Vermilion River Research Articles

Using environmental DNA to elucidate range expansion of bigheaded carp in two Missouri River tributaries in eastern South Dakota

AbstractObjectiveWe used environmental DNA (eDNA) sampling methods to determine the possibility of Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix (hereafter, bigheaded carp) range expansion above barriers to fish movement in two tributaries of the Missouri River in eastern South Dakota.MethodsWe collected water samples above and below two perceived barriers to fish movement: a natural chain of waterfalls in the Big Sioux River and a spillway at the downstream end of a man‐made reservoir in the Vermillion River. We used filtration methods to collect bigheaded carp eDNA from water samples and implemented real‐time quantitative polymerase chain reaction techniques to quantify the amount of eDNA in each sample. A total of 198 water samples and 35 field blanks were collected over 2 years (2021 and 2022).ResultWe detected bigheaded carp eDNA below both barriers in 2021 and 2022 and above the barrier in the Vermillion River during 2022. The median posterior prediction value for detecting eDNA below both barriers was 75.3% (95% credible interval [CrI] = 73.2–77.2%) for Bighead Carp eDNA and 54.2% (95% CrI = 51.5–56.4%) for Silver Carp eDNA. The probability of detecting eDNA above the barriers was significantly smaller: 1% (95% CrI = 0.01–1.10%) in the Big Sioux River and 1% (95% CrI = 0.01–1.30%) in the Vermillion River.ConclusionThe detection of positive samples above the spillway barrier in the Vermillion River provides the first evidence that bigheaded carp may have expanded their range to habitats upstream of their documented range in eastern South Dakota.

Data for Barrera and Ielpi's manuscript "Floodplain organic-carbon dynamics modulated by meandering-channel migration: Vermilion River, Ontario, Canada"

Data for Barrera and Ielpi's manuscript "Floodplain organic-carbon dynamics modulated by meandering-channel migration: Vermilion River, Ontario, Canada"

Managed diversion lead time effects on flood response in a tidal freshwater river

AbstractRiver diversions are a commonly used water management tool throughout the world. Low‐gradient coastal rivers exhibit complex floodplain interactions and are subject to multiple uncertain drivers of future flood risk. The interacting factors make quantification of downstream diversion effects on ambient flood hazards in coastal riverine ecosystems challenging. This article analyzes the effects of a managed ecological diversion (MED) on downstream flood hazards in the flood‐prone tidal freshwater Vermilion River system situated within the Atchafalaya Basin region of Louisiana, USA. A flexible and efficient hydraulic and hydrologic (H&H) modeling setup and counterfactual approach is utilized to develop and analyze 60 simulation scenarios aimed at quantifying the effects of an existing baseflow augmentation program on downstream flood hazards under uncertain future conditions. The analysis demonstrated the significance of preemptive diversion closure on the downstream flood levels in downstream rivers. The role of wetland topography and residual floodplain storage on MED‐induced flood response was also highlighted. A variety of uncertain parameter/forcing scenarios were also evaluated to establish robustness of the findings and to extend the results to more general settings. The study provides insights on downstream flood response induced by MEDs, which are expected to become more prevalent in the future.

Spawning schedule of the imperiled Bigeye Chub (Hybopsis amblops) in Illinois

The Bigeye Chub (Hybopsis amblops) once inhabited streams and rivers in eastern and southeastern Illinois and was thought to be extirpated in the state by the 1970s. However, it was rediscovered in the 1990s from the Little Vermilion River. Today, H. amblops has become widespread and locally abundant in streams of the Wabash River drainage. Currently, little is known about the spawning and reproductive ecology of H. amblops. We conducted a study in the Salt Fork Vermilion River to determine the spawning schedule and microhabitats of H. amblops. Based upon near-weekly samples in May and June in 2019 and 2021, we determined H. amblops spawns in moderate water velocity over sandy gravel substrates when water temperatures are between 18–22 °C. Understanding such ecological traits is necessary for the continued success of H. amblops throughout its range.

