Metropolitan Houston Watershed Assessment: Considering Feedbacks in a Highly Urban Setting

The Metropolitan Houston Regional Watershed Assessment (MHRWA) is a section 729 watershed assessment being conducted by the US Army Corps of Engineers (USACE) throughout the greater Houston area. The overarching purpose of the project is to review existing flood risk management (FRM) infrastructure in the area and opportunities for future projects. In association with FRM projects, there is interest in Engineering with Nature (EWN) and incorporation of natural and nature-based features (NNBFs) where practical. Houston is already the fourth largest city in the US and is continuing to grow. As development continues over the next decades, it is important to be wise about that development and the implemented FRM infrastructure. Herein we present overview of this assessment, observations of existing conditions and future projections, and measures being considered for recommendation and the relative applicability.

Section 729 watershed assessments are relatively flexible conduits for USACE to evaluate water-related issues in a particular study area. Though the focus of this project is FRM (one of the overt USACE business lines), there is latitude for the study team to consider the intersection with other considerations including ecosystem restoration opportunities, water quality concerns, navigation sedimentation, geomorphological concerns, and the social effects of project planning and execution. To that end, the study team has undertaken a review of existing FRM infrastructure and the associated performance, but also a forecast of future conditions from a development and climate perspective. Resilience in Houston is potentially impacted from a climate perspective from both sea-level change and changes in rainfall-runoff. Lastly, given the existing conditions, and future forecast, measures will be evaluated and recommended for various stakeholders (potentially, though not necessarily, including USACE). Houston composes a large geographic area and not all measures are applicable in all areas. Multiple watersheds are 90+% developed at current which naturally lends itself to a different approach than one only 30% developed. Houston will continue to grow; this will ideally occur while preserving as much of the natural geomorphic and ecologic form and function as practical.