Quenching the Thirst: Designing Sustainable Water Systems

Part 1: Engage (Global Context)

In 2018, Cape Town, South Africa, nearly became the first major city in the world to run out of water. This event, known as “Day Zero,” highlights a global challenge: how do we provide clean water to growing urban populations while managing finite budgets and protecting the environment?

Initial Analysis:

1. What are the three biggest challenges a city faces when trying to increase its water supply?
2. If you were a city planner, what would be your “non-negotiable” rule for a new water project?
3. Generate two criteria (success markers) and two constraints (limitations) for a city water project.

Part 2: Explore (Simulation Investigation)

Open the City Water Infrastructure Simulation and prepare to define your project boundaries.

Phase 1: Defining the Problem

Before starting the clock, you must set your “Constraints and Criteria.”

Trial 1: The “Strict Environmentalist” Approach

• Max Budget: $200M
• Target Capacity: 300 ML/day
• Max Environmental Impact: 15 (Strict)

Trial 2: The “Rapid Growth” Approach

• Max Budget: $500M (High)
• Target Capacity: 500 ML/day (High)
• Max Environmental Impact: 80 (Loose)

Reflection: Which of these scenarios is more difficult to solve? Why?

Phase 2: Implementation & Trade-offs

Run Trial 1. Try to reach the 300 ML/day target.

Part 3: Explain (Evaluating Solutions)

1. The Cost of Infrastructure: Compare the “Desalination Plant” to “Pipe Network Repair.” Which gives more water per dollar? Which has a higher environmental cost?
2. Social Constraints: Why did projects like “Wastewater Recycling” or “Conservation Campaigns” lead to negative public approval? How can an engineer account for the “yuck factor” or “social inconvenience” in their designs?
3. Dynamics of Demand: As you advanced each year, what happened to the “Population Demand” line on the chart? Why does an engineering solution need to account for future growth, not just current needs?

Part 4: Elaborate/Evaluate (The Sustainable City Challenge)

Your final task is to design a water system for a city that is both fiscally responsible and environmentally sustainable.

Final Mission Constraints:

• Max Budget: $180M
• Target Capacity: 350 ML/day
• Max Environmental Impact: 30
• Success Metric: Must reach 2032 without violating any constraints.

Engineering Report:

1. System Roadmap: List the specific projects you chose and the order you built them.
2. Justification: Explain how your solution accounts for societal needs (public approval) and environmental health.
3. Refinement: If you failed your first attempt, what specific constraint was the “weakest link”? How did you adjust your strategy to overcome it?