Vegetative based stormwater control measures (VB-SCMs) attempt to maintain natural hydrologic conditions in urban development. The suitability for two VB-SCMs in Coastal SC (Georgetown, Horry, Charleston, and Beaufort Counties) were investigated: retention-based stormwater wetlands and infiltration based bioretention systems. Two GIS based models (weighted linear combination (WLC), and spatial query (SQ) were developed and compared for determining the suitability of the two VB-SCMs. Although both models identified a very low percentage of areas suitable for either VB-SCMs, the SQ model identified less suitable sites than the WLC. The more stringent criteria and smaller footprint needed for bioretention systems than for stormwater wetlands is most likely why there was better agreement among the models for identifying suitable areas for bioretention systems than for stormwater wetlands. The area required for the two VB-SCMs was a limiting factor and is the primary reason why only 68 % and 48 % of the existing natural wetlands were predicted suitable as stormwater wetlands (WLC and SQ, respectively). The SQ model determines whether a site requires standard construction, while the WLC model helps identify actions needed to construct and maintain certain VB-SCMs successfully. Thus, both models can help the stakeholders identify and properly place VB-SCMs to minimize the impairments. Nevertheless, further studies are required at the field scale to evaluate the suitability of the developed models.

Highlights A floating treatment wetland (FTW) planted with Pontederia cordata reduced the flow-through of viable zoospores. Bacterial communities associated with FTWs that differed in remediation efficacy were characterized. FTWs have the potential to reduce plant pathogen load in water recycled for agricultural irrigation. Abstract. The increased incidence and severity of drought have reduced reliable access to freshwater irrigation sources for nursery and greenhouse plant producers. Many plant producers are now considering onsite remediation and reuse of water captured from irrigation return flow. However, potential contamination of recycled water with plant pathogens, primarily species of Phytophthora, is the primary concern preventing many growers from reusing their water. Floating treatment wetlands (FTWs) consist of plants established on a buoyant structure that floats on the surface of a water body with roots extended down into the water column. FTWs effectively remediate nutrients in agricultural runoff, but their potential to manage plant pathogens was previously unknown. Therefore, our objective was to investigate the potential efficacy of FTWs to manage species of Phytophthora in recycled irrigation water. Amplicon sequencing was performed to observe how the bacterial communities associated with the roots of plants in the various FTWs differed. The research was conducted using a controlled model system. Each model FTW consisted of a 3-m-long plastic trough that contained no plants, Agrostis alba plants, or Pontederia cordata plants. Nutrient-amended pond water continuously flowed through each trough at a set hydraulic retention time (HRT) of 1 h or 4 h. A standard inoculum concentration of Phytophthora nicotianae zoospores in aqueous suspension was added to influent water entering each trough, and zoospore activity in effluent water leaving each trough at predetermined time intervals was monitored with a baiting bioassay. Results from this study demonstrated that controlled model FTWs containing P. cordata plants effectively reduced the movement of viable P. nicotianae zoospores through a channel of nutrient-amended water at a target HRT of approximately 4 h. Movement of viable zoospores through the troughs was not reduced at the higher flow rate of 1 h HRT or for FTWs containing A. alba plants. Furthermore, the roots of A. alba and P. cordata had enriched bacterial communities that differed from one another. The mechanism by which FTWs containing P. cordata plants reduced zoospore activity was not determined; however, it may be due to interception of zoospores by plant roots, effects from plant root exudates, interactions with the root microbiome, or differences in water quality parameters. This is the first published study evaluating the potential efficacy of floating treatment wetlands to manage plant pathogens in irrigation water. Keywords: Ecological remediation, Horticulture, Microbial community analyses, Pathogens, Water reuse.

This study evaluates spatiotemporal relationships between water quality parameters (WQPs), nutrients, suspended solids, and biochemical oxygen demand (BOD) concentrations within an engineered wastewater treatment wetland system in the Georgia Piedmont, USA. We explored factors related to treatment efficiency within a heavily loaded 630-m(2) surface flow wetland system over a 2-yr period. Relationships between temperature, dissolved oxygen (DO), and oxidation-reduction potential (ORP) were observed; relationships were also seen between these WQPs and nutrient concentrations. Because temperature, DO, and ORP affect nitrogen (N) cycling rates, seasonal trends in N forms were evident in the system. Organic N and inorganic/organic phosphorus concentrations correlated with solids concentrations in the vegetated system without exhibiting seasonal trends. Surface water within the vegetated section generally exhibited anoxic conditions, leading to removal of nitrate-N within the system; however, limited mineralization and nitrification occurred, which greatly limited overall N removal. Plant selection and lack of maintenance likely led to high solids and BOD contributions to treatment wetland surface water, which varied substantially between and along monitored transects. Because so few studies have investigated treatment dynamics within treatment wetland cells, focusing solely on influent/effluent characterization, radical spatiotemporal variability may be the norm as opposed to the commonly accepted assumptions of relatively uniform pollutant degradation across treatment wetland cells. This spatiotemporal variability in WQPs underscores the dynamic nature of treatment wetlands and the need for routine maintenance, including sludge removal and plant harvesting.

