Guest Editors' Introduction to Water and Rivers in the South (Part 2)

Issue 2

The first part of this special issue on Rivers and Water in the South showcased some of the innovative geography research being done on the region's diverse river systems. In Part 1, Hess et al. (2024) developed and tested novel applications of UAV technology to measure the distribution and volume of large wood, a geomorphologically and ecologically important element of floodplains such as those found in their study area in the southern Missouri Ozarks. Another study in the Missouri Ozarks, this one by Owen et al. (2024), used several decades' worth of aerial imagery to measure planform change and identify disturbance zones associated with historical land-use changes on the Big River. Dobbs and Styers (2024) used Light Detection and Ranging (LiDAR) data to identify locations of rivercane breaks in western North Carolina, finding that protected areas are vital for the conservation of this endangered and culturally significant vegetation type. Finally, Mossa et al. (2024) examined the vegetative recovery of sand bars and the effectiveness of willow plantings for restoration of sand bars on Florida's Apalachicola River that were disturbed by decades of dredging and snagging operations. While these papers varied in their goals, methods, and study sites, they each demonstrated in their own way the complexity of river systems in the South and how these rivers are affected by the interactions between physical, biological, and human systems.

Here, in Part 2 of the special issue on Rivers and Water in the South, the scope expands to include not only the biophysical processes governing river systems, but also an increased emphasis on the significance of water resources for society. One of the ways in which water resources benefit society is through dams, which generate hydroelectric power and assist in flood control. However, dams also bring some negatives to the environment. As dams have aged, lost their original purpose, develop more risks, and impair rivers, removing dams has become more common for restoring riverine ecosystems as the ecological benefits of a removal can outweigh the ecological costs and those of maintaining an aging infrastructure. Since the turn of the century, over 2000 dams

Map of the study sites of the research projects presented in this special issue

have been removed in the United States (American Rivers, 2023), with the numbers removed generally increasing over time, but less than 10% of removals have been studied (Bellmore et al. 2017).

In their paper "Geomorphic Response to the Removal of the Ward's Mill Dam on the Watauga River, North Carolina," Platt et al. (this issue, Figure 1) are amongst the few to investigate channel response to dam removal in the South, specifically in the Blue Ridge province in Southern Appalachia. They studied the removal of the 6-m high Ward's Mill Dam by identifying changes in channel form, analyzing bed sediment characteristics, and quantifying rates of volumetric evacuation and deposition in upstream and downstream reaches. Dam removal took four days, from May 13 to 16, 2021, and fieldwork began the next day. Flows removed nearly 30% of the sediment in the first five days and transported another ~40% during the following 100 days with about one-fifth to one-third of the sediment stored within 200 m downstream of the dam. The authors found that transport of formerly impounded sediment in downstream reaches translated as a dispersive process, as opposed to a wave, and that more than a year following dam removal, previous bed textures of cobble remain buried by gravel-sized sediments within one kilometer downstream. Knowledge of stream behavior post dam removal has implications for management of biological communities.

Water quantity, such as floods and droughts, and the quality of water for human consumption and its impacts on aquatic biota are some concerns for scientists, including geographers. Not only have humans allocated water to suit their needs, but human activities impact the water quality as well. Declining water quality, be it through eutrophication or the release of harmful chemicals, impacts...