Date of Award

8-1-2011

Degree Name

Master of Science

Department

Civil Engineering

First Advisor

Chevalier, Lizette

Abstract

Scientific studies have suggested an increase in the frequency and intensity of flooding. The research presented herein is focused on a small watershed, which has experienced intense flooding of a downstream, urbanized area. For emergency response and preparedness, it is pertinent to have the ability to predict intensity and peak flows of a flood. The Town of Dyer, Indiana has been severely impacted by flooding in the last twenty years. A 37.6 square mile watershed begins in a rural section of Illinois with tributaries draining into Plum Creek. The creek crosses into Indiana and becomes Hart Ditch, a straight, narrow, deep channel through the urbanized Town of Dyer. A HEC-HMS hydrologic model was used and calibrated based on USGS gage data. Storm events ranging from short, high intensity to long, intermittent precipitation provided a vast representation of possible scenarios within the watershed. The hydrologic model was paired with an unsteady HEC-RAS hydraulic model to allow for different lateral inflows to the creek providing variations of flow. A comparison between upstream and downstream stream gage readings was utilized to create a working model that predicts downstream water surface elevations for previous real-time storm and hypothetical storms. These conditions were analyzed by two stream gages and a correlation between the two gages was developed. This correlation was used to predict downstream water surface elevations. The correlation was also used to determine the time to crest based on readings at the upstream gage for many different storm events. The ability to know downstream water surface elevations for real-time storm events allows a window of time to implement emergency response in areas where flooding is imminent. The downstream area of concern has known flood elevations that represent various damage levels.

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