University Digital Conservancy :: Browsing by Author "Stefan, Heinz"

Browsing by Author "Stefan, Heinz"

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Analysis of Flow through Sturgeon Lake and Backwater Channels of Mississippi River Pool No. 3 Near Red Wing, Minnesota
(St. Anthony Falls Hydraulic Laboratory, 1977-04) Stefan, Heinz; Anderson, Keith
Flow rates through Sturgeon Lake and backwater channels of the Mississippi River in the vicinity of the Prairie Island Nuclear power Generating Plant are determined as a function of total river flow and of wind direction and wind velocity, particularly for low flow conditions. The analysis is made in order to determine; (a) how much of the Sturgeon Lake flow is drawn into the cooling water intake of the plant, and (b) by how much plant effluent cooling water or blow down water is diluted by sturgeon Lake effluent before entering the Mississippi River. A channel network analysis including effects of wind stress on the water surface in addition to bed shear stress and local (minor) energy losses was made to provide the required information. Forty-three channel and channel segments were used to describe the entire system. The Sturgeon Lake/North Lake system was studied before the complete analysis was made. In the absence of wind, flow through Sturgeon Lake amounted to about 22 percent of total river flow. At low plant withdrawal rates and at zero wind, the flow through the backwater channel in front of the plant outlet (channel 42) was about 10 percent of total river flow. Winds from 5 to 30 mph had a very noticeable effect on flows through Sturgeon Lake, particularly when total river flows were less than 10,000 cfs. The analysis was made without consideration of stratification effects near the plant intake and outlet.
Analysis of Vermillion River Stream Flow Data (Dakota and Scott Counties, Minnesota)
(St. Anthony Falls Laboratory, 2008-07) Herb, William; Stefan, Heinz
As part of an effort to characterize the response of the Vermillion River to surface runoff, the flow records from seven gaging stations were analyzed to determine the data quality, typical low flows, and the contribution of major tributaries to the total flow. The flow record from the U.S. Geological Survey gaging station at Empire appears to give the most reliable flow data and has the longest record (33 years). An effort by the Minnesota Department of Natural Resources (MNDNR) to recalibrate other Vermillion River flow gaging stations appears to have resulted in self-consistent data for 2007 flows in the main stem and at tributary stations. Although many of the stream gaging stations examined in this study have flow records of up to eight years, flow data prior to 2007 have to be used with caution. To select a representative summer low flow for a stream temperature analysis, the 33 year record at the USGS station at Empire was analyzed to determine 7Q2, and 7Q10 low flows, and monthly median and mean flows. The monthly and 7Q2 flows are representative of typical flow conditions, while the 7Q10 flow is an extreme low flow condition. Analyses were made both with and without the flow contribution of the Empire WWTP (wastewater treatment plant), to asses both pre- and post-2007 conditions. For a July/August composite average, the mean, median, 7Q2, and 7Q10 flows at the USGS station are 68.0, 43.4, 28.6, and 12.5 cfs, respectively, without the WWTP effluent.
An Analytic Model for Runoff and Runoff Temperature from a Paved Surface
(St. Anthony Falls Laboratory, 2006-10) Herb, William R.; Janke, Ben; Mohseni, Omid; Stefan, Heinz
Existing simplified runoff models such as SCS synthetic hydrographs give some ability to predict surface runoff, but are generally developed for larger watersheds, and do not necessarily represent the actual variation in flow rate with varying precipitation rate. For the purposes of simulating runoff rate and runoff temperature from small parcels of land, a new runoff model was developed based on Manning’s equation. The runoff model is analytical and spatially integrated (zero-dimensional), in that flow depth, flow rate and runoff temperature are computed at one point, the outlet. By taking into account expected variations in the upstream flow depth, the model closely matches the simulations results of a 1D kinematic wave model. The analytic runoff model was coupled to a 1D soil temperature and moisture model, to enable simulation of infiltration, runoff rate and runoff temperature.
