* The flow vectors are not to scale and have been magnified for illustrative purposes.
ICWW at Socastee, SC
This video shows a portion of the 1-percent-annual-chance event simulation along the Intracoastal Waterway (ICWW) in the vicinity of the Harbor Towne neighborhood. Calculated flood elevation and flow direction data for this area reveal that the influence of the Pee Dee River is the controlling factor during large magnitude riverine flooding events, as the flow vectors depicted in the video can be seen flowing to the north east up the ICWW in opposition to the flow direction observed under typical conditions. The time frame of the video coincides with the point in the simulation when the flow that spills from the Pee Dee River via Bull Creek is at its highest level. This Pee Dee River overflow combines with the Waccamaw River flood wave to yield the highest flood elevations in this area.
This video depicts a portion of the model output from the 1-percent-annual-chance event simulation for the Pee Dee River at Bull Creek (near Bucksport). The low altitude perspective of the video’s point-of-view is intended to provide a close look at the way in which flow that escapes from the Great Pee Dee propagates in both the upstream and downstream direction along Waccamaw River from the vicinity of the confluence with Bull Creek. Flow vectors in the animation highlight this phenomenon, illustrating the complex interaction between the flooding sources within the system.
Waccamaw River at Bucksport Marina
This video highlights the calculated flood data from the 1-percent-annual-chance event simulation along the Waccamaw River at the Bucksport Marina. After water is shown to fill the channel and its immediate vicinity in the early parts of the simulation, the flow vectors are added to show the effect that the Pee Dee River has on this area, causing flood waters to flow northward up the Waccamaw River in opposition to the typical direction of flow. Subsequent to the simulation time period from which this animation was captured, the arrival of the Waccamaw River flood wave eventually causes flood waters to flow in the downstream direction. However, this video is intended to provide a sense of the extents of the impacts of the flow that escapes the Pee Dee River during large magnitude flooding events, reaching areas in the vicinity of the confluence with of the Waccamaw River and the Intracoastal Waterway.
Waccamaw River / ICWW Confluence
This video features an excerpt from the 1-percent-annual-chance event simulation in the vicinity of the confluence of the Waccamaw River and the Intracoastal Waterway (ICWW). Initially, the flow vectors that are depicted in the video illustrate the surprising effect that the Pee Dee River has on this area, causing flood waters to flow northward up the Waccamaw River and ICWW in opposition to the typical direction of flow. This occurs because of differences between the Pee Dee and Waccamaw, with the Pee Dee River more closely resembling a “white water” river and the Waccamaw River being a slower moving “black water” river. As a result, the flood wave on the Pee Dee River will arrive in the area much more quickly than on the Waccamaw River, despite the Pee Dee’s significantly greater contributing area. Later in the video, the flow vector directions can be seen to reverse and flow in the downstream direction as the flood wave from the Waccamaw River moves through the area.
Pee Dee River at Hwy 701
This video highlights the interaction between the Pee Dee River flood wave of the 1-percent-annual-chance event with the Highway 701 crossing near Bucksport, upstream of Bull Creek. Flow vectors depicted in the video illustrate the contraction and expansion of flow as the flood waters pass through the openings in the Highway 701 bridge before escaping overland into the Waccamaw River floodplain. Computations and mapping at this level of detail are possible due to the use of 2D modeling techniques, which can provide significant increases in the level of accuracy in comparison to traditional 1D modeling techniques in certain applications. The advantages associated with these modeling techniques have been beneficial in providing insight into the interaction between the various elements of this river system at a number of locations, improving the overall quality of the results.
Waccamaw River downstream of Conway, SC
This video depicts a portion of the model output from the 1-percent-annual-chance event simulation for the Waccamaw River in the vicinity of Bucksville. Flow vectors and flood depth data are shown as the flood wave moves downstream towards the confluence with the Intracoastal Waterway, with the extents of the inundation steadily increasing until the peak of the flood wave reaches the area. Flooding in this area is shown to generally remain within the vast, but well defined floodplain of the Waccamaw National Wildlife Refuge. However, areas of more distant flooding are observed where flood waters escape and inundate properties in the vicinity of SC Highway 544.