The Contribution of Improvements in Irrigation Efficiency to Environmental Flows

Abstract

Increasing irrigation efficiency is often assumed to be a means of saving water and a route to increasing irrigated agricultural production or making water available for other purposes, such as communities, industry or ecosystems. There is a growing body of literature arguing that increasing irrigation efficiency does not reduce consumptive water use in agriculture, implying that no additional water is made available for supporting environmental flows. However, understanding the implications of changes in irrigation efficiency for environmental flows requires assessment at temporal and spatial scales between the daily to seasonal field level analysis of advocates for increasing irrigation efficiency to save water, and the annual basin scale view of some of its critics. When investigated at these intermediate temporal and spatial scales, there may be potential for improvements in irrigation efficiency to mitigate the effects of irrigation on flow timings to an ecologically meaningful extent. In situations where this is possible, in advance of implementing irrigation efficiency programmes, overall water consumption must be limited by an effective water allocation regime that explicitly recognises environmental flow needs in order to prevent expansion or intensification of irrigated agriculture. This paper sets out some of the key issues that practitioners working on environmental flows should consider in order to assess whether or not interventions to increase irrigation efficiency can support environmental flow objectives.

Evaluating Irrigation Efficiency: Toward a Sustainable Water Future for Montana

“…Thus, much of the time, shifts in irrigation technology are not truly How we calculate and understand irrigation efficiency also depends on the spatial scale being considered. 19,20 For example, if water is diverted to a farm from a stream or river and only half of that volume is consumed by crop transpiration, this would traditionally be considered a 50% irrigation efficiency ( Figure 6). However, water not consumed on one farm may pass through surface water or the shallow aquifer to be reused and consumed by crops on a downstream farm.…”

Explaining Water Pricing through a Water Security Lens

“…This analysis provides a different approach to manage water consumption in the sector and focuses on irrigation efficiency. Linstead [15] examined the improvements in irrigation efficiency in environmental services and concluded that allocation of water use should account for actual consumptive use (i.e., irrigation consumption) and should be adaptable to changes over time in irrigation efficiency, i.e., withdrawal or use allocation should decline as the irrigation efficiency increases to prevent overall increases in consumptive use. In this sense, management and planification strategy have a positive effect when water pricing is used as a tool by reducing and regulating consumption growth by MATA modelling, and at the same time ensuring the incentive in the sector remains focused on irrigation efficiency.…”

“…The discussions presented in this paper explain how a utility service provider (private or public) can employ water pricing policies to encourage customers (users) to manage consumption, maintain financial viability, and promote the mindset of water conservation. In this sense, allocations should account for actual water use and could be adaptable to changes caused by other water security strategies-like water use efficiency-to prevent and manage as many aspects as possible of the increase in water demand [15].…”

Combined influences of irrigation diversions and associated subsurface return flows on river temperature in a semi‐arid region

“…While these efforts could be beneficial because more water could be left in streams, related policies need to balance irrigation and ecosystem requirements, including water temperature (Elmore et al, 2016; Grafton et al, 2018; Olden & Naiman, 2010). Environmental flows, which are flow regimes specifically intended to maintain or restore suitable aquatic habitat conditions, are increasingly being used to guide these efforts (Linstead, 2018; Lane & Rosenberg, 2020). However, to successfully implement these policies, water managers need an explicit understanding of the linkages between irrigation activities, streamflow, temperature patterns and ecological impacts under different hydrologic, weather and channel conditions.…”