ABSTRACT The built environment of peninsular Charleston, South Carolina, has been strongly influenced by the ethos of architectural preservation. However, increased frequency of storm and tide-related flooding has been affecting property and public services, and threatens human and environmental health. Management processes for excess water in this urban area must adapt to the challenges resulting from historic development including the fill of tidal creek systems, sea-level rise, and the influence of large storm events on drainage infrastructure. The City of Charleston has adopted several strategies to manage flooding and encourage progressive development. Large-scale drainage improvement projects capitalize on a geologic framework that provides for deep tunnel excavation and drainage system construction. Novel approaches in zoning codes provide some incentives for land owners to use lower impact design techniques in return for more flexible design standards. This field tour will guide participants through this historic city, and will provide a glimpse of the geologic setting, development history, and environmental pressures that have compelled the city’s proactive stormwater management.

Our models show patterns reflecting local fault control on both shoreline regression and river deflections along the Atlantic Coastal Plain. In these models, maximum displacement is assumed to be at the center of a fault, and both uplifts and downwarps are assumed to be of sufficient magnitude to influence surface processes. Models show regional shoreline regression: (1A) without localized uplifts; (1B) with different rates of regional uplift at either end; (1C) without any localized uplifts but with a large river-dominated delta; (2A) with a fault parallel to the shoreline with seaward side down or (2B) with seaward side up; and (3) with a fault perpendicular to the shoreline. Model 1A has consistently spaced parallel shorelines and an absence of river deflections, such as characterizes most of the late Pleistocene coastal plain across Georgia. Model 1B has divergence of shorelines toward and deflection of rivers away from the end with greater uplift. Model 1C has seaward deflections of shorelines with spacing dependent upon rates of sediment influx and removal by coastal processes. Models 2A and 2B represent interruptions of model 1 patterns. Both produce a seaward deflection and wider spacing of younger shorelines on the uplifted side of the fault with associated river deflections toward the margins of the uplift. Both also produce a landward deflection and closer spacing of younger shorelines coupled with convergence of rivers toward the downdropped basin. Model 3 produces a seaward deflection and wider spacing of older shorelines across the uplift associated with river deflections toward the margins of the uplift on one side of the fault. On the other side, there is a landward deflection and narrower spacing of younger shorelines on the downdropped side of the fault where river deflections merge toward the lowest area. In model 3, shorelines are discontinuous and may be difficult to correlate across the fault, and fault length is constrained by resumption of model 1 shorelines seaward of the fault. Model 3 matches patterns in the vicinity of the 1886 Charleston earthquake, South Carolina, with a NW-trending fault of ~50 km length with the NE side up and uplift continuing since the early Pleistocene. Very similar patterns occur in the vicinity of Beaufort, South Carolina, and Wilmington, North Carolina, which suggest other NW-trending faults of comparable or greater length may be present near these localities. Model 2A matches patterns near the Okefenokee Swamp, which suggests that a 100-km-long, N-trending fault may border the east side of Trail Ridge near the Georgia-Florida state boundary. Model 2B was used by previous workers to explain zones of river anomalies in the Carolinas, but those anomalies do not match this model.