1,720,958 research outputs found
Stream Temperature Modeling of Miller Creek, Duluth, Minnesota
No full textThis report summarizes a modeling study of heat loading and stream temperature in Miller Creek
in support of the MPCA Miler Creek temperature TMDL. The MINUHET surface runoff
modeling tool was used to characterize runoff temperatures for typical residential and
commercial watersheds for the continuous period June 15 to September 15, 2008. These results
were then generalized to the entire Miller Creek watershed using runoff volumes from a SWMM
model developed at SAFL. These simulated runoff temperatures and volumes were then used to
estimate point source heat loadings to Miller Creek for the same time period.
Separate models for wet detention ponds, infiltration basins, and underground stormwater vaults
were used to estimate possible reductions in heat loading from surface runoff. Standard wet
ponds were found to increase overall heat inputs, but reduce peak heat loading rates and
maximum stream temperature increases due to stormwater. The use of wet ponds with bottom
outlet structures and underground vaults gave some reductions in effluent temperature for
smaller rainfall events (< 1 cm), but were of little benefit for larger events. Infiltration practices
give the greatest benefit in reducing temperature impacts of runoff, by direct reduction in runoff
volume, however, widespread implementation of infiltration practices in the Miller Creek
watershed may be difficult.Minnesota Pollution Control AgencyHerb, William R.; Erickson, Timothy O.; Stefan, Heinz G.. (2009). Stream Temperature Modeling of Miller Creek, Duluth, Minnesota. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/115561
Groundwater Recharge in a Coldwater Stream Watershed during Urbanization
No full textUrban development of rural land is of concern for water resources. The quantity and
quality of surface runoff and groundwater recharge can be significantly affected by urbanization.
Base flow in streams and cold water habitat, e.g. for trout, depend on groundwater. If water
recharge to aquifers is reduced, and surface runoff is increased, cold-water fish habitat can be
adversely affected. The change to groundwater recharge resulting from the urbanization of a
rural/natural area in the Vermillion River watershed in Minnesota was investigated. The
Vermillion River is a groundwater-fed designated trout stream at the southern fringes of the
Minneapolis/St. Paul metropolitan area in Minnesota. In this watershed urban development has
encroached on farmland and natural areas in the last 25 years. The process is projected to
continue into the future.
Three studies related to groundwater recharge were conducted: (1) a soil water budget
study to estimate the influence of changed imperviousness and surface vegetation on natural
recharge in a small tributary watershed of the Vermillion River, (2) a trend analysis of
stream/base flow at the USGS stream gauging site on the Vermillion River near Empire, MN,
and (3) a water use study to estimate the influence of imported water on artificial recharge
stemming from.
The results of the first study confirm that the increase in impervious surface area
associated with urban development will decrease annual natural groundwater recharge. The
trend analysis (second study) showed no statistically significant trend in the streamflow record
during the period of 1982 to 2006 even though imperviousness in the watershed increased from
8% in 1984 to 13% in 2005. The third study revealed that groundwater recharge from urban
water supply and drainage systems and from irrigation has more than doubled from 1982 to
2006; it accounts for nearly 10% of annual recharge in the watershed and matches the reduction
in natural recharge predicted by the soil water budget models (first study). The net effect of
urbanization on groundwater recharge, seen in the trend analysis of the Vermillion River base
flow was close to zero.Minnesota Pollution Control AgencyStefan, Heinz G.; Erickson, Timothy O.. (2009). Groundwater Recharge in a Coldwater Stream Watershed during Urbanization. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/117643
Streamflow Modeling of Miller Creek, Duluth, Minnesota
No full textA Storm Water Management Model (SWMM) was constructed to model flow in the Miller
Creek watershed using readily available data. Miller Creek is an urban trout stream flowing
through Duluth/Hermantown, Minnesota. Miller Creek starts near the Duluth Airport, flows
south through Duluth and discharges into the St. Louis River estuary of Lake Superior. In 2008
and near its mouth, Miller Creek had a mean annual flow of 9.1 cfs, a recorded peak flow of 291
cfs, and base flow of less than 0.1 cfs. Despite extensive commercial and some residential
development in the Miller Creek watershed over the past 30 years, Miller Creek has still a
naturally reproducing Brook Trout fishery. The urban development included the filling of
wetlands to create parking lots, the removal of riparian tree cover, and the introduction of storm
water runoff from impervious surfaces (SSWCD, 2001). These changes have lead to elevated
stream temperatures, and consequently Miller Creek was put on the list of impaired waters by the
Minnesota Pollution Control Agency (MPCA) in 2007. The Minnesota Pollution Control
Agency (MPCA) has mandated a temperature Total Maximum Daily Load (TMDL) study. This
report summarizes the development of a Storm Water Management Model (SWMM) for Miller
Creek in support of the TMDL study.
