Web-Mapping Application of Flow Runout For Wotus Calculations

A critical impact of understanding the environmental impact of point water discharge is the extents and mapped delineation of its steady state runout, particularly since runout prediction determines if the flow reaches the Waters of the United States (WOTUS). To help with this assessment, the Arizona Department of Water Quality requested that Matrix New World Engineering (Matrix), with assistance from WEST Consultants (WEST), provide a web-mapping application that uses minimal, readily available parameters, to predict the runout from any point in Arizona. Matrix successfully developed this application, which first creates a base flow path by seamlessly combining multiple programs and programming languages, including Leaflet, Calcite Maps, Bootstrap, Esri ArcGIS API JavaScript, Turf.js, jQuery, and the USGS StreamStats Flow (Raindrop) Path algorithm. This overarching delineation is then truncated to a predicted runout path length determined by a closed-form equation developed by WEST. Both the runout application and runout length equation are believed to be the first of their kind.