OptALL - Optimal Allocation of Water Resources
The software package OptAll has been developed as a decision support tool for real time water allocation. The required components of a decision support system may vary significantly between irrigation systems. A toolbox of component routines will assist in improving the efficiency with which support systems can be put together. OptAll provides important components of such a toolbox.
Background
In many run of river irrigation systems, it is important to be able to distribute available resources equitably, particularly during periods of water stress. Ensuring equitable distribution becomes difficult in systems with complex distribution networks, and in which there is drainage water re-use. The package OptAll has been developed as a decision support tool for real time water allocation.

The required components of a decision support system may vary significantly between irrigation systems. A toolbox of component routines will assist in improving the efficiency with which support systems can be put together. OptAll provides important components of such a toolbox.

The software package
The software package comprises three components:

  • A soil moisture balance model
  • Water allocation optimisation routines
  • A crop yield response model

    It may be applied in its full form, or users may simply use the water allocation optimisation routines as a solver called from their own programs. The soil moisture balance model is used to determine irrigation requirements in real time, and is based on standard water balance approaches. A GUI has been developed for preparation of network definition files, and the entire model can be run from the GUI.

    What it covers
    The fundamental output from the package is the required distribution of available irrigation supplies to minimise the chosen objective function. Two objective functions are available. The function for equitable water allocation is:

    		•   Minimise:

    Where,
    n = number of irrigation schemes
    di = irrigation demand for scheme i
    xi = irrigation supply to scheme i

    There is also a yield based objective function:

    Minimise:

    Where,
    kij= crop yield response factor in block j of scheme i
    n = number of irrigation schemes
    b(i) = number of irrigation blocks in scheme i
    dij = irrigation demand in block j of scheme i
    xij = irrigation supply to block j of scheme i

    The fundamental data requirements are a network description of the irrigation distribution system, that can be achieved through the GUI, and irrigation demands for each irrigation scheme. The irrigation demands can be supplied by the user, or can be computed by the soil moisture balance model. The crop yield based objective function is only available if the soil moisture balance model is being used.

    Contributors
    University of Edinburgh, UK.
    Intended users
    The software is intended for use by irrigation managers, consultants and researchers.

    Click here to run the OptALL pre-processor


    The OptALL pre-processor can be used to set up network files and gives an indication of the potential of the package. It is available at: http://www.dfid-kar-water.net/w5outputs.html and http://www.civ.ed.ac.uk/research/rbw
    For a full CD-ROM version of the software, including manuals, contact:
    Dr Robin Wardlaw, School of Civil and Environmental Engineering, University of Edinburgh, Crew Building, King’s Buildings, Edinburgh, EH9 3JN
    Tel: +44 (0) 1316 505944 Fax: +44 (0) 1316 505736, E-mail: Robin.Wardlaw@ed.ac.uk