Detention and retention in stormwater management represent two distinct approaches with unique functions and benefits. .
Detention systems primarily focus on temporarily holding stormwater runoff to control its flow and mitigate peak discharge rates, thus reducing the risk of flooding and erosion downstream. These systems are particularly effective during intense rainfall events when the volume of runoff exceeds the capacity of natural drainage systems. By temporarily storing excess water, detention systems help to regulate the flow and prevent overwhelming downstream infrastructure.
Retention systems aim to capture and utilise stormwater on-site, promoting infiltration, groundwater recharge, and the reuse of water resources. By retaining runoff within the landscape, these systems offer multiple benefits, including improved water quality, enhanced soil moisture, and reduced demand on municipal water supplies.
Retention techniques such as bioretention and underground storage complement detention systems by providing additional opportunities for stormwater management and environmental enhancement.
When implemented together, detention and retention strategies create a comprehensive approach to stormwater management that addresses both quantity and quality concerns.