A prototype DSS to evaluate irrigation management plans

Inefficient irrigation strategies delivering an excess of irrigation water can result in pesticides and nitrates being leached to groundwater. However , information on the environmental impact of irrigation strategies is not r eadily available to either growers or the local authority responsible for w ater consents. Improved irrigation practices can be promoted by making this information more readily available in the form of a decision support syste m (DSS) linked to the water allocation process. Under this approach, grower s would be required to submit to the local authority an irrigation manageme nt plan (IMP) which details how they intend to irrigate the crop in each of their management blocks. Sufficient information about the soil, crop, irri gation system and scheduling mechanism would have to be supplied in the IMP to allow it to be evaluated from an environmental impact perspective. The IMP is evaluated by a water allocation consent officer with the help of the decision support system, in which is incorporated environmental impact kno wledge. This DSS integrates a simulation model SWIM, a decision tree, and s cientific soil hydraulic data. The simulation model is used to estimate the likely water requirement of the grower under the IMP. The decision tree re presents expert heuristics on the effects of the various irrigation strateg ies. The soil hydraulic data provides soil hydraulic properties to SWIM and to the decision tree. Local authorities and growers can use the DSS to lea rn about the likely environmental impact and water requirements of each gro wer. (C) 1998 Elsevier Science B.V. All rights reserved.