Urban Stormwater Management PDF

Urban stormwater management  Announcements Quiz 1 : 15 August 2024. Practical 1: 16 August 2024. Test 1: 29 August 2024 (Urban water management, agricultural water management, practicals). One-minute talks every Thursdays. Presentation Outline  Effects of heavy...

Urban stormwater management  Announcements Quiz 1 : 15 August 2024. Practical 1: 16 August 2024. Test 1: 29 August 2024 (Urban water management, agricultural water management, practicals). One-minute talks every Thursdays. Presentation Outline  Effects of heavy rainfall Due to heavy rainwater or smelted snow, ground becomes saturated. Excess water runs across the surface and into storm sewers and road ditches. This water carries debris, chemicals, bacteria, eroded soil, and other pollutants How does stormwater management help? Impervious surfaces such as pavement and roofs prevent precipitation from naturally soaking into the ground. Water runs rapidly into storm drains, sewer systems and drainage ditches. Stormwater infrastructure slows down the surface runoff, allow infiltration into ground Stormwater design and “green infrastructure” capture and reuse stormwater to maintain or restore natural hydrologies. Detaining stormwater and removing pollutants is the primary purpose of stormwater management.  Urban Stormwater management Urban infrastructure expansion during the industrial revolution gave rise to the need for drainage systems to safely remove stormwater. hydrologic models and computational cost- benefit tools for predicting maximum rainfall and the scale of drainage infrastructure. Focus shifted to stormwater runoff quality in the 1980s. Increased runoff was delivering more pollutants to the streams. History of Stormwater Practice Approach to managing stormwater runoff evolved through TWO eras: Pave and drain stream channel and flood protection The Pave and Drain Era  Stream channel and flood protection Stream channel describes river and stream channel engineering undertaken for flood control, navigation, and drainage improvement. Activities that fall into this category include straightening, widening, deepening, or relocating existing stream channels. when a flood occurs, the water will run into these channels, and eventually drain into a river or other body of water. Negative impacts of stream channeling Increase in downstream delivery of pollutants and sediment that enter the water. Create changes in stream velocities Eliminate the function of floods to control channel-forming properties (i.e floodplains, levees) Alter the base level of a stream Increase erosion and sediment load Stormwater management infrastructure - Pervious surfaces - Grey infrastructure - Green infrastructure  Stormwater management infrastructure 1. Pervious surfaces: porous and allow rainfall and snowmelt to soak into the soil. Benefits/functions: - Recharge groundwater resources - Filter out pollutants in the water - Reduce contamination in surface waters like rivers, lakes, and the ocean - Reduce the heat island effect - Reduce the chance of flooding and erosion 2. Grey infrastructure: human-engineered infrastructure such as culverts, gutters, storm sewers/drains, conventional piped drainage Slow the flow of stormwater during rain events to prevent flooding and reduce the amount of pollutants entering waterways. 3. Green infrastructure: encompasses a variety of water management practices, such as vegetated rooftops, roadside plantings, absorbent gardens, and other measures that capture, filter, and reduce stormwater. Mimics natural hydrological processes and uses natural elements such as soil and plants to turn rainfall into a resource instead of a waste Group work: Climate hazards and their effects on urban systems Decreased precipitation (Room 1) Increased precipitation (Room 2) Higher temperatures (Room 3) Sea level rise (Room 4) (Identify effects on the environment , vulnerable urban systems , possible consequences