Landscape Architect & Specifier News

JAN 2018

LASN is a photographically oriented, professional journal featuring topics of concern and state-of-the-art projects designed or influenced by registered Landscape Architects.

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• Schlumpberger Consulting Engineers (civil engineering) • Hydmet, Inc. (hydrologic analyses) • GeoServ and Streamwise (stream geomorphologic analyses) • GeoGraphics Unlimited and Erica Fielder Studio (MP document preparation and interpretive plan) • The city brought in Michael Baker International and ECORP for environmental compliance of the California Environmental Quality Act (CEQA), National Environmental Policy Act (NEPA) and regulatory permits. The flood reduction design solution developed by THA involved taking advantage of the incised condition of Yreka Creek to construct a new accessible floodplain at the lowered level of the creek. [Editor's note: "Incised" simply refers to a waterway that has cut through sediment or bedrock, leaving the riverbed now even lower in relation to the floodplain.] Many urban streams are incised due to increased peak flows from impervious surfaces. Raising or rerouting the channel to reaccess its historic floodplain is not possible since the floodplain has already been built-out. Top, Right: A 25-year flood event occurred in Yreka in 2005, resulting in $1 million in property damage and claiming the life of a young woman who was swept away. A flood one foot higher and the houses in the photo (upper right) would have been flooded. That flood was the catalyst to include methods of flood hazard reduction in the Yreka Creek Greenway master plan. PHOTO: JERRY MOSIER, SISKIYOU GARDENS, PARKS AND GREENWAYS ASSOCIATION (SGPGA) Bottom, Right: This is the existing FEMA 100-year flood zone along a portion of Yreka Creek next to Interstate 5. IMAGE FROM GOOGLE EARTH; GIS OVERLAY BY NATURAL RESOURCE GEOSPATIAL January 2018 53

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