Improving water use efficiency is important because it results in making more water available either for productive use, or to meet environmental needs. Efficiencies can be generated in field applications, through farm delivery systems, through district irrigation delivery schemes, and at the catchment scale. These benefits often come at a cost – either financial or increased risk. An example would be accepting more risk by holding less water in reservoirs, based upon favourable seasonal climate forecasts.
Without policy intervention of some kind savings generated by efficiency gains are generally enjoyed by those creating the gains, usually to increase production. While improving WUE can jointly provide production and environmental benefits, policy drivers (eg market intervention or claw-back arrangements) are usually needed to optimise the conversion of water savings into environmental benefits.
Inefficient water use (eg irrigation that generates drainage that is returned to a water-body) is not always detrimental to the environment. The quality of “beneficial losses” may be poor (eg due to salinity or nutrient loads), but the volume of water generated can provide an environmental service. Losses with an overall negative impact are referred to as “non-beneficial losses”.
Water use efficiency is hard to measure. It is extremely variable spatially (eg in response to soil types or differing irrigation rates) and temporally (eg as atmospheric conditions such as wind, temperature and radiation vary, or as soil moisture changes). Responses to this variability that seek more precision also encounter problems – it is hard to be accurate. Understanding these caveats provides important context for the analysis of WUE data.
Understanding efficiencies of different types and at different scales reveals that improvements in efficiency at one scale may come at the cost of reduced efficiency of another sort or at a different scale. A management option that is of marginal performance against one measure of efficiency may be very good against another measure. A number of different efficiency measures are therefore often required to fully appreciate the effectiveness of any production or delivery system, and to make choices with the most overall gain.
Rural Solutions - Irrigation, water management and reclaimed water
SARDI - Water resources and irrigated crops
National Program for Sustainable Irrigation - Irrigation research
CRC for Irrigation Futures - Irrigation research
Irrigation Australia - Irrigation industry links
Water Industry Alliance - Irrigation industry links
SA Murray Darling Basin NRM Board - Irrigation Management Program
SE NRM Board - Irrigation management planning