A System Dynamic Approach and Irrigation Demand Management Modelling

Amgad ELMAHDI, CCivil & Environmental Engineering Department The university of Melbourne Uni-3010 Victoria-Australia.
Hector Malano, CRC Irrigation Future, Dept Civil & Env Engineering, The University of Melbourne
Shahbaz Khan, 3 CRC for Irrigation Futures, CSIRO Land and Water, Griffith, 2680 NSW

Abstract

Irrigation, over extraction and land clearing has had major impacts on river environment particularly in the Murrumbidgee river catchment. Increased water demands for agriculture and other uses have led to low flows and changes in the seasonal flow patterns. However, as further growth in water diversions is not possible due to the imposition of the Murray Darling Basin Cap, the need to achieve improved environmental and economic outcomes in allocation policies requires greater efficiency in the use the limited water resources. This paper presents a system dynamics approach to modelling aimed at assisting stakeholders in understanding, predicting and resolving potential water sharing conflicts which have becomes more acute after the imposition of Cap on diversions and new environmental flow rules. A dynamic agricultural network simulation model based on an economic concept was developed to analyse the historical water allocation in the Coleambally irrigation area within the constraints of existing environmental flow rules. This is the first attempt to apply a system dynamics approach for irrigation demand management at the irrigation area level. This network model uses a node-link approach to represent the Coleambally irrigation system. The model is tested using various hypothetical scenarios, such as change the crop areas, environmental flow targets, and water pumping. Furthermore, the model is shown to be a useful policy and planning tool for water supply authorities, policy and decisions makers and irrigators.