The model simulates continuous time series of stream flow at 15-minute time intervals in Miller
Creek using observed precipitation, stream bathymetry, watershed hydrogeology, and tributary
and storm sewer characteristics as input. The model was calibrated and validated against flow
data from 2008, and is able predict mean flows, peak flows, base flows, and storm runoff
volumes. The SWMM was also used to simulate the effect of a a few stream alteration scenarios
on the streamflows in Miller Creek/Minnesota Pollution Control AgencyHerb, William R.; Stefan, Heinz G.; Erickson, Timothy O.. (2010). Streamflow Modeling of Miller Creek, Duluth, Minnesota. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/117638
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Stream Temperature Modeling of Miller Creek, Duluth, Minnesota
No full textThis report summarizes a modeling study of heat loading and stream temperature in Miller Creek
in support of the MPCA Miler Creek temperature TMDL. The MINUHET surface runoff
modeling tool was used to characterize runoff temperatures for typical residential and
commercial watersheds for the continuous period June 15 to September 15, 2008. These results
were then generalized to the entire Miller Creek watershed using runoff volumes from a SWMM
model developed at SAFL. These simulated runoff temperatures and volumes were then used to
estimate point source heat loadings to Miller Creek for the same time period.
Separate models for wet detention ponds, infiltration basins, and underground stormwater vaults
were used to estimate possible reductions in heat loading from surface runoff. Standard wet
ponds were found to increase overall heat inputs, but reduce peak heat loading rates and
maximum stream temperature increases due to stormwater. The use of wet ponds with bottom
outlet structures and underground vaults gave some reductions in effluent temperature for
smaller rainfall events (< 1 cm), but were of little benefit for larger events. Infiltration practices
give the greatest benefit in reducing temperature impacts of runoff, by direct reduction in runoff
volume, however, widespread implementation of infiltration practices in the Miller Creek
watershed may be difficult.
In tandem with the runoff models, several stream temperature models for Miller Creek were
developed based on the USGS SNTEMP modeling package. The stream temperature models
were used to characterize atmospheric (non-point source) heat inputs to Miller Creek for current
riparian shading conditions and for several mitigation scenarios with increased shading.
Reductions of up to 1 ºC in maximum daily stream temperature were predicted for increasing
shading levels in impacted areas from the wetland upstream of Kohl’s to Miller Hill Mall.
Stream temperatures in Miller Creek were modeled with a focus on low flow (baseflow)
conditions when trout habitat becomes critical. Both the stream temperature models used in this
study and previous studies of the relationship of stream temperature to stream flow suggest,
however, that increasing baseflow, by itself, will not necessarily lead to reductions in stream
temperature. The temperature of Miller Creek was found to be relatively sensitive to air
temperature, i.e. a 1 ºC increase in air temperature led to a 0.6 ºC increase in stream temperature.
This sensitivity is likely due to low groundwater inputs, which tend to buffer diurnal and
seasonal changes in air temperature. This suggests that Miller Creek, and perhaps North Shore
streams in general, may be particularly sensitive to climate change.Minnesota Pollution Control AgencyHerb, William R.; Erickson, Timothy O; Stefan, Heinz G.. (2009). Stream Temperature Modeling of Miller Creek, Duluth, Minnesota. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/117637
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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