Final answer:
Diurnal variation is the water-use concept that does not pose a detriment to human health, as it refers to the natural 24-hour cycle of environmental changes and is not a source of pollution. The other options, leachate, combined sewage overflow, and saltwater intrusion, all have negative impacts on water quality and human health. The correct option is d.
Step-by-step explanation:
The water-use concept that does not pose as a detriment to human health is diurnal variation (d). Diurnal variation refers to the natural fluctuations in environmental conditions, such as temperature and humidity, within a 24-hour period. This concept does not directly impact water quality or contribute to water pollution.
In contrast, the other options listed are all associated with negative consequences for water quality and human health:
- Leachate (a) can be a contaminant that results from water percolating through waste material and picking up hazardous substances.
- Combined Sewage Overflow (b) occurs when the volume of waste and stormwater in a combined sewer system exceeds capacity, resulting in the discharge of untreated sewage into water bodies.
- Saltwater Intrusion (c) is a process where saltwater encroaches into freshwater aquifers, leading to the deterioration of water quality and affecting freshwater supplies.
Unlike these detrimental concepts, diurnal variation is a non-polluting natural process that is essential for maintaining ecological balance and does not harm water quality or human health.
Hence, Option d is correct.