Researchers studied a pond-wetlands system in Wuhan Zoo, China, to control stormwater pollution. The system effectively reduced pollutants like sediment, organic matter, nitrogen, and phosphorus in runoff water. During a heavy rain event, the system decreased flow velocity and volume, leading to significant pollutant retention. In a medium rain event, all pollutants were captured, preventing any runoff. The system's functions of interception, buffering, and storage helped regulate runoff and reduce pollution in the watershed.