Kansas City, Missouri
an approach we term, “Physical First.” Building on a history of physical modeling experience that now includes construction of nearly a dozen mesoscale models, Water Resources Solutions builds fixed-bed and movable-bed, distorted-scale models of problem river reaches and structures. Our most recent 80-foot by 40-foot model of a reach of Kansas City’s Indian Creek was funded by the U.S. Army Corps of Engineers in partnership with Kansas City, Missouri, (figure below) under task order W912DQ19F1050 (2019-2020).
Using a combination of one-, two-, and three-dimensional computational modeling validated by physical modeling, WRS made several key discoveries regarding flood events that didn’t concur with FEMA models (figure above right), allowing the city to quickly and efficiently test solution alternatives.
Authorized under USACE’s Planning Assistance to States program, this study evaluated the existing condition, possible contributors to, and initial alternative concept-level solutions to flooding events along Indian Creek just downstream of Johnson County. Observed flows during two 2017 flood events conflicted with the predictions of existing FEMA modeling, so this study developed a two-dimensional hydraulic model and a lab-based, 60-foot-by-25-foot 3-D physical model, along with documentation to support each, designed to help the City of Kansas City and other water-resources professionals better define the hydraulic conditions, the area’s unique problems, and possible opportunities to manage the flood risk. The study found that the flood limits predicted by FEMA’s model differed in several important areas from the calibrated 2-D HEC-RAS model. In conjunction with the numerical hydrologic/hydraulic modeling, the physical model is a valuable tool to guide engineers and policymakers to manage flooding issues and flood-related hydromodification. It also provides a valuable physical and tactile tool to educate and involve stakeholders.
WRS’s Physical First approach demonstrates that accurate and cost-effective analysis of complex flow problems like those at the New Bourbon site must regard physical and computational modeling approaches as complimentary, not exclusionary. Any river project, regardless of size, can have significant hydraulic issues that complicate its design. Without a comprehensive analysis, designers must compensate for the resulting uncertainty by creating designs that are unnecessarily conservative and, as a result, more expensive. Worse yet, critical hydraulic issues may be completely missed. It is our experience and opinion that the digital and physical approach—when employed together—provides:
Significantly improved hydraulic designs and
Significantly reduced overall project costs.