Question 7 of 7: Water Resource Management, Greenhouse Effect, Noise Pollution and Environmental Principles

Question 7: Water Resource Management, Greenhouse Effect, Noise Pollution and Environmental Principles (20 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Protecting a Drinking-Water Reservoir from Agricultural Nutrient Loading

A watershed-scale source-control strategy — establishing and enforcing vegetated riparian buffer zones along all watercourses draining agricultural land into the reservoir — is the most effective long-term protection: buffers intercept nutrient-laden surface runoff and shallow subsurface flow before it reaches open water, using vegetation uptake, infiltration and sediment trapping to reduce both dissolved N and particulate-bound P loading, and (unlike in-reservoir treatment) address the pollution at its source across the entire contributing watershed rather than only where it has already concentrated in the source water. Sustaining this over the long term additionally requires a watershed source-water protection plan coordinated with upstream agricultural operators (best-management-practice adoption, nutrient-management planning tied to the buffer program), since a buffer network alone can be undermined if upstream fertilizer-application practices continue unchanged.

(ii) Two Pollution Issues Worsened by Global Greenhouse Effect and a Non-Technical Mitigation Principle

1. Ground-level ozone / photochemical smog formation. Higher ambient temperatures driven by the greenhouse effect accelerate the photochemical reactions between NO_x and VOCs that form ground-level ozone, so the same emission inventory produces more smog on hotter days — meaning greenhouse warming worsens urban air-quality outcomes even without any increase in the underlying emissions.
2. Thermal and water-quality stress on surface waters. Rising ambient and water temperatures reduce dissolved-oxygen saturation and accelerate eutrophication (faster algal growth, more frequent harmful algal blooms) in lakes and reservoirs, compounding any existing nutrient-loading problem and further stressing aquatic ecosystems and drinking-water treatability.

Non-technical principle: the polluter-pays principle. Applying a carbon price (or equivalent charge) that makes greenhouse-gas emitters bear the cost of the emissions they generate creates a direct economic incentive to reduce emissions at the source, reducing the underlying driver of both worsened smog formation and surface-water thermal/eutrophication stress — a policy/economic lever rather than a piece of hardware, which is what makes it “non-technical.”

(iii) Two Engineering Methods to Reduce Airport Noise Pollution

1. Flight-path and operational noise-abatement procedures (preferential runway use, steeper approach/departure angles, restricted night-time operating hours). Routing departures and arrivals over less noise-sensitive corridors and away from the residential community, combined with restricted hours for the noisiest operations, directly reduces the noise dose reaching residents without requiring any capital construction.
2. Noise barriers and building-envelope sound insulation for the affected community. Physical barriers/berms along the flight corridor and retrofit sound insulation (upgraded windows, wall assemblies) for the most severely affected residences reduce the noise level actually experienced indoors.

Preferred method: flight-path and operational noise-abatement procedures. Because it reduces the noise generated at (or reaching) the community in the first place rather than only attenuating it after the fact, it protects both indoor and outdoor noise exposure (barriers and insulation help indoors but do little for residents outside), is far lower-cost than large-scale barrier construction or a community-wide insulation retrofit program, and can be adjusted operationally as traffic patterns or community sensitivity change, whereas physical barriers/insulation are fixed, capital-intensive investments.

(iv) Technical Versus Non-Technical Principles to Reduce Combined Sewer Overflow Pollution

Technical principle — source control/best-available-technology (green infrastructure). Installing low-impact development features (bioswales, permeable pavement, distributed stormwater detention) across the sewershed physically reduces the volume of stormwater entering the combined system during a storm event, directly cutting the frequency and volume of overflow events through engineered infrastructure.

Non-technical principle — the polluter-pays principle applied as a stormwater utility fee. Charging property owners a fee proportional to their site’s impervious area (with credits for on-site stormwater management) creates a direct financial incentive for property owners to reduce runoff voluntarily (installing rain gardens, disconnecting downspouts), complementing the engineered green-infrastructure investment with a behavioural/economic lever rather than a piece of hardware.

The comparison shows the two principles are complementary rather than substitutes: the technical (green-infrastructure) solution physically removes stormwater volume from the system, while the non-technical (pricing) principle sustains and extends that reduction by giving every property owner in the sewershed an ongoing incentive to keep contributing to it.