Forcing uncertainty and salinity response to dredging in a tidal freshwater river

ABSTRACT This study evaluates the salinity response to dredging under different forcing regimes for a 75-kilometer segment of the flood-prone Vermilion River located in coastal Louisiana, USA. The Vermilion is a tidal freshwater river affected by baseflow regulation, rapid urbanization, and hydromodification. This river also serves as major freshwater resource for the region. An efficient one-dimensional model calibrated previously for stage and water temperature is used to analyse the salinity impacts due to a large-scale flood control dredging. The analysis is based on 200 alternative scenarios based on combinations of uncertain key forcing variables for a critical 13-day intrusion period. The analysis reveals a nonlinear effect on mean salinities and position of the brackish water limit as a function of uncertain forcing variables. Dredging also increases the variability of salinity encroachment effects due to uncertainty in future forcing conditions (e.g. relative sea level rise, baseflow diversion volumes, and salinities at the river mouth). The robust analysis presented here provides a foundation for future model-based assessments of under-studied tidal freshwater rivers and provides key insights for coastal management and sustainability efforts in general.

Molecular evaluation of Plasmodiophora brassicae collections for the presence of divergent genetic pathogen populations before and after the release of clubroot resistant canola

Plasmodiophora brassicae Woronin, the cause of clubroot of crucifers, is now established across most of Alberta, Canada, and has become a major constraint in canola (Brassica napus L.) production. Disease control is achieved mainly by planting clubroot-resistant (CR) canola varieties. The first CR canola in Canada was released in 2009. In 2013, severe clubroot was detected on CR canola in several fields in Westlock County, Alberta, and found to be caused by a ‘new’ strain of P. brassicae termed ‘5X’. These strains have been shown to be genetically distinct from other P. brassicae strains in Alberta (‘population one’) and belong to a second population (‘population two’) of the pathogen. In this study, multiple molecular markers, specific for ‘population two’, were used to determine the occurrence of members of this population over time throughout central Alberta. Two hundred and twenty-four clubroot galls collected from 2005 to 2016 from non-CR canola varieties were examined. The presence of ‘population two’ DNA was detected at low levels in at least 47 of the galls, and it was the predominant population of P. brassicae in another 10 of the samples. These samples were found in Flagstaff County starting in 2008, Westlock County starting in 2009, the County of Vermillion River in 2011 and Red Deer County in 2014. Although relatively uncommon, members of this population were widespread, occurring at locations 168 km apart prior to the release of CR canola.

Assessment of Riverine Dredging Impact on Flooding in Low-Gradient Coastal Rivers Using a Hybrid 1D/2D Hydrodynamic Model

The current study investigates the effect of large-scale channel modifications via riverine dredging on flood dynamics in low-gradient river systems located in inland-coastal flood transition zones. The study site is the Vermilion River in south Louisiana, US, which is characterized by complex flow regimes, reversal and bi-directional flows, presence of large swamps with significant river-swamp interactions, and large volumes of runoff contributions from lateral tributaries. The study aims to understand the interplay of these factors and how they modulate and get affected by different dredging approaches that vary in spatial extent and the modifications introduced to the channel. The study deploys a hybrid, one-/two-dimensional (1D/2D), hydrodynamic model that simulates flow and stage dynamics in the main river and its major tributaries, as well as the flow exchanges with the interconnected swamp system. Overall, the results show that the dredging activities can significantly alter the flow regime in the watershed and affect flow exchanges between the river and the swamp system. In terms of flooding impact, only dredging approaches that are extensive in spatial extent and modifications to channel longitudinal slope can result in sizeable reductions in flood stages. However, these benefits come at the expense of significant increases in the amplitude and inland propagation of the Gulf tidal wave. On the other hand, less-extensive dredging can still provide moderate and spatially limited flood mitigation; however, they further expose downstream communities to increased levels of flooding, especially during more frequent events. The results reveal that while dredging can increase the hydraulic conveyance of the river system, the large runoff volumes delivered by the urbanized tributaries seem to outweigh the added improvement in the in-channel storage, thus reducing the anticipated flood relief. The results suggest that a watershed-centered approach, instead of a riverine-centered approach is needed for flood management in these systems so that the relative benefits and tradeoffs of different mitigation alternatives can be examined.

