Z-03 Countywide Level of Service Analysis

Z-03 Countywide Level of Service Analysis

Last Modified: 07/20/2020 01:37 PM


Recent Actions

May 19, 2020 - Harris County Commissioners Court approved new Bond ID added to the 2018 Bond Program List.

April 28, 2020 - Harris County Commissioners Court approved a $1.16 million agreement with an engineering firm in support of this project.

April 7, 2020 - Harris County Commissioners Court approved a total of $2,400,000 in agreement for engineering and related consulting services.

September 24, 2019 – Harris County Commissioners Court approved negotiations with engineering firms to conduct a countywide Level of Service analysis.

What is a level of service analysis?

This countywide planning project, funded through a Community Development Block Grant – Disaster Recovery (CDBG-DR), will determine how much stormwater each existing channel in Harris County can carry before it overflows its banks and begins to affect nearby structures. The flow carrying capacity is referred to as level of service.

Harris County maintains approximately 2,500 miles of bayous and tributaries that are essentially responsible for draining all of Harris County. About 1,300 miles of channels have been studied using computer models for FEMA regulatory floodplain mapping, but approximately 1,200 miles of streams have not been studied to determine their level of service. This planning project will study Harris County’s channel system using computer modeling and the results will allow us to define the level of service of every channel within the jurisdiction of the Flood Control District.

What will the analysis help us understand? 

The project will use new topographic data, acquired in 2018, to define the channel's physical characteristics. The analysis will also use rainfall totals guidelines as seen in the recently released NOAA Atlas 14 document. The Flood Control District will build computer models to measure the channel flow carrying capacity and the results will be used to determine how much flow each channel segment can handle before overflowing. The channel segments will be color coded on a map to visually represent the findings of the analysis.

How will we use the information yielded from the analysis? 

The results of the analysis will be used to identify segments of channels that need to be improved in order to carry a consistent amount of stormwater efficiently downstream and ultimately to Galveston Bay. Identifying the “choke points” or areas of limited capacity will help in determining and prioritizing future projects. The results generated by this planning study will serve as an additional tool for engineers to evaluate the benefits of ongoing bond projects as they are constructed; proposed bond projects that increase the size of a channel and provide storm water detention ponds will be inserted into the computer models so that their effect on the channel level of service can be determined. In addition, the information will be used to determine how much bigger each channel section needs to be in order to provide a desired level of service along with estimates of the additional land cost and construction costs to achieve the desired level of service. 

How long will the analysis take?

The project is anticipated to begin in Fall 2019 and is expected to be complete in the first quarter of 2021.