8 Worked Case: A Smart Watering System
Consider a campus project to reduce irrigation waste without damaging established plantings. The goal here is to demonstrate a design process, not to present a complete engineered system.
8.1 Frame the problem
Stakeholders include grounds staff, campus finance personnel, visitors, and maintenance technicians. Preliminary needs include predictable watering, manual override, water-use accounting, and safe operation.
8.2 Candidate requirements
- Record commanded valve states with timestamps.
- Provide a manual stop for maintenance personnel.
- Report daily water use within a stated measurement tolerance.
- Remain within an agreed equipment and operating budget.
The actual thresholds and test conditions must be negotiated with stakeholders.
8.3 Evaluate concepts
Compare a simple time-based controller, moisture-sensor feedback, and a weather-informed schedule. Establish criteria for cost, robustness, maintenance burden, environmental benefit, and controllability.
8.4 Prototype and test
Start with a benchtop controller and one valve. Test fail-safe behavior, then expand to a representative outdoor zone. Validate water-use reduction and landscape health over an appropriate interval.
Deliverable: Build a traceability matrix connecting each stated need to a test and an evidence file.
Living chapter. This is an initial working treatment. Derivations, examples, and references will be expanded in future editions.