Modeling response of water temperature to channelization in a coastal river network

AbstractThis study investigates the role of channelization works on water temperatures in the Vermilion River network located in coastal Louisiana, USA. A physically based one‐dimensional (1D) approach is taken for hydrodynamics and heat exchange in the Vermilion River as an initial step toward understanding the cumulative effects of flood control on riverine water quality and aquatic population dynamics. The model performs acceptably well against available measurements for stage (root mean square deviation [RMSD] = 0.27 m, Nash–Sutcliffe efficiency [NSE] = 0.69—mean) and water temperature (RMSD = 1.6°C, NSE = 0.91—mean) for the purposes of scenario evaluation. Alternative forcing scenarios are developed to assess thermal impact sensitivities to dredge‐type channelization under various atmospheric and headwater boundary conditions. The results suggest that river dredging enhances daily temperature fluctuations in the adjacent swamp while reducing thermal variation in the river. Temperature variation and cumulative effects are also analyzed during critical biological periods at daily time scales as increased temperature fluctuation may increase thermal stress, while net cooling (cumulative temperature reduction) may affect reproduction and growth rates of riverine fish populations. The findings are relevant in the management, protection, and restoration of coastal riverine ecosystems and future modeling of the cumulative ecological effect of river channelization measures.

Agricultural Nitrogen Budget for a Long-Term Row Crop Production System in the Midwest USA

In the Midwestern United States, subsurface drainage (commonly known as tile drains) systems have been extensively used for sustaining agricultural production. However, the tile drains have raised concerns of facilitating the transport of agricultural chemicals from the fields to receiving waters. Data from a long-term field experiment in the Little Vermilion River (LVR) watershed of east-central Illinois, USA, shows that the tile drain systems have contributed to increased nitrate N (NO3-N) to the receiving water body, Georgetown Lake Reservoir, over time. We conducted more than 10 years of research on fate and transport of NO3-N in tile drain water, surface runoff and soil N. Corn (Zea mays L.) and soybean (Glycine max L.) were planted in rotation for this watershed. We evaluated N balance (inputs and outputs) and transfer (runoff and leaching) components from three sites with both surface and subsurface flow stations within this watershed, and N budgets for individual sites were developed. Nitrogen fertilizer application (average 192 kg ha−1 y−1) and soil N mineralization (average 88 kg ha−1 y−1) were the major N inputs for corn and soybean, respectively in this watershed. Plant N uptake was the major N output for both crops during this entire study period. Annual N uptake for the LVR watershed ranged from +39 to +148 (average +93) kg ha−1 and −63 to +5 (average −32) kg ha−1, respectively, for corn and soybeans. This data indicates that most of the soil mineralized N was used during soybean production years, while corn production years added extra N in the soil. Surface runoff from the watershed was negligible, however, subsurface leaching through tile drains removed about 18% of the total rainfall. Average NO3-N concentrations of leaching water at sites A (15 mg L−1) and B (16.5 mg L−1) exceeded maximum contaminant level (MCL; 10 mg L−1) throughout the experiment. However, NO3-N concentrations from site E (6.9 mg L−1) never exceeded MCL possibly because 15–22% lower N was received at this site. We estimated that the average corn grain yield would need to be 28% higher to remove the additional N from this watershed. Our study suggests that N application schemes of the LVR watershed need to be reevaluated for better N management, optimum crop production, and overall environmental sustainability.

