Water-use efficiency and productivity: rethinking the basin approach

Abstract

This paper provides an analysis of three fundamental flaws in traditional water-efficiency discussions, as exemplified by a recent paper in Water International (Frederiksen and Allen 2011). In particular, we identify major components of inefficient water use typically ignored in theoretical discussions, address the concept of water productivity beyond simple efficiency, and identify important non-water “co-benefits” that are either ignored or discounted in most basin assessments, including improved water quality, increased production, greater reliability, decreased energy demands, and reduced or delayed infrastructure investments. While there are no silver bullets, water conservation and efficiency can play an important role in solving water management challenges.

Keywords:

• water-use efficiency
• water productivity
• basin efficiency
• field efficiency
• water conservation
• co-benefits

Acknowledgements

We thank two reviewers for their thoughtful comments and suggestions. We thank David Brooks for calling our attention to the original Frederiksen and Allen paper and to James Nickum, editor of Water International for giving us the opportunity to respond.

Notes

1. As one reviewer noted, it is possible to explore other changes in productivity associated with different components of this equation, such as: P/Q_W  = P ₁/[Q_CF(P)  + Q_CF(P) ] + P2/[Q_RF  + Q_NRE ] where P = P₁ + P₂. We leave this for another paper.

2. Twenty-four percent of domestic wells in tested in Eastern San Joaquin Valley during 1993-95 had nitrate concentrations above the legal limit of 10 mg/L nitrate-nitrogen (nitrate-N) (Dubrovsky et al. 1998). In 2006, the State Water Resources Control Board sampled 181 domestic wells in Tulare County and found that 40% had nitrate levels above the legal limit, in part precisely because of excess application of fertilizer combined with excess application of water and subsequent groundwater recharge with contaminated return flow (Moore et al. 2010).