Multi Criteria Water Allocation Modelling to Demonstrate the Need of a Comprehensive Water Policy for Sri Lanka

In Sri Lanka, over 30 national institutions compete to obtain access and priority to use water to perform a variety of water service delivery functions. Water sharing problems have created many conflicts among stakeholders. Presently, there is a lack of transparent and verified models for the assessment of water availability, demand and perform water allocation. It appears that the current practice based on weak information combined with stakeholder judgement is considered as acceptable mainly because of the absence of a water policy and regulatory system. The objective of the present work is to perform a multi criteria assessment to compare the priority of water allocation based on the judgement of water experts and then to evaluate the adequacy of same to evaluate the need to establish a comprehensive water policy. Five multi criteria modelling options based on stakeholder perceptions from 11 water user institutions were compared with the order of magnitude of present water use. Available water was first prioritised using the model weights and then reallocated to the three top ranked water users by considering their annual water use. Multi criteria water allocation models with consistent parameters could be developed by using stakeholder perceptions and rational assumptions. Comparative evaluation of model outputs and the order of magnitude water use data showed that any attempts to use stakeholder consultation with water allocation models must be well supported with transparent and verified water availability and demand assessments. Demonstrating that water allocation based on stakeholder opinion alone is not satisfactory, the present work points to the urgent need for Sri Lanka to seek a comprehensive water policy, rules and regulations.