A model for equitable distribution of canal water

Abstract

The equitable distribution of canal water is imperative to ensure social justice as well as crop productivity. In north-west India and Pakistan, water from the tertiary canal (watercourse) is distributed to the farmers through a rotational system of irrigation. In this system the duration of supply to each farmer is in proportion to his holding in the outlet (watercourse) command, without considering the seepage loss. The rate of seepage loss increases with increase in length of watercourse from head to tail. Thus, the farmers in the lower reaches get much less water per unit area than the farmers in the upper reaches. The farmers must be compensated for the seepage loss. Therefore, a model was developed to ensure equitable distribution of water to the farmers located on a watercourse in proportion to their land holdings giving due compensation for the seepage loss. The model is based on the assumption that soil throughout the length of flow is homogeneous and loss through evaporation is negligible. The model developed ensures an equitable distribution of water to the farmers according to their land holdings. A comparison of existing and revised time allocation reveals that the farmers located in the upper reaches were getting more time (up to 12.2 min per unit area), while the farmers located in the lower reaches have been getting less time (up to 28.1 min per unit area). The existing allocation of time of 0.75 h per unit area to all the farmers according to the old rules was revised to 0.546–1.219 h per unit area from head to tail. The conclusions drawn suggest that the strategy developed here should be adopted elsewhere in the existing system of irrigation for equitable distribution of canal water.