Hydraulic Performance of Geocell-Based Channel Protection Systems for Stormwater Management and Flood Mitigation By Michael Dickey, P.E. (WI, FL, GA, NC), Presto Geosystems Director
cells that are interconnected to form a flexible, three-dimensional matrix that is compatible with a variety of infill options. When used in conjunction with permeable infill options such as engineered fill or aggregate, the system allows stormwater to infiltrate the ground, recharge groundwater supplies, and reduce the risk of flooding. When used in conjunction with impermeable infill such as concrete, the system can be designed to resist very high shear forces for protection against scour and undercutting. Hydraulic Performance Testing of the GEOWEB® Channel Protection System at CSU To evaluate stability threshold conditions and quantify hydraulic forces and infill loss, the GEOWEB Channel Protection System was subjected to a series of hydraulic performance tests at the Hydraulics Laboratory located at the Engineering Research Center (ERC) at Colorado State University (CSU). The hydraulic performance program incorporated a variety of infill materials and geosynthetic products to simulate three different types of channel lining options as summarized in Table 1, and results for each of the major channel lining types are discussed in the sections that follow. Vegetated Channel Protection: Hydraulic Test Results for GEOWEB Infilled with Common Soil After the completion of multiple tests, no instability was observed for the vegetated channel tests, and the system showed no measurable soil loss. Outstanding performance was confirmed for shear stresses of up to 15.9 pounds per square foot (psf) and at average flow velocities of up to 26.5 feet per second (ft/sec). Moreover, at the conclusion of the tests, an extracted soil sample showed vegetative root penetration to a depth of 1.5 inches, with larger roots interacting with the cell wall perforations. Researchers further concluded that as future growth occurs, root interaction can be expected to increase, further improving system stability as the vegetative cover matures over time.
Civil engineers are responsible for designing resilient urban infrastructure that can withstand the impact of natural disasters, extreme weather events, and changing climate patterns. To achieve this, they must pay special attention to stormwater management, which plays a crucial role in preventing flooding, controlling erosion, and maintaining water quality. A vital component of stormwater management is the construction of stormwater channels. The construction of these channels is an essential aspect of promoting the sustainability and resilience of the urban environment by helping communities withstand flooding and facilitating faster recovery from the impacts of severe weather events. Geocells provide a cost-effective and sustainable alternative to traditional channel lining methods and provide some unique advantages. In this article, we will discuss the results of hydraulic tests conducted at Colorado State University to evaluate performance parameters for the use of GEOWEB® Geocells in stormwater channel design and construction. Overview of Channel Lining Options Using GEOWEB® Geocells The GEOWEB® Channel Protection System incorporates an advanced geosynthetic technology known as geocells, which can be used to facilitate a range of channel lining options for stormwater channel construction. The system integrates high-density polyethylene (HDPE)
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csengineermag.com
June 2023
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