Do water-saving technologies improve environmental flows?

• Published in: Journal of hydrology (Amsterdam) 2014-10, Vol.518, p.140-149
• Main Authors: Batchelor, Charles, Reddy, V. Ratna, Linstead, Conor, Dhar, Murli, Roy, Sumit, May, Rebecca
• Format: Article
• Language: English
• Subjects: Amplification; Conservation; Consumptive and non-consumptive water uses; Environmental flows; Evapotranspiration; Farming; Freshwater; Governance; Hydrology; India; Productivity; Recognition; Water saving; Water use efficiency and productivity; Water-saving technologies
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2013.11.063

•Well-managed water saving technologies (WCTs) can improve water productivity.•When WCTs improve profitability, farmers often increase net consumptive water use.•WCTs tend not to free-up water for other uses such as environmental flows.•In some situations, intensive use of WCTs can reduce environmental flows.•A decision-support tool is proposed for identifying these problematic situations. Water saving and conservation technologies (WCTs) have been promoted widely in India as a practical means of improving the water use efficiency and freeing up water for other uses (e.g. for maintaining environmental flows in river systems). However, there is increasing evidence that, somewhat paradoxically, WCTs often contribute to intensification of water use by irrigated and rainfed farming systems. This occurs when: (1) Increased crop yields are coupled with increased consumptive water use and/or (2) Improved efficiency, productivity and profitability encourages farmers to increase the area cropped and/or to adopt multiple cropping systems. In both cases, the net effect is an increase in annual evapotranspiration that, particularly in areas of increasing water scarcity, can have the trade-off of reduced environmental flows. Recognition is also increasing that the claimed water savings of many WCTs may have been overstated. The root cause of this problem lies in confusion over what constitutes real water saving at the system or basin scales. The simple fact is that some of the water that is claimed to be ‘saved’ by WCTs would have percolated into the groundwater from where it can be and often is accessed and reused. Similarly, some of the “saved” runoff can be used downstream by, for example, farmers or freshwater ecosystems. This paper concludes that, particularly in areas facing increasing water scarcity, environmental flows will only be restored and maintained if they are given explicit (rather than theoretical or notional) attention. With this in mind, a simple methodology is proposed for deciding when and where WCTs may have detrimental impacts on environmental flows.