Equity in a tertiary canal of the Indus Basin Irrigation System (IBIS)

This paper examines the fairness in distribution of water in a tertiary canal within the Indus Basin Irrigation System. Two methodologies are proposed: canal rating equations, and outlet discharge equations. The methodology is applied to a tertiary canal located in the Punjab, Province of Pakistan. Fairness/equity is expressed quantitatively using the Gini index. There is a difference in the estimated discharge depending on the methodology employed, however as we move along the canal the water allowance does not vary significantly with the distance along the canal. Hence for this particular canal the head-middle-tail inequity often reported and generalized in the literature is not observed. The advantage of a quantitative measure of inequity such as the Gini is exemplified by comparing the Gini with that at the secondary canal and also against itself if the tertiary canal could be operated “as designed”. We introduce two new concepts: systematic and operational inequity. Provided the costs of data acquisition can be reduced this technology has the potential to be scaled up and included in future development investments in large scale irrigation systems. Further work exploring the impact of information on stakeholders needs to be undertaken.