HR: 0830h
AN: H41C-1020    [PDF]
TI: Assessing the Erosion Potential of Coal Bed Methane Surface Water Discharges in the Powder River Basin, WY
AU: * Wilkerson, G V
EM: gw@uwyo.edu
AF: Univ. of Wyoming, Dept. Civil and Arch. Engr., P.O. Box 3295, Laramie, WY 82071 United States
AB: The mining of coal bed methane (CBM) in the Powder River (structural) basin (PRB) in northeast Wyoming has been an economic windfall for Wyoming. However, a critical issue in the production of CBM is the removal and disposition of the associated product water. The process of extracting coal bed methane involves drilling a well into a coal seam and then pumping water out of the well. Among other things, the pressure gradient created by pumping water out the well causes the methane to flow towards the well where it is retrieved. As a result of CBM development, many ephemeral streams in the Powder River (structural) basin (PRB) in northeast Wyoming are seeing a significant increase in water discharges. A potential consequence of the increased discharges is accelerated channel erosion. The Wyoming Department of Environmental Quality (WDEQ) issues permits that legally allow CBM developers to discharge CBM water into channels and therefore they must be able to anticipate how much water can be discharged into a channel before there is a significant risk of accelerated erosion. Erosion Potential (EP) Modeler is a GIS based program that was developed to facilitate the calculation of an index that can be used to assess the potential for accelerated channel erosion in response to increased discharges in a channel. In general, EP Modeler was developed to help those responsible for or concerned about watersheds affected by CBM development in the PRB. In particular, EP Modeler was developed to assist WDEQ personnel formulate appropriate management decisions associated with the National Pollution Discharge Elimination System permitting process. EP Modeler estimates pre- and post-CBM development equilibrium channel widths and reports the percent change in width as an index of the potential for channel erosion. Pre- and post-CBM development channel widths are computed as a function of the bankfull discharge and the sum of bankfull discharge and anticipated CBM product water discharge, respectively. Data from field surveys was used to calibrate EP Modeler and data obtained in the future will be used to verify predictions from EP Modeler. Results from EP Modeler indicate that the potential for accelerated erosion because of CBM development is proportional to basin size and that changes in channel width on the order of one to ten percent could occur in the PRB.
UR: http://wwweng.uwyo.edu/civil/research/water/epmodeler.html
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2003 Fall Meeting