NETWORK ANALYSIS APPLICATIONS IN URBAN HYDROLOGY: EXAMPLES FROM ATLANTA

Applied network theory has seen pronounced expansion in recent years, in fields such as epidemiology, computer science, and sociology. Concurrent development of analytical methods and frameworks has increased possibilities and tools available to researchers seeking to apply network theory to a variety of problems. While water and nutrient fluxes through stream systems clearly demonstrate a directional network structure, the hydrological applications of network theory remain under-explored. This presentation covers a review of network applications in hydrology, followed by an overview of promising network analytical tools that potentially offer new insights into conceptual modeling of hydrologic systems, identifying behavioral transition zones in stream networks and thresholds of dynamical system response.

Network applications were tested in two urbanized watersheds in Atlanta, Georgia: Peachtree Creek and Proctor Creek. Peachtree Creek contains a nest of five long-term USGS streamflow and water quality gages, allowing network application of long-term flow statistics. The watershed spans a range of suburban and heavily urbanized conditions. Summary flow statistics and water quality metrics were analyzed using a suite of network analysis techniques, to test the conceptual modeling and predictive potential of the methodologies. Proctor Creek contains a larger nest of shorter-term flow monitoring stations. Storm events and low flow dynamics during Summer 2016 were analyzed using multiple network approaches, with an emphasis on tomogravity methods.

Results indicate that network theory approaches offer novel perspectives for understanding long-term and event-based hydrological data. Key future directions for network applications include 1) optimizing data collection, 2) identifying “hotspots” of contaminant and overland flow influx to stream systems, 3) defining process domains, and 4) analyzing dynamic connectivity of various system components, including groundwater-surface water interactions.