Reallocating water from canal irrigation for environmental flows: benefits forgone in the Upper Ganga Basin in India
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Reallocating water from canal irrigation for environmental flows: benefits forgone in the Upper Ganga Basin in India Upali A. Amarasinghe • Vladimir Smakhtin • Luna Bharati Ravinder P. S. Malik
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Received: 3 April 2012 / Accepted: 17 August 2012 / Published online: 29 August 2012 Springer Science+Business Media B.V. 2012
Abstract This paper assesses the potential loss of irrigation benefits in reallocating water from irrigation to meet requirements for environmental flows (e-flows) in the Upper Ganga Basin (UGB) in northern India. The minimum requirement for e-flows in the UGB is 32 billion cubic meters (BCM), or 42 % of the mean annual runoff. The current runoff during the low-flow months falls below the minimum requirement for e-flows by 5.1 BCM. Depending on irrigation efficiency, reallocation of 41–51 % of the water from canal irrigation withdrawals can meet this deficit in minimum e-flows. The marginal productivity of canal irrigation consumptive water use (CWU), estimated from a panel regression with data from 32 districts from 1991 to 2004, assesses the potential loss of benefits in diverting water away from crop production. In the UGB, canal irrigation contributes to only 8 % of the total CWU of 56 BCM, and the marginal productivity of canal irrigation CWU across districts is also very low, with a median of 0.03 USD/m3. Therefore, at present, the loss of benefits is only 1.2–1.6 % of the gross value of crop production. This loss of benefits can be overcome with an increase in irrigation efficiency or marginal productivity. Keywords Environmental flows Canal irrigation Consumptive water use Irrigation efficiency Marginal productivity Irrigation benefits
U. A. Amarasinghe (&) International Water Management Institute, South Asia Regional Office, No 401/5 ICRISAT Campus, Patancheru, Hyderabad 502 324, Andhra Pradesh, India e-mail: [email protected] V. Smakhtin International Water Management Institute, Head Quarters, Colombo, Sri Lanka L. Bharati International Water Management Institute, Nepal Office, Kathmandu, Nepal R. P. S. Malik International Water Management Institute, New Delhi Office, New Delhi, India
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1 Introduction Although contentious, allocation of water for the environment in river basins is important and timely (IWMI 2007; Forslund et al. 2009). It is important because river basins are increasingly environmentally stressed due to overexploitation of water resources (Smakhtin et al. 2004). It is timely now, more than ever before, since climate change shall severely impact local water resources and their services (Bates et al. 2008). However, environmental water allocation, especially in developing countries, is contentious, because it is difficult to leave water as environmental flows (e-flows) to keep rivers in desired environmental condition for many reasons (Rafik and Davis 2009; Swainson et al. 2011). The leading argument for this is the ever-increasing demand for water due to increasing population and economic development. Following closel
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