Effect of Model Setup Complexity on Flood Modeling in Low‐Gradient Basins

AbstractThe flat topography, large natural storage features, backwater effects, and boundary conditions all play different roles in the flood response of rivers in low‐gradient environments. The combined effects of these factors result in frequent episodes of reverse flows, slow recession of flood waters, and complex flow interactions. This study investigates the value of varying degrees of model complexity and setup features on the model ability to reproduce some of the unique flooding characteristics in low‐gradient basins. The study focuses on (1) effect of streamflow routing techniques; (2) effect of incorporating large natural storage areas; (3) effect of model dimensionality; and (4) effect of downstream boundary conditions. The study assessed six different model setups for the Vermilion River in south Louisiana, during a series of flood‐inducing storm events in May–June 2014. A successful simulation of the repetitive reverse flows in the river was only possible after incorporating the large swamp areas within the basin. The slow recession of the flood peaks was accurately reproduced with the use of a two‐dimensional representation in characterizing the swamp areas. The results of this study have implications for understanding flood dynamics in low‐gradient basins, and for guiding the development of reliable flood models that take advantage of available technologies and information without adding unwarranted complexities that require extensive, yet typically unavailable calibration data.

A comparison of three methods to evaluate otter latrine activity

ABSTRACTWe compared methods commonly used in the field of river otter (Lontra canadensis) ecology to estimate visitation rates. We evaluated visitation rates estimated from 2 survey protocols based on video detection—individual visitation rate (IVR) and recording visitation rate (RVR)—and one indirect method based on scat detection—scat visitation rate (SVR). From August 2011 through August 2012, overall scat detection and cumulative video data from 403 camera‐days in 2 latrine sites (River and Pond, at a study site adjacent to the Salt Fork of the Vermilion River near Fairmount, Illinois, USA) located <50 m apart did not reveal monthly or seasonal differences between SVR and video detection methods. We identified positive correlations among the 3 visitation rates and differences between overall IVR and RVR. All 3 methods resulted in peak visitation rates during winter. However, when these data were stratified by latrine site, we found both positive and negative correlations at the River latrine. Our work supports that SVR, IVR, and RVR are valuable methods to estimate otter visitation rates at latrine sites. However, it is clear that even within such a short distance between these 2 latrines, these methods detected differences in site utilization. The significant positive correlation observed between IVR and RVR (overall and by latrine site) suggests these methods can be used interchangeably. Otter detection using SVR may serve as a complementary assessment tool for IVR and RVR. To optimize cross‐study comparisons and interpretation of results, future studies should detail the type of otter detection and visitation rate used, how variables are measured, formulas used in the calculation of the visitation rates, and detailed descriptions of scat counting efforts when using scat as a tool to evaluate otter visitation rates. © 2019 The Authors. Wildlife Society Bulletin Published by Wiley Periodicals, Inc.

Comparison of performance of tile drainage routines in SWAT 2009 and 2012 in an extensively tile-drained watershed in the Midwest

Abstract. Subsurface tile drainage systems are widely used in agricultural watersheds in the Midwestern US and enable the Midwest area to become highly productive agricultural lands, but can also create environmental problems, for example nitrate-N contamination associated with drainage waters. The Soil and Water Assessment Tool (SWAT) has been used to model watersheds with tile drainage. SWAT2012 revisions 615 and 645 provide new tile drainage routines. However, few studies have used these revisions to study tile drainage impacts at both field and watershed scales. Moreover, SWAT2012 revision 645 improved the soil moisture based curve number calculation method, which has not been fully tested. This study used long-term (1991–2003) field site and river station data from the Little Vermilion River (LVR) watershed to evaluate performance of tile drainage routines in SWAT2009 revision 528 (the old routine) and SWAT2012 revisions 615 and 645 (the new routine). Both the old and new routines provided reasonable but unsatisfactory (NSE < 0.5) uncalibrated flow and nitrate loss results for a mildly sloped watershed with low runoff. The calibrated monthly tile flow, surface flow, nitrate-N in tile and surface flow, sediment and annual corn and soybean yield results from SWAT with the old and new tile drainage routines were compared with observed values. Generally, the new routine provided acceptable simulated tile flow (NSE = 0.48–0.65) and nitrate in tile flow (NSE = 0.48–0.68) for field sites with random pattern tile and constant tile spacing, while the old routine simulated tile flow and nitrate in tile flow results for the field site with constant tile spacing were unacceptable (NSE = 0.00–0.32 and −0.29–0.06, respectively). The new modified curve number calculation method in revision 645 (NSE = 0.50–0.81) better simulated surface runoff than revision 615 (NSE = −0.11–0.49). The calibration provided reasonable parameter sets for the old and new routines in the LVR watershed, and the validation results showed that the new routine has the potential to accurately simulate hydrologic processes in mildly sloped watersheds.

