GEOG 256 1nd Edition Lecture 9 Outline of Last Lecture II Urbanization Outline of Current Lecture III Risks of Natural Hazards IV Mitigation V Floods VI Fire VII Landslides Current Lecture Natural Hazards Risk hazard exposure vulnerability Mitigation hierarchy Avoid o Move people valuables away prevent any exposure development Mitigate o Reduce hazard by reducing anthropogenic causes e g preserve slope stabilizing vegetation dust control measures when building o Reduce exposure live work in less exposed areas o Reduce vulnerability Allow less vulnerable uses e g warehouses not apts Apply tougher use engineering and design standards e g prohibit use of hazardous chemicals strengthen structural resistance Improve prediction and warning Compensate Victims o Provide relief insurance reconstruction recreation repopulation Floods Floodplain area susceptible to flooding 100 year floodplain a floodplain with a 1 chance of flooding in any year Floodway narrow area close to a channel stream or wash that mush remain open so flood waters can pass thru and so flood is not made worse downstream by upstream development These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Floodway fringe area in the 100 year floodplain that can be obstructed without causing significant increase in the 100 year flood carried by the floodway Pima Co Regulations National flood insurance program subsidizes private flood insurance for commercial 1 million building and contents and residential property 350 000 in any location Requires local floodplain zoning Pima county zoning o Existing property and repairs are exempted o A use permit from flood control district required for development in special flood hazard areas o The engineer may require special studies and information o No uses are allowed in floodways except parking lots farms open space o In floodway fringe lowest floor of habitable structures must be 1 inch above base flood regulatory flood elevation Non habitable structures and walls can be flood proofed with brick block steel and openings and exits for water o Erosion setbacks of 75 500 feet depending on base flood peak discharge rate cfs for major washes 25 50 feet for minor washes Fire Hazard based fire rating based on slope weather fuel Vulnerability based rating focused on man made features Landslide Debris flow o Torrential rainfall swells streams o Sediment slumps into a raging stream forming a slurry debris flow o The debris flow swells in volume as it picks up additional sediment and trees from the channel and canyon walls o The debris flow emerges from the canyon onto a fan where it damages houses roads bridges etc Sabino Canyon is forever changed o Record flood that swept through July 31 2006 left the treasured site a difficult place Leading causes of death and city related risk factor s Heart disease Cancers breast colon esophagus kidney uterus Stroke Chronic lower respiratory disease Motor vehicle crashes