Speaker: Dr. Jessica Rogers, SSP&A, Environmental & Water Resource Consultants, Boulder
 

Title: The Distributed Drawdown Function: An Analytical Tool for Estimating Effects of Pumping Adjacent to Complex Stream Networks
 

Abstract
Quantifying streamflow depletion is a critical component of riparian resource management; however, direct measurements are not available and thus depletion must be estimated. Analytical models are generally rapid and cost-effective but are limited by assumptions including, typically, oversimplified stream geometry. Numerical models require considerably more data and intensive computation to improve upon analytical estimates. To help bridge this gap, SSP&A has developed the Distributed Drawdown Function (DDF), an analytical tool designed to efficiently estimate groundwater drawdown and stream depletion caused by pumping near complex, meandering stream networks. DDF extends the Theis solution by discretizing stream networks into multiple nodes. The tool solves a system of linear equations to determine the leakage rate at each stream node that results in zero drawdown at the stream boundary. This talk will introduce the theory behind DDF and demonstrate how DDF reproduces traditional analytical drawdown and stream depletion results for directly comparable linear boundary conditions and accurately captures spatial variations for real-world stream networks with arbitrary geometry. An example will be shown for an application of DDF within user friendly map-based interfaces which facilitate the construction of pumping scenarios and visualize spatial and time series outputs. DDF is scheduled to also be freely available to the public as a stand-alone command line tool.
 

Bio
Dr. Jessica Rogers is a water resources and environmental consultant with S.S. Papadopulos & Associates. She specializes in numerical modeling of groundwater systems, with a focus on quantifying exchanges between groundwater and surface-water systems. Dr. Rogers has developed, calibrated and applied numerical models in groundwater basins across the western United States, including the role of lead modeler for the groundwater component of an integrated groundwater/surface-water model developed in support of Texas v. New Mexico in the U.S. Supreme Court.