Stephanie S. Day

• PhD
• Professor (Associate) at Verdantas

In landscapes recently impacted by continental glaciation, landslides may occur where topographic relief has been generated by the drainage of glacial lakes and ensuing post-glacial fluvial network development into unconsolidated glacially derived sediments and exhumed bedrock. To investigate linkages among environmental variables, post-glacial lan...

North Dakota glaciolacustrine deposits are susceptible to leaching of sodium sulfate, potentially emerging from the Dakota sandstone. The current work is designed to investigate the effects of sodium sulfate on the consistency limits and fully softened shear strength of cohesive deposits of glacial lake Agassiz, around the riverbanks of the Red Riv...

Virulent genes present in Escherichia coli (E. coli) can cause significant human diseases. These enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC) isolates with virulent genes show different expression levels when grown under diverse laboratory conditions. In this research, we have performed differential gene expression analysis us...

Soils and agriculture are inextricably linked, in the past as well as today. The Pacific islands, which often represent organized gradients of the essential soil-forming factors of substrate age and rainfall, represent excellent study systems to understand interactions between people and soils. The relationship between soil characteristics and indi...

Iron deficiency chlorosis (IDC), a symptom of reduction in chlorophyll and stunted growth, causes a great yield loss in soybean every year in the Midwest, USA and the most efficient method to manage IDC is to plant tolerant cultivars. The assessment of cultivars' tolerance is traditionally performed by visually rating the IDC symptoms based on leav...

Exchange plays a number of roles within societies, including the provisioning of necessary and prestige resources. The elucidation of these different roles requires documenting how different kinds of material were used and how these resources became distributed. These studies are particularly prominent in Polynesia, especially the Sāmoan archipelag...

Successful settlement on Polynesian islands required the alteration of environments, and such alteration produced extensive cultural landscapes. While some of the characteristics of these landscapes are well-established, what drives the spatial and temporal structure of these settlements is not clear across the entire region. Here, we present data...

Near-channel sediment loading (NCSL) is localized and episodic, making it difficult to accurately quantify its cumulative contribution to watershed sediment loading, let alone predict the effects from changes in river discharge due to climate change or land management practices. We developed a methodological framework, using commonly available stre...

Iron deficiency chlorosis (IDC) is the most common reason for chlorosis in soybean (Glycine max (L.) Merrill) and causes an average yield loss of 120 million dollars per year across 1.8×106 ha in the North Central US alone. As the most effective way to avoid IDC is the use of tolerant cultivars, they are visually rated for IDC by experts; however,...

Stone and earthen architecture is nearly ubiquitous in the archaeological record of Pacific islands. The construction of this architecture is tied to a range of socio-political processes, and the temporal patterning of these features is useful for understanding the rate at which populations grew, innovation occurred, and social inequality emerged....

The late 1980’s and 1990’s brought about concerns regarding how cropping and tillage patterns interacted with soil wind erodibility potential of high clay soils in the Red River Valley of North Dakota. Normanna Township in southern Clay County, North Dakota was visually mapped each fall or early spring with regard to low or no protective residue co...

Successful adoption of drone‐based remote sensing depends on changes in sensitivity over vegetation indices (VIs) and growth stage(s). During 2017–2018, experiments were conducted to relate between vegetation indices and corn (Zea mays L.) and sugarbeet (Beta vulgaris L.) yields in western Minnesota. Aerial images were collected using an unmanned a...

Permanent gullies grow through head cut propagation in response to overland flow coupled with incision and widening in the channel bottom leading to hillslope failures. Altered hydrology can impact the rate at which permanent gullies grow by changing head cut propagation, channel incision, and channel widening rates. Using a set of small physical e...

Aerial LiDAR data offers a valuable tool in locating ancient anthropogenic landscapes around the world. This technology is particularly ideal in places where thick vegetation obscures the ground surface, reducing the utility of satellite imagery. On the islands of American Samoa, many interior anthropogenic landscapes remain unsurveyed, largely bec...

