Flood Management Workshop Flood Mi;ga;on Approaches – Group Discussion Photo: A Tweedie Sheraton Guildford Hotel | Surrey Scope and Scale Table 1: Sediment Management Dredging Gravel Removal Nourishment Channelization Purpose: Purpose: Purpose: Purpose: To increase channel To facilitate natural To reduce bank To increase volume for water sediment transport erosion by 'training' conveyance of flow flow (to lower local processes (riverine the channel quickly water level) or coastal) Where is it used? Where is it used? Where is it used? Where is it used? eg. Coquitlam River Presently rare in Presently common Mouth of the Fraser & Vedder River, the Lower Mainland in Lower Mainland for navigation Gravel Reach & (eg. West for tributaries to Seabird Island Vancouver) the Fraser Table 2A: Hard Engineered Infrastructure River and Sea Dikes Flood gates and Pumps Diversions Purpose: Purpose: Purpose: Drainage systems to To protect land area from regulate water levels New channels are created unwanted inundation and between a structurally or existing channels are confine river protected land area and a reinforced convey flow waterbody Where is it used? Where is it used? Where is it used? Tributaries and Presently common in Presently common in subwatersheds to the Lower Mainland Lower Mainland Fraser (eg. Nechako, Chilliwack) Table 2B: Hard Engineered Infrastructure SeaWalls and Floodwalls Rip rap and revetments Dams Purpose: Purpose: Purpose: Large rocky deposits and To protect land area from Structures that store structures used to protect unwanted inundation water (for hydro power or land areas from the (smaller footprint than for flow reduction in main erosive power of waves dike) channel) and high flow Where is it used? Where is it used? Where is it used? Presently common in Kenney Dam on Nechako Presently common in Vancouver, West Van and River, and BC Hydro Lower Mainland North Van facilities Table 3A: Soft Engineered Infrastructure Wetlands, riparian buffer Bioengineered banks & Barrier islands & reefs zones and green shores shorelines Purpose: Purpose: Purpose: Protection of land from Bank stabilization using Preservation and/or erosive power of waves plants to protect land from restoration of riparian, associated with coastal erosion- used in place of foreshore and ecosystem storm surge events rip rap where feasible processes Where is it used? Where is it used? Where is it used? Common (not specific to Presently uncommon in Currently rare in Lower flood management). Green Lower Mainland for Fraser Mainland Shores in Vancouver & River and coast Surrey. Table 3B: Soft Engineered Infrastructure Channel reconstruction and Set-back Dikes reconnection Purpose: Purpose: Re-connecting main channel Allows temporary inundation, to historic meanders and side regulates water level through channels. Creates additional storage storage/capacity Where is it used? Where is it used? Presently uncommon in Lower Presently uncommon in Lower Mainland (eg. Vedder Mainland (eg. Browne Creek Greenway) wetlands) Table 4: Nonstructural approaches (Policy and Regulation) Property Level Floodplain Policy and Management Protection/Floodproofing and design guidelines Purpose Purpose: Reduced vulnerability and To control land use & development to reduce exposure to risk at property vulnerability and exposure to risk level Where is it used? Where is it used? Presently common Presently common throughout Lower throughout Lower Mainland Mainland (eg. Zoning, development permit (eg. Flood construction areas, etc.) levels) Group Acvity • Choose a table by topic of interest • Each table will focus on one approach to flood mi8gaon • Consider S.W.O.C for selected flood mi8gaon approach • Write your ideas onto sckies – place onto flipchart, discuss at your table • 2 rounds of 25 mins discussion (i.e. choose a 2nd topic/table and repeat!) .