Date of Award

May 2021

Degree Type

Thesis

Degree Name

Master of Science

Department

Engineering

First Advisor

Qian Liao

Committee Members

Changshan Wu, Yin Wang

Abstract

Flood is the most frequent natural disaster across the world which causes widespread destruction, loss of life, damage to property and infrastructure. There is a general assumption that beavers can help in flood mitigation by attenuating peak during large flood events though development of numerical model to analysis the impact of beaver dams on flood hydrograph is still uncommon. This study aims to combine beaver restoration strategy with a hydrologic model to assess the impact of beavers in peak flow attenuation. Based on the results of Beaver Restoration Assessment Tool (BRAT) and field survey 42 stream reaches were identified as suitable for beaver dam construction. To evaluate the impact of these beaver dams on the hydrographs of the stream flows, a numerical model was developed in the United States Army Core of Engineers-developed (USACE) Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS). Soil moisture accounting loss method was parameterized, calibrated and validated in HEC-HMS to capture the influence of soil moisture on peak flows. With beaver dams added as “reservoir” components model simulations were conducted with both past storm events and synthetic frequency storms. Four past storm events from the year 2010, 2014, 2018 and 2019 and six frequency events between 10 and 100 year recurrence interval were applied to evaluate the impact of the dams at the eight observed locations (outlet of five sub-basins of the Milwaukee watershed and in three flood zones in the South Milwaukee river sub-basin) . The past storm simulation results showed that at these eight locations, average percentage of peak flow reduction ranged between 11% and 48%; and averaged percentage of volume reduction ranged between 15% and 48%. The frequency storm results showed average flood peak reduction ranged between 6% and 23% though volume reduction is not significant. In can be concluded from the analysis with both past storm events and frequency storm events that restoration of beaver habitats can help in peak flow attenuation.

Download

Share

COinS