In this study, we calibrated and tested the Soil Conservation Service Curve Number (SCS-CN) based Modified Sahu-Mishra-Eldo (MSME) model for predicting storm event direct runoff (Q(tot)) and its soil saturation coefficient alpha as a threshold antecedent moisture condition for partitioning into overland surface and shallow subsurface runoff components. The model calibration was performed using 36 storm events from 2008 to 2015 on a 160-ha low-gradient forested watershed (WS80) on poorly drained soil. The model was further validated without cali-bration using data from 2011 to 2015 on two sites [115 ha (Conifer) and 210 ha (Eccles Church)] and from 2008 to 2011 on a third site, the 100-ha Upper Debidue Creek (UDC), all similar forested watersheds on the Atlantic Coastal Plain, USA. The calibrated MSME model was able to accurately predict the estimated Q(tot_pred) for the WS80 watershed, with calculated Nash-Sutcliffe efficiency coefficient (NSE), RMSE-standard deviation ratio (RSR), and percent bias (PBIAS) of 0.80, 0.44, and 16.7%, respectively. By applying the same calibrated alpha value of 0.639 from the WS80 to two other similar poorly drained watersheds, the MSME model satisfactorily predicted the estimated Q(tot_pred) for both the Eccles Church (NSE = 0.64; RSR = 0.57; PBIAS = 28.9%) and Conifer (NSE = 0.60; RSR = 0.58; PBIAS = 21.3%) watersheds, respectively. The MSME model, however, yielded un-satisfactory results (NSE =-0.13, RSR = 2.06, PBIAS = 616.3%) on the UDC watershed with coarse-textured soils, indicating the possible association of the alpha coefficient with soil subsurface texture. Based on the analysis of event rainfall and pre-event water table elevation, and linking them with the calibrated alpha coefficient that describes the proportion of saturated depth in a soil profile, it was found that rainfall was the main determining factor for overland runoff generation. These results demonstrate the MSME model's potential to predict direct runoff in poorly drained forested watersheds, which serve as a reference for urbanizing coastal landscapes in a changing climate.

Investigations of the susceptibility of aquatic plants to species of Phytophthora are limited. Therefore, the objective of this study was to assess the potential susceptibility of six aquatic plant species, frequently used in constructed wetlands or vegetated channels, to infection by five species of Phytophthora commonly found at nurseries in the southeastern United States. In a greenhouse experiment, roots of each plant species (Agrostis alba, Carex stricta, Iris ensata 'Rising Sun', Panicum virgatum, Pontederia cordata, and Typha latifolia) growing in aqueous solutions were exposed to zoospores of each of the species of Phytophthora (Phytophthora cinnamomi, Phytophthora citrophthora, Phytophthora cryptogea, Phytophthora nicotianae, and Phytophthora palmivora). Zoospore presence and activity in solution were monitored with a standard baiting bioassay with rhododendron leaf discs as baits. Experiments were initiated in 2016 and repeated in 2017 and 2018. During the 2016 trials, Phytophthora spp. were not isolated from the roots of any of the plants, but some roots of C. stricta, P. virgatum, and T. latifolia were infected with multiple species of Phytophthora during trials in 2017 and 2018. Presence of plant roots reduced the percentage of rhododendron leaf discs infected by zoospores of four of the species of Phytophthora but not those infected by P. cinnamomi, which suggested that roots of these plants negatively affected the presence or activity of zoospores of these four species of Phytophthora in the aqueous growing solution. Results from this study demonstrated that certain aquatic plant species may be sources of inoculum at ornamental plant nurseries if these plants are present naturally in waterways or used in constructed wetlands treating water flowing off production areas, which could be of concern to plant producers who recycle irrigation water.

Undeveloped forested wetlands in the valleys of coastal plain rivers can play a large role in storing floodwater and attenuating river flooding. In the lower Pee Dee, Little Pee Dee, and Lynches Rivers, these wetlands played a large role in mitigating downstream flooding following Hurricane Florence. Wetland forest flood mitigation was most effective for large flows in the Great Pee Dee River, where flooding on former river terraces determined the course of overbank flow and the potential storage of floodwaters. Floodwater storage and attenuation of water level were less effective if larger flows were limited to the Little Pee Dee River. Large rains prior to Hurricane Matthew, and to a lesser extent Tropical Storm Bertha, caused the forested wetland to be a source of additional flow, although with little increase in peak stage.