Channel Evolution Models as Predictors of Sediment Yield

AbstractThis paper recounts our predictions of channel evolution of the Black Vermillion River (BVR) and sediment yields associated with the evolutionary sequence. Channel design parameters allowed for the prediction of stable channel form and coincident sediment yields. Measured erosion rates and basin‐specific bank erosion curves aided in prediction of the stream channel succession time frame. This understanding is critical in determining how and when to mitigate a myriad of instability consequences. The BVR drains approximately 1,062 km2 in the glaciated region of Northeast Kansas. Once tallgrass prairie, the basin has been modified extensively for agricultural production. As such, channelization has shortened the river by nearly 26 km from pre‐European dimensions; shortening combined with the construction of numerous flow‐through structures have produced dramatic impacts on discharge and sediment dynamics. Nine stream reaches were established within three main tributaries of the BVR in 2007. Reaches averaged 490 m in length, were surveyed, and assessed for channel stability, while resurveys were conducted annually through 2010 to monitor change. This work illustrates the association of current stream state, in‐channel sediment contributions, and prediction of future erosion rates based on stream evolution informed by multiple models. Our findings suggest greater and more rapid sedimentation of a federal reservoir than has been predicted using standard sediment prediction methods.

Assessing landscape and contaminant point-sources as spatial determinants of water quality in the Vermilion River System, Ontario, Canada.

The Vermilion River and major tributaries (VRMT) are located in the Vermilion watershed (4272km2) in north-central Ontario, Canada. This watershed not only is dominated by natural land-cover but also has a legacy of mining and other development activities. The VRMT receive various point (e.g., sewage effluent) and non-point (e.g., mining activity runoff) inputs, in addition to flow regulation features. Further development in the Vermilion watershed has been proposed, raising concerns about cumulative impacts to ecosystem health in the VRMT. Due to the lack of historical assessments on riverine-health in the VRMT, a comprehensive suite of water quality parameters was collected monthly at 28 sites during the ice-free period of 2013 and 2014. Canadian water quality guidelines and objectives were not met by an assortment of water quality parameters, including nutrients and metals. This demonstrates that the VRMT is an impacted system with several pollution hotspots, particularly downstream of wastewater treatment facilities. Water quality throughout the river system appeared to be influenced by three distinct land-cover categories: forest, barren, and agriculture. Three spatial pathway models (geographical, topographical, and river network) were employed to assess the complex interactions between spatial pathways, stressors, and water quality condition. Topographical landscape analyses were performed at five different scales, where the strongest relationships between water quality and land-use occurred at the catchment scale. Sites on the main stem of Junction Creek, a tributary impacted by industrial and urban development, had above average concentrations for the majority of water quality parameters measured, including metals and nitrogen. The river network pathway (i.e., asymmetric eigenvector map (AEM)) and topographical feature (i.e., catchment land-use) models explained most of the variation in water quality (62.2%), indicating that they may be useful tools in assessing the spatial determinants of water quality decline.

