Glendale (PDF) - Hazard Mitigation Web Portal - State of California

Natural Hazards Mitigation PlanCity of Glendale, CaliforniaSection 8 – Floodsvulnerability assessments of flooding hazards involve assessing the amount of property in thefloodplain, as well as the type and value of structures on those properties. Once that is done,then a working estimate for potential flood losses can be calculated. The HAZUS software has acomponent to estimate losses due to flooding. Input to the program can include FEMA floodinundation zones, or site-specific engineering studies of flood potential prepared by othersrather than FEMA. Since there are no FEMA maps available for Glendale, nor are there morerecent and city-specific studies that identify potential flooding areas, this loss estimationanalysis was not conducted for this report. Should data be developed in the future to more fullymap this hazard, loss estimation analyses based on that mapping can then be conducted.Community Flood Issues:What is Susceptible to Damage During a Flood Event?The largest impact on communities from flood events is the loss of life and property. Duringcertain years, property losses resulting from flood damage are extensive. Property loss fromfloods strikes both private and public property. Although there has been no significant floodingin Glendale since at least 1969, as described above, localized flooding does occur sporadically.Furthermore, storm damage in the form of drips into structures, amounting to considerableamount of money in the form of repairs, have been reported as recently as with the storms of2005.Property Loss Resulting from Flooding Events: The type of property damage caused byflood events depends on the depth and velocity of the floodwaters. Faster moving floodwaterscan wash buildings off their foundations and sweep cars downstream. Pipelines, bridges, andother infrastructure can be damaged when high waters combine with flood debris. Extensivedamage can be caused by basement flooding and landslide damage related to soil saturationfrom flood events. Most flood damage is caused by water saturating materials susceptible to loss(i.e., wood, insulation, wallboard, fabric, furnishings, floor coverings, and appliances). In manycases, flood damage to homes renders them unlivable.Risk Analysis:Risk analysis is the third and most advanced phase of a hazard assessment. It builds upon thehazard identification and vulnerability assessment. A flood risk analysis for the city of Glendaleshould include two components: 1) the life and value of property that may incur losses from aflood event (defined through the vulnerability assessment); and 2) the number and type of floodevents expected to occur over time. Within the broad components of a risk analysis, it ispossible to predict the severity of damage from a range of events. Flow velocity models canassist in predicting the amount of damage expected from different magnitudes of flood events.The data used to develop these models is based on hydrological analysis of landscape features.Changes in the landscape, often associated with human development, can alter the flow velocityand the severity of damage that can be expected from a flood event. Using GIS technology andflow velocity models, it is possible to map the damage that can be expected from flood eventsover time. It is also possible to pinpoint the effects of certain flood events on individualproperties. At the time of publication of this Plan, data was insufficient to conduct a riskanalysis for flood events in the city of Glendale.However, the current mapping projects will result in better data that will assist inunderstanding risk. This Plan includes recommendations for building partnerships that willsupport the development of a flood risk analysis in the City of GlendaleManufactured Homes:Statewide, the 1996 floods destroyed 156 housing units. Of those units, 61 percent were mobile2006 PAGE 8- 21