Over past years, extreme tropical storm events along the North and South Carolina coasts—and subsequent river flooding—have warranted the need for a better understanding of the hydrologic response to these events to protect life, property, businesses, and natural and cultural resources. Our focus in this study is the Pee Dee and Waccamaw River systems, which ultimately flow into Winyah Bay near Georgetown, South Carolina. River flows, coupled with the tidal nature of these freshwater systems, are complex and difficult to predict. The objective of the work is to analyze publicly available data from gauging stations along those river system as measured during Hurricanes Matthew and Florence and Tropical Storm Bertha—three uniquely different storm systems that produced varying rainfall depth, duration, and intensity across the Pee Dee Basin. The most important factor in tidal river analysis is the location of the stagnation point , where downstream river flow exactly balances upstream tidal flow. River flow only controls water level upstream of a tidal stagnation point, while ocean tide controls the water level downstream of a tidal stagnation point. An analysis of major flooding following Hurricanes Matthew, Florence, and Tropical Storm Bertha was used to determine the river flows associated with tidal stagnation at each stream gauge active during these storms. A major limitation of the analysis was a lack of flow data for the tidal channels in Georgetown County, which resulted in uncertainty in the flow associated with stagnation and uncertainty in the role played by each of the creeks that connect the Pee Dee and Waccamaw Rivers. Ignorance of the roles of these creeks most limited understanding of the relative importance of Pee Dee and Waccamaw flow to cause stagnation near Pawleys Island and Hagley gauges on the Waccamaw River and the Socastee gauge on the Atlantic Intracoastal Waterway.

This paper examines data from 18 USGS gauges in the lower Pee Dee Basin in an effort to explain the behavior of the flooding following Hurricane Florence (2018) in Georgetown County, South Carolina. Despite record or near-record flooding in all the tributaries to the Winyah Bay estuary, water levels near the city of Georgetown were well below predicted heights. Floodplain storage in the lower Great Pee Dee, Lynches, and Little Pee Dee River valleys stored over 1.2 million acre-feet of floodwaters, delaying peak stage near Bucksport for five days and reducing peak flow into the Winyah Bay tidal river/estuary system by nearly 50%. An unknown amount of flow from the Winyah Bay tidal river/estuary system flowed through the Atlantic Intracoastal Water Way to Little River rather than through Winyah Bay. The resulting freshwater flow to Winyah Bay only moved the point of tidal stagnation (where upstream tidal flow balances downstream freshwater flow) to near Georgetown. Since the city of Georgetown was near the point of stagnation, water level there was driven by ocean tidal height rather than river flood stage. The lack of discharge data from the tidal rivers in Georgetown County prevents evaluation of the importance of each of these factors and will limit efforts to make quantitative predictions of future flooding in the county.

While governments and individuals strive to maintain the availability of high-quality water resources, many factors can "change the landscape" of water availability and quality, including drought, climate change, saltwater intrusion, aquifer depletion, population increases, and policy changes. Specialty crop producers, including nursery and greenhouse container operations, rely heavily on available high-quality water from surface and groundwater sources for crop production. Ideally, these growers should focus on increasing water application efficiency through proper construction and maintenance of irrigation systems, and timing of irrigation to minimize water and sediment runoff, which serve as the transport mechanism for agrichemical inputs and pathogens. Rainfall and irrigation runoff from specialty crop operations can contribute to impairment of groundwater and surface water resources both on-farm and into the surrounding environment. This review focuses on multiple facets of water use, reuse, and runoff in nursery and greenhouse production including current and future regulations, typical water contaminants in production runoff and available remediation technologies, and minimizing water loss and runoff (both on-site and off-site). Water filtration and treatment for the removal of sediment, pathogens, and agrichemicals are discussed, highlighting not only existing understanding but also knowledge gaps. Container-grown crop producers can either adopt research-based best management practices proactively to minimize the economic and environmental risk of limited access to high-quality water, be required to change by external factors such as regulations and fines, or adapt production practices over time as a result of changing climate conditions.

Study region: The study region comprised sixteen stream sites and associated contributing watersheds located in the Middle Pee Dee River Basin (MPDRB) of South Carolina, USA.Study focus: The study was conducted between 2008 and 2010 to quantify how indices of streamflow varied with land cover characteristics analyzed at multiple spatial scales and fluvial geomorphic characteristics of sampled streams in the MPDRB. Study objectives were to relate three indices of streamflow that reflect recent temporal flow variability in a stream, with synoptic stream geomorphological measurements, and land cover type at specific spatial domains.New hydrological insights for the region: Modifications to the landscape, hydrologic regime, and alteration to channel morphology, are major threats to the functioning of riparian ecosystem functions but can rarely be linked to a single common stressor. Results from the study showed that in the MPDRB, wetland cover in the riparian corridor was an important factor, correlating significantly with stream flashiness, channel enlargement, and bed substrate character. It was also shown that a combination of stream geomorphological characteristics when combined with landscape variables at specific spatial scales were reasonable predictors of all three indices of streamflow. The study also highlights an innovative statistical methodology to relate land cover data to commonly measured metrics of streamflow and fluvial geomorphology. (C) 2015 The Authors. Published by Elsevier B.V.