Abstract: Session E  4:20 pm (Back to Session F)
An Analysis of Geomorphic Monitoring for Harris County Flood Control District K100-00-00 Channel Restoration

Roberto J. Vega III
Harris County Flood Control District
Houston, Texas

Authors: Roberto Vega, Catherine Elliott, Mathew Chastain, Robert Snoza

The Harris County Flood Control District (HCFCD) holds a Phase 1 Municipal Separate Storm Sewer System (MS4) discharge permit for stormwater, administrated by the TCEQ. In accordance with HCFCD’s Storm Water Management Program and mission, channel restoration projects incorporate practices detailed in the District’s draft Natural Stable Channel Design Guideline document whenever practicable.

HCFCD channel K100-00-00 (Cypress Creek) at Meyer Park in North Harris County exhibited characteristics of an unstable channel with signs of adjustment and no connectivity to the floodplain. HCFCD adapted Watershed Assessment of River Stability and Sediment Supply (WARSSS) (Rosgen et al 2006) methodology to design and build the K100-00-00 restoration project. The goal of the project was to improve stability in these 6,992 Linear Feet of channel, which constitutes the study area.

The purpose of this study was to evaluate the effectiveness of Natural Stable Channel Design practices. The methods applied to design are expected to provide results that do not cause additional erosion of the channel banks while maintaining slope and bed material.

The preliminary analysis of HCFCD K100-00-00 fluvial geomorphic monitoring indicates a stable channel in comparison to design. Preliminary data exhibit an increase in bankfull cross sectional area, a decrease in average water surface slope, entrenchment ratio has decreased, and bed material size has increased slightly. Low bank height ratio is unchanged and the high bank erosivity potential also remains high due to the native soils. Although the data is not statistically significant, this snapshot of monitoring events points towards a stable channel classification, one which is not aggrading or degrading.

This presentation will cover the methods for channel restoration project using HCFCD natural stable design guidelines and the results of post- construction monitoring study.