Ravines grow through head cut propagation in response to overland flow coupled with incision and widening in the channel bottom leading to hillslope failures. Altered hydrology can impact the rate at which ravines grow by changing head-cut propagation, channel incision, and channel widening rates. Using a set of small physical experiments, we teste...

The availability of lidar datasets has led to several advances in archaeology, notably in the process of site prospection. Some remote sensing practitioners have aimed to create automated feature extraction (AFE) techniques that increase the efficiency and efficacy of identification and analysis. While these advances have been successful, many arch...

While cultural similarities exist throughout Polynesia, environmental variation can lead to variable strategies of subsistence and settlement. This is particularly visible on small islands, where landscape change, both human and naturally induced, can have a profound impact on human communities. Here, we explore environmentally influenced patterns...

In the Minnesota River Watershed near channel erosion is a significant concern to ecologic health and infrastructure safety. Processes like channel widening and bluff erosion have accelerated since the arrival of European settlers, yet it is only recently that action has been taken to better understand these processes and stabilization efforts have...

This study summarizes the impacts of geomorphological processes on human settlement strategies on the island of Ofu in the Samoan Archipelago from island colonization to permanent settlement in the interior uplands (c. 2700-900 b.p.). Previous archaeological research on Ofu has documented a dynamic coastal landscape at one location, To’aga, on the...

Effectively managing and reducing high suspended sediment loads in rivers requires an understanding of the magnitude of major sediment sources as well as erosion and transport processes that deliver excess fine sediments to the channel network. The focus of this research is to determine the magnitude of erosion from tall bluffs, a primary sediment...

Human activities influence watershed sediment dynamics in profound ways, often resulting in excessive loading of suspended sediment to rivers. One of the primary factors limiting our ability to effectively manage sediment at the watershed scale has been our inability to adequately measure relatively small erosion rates (on the order of millimeters...

The Minnesota River Valley was carved by the draining of glacial Lake Agassiz ~13,400 years ago. Up to 85 m of incision along the proto–Minnesota River during this event spawned knickpoints that have been migrating upstream on tributaries, including the Le Sueur River in south-central Minnesota. This trip will explore the evolution of the Minnesota...

Although sediment is a natural constituent of rivers, excess loading to rivers and streams is a leading cause of impairment and biodiversity loss. Remedial actions require identification of the sources and mechanisms of sediment supply. This task is complicated by the scale and complexity of large watersheds as well as changes in climate and land u...

The effects of changes in flow rate on erosion volumes in young incising river systems Rainfall events, and the way in which water drains from the landscape after them, can have an impact on erosion rates in a river system. We are running a series of experiments to test how increased rate of flow either from rapid large rainfall events or more comm...

Like with aerial LiDAR, the many benefits of ground ground-based LiDAR are continuing to be discovered. Ground Ground-based LiDAR offers high high-resolution surveys of vertical features like bluffs and stream banks. When the surveys are repeated and compared, the data can reveal not only the rate of erosion, but in some cases the processes respons...

There is clear evidence that the Minnesota River is the major sediment source for Lake Pepin and that the Le Sueur River is a major source to the Minnesota River. Turbidity levels are high enough to require management actions. We take advantage of the well-constrained Holocene history of the Le Sueur basin and use a combination of remote sensing, f...

Preliminary studies indicate that bluffs contribute 31-80% of the total annual suspended sediment load for the LeSueur River basin. In an effort to improve this estimate and better quantify the types and locations of bluffs contributing the most sediment, various remote sensing techniques are being utilized. Bluff height, steepness, and location we...

Low-relief, tectonically quiescent landscapes are fundamentally important for fulfilling economic and societal needs. In historic times humans have, no doubt, greatly enhanced sediment yield from these landscapes to an extent that is comparable to, if not greater than that from many tectonically active areas, yet they have received little attention...

The Le Sueur River is the primary sediment contributor to the Minnesota River, which is impaired by sediment under the Clean Water Act. The necessary first step toward developing a watershed management plan is identifying sediment sources and sinks throughout the basin. The focus of this study is to quantify the contribution of sediment from differ...