Storm water management

Stormwater runoff, from agriculture, natural erosion lands, roadside and construction sites, often contains variety of contaminants, such as bacteria, toxic metals, nutrients causing eutrophication and automobile oils, which harm aquatic environment by lowering the amount of dissolved oxygen, decreasing organism's fertility and even abolishing some species.

An excessive sediment, for example,  in storm water runoff reduce the fresh water usefulness, contaminants, such as notably lead and most of the carbon-based toxic substances such as pesticides and polychlorinated biphenyls (PCB's) tend to adhere strongly to sediment particles in water, where they are transported from roadside into aquatic environment.

Stormwater management is important issue as how to moderates runoff risk through reducing peak flows (see the photo attached)

which indicates that metal concentration in storm water runoff decrease with rain events) by
1. addressing contaminant transport issues
2. characterising storm water runoff

3. estimating contaminant loads

4. designing stormwater improvement basins, online traps and wetlands

5. introducing drainage network flow capacity

6. improving storm water quality.

Storm water runoff management  techniques include

1. stormwater harvest through the use of underground storage tanks or retention ponds

2. infiltration through sustainable pavements (e.g. permeable paving),

3. bio-filtration or bio-retention though natural wetland or artificial wetland.