Proposal Defense: John Gunnell

“Surveying Reservoirs of the U.S. Piedmont for Records of Sediment Yield Response to Urbanization from the Mid-20th Century to Present” In the near future, population growth in the U.S. will tend to be in and around cities.  The changes in land use and land cover accompanying this urbanization are expected to increase suspended sediment yields in watersheds, ultimately leading to the impairment of water resources.  Given the rates of population growth around urban centers, this may be troubling news indeed.  Unfortunately, it is difficult to predict the extent of this impairment due to the compounded complexity one encounters when human and natural systems are combined.  This proposed study takes an empirical approach, looking at the past to make sense of the future.  First, we will discuss our recent research using sediment flux records spanning the years 2000-2012 for 52 watersheds within the Piedmont, a rapidly urbanizing region in the southeastern United States.  Then, we will propose further research requiring a survey of sedimentation rates in several Piedmont reservoirs.  A combination of bathymetric survey and sediment geochronology will be employed and compared to the USGS database of reservoir sedimentation (RESSED), yielding multiple independently-derived data sources for method validation.  Reservoir sedimentation will act as a proxy for suspended sediment yield, and will extend the timeframe of interest back to the mid-20^th century.  This expanded timeline is needed to trace a trajectory of population growth that is comparable to the magnitude of growth we will see in the coming years.  Population growth’s exponential trend forces us to look twice as far into the past to see half as far into the future.