Fate of water and nitrate using drainage water management on tile systems in east-central Illinois

Drainage water management (DWM) is a potential edge-of-field technique that is being studied as a method to improve soil water management in agricultural fields, which may reduce nitrate losses to surface waters during the non-growing season. Inline water level control structures were installed on two adjacent tile systems draining a 34ha field located in the Upper Salt Fork of the Vermillion River Watershed in central Illinois to evaluate DWM from 2011 through 2013. The overall objective of this study was to determine the effectiveness of DWM in reducing nitrate losses from fields in a corn and soybean production system in east-central Illinois, as well as to investigate the fate of the retained water. A paired watershed approach was used to determine the impact of DWM on tile flow and nitrate load compared to a control treatment or free drainage (FD) tile system. The entire 34 ha field was under a corn (Zea mays L.) and soybean (Glycine max L.) rotation with continuous no-till. During 2011 and 2012, DWM was able to greatly reduce tile flow compared to the FD tile system. However, based on runoff and nitrate yields from the entire field, there was no measureable reduction in nitrate loss and shallow ground-water wells showed little area of influence in the field (∼2ha). Water from the DWM tile system flowed laterally to the nearby FD tile system, increasing flow and nitrate loss from the FD system. In 2013, when both tiles were under DWM, water was retained and the water table level was increased in a larger area of the field (∼6ha). However, at the end of the experiment when the control stoplogs were lowered the retained water was discharged through the tiles lines with little apparent reduction (10%) in overall water and nitrate loss for the year. Measurements of tile and well nitrate concentrations suggested that nitrate was not denitrified in the shallow groundwater of the field during the three-year study. Nitrate losses were directly proportional to tile flow each year of the study. Retrofitting DWM on an existing tile system was found to have a limited water quality benefit.

An Integrated Moral Obligation Model for Landowner Conservation Norms

ABSTRACTThis study applies an integrated moral obligation model to examine the role of environmental and cultural values, and beliefs in the activation of landowner conservation norms. Data for this study were collected through a self-administered survey of riparian landowners in two Minnesota watersheds: Sand Creek and Vermillion River watersheds. Study findings suggest that collectivistic and biospheric–altruistic values form the bases for the activation of personal norms. Further, beliefs about local responsibility and ability to act influence personal norms to protect water resources. Findings suggest that landowners’ personal norms of water conservation are more likely to be activated by conservation strategies that appeal to biospheric–altruistic and collectivistic values, emphasize adverse consequences of water pollution, highlight water resource protection as a local responsibility, and provide the resources needed to protect water resources.

Analysis of Best Management Practices Implementation on Water Quality Using the Soil and Water Assessment Tool

The formation of hypoxic zone in the Gulf of Mexico can be traced to agricultural watersheds in the Midwestern United States that are artificially drained in order to make the land suitable for agriculture. A number of best management practices (BMPs) have been introduced to improve the water quality in the region but their relative effectivenss of these BMPs in reducing nutrient load has not been properly quantified. In order to determine the BMPs useful for reducing nutrient discharge from a tile drained watershed, a Soil and Water Assessment Tool (SWAT) model was calibrated and validated for water flow and nitrate load using experimental data from the Little Vermillion River (LVR) watershed in east-central Illinois. Then, the performance of four common BMPs (reduced tillage, cover crop, filter strip and wetlands) were evaluated. For BMPs, the usage of rye as cover crop performed the best in reducing nitrate discharge from the watershed as a single BMP, with an average annual nitrate load reduction of 54.5%. Combining no tillage and rye cover crops had varying results over the period simulated, but the average nitrate reduction was better than using rye cover crops with conventional tillage, with the average annual nitrate discharge decreased by 60.5% (an improvement of 13% over rye only).

When to sample: flow variation mediates low-head dam effects on fish assemblages

Low-head dams are a primary source of anthropogenic disturbance to river systems. They have the ability to change rivers from lotic to lentic habitats, affect sediment transportation, connectivity, water quality, linkages with wetlands and the quality of in-stream and riparian habitats. These changes can effect fish community structures and have the potential to alter the success of organisms in the system. However, there is no standard sampling protocol to assess dam impacts under varying flow regimes. The Vermilion River and its tributary, the North Fork Vermilion, are both impacted by low-head dams creating lentic habitats within each system. In October 2012 and May 2013, fish assemblages were sampled using direct current (DC) electrofishing at a total of 12 sites. Community composition at base flow responded strongly to both dams and differed between the two drainages. In sharp contrast, there was no effect of dams or differences between rivers during high flow. To adequately assess dam impacts on fish assemblages, we recommend sampling after base flow has been established. Sampling at high flow will reflect the homogenization of habitats and fish assemblages.

