Risk Based, Site-Specific, Irrigation Water Quality Decision Support System

This software-based decision support system (DSS) that provides generic and site-specific, risk-based irrigation water quality guidelines for South Africa. The work had been initiated through the Water Research Commission (WRC) and co-funded by the Department of Agriculture, Forestry and Fisheries (DAFF). The DSS had been designed to support two main applications: (i) assessing the fitness-for-use of irrigation water of known composition, and (ii) determining water quality requirements for irrigation users. It had operated using a three-tier framework, where Tier 1 produced conservative guideline assessments with minimal user input, Tier 2 enabled more detailed site-specific analyses using selectable variables (e.g., crop, soil texture, climate station and irrigation management), and Tier 3 had been reserved for specialised ad hoc investigations.

The project had progressed through phased deliverables that included an inception workshop, a literature review, a “technology demonstrator”, stakeholder engagement sessions, development of a fully functional draft DSS, expert testing/evaluation, and final reporting. The DSS had integrated calculation engines and databases and had used open-source development tools (Lazarus for software development and Firebird as the relational database). For Tier 2 site-specific modelling, a simplified version of the Soil Water Balance (SWB) model had been used to simulate soil–crop–climate interactions over multi-year climatic records. Outputs had been presented via printable PDF screens grouped by agricultural production components (soil quality, crop yield/quality, and irrigation equipment), using a four-category fitness-for-use classification (Ideal, Acceptable, Tolerable, Unacceptable).