Big Rock and Welch Creek Flood Study, Kane County, Illinois.

摘要

Big Rock and Welch Creeks are located in southwestern Kane County, Illinois. This area of Kane County is expected to experience development in the coming years; thus an accurate representation of local flood hazards is important. Regulatory floodplain maps now in effect for these streams show floodplain boundaries based on observations of flood events that occurred more than 30 years ago and lack engineering analyses that meet current standards and expectations. The purpose of this project is to better define flood hazards posed by streams in the Big Rock and Welch Creek watershed based on hydrologic and hydraulic analyses of existing conditions. Illinois State Water Survey (ISWS) staff worked with Kane County and community representatives to identify stream reaches for study and the level of study detail for each reach. Hydrologic and hydraulic analyses were conducted and used to delineate floodplain boundaries corresponding to the 1-percent-annual-chance flood, the base flood used by the Federal Emergency Management Agency (FEMA) for regulatory flood protection. Information was generated using spatial datasets and field data. Digital floodplain boundaries and attendant data are stored in the FEMA-prescribed Digital FIRM (DFIRM) database format for ready incorporation in the regulatory maps upon review and approval by FEMA. This study will provide information for floodplain management in both urban and rural areas.