sectors

AbstractAn effective urban water demand management program can greatly influence both peak and average demand and therefore long‐term water supply and infrastructure planning. Although a theoretical framework for evaluating residential indoor demand management has been well established, little has been done to evaluate other water use sectors such as residential irrigation in a compatible manner for integrating these results into an overall solution. This paper presents a systematic procedure to evaluate the optimal blend of single family residential irrigation demand management strategies to achieve a specified goal based on performance functions derived from parcel level tax assessor's data linked to customer level monthly water billing data. This framework is then generalized to apply to any urban water sector, as exponential functions can be fit to all resulting cumulative water savings functions. Two alternative formulations are presented: maximize net benefits, or minimize total costs subject to satisfying a target water savings. Explicit analytical solutions are presented for both formulations based on appropriate exponential best fits of performance functions. A direct result of this solution is the dual variable which represents the marginal cost of water saved at a specified target water savings goal. A case study of 16,303 single family irrigators in Gainesville Regional Utilities utilizing high quality tax assessor and monthly billing data along with parcel level GIS data provide an illustrative example of these techniques. Spatial clustering of targeted homes can be easily performed in GIS to identify priority demand management areas.

Estimation of single‐family residential irrigation demand management effectiveness

This article presents a systematic procedure to quantify savings potential of single‐family residential irrigation demand management strategies that can be used to evaluate the optimal blend of these strategies to achieve specified goals. Current irrigation practices, irrigable area, and irrigation application rate are derived for each single‐family residence based on parcel‐level tax assessor's data linked to customer‐level monthly water billing data. Water savings are calculated directly as the difference between current and proposed use after implementation of a management option for each residence. This information is used to develop performance functions that estimate total water savings as a function of the number of implementations for each residence. This procedure allows demand management options to be compared directly with other supply augmentation options when determining the optimal blend. Probabilistic models are derived from benchmark parcel‐level datasets for evaluation of other utilities where direct measurements are unavailable.

Promoting irrigation demand management in India: options, linkages and strategy

Against the backdrop of a discussion on the rationale, logic and scope of irrigation demand management in India, this paper provides a brief overview of the status, effectiveness and technical and institutional requirements of six demand management options, that is, water pricing, water markets, water rights, energy regulations, water saving technologies and user organizations. The paper then develops a framework that captures the analytics of irrigation demand management in terms of both the impact pathways of and the operational linkages between the options and their underlying institutions. Using this framework, the paper also outlines a strategy for irrigation demand management that can exploit the inherent synergies between the options and align them well with the underlying institutional structure and its environment. After discussing how such a strategy can be effectively promoted within the institutional and political constraints facing countries such as India, the paper concludes with the policy implications of irrigation demand management.

Managing irrigation demand to improve seasonality of river flows

AbstractHuman interventions often lead to unsustainable river systems. There is always a trade‐off between level of socio‐economic gains from consumptive use in the river system and the need to maintain the natural seasonality of river flows supporting the ecosystem function. In the case of the Murrumbidgee River, Australia, irrigation demand is concentrated in the summer season while natural inflows to the river occur during the winter season. The summer‐dominated irrigation water demand has created environmental and supply problems by altering the natural flow regime. This paper presents a hydrologic assessment of a range of irrigation demand management options for improving the natural seasonality of the river flow. Among the possible alternatives, change of cropping pattern by achieving a better mix of summer and winter crops is recommended as the most feasible alternative, which can also save up to 211 million m3 of water yearly. This water can then be released during the winter time to augment the environmental flows of the river. Other irrigation demand management options explored in this paper include aquifer storage and recovery, on‐farm and off‐farm water savings and construction of intermediate surface water storages. Copyright © 2008 John Wiley & Sons, Ltd.

Trade-off analysis for restoring environmental flows through irrigation demand management

The aim of this paper is to evaluate economic trade-offs of introducing irrigation demand management measures to modify river flows in order to mimic natural flow variations in the rivers. A number of irrigation demand management options were identified through rigorous discussions with the key stakeholder groups in the Murrumbidgee Catchment. The impacts of alternative demand management options are presented in terms of a matrix of economic costs and associated water savings. The modelling results revealed that 10–15% of peak water use during summer can be reduced from the average total annual water use of 1400 GL. This may result in reduced economic return or require private and public investments in the form of on-farm water saving technologies, canal lining or construction of en-route storage. However, if we value the saved water at current market prices, then benefits are expected to be higher than the costs involved. Among all other options, spreading water use over summer and winter season through new crop mixes promises to be the most cost-effective irrigation demand management option for improving seasonality of flow in the rivers. The study also found that increasing on-farm water use efficiency to reduce peak water use is in the farmer’s economic self-interest through reduced water inputs per unit of production; it will also help increase streamflows if suitable mechanisms for securing environmental flows can be implemented.

Mapping the total volumetric irrigation water requirements in England and Wales

The net volumetric (m 3) irrigation water requirements for the main crop categories currently irrigated in England and Wales have been calculated and mapped within a geographic information system (GIS). The procedure developed by Knox et al. (1996, Agric. Water Manage., 31: 1–15) for maincrop potatoes ( Solanum tuberosum) was extended to cater for the other crops currently irrigated. The annual irrigation needs (mm) for the eight major irrigated crop categories, grown on three contrasting soil types at 11 representative weather stations, were determined using a daily water balance irrigation scheduling model. The results were correlated with existing national datasets of climate, current land use, soils and irrigation practice, to generate volumetric (m 3) irrigation water requirement maps at 2 km resolution. The total net volumetric irrigation water requirements for a UK ‘design’ dry year (defined as the requirement with a 20% probability of exceedance) are estimated to be 140 × 10 6 m 3 for the eight main crop categories currently irrigated and the 1994 cropping pattern. Previous theoretical dry year demand estimates, using scheduling models and large agroclimatic areas, were 109 × 10 6 m 3 and 222 × 10 6 m 3. The irrigation demand for other crops grown in the open would typically add another 4%. The procedure has been validated nationally, by comparing the calculated dry year demand for 1990 against government irrigation survey returns for 1990, for each crop category, and regionally against National Rivers Authority (NRA) abstraction records for 1990, for each NRA Region. The estimates obtained agree well with the reported distribution between crops and between regions. The most recent actual ‘dry’ year for which comparative data are available is 1990. It is estimated that the dry year requirements for the 1990 land use would have been 148 × 10 6 m 3. Although farmer demand, actual abstractions and crop requirements are not necessarily the same, irrigation survey returns to the Government indicated that 134 × 10 6 m 3 were actually applied, and the NRA estimated from meter returns that 138 × 10 6 m 3 were abstracted. It is noted, however, that some abstraction restrictions were in force, the scope of the data is slightly different and all figures contain inaccuracies. Potential applications for improving irrigation demand management and water conservation at regional and catchment levels are discussed with reference to two contrasting regions.