Three Decadal Inputs of Nitrogen and Phosphorus from Four Major Coastal Rivers to the Summer Hypoxic Zone of the Northern Gulf of Mexico

Nutrient enrichment is considered one of the most important causes for summer hypoxic conditions in the northern Gulf of Mexico (NGOM) off the Louisiana coast. While many studies on nutrient inputs from the large Mississippi-Atchafalaya River System have been conducted, little is known about nutrient inputs from other coastal rivers in Louisiana. In this study, we utilized long-term (1980–2009) records on river discharge and nutrient concentrations of four major Louisiana coastal rivers—the Sabine, Calcasieu, Mermentau, and Vermilion—to estimate daily, monthly, and annual inflows of nitrate and nitrite nitrogen (NO3 + NO2), total Kjeldahl nitrogen (TKN), and total phosphorus (TP) into the NGOM. The three-decade-long nutrient inflows from these rivers were analyzed for their seasonal fluctuations, interannual variabilities, and decadal trends. Fluxes of NO3 + NO2, TKN, and TP for these river basins were estimated to assess land use effects on riverine nutrients. Our study found that the four coastal rivers discharged each year a considerably large amount of NO3 + NO2 (total of 1755 t), TKN (12,208 t), and TP (1833 t) into the NGOM, with a peak input of nitrogen during the spring. The Mermentau and Vermilion Rivers, which drain intensive agriculture areas, had significantly higher NO3 + NO2, TKN, and TP concentrations when compared with the Sabine and Calcasieu Rivers, which drain forest-pasture-dominated lands. The fluxes of NO3 + NO2, TKN, and TP from the Mermentau River Basin (156 kg km−2 year−1 NO3 + NO2, 942 kg km−2 year−1 TKN, and 206 kg km−2 year−1 TP) and the Vermilion River Basin (374, 1078, and 360) were much higher than those combined from the Sabine and Calcasieu River Basins (66, 710, and 62). These findings fill a major knowledge gap concerning the quantity and characteristics of nitrogen and phosphorus transport from coastal watersheds to North America’s largest hypoxic zone.

Collection and Application of Outcrop Measurements in Glacial Materials for Geo-Engineering and Hydrogeology along the Vermilion River, East-Central Illinois

Outcrop mapping by close-range photogrammetry was undertaken at three remote sites as part of a study of water resources to improve characterization of glacial sedimentary assemblages and to evaluate the utility of terrestrial remote sensing to supplement routine geologic mapping. Two features were measured from georeferenced stereomodels, clast pavements, and buried channel deposits over a 2-year period along a segment of the Middle Fork of the Vermilion River. Cobble-size clasts, spaced less than 3.28 ft (1 m) apart, form clusters approximately 6.56 to 9.84 ft (2 to 3 m) in length. These clasts compose a semi-continuous pavement between two tills deposited during the Wisconsin Episode. Five of the 26 clusters measured occur within the Tiskilwa Formation. Deposits of coarse- and fine-grained sediments, informally assigned to the Glasford Formation lithostratigraphic unit, fill buried channels that provide an important source of groundwater in east-central Illinois for areas that do not receive water from the Mahomet aquifer. Measurements of buried channels included width, maximum sediment thickness, area, and perimeter. Widths equated to more than half of the outcrop length. Aspect ratios (width: thickness) of the channels are consistent with deltaic distributary systems formed in front of retreating ice margins, and systems having varying interconnectivity. Differences in area: perimeter of the buried channels provide a measure of shape that may partially account for the variation in yields from water wells in this area. Consequently, we postulate that yield could be improved through lateral drilling within the channel or by connecting adjacent channels.