Abstract

Determining upstream/downstream spatial distribution among point sources:Comparison of GIS-based methods
Track: Water Resources
Authors: Ziyan Chu

Quantitative analysis of upstream point sources pollution transported by hydrological flow requires the identification of upstream and downstream linkage. Using the geographic locations of shale gas wells and treatment facilities in Pennsylvania and downstream water quality monitors, this paper is comparing six GIS-based methods to find the point-to-point relationship, and which is better off in picking up the effect of shale gas development on downstream chlorides concentrations. These are: 1).Cost Distance; 2).Flow Length calculation; 3).Watershed Delineation; 4).Comparison of flow length in sub-watersheds; 5).Comparison of elevation in sub-watersheds; 6). USGS Enhanced River Reach File (ERF) flow database as a control set. Results suggest that: 1). Cost distance and flow length calculation perform better when the elevations of downstream monitors are higher 2).Comparison of flow length identifies more point pairs at sub-watershed scale; 3). All top four methods indicate treatment of shale gas waste by treatment plants raises downstream chloride concentrations.