Agricultural Water Management (Sep 2023)
Improving equity in demand-driven irrigation systems through a rights-preserving water allocation mechanism
Abstract
Allocation mechanisms for irrigation water distribution are largely categorized into demand and supply based methods. Traditional supply-based mechanisms are built on the notion of equitable distribution, where the water rights of each farmer determine their entitlement of irrigation water. However, many studies show that these mechanisms often result in inefficient utilization and wastage of surface water. On the other-hand, the development of smart, ICT driven technologies have ushered-in the age of demand based delivery, which ensures an optimal utilization of water, based on some selected objective. These allocation schemes, while rapidly being adopted in a multitude of irrigation systems worldwide have been shown to result in inequitable water distribution, and special measures need to be taken to protect vulnerable farmers in the system. In this paper, we present a demand-driven allocation scheme that incorporates an initial entitlement for each farmer to ensure equitable water allocation. The allocation mechanism has two stages: first, initial allocation of surface water based on individual water rights; second, a demand-based distribution coupled with an auction-based pricing mechanism. The initial allocation from the first stage may be adjusted in the second stage if the corresponding farmers do not require water at that point in time. After the mathematical formulation of the allocation scheme, we simulate its implementation for a selected irrigation district in the central Punjab region of Pakistan. Results from exhaustive numerical simulations show that the proposed mechanism improves performance with respect to socio-hydrological metrics such as equity, reliabili‘ty, compliance and consistency. Due to the demand-based reallocation stage of the proposed mechanism, this increase in performance does not come at the cost of degraded utilization of irrigation water as compared to a purely demand-based allocation scheme.
