2017 Spencer Comprehensive Land Use Plan

Spencer, Iowa  2017  Comprehensive Plan

snowmelt, ice jam release, saturated soil, or impermeable surfaces. ▪ River Flood - River flooding is a rising or overwhelming of a tributary or body of water that covers adjacent lands, not usually covered by water; and when the volume of water exceeds the channel’s capacity. Floods are the most common and widespread of all natural disasters, except fire. ▪ Hail Storm - Hail storms are an outgrowth of a severe thunderstorm in which pellets or irregularly shaped lumps of ice greater than one inch (1”) in diameter fall with rain. ▪ Landslide - Landslides occur when susceptible rock, earth or debris moves down a slope under the force of gravity and water. Landslides may be small or large and can move slow or at very high speeds. ▪ Severe Winter Storm - Severe winter weather conditions affecting day-to-day activities can include blizzards, heavy snow, blowing snow, freezing rain, heavy sleet, and extreme cold. Winter storms are common during the months of October through April. ▪ Thunderstorms and Lightning - Thunderstorms are common in Iowa and can occur singularly, in clusters, or in lines resulting in heavy rains, winds reaching or exceeding 58 mph, producing a tornado, or dropping surface hail at least 1 inch in diameter. Lightning is an electrical discharge that results from the buildup of positive and negative charges within a thunderstorm. ▪ Tornado - Tornado is a violent wind characteristically accompanied by a funnel shaped cloud extending down from a cumulonimbus cloud that progress in a narrow, erratic path. Rotating winds can exceed 300 mph. Iowa is in “Tornado Alley”. ▪ Wind Storm - Wind storms are created when extreme winds, typically associated with severe thunderstorms, downbursts or very steep pressure gradients generate excessive and damaging wind speeds and can be responsible for structural and property damage. ▪ Dam Failure - Dam failure is the uncontrolled release of impounding water resulting in downstream flooding, which can affect life and property. Flooding, blockages, landslides, lack of maintenance, improper operation, poor construction, vandalism or terrorism can all cause dam failures. ▪ Levee Failure - The failure of a levee may be attributed to the structural integrity of a wall, dike, berms, or elevated soil by erosion, piping, saturation or under seepage resulting in water to inundate normally dry areas. ▪ Grass and Wildland Fires - A grass or wildland fire is an uncontrolled fire that threatens life and property in either a rural or wooded area. Grass and wildland fires can occur when conditions are favorable (drought), or they can occur from other natural occurrences (lightning strikes). HAZARD MITIGATION RISK ASSESSMENT RESULTS Clay County has a multijurisdictional hazard mitigation plan for the entire county, with individual sections with city specifics. The overall hazard rankings for Clay County may be different from any of the cities located within. The overall county overview is the average of the rankings for all the cities included and how they ranked each hazard. Below are the hazard risk rankings for the City of Spencer. Implementation of measures to reduce the risk of these hazards will be based on social acceptability, technical feasibility, administrative capacity, political willingness, legal authority, economic benefits, and environmental compatibility. While these factors will be addressed more specifically in the

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NW Iowa Planning & Development