Application of a Runoff Temperature Model (MINUHET) to a Residential Development in Plymouth, MN
(St. Anthony Falls Laboratory, 2007-06) Janke, Ben; Herb, William; Mohseni, Omid; Stefan, Heinz
The MINUHET (MINnesota Urban Heat Export Tool) model is a simulation tool used to route heat and storm water through a sub-watershed for a rainfall event or events of interest. The model includes components for developed land uses, undeveloped or vegetated land uses, pervious and impervious open channels, storm sewer systems, and storm water ponds. As a case study, the model has been applied to a 12.5 acre housing development in Plymouth, MN. The process of identifying necessary data is outlined, as well as a general strategy for organizing the input data and setting up the model for this particular watershed. A catch basin at the outlet of the development was instrumented for flow and temperature, and data were collected at the site from August 25, 2005 to October 1, 2005. The model was run for three rainfall events, and a comparison was made between observed and simulated flow rate and flow temperature at the development outlet. Overall, the model performed well. The RMSE for flow was 42.0 L/s, 10.4 L/s, and 14.3 L/s for the three events respectively, and the corresponding RMSE in storm water runoff temperature was 1.6 °C, 1.2 °C, and 1.9 °C. Observed and simulated volumeaveraged mean runoff temperature differed by less than 1.5 ºC for all three events. Total volume of runoff was predicted with reasonable accuracy by the model, especially for the first two events. Heat export, which is a measure of the heat content of the runoff above a certain reference temperature (in this case 16.0 °C), was accurately predicted for the second and third events. The model was found to be highly sensitive to saturated hydraulic conductivity and rainfall temperature (dew point temperature): volume of runoff from the pervious areas varied considerably with changes in hydraulic conductivity, and runoff temperature often tended toward dew point temperature, especially in the absence of large atmospheric or ground heat fluxes (e.g., late at night or early in the morning). This suggests that special care should be taken in selection of soil properties, and that all climate data should be collected as near to the study site as possible to improve the accuracy of runoff temperature estimation.
Bedload Transport In A Model Gravel Stream
(Saint Anthony Falls Laboratory, 1980-12) Dhamotharan, S.; Wood, A.; Parker, Gary; Stefan, Heinz
The presence of a natural pavement consisting of coarse materials in gravel streams is of great interest with regard to fluvial hydraulics and stream ecology. Very little information is available on the mechanics of pavement formation and its characteristics. In this study, insight into the characteristics of sediment transport and pavement evolution in gravel streams was gained by means of a physical model of a gravel stream in the Pacific Northwest. The results from the geometrically undistorted Froude model (scale 1:8) agreed well with the field data. The agreement was further improved when laboratory data and field data were compared in terms of dimensionless bedload W* and relative Shields shear stress ¢. The W* - ¢ plots allow for the quantification of differences in Reynolds number and roughness which were not or could not be scaled by means of Froude similarity. The study leads to the conclusions that bedload transport in natural gravel streams can be simulated in the laboratory and that prototype behavior can be predicted from laboratory data, The experiments also illustrate that pavement can form under conditions of continuous equilibrium transport of all available sizes of interest. This report was submitted in fulfillment of grant No. EPA R 806632-01. The report covers a project period from July 5, 1979 to January 4, 1980. A first draft of this report was submitted in April, 1980.
Calumet Pumping Station Hydraulic Model Study
(St. Anthony Falls Hydraulic Laboratory, 1977-05) Stefan, Heinz; Wood, Addison
A hydraulic model of the underground pump suction intake structure of the Calumet Pumping Station was built and tested. The pumping station is an element of the projected Chicago storm runoff collection and treatment system, to be completed within the next few years. The study was conduoted for DeLeuw, Cather and Co., Consulting Engineers and Planners, Chicago, Illinois, on behalf of the Metropolitan Sanitary District of Greater Chicago. The model was built at a scale of 1:14, mostly out of plexiglass to facilitate observation. The model included the downstream end of the Calumet Tunnel, a drop structure, two symmetrically placed ducts, a wet shaft and a suction header with three branch pipes as shown in Figs. 1 through 8. It was the objective of the hydraulic model study to identify and document (a) problems with flow separation, secondary currents and vortex formation by flow visualization, (b) air entrappment and air entrainment during filling and during pump operation, (c) piezometric heads and head losses throughout the structure, (d) accumulation and entrainment of fuel oil, resulting from accidental spills, throughout the structure (e) transport and deposition of grit throughout the structure. As a result of the initial observations made in the model, the structure was modified in two locations to improve flow characteristics and to reduce grit deposition. The observations made in the model with regard to flow patterns, air entrainment and fuel entrainment have been documented by still pictures (black and white) and color motion picture. Head losses are reported in tabular and graphical form. The performance of the structure (Design C in Fig. 10) with respect to air entrainment, fuel entrainment and head losses appears quite satisfactory. Grit deposition was largely reduced but not fully eliminated. The following specific findings and recommendations were made: At high stages, that is at the beginning of the pumping cycle, flow through the structure is at low velocity and with little flow separation occurring. At low stages, flow in the drop structure becomes highly turbulent resulting at first in entrainment of floating materials and at W.S. stages below -320 in entrainment of air into the duct. In the wet shaft, there appears to be no tendency for vortex formation or air entrainment into the suction header. Only the complete blockage of the lower portion of the bar screen caused a vortex in the wet shaft. It was recommended that three air vents be installed on the suction header at the intersection of each of the three branch pipe axis with the suction header wall. These vents will prevent air accumulation in the branch header during filling. Head losses throughout the structure were found to be small. They are summarized on pages 47 and 48. Piezometric grade lines are shown in Figs. 46, 47, and 48. A major grit deposition problem existed in the divided duct due to the large reduction in flow velocities and bed shear stresses in that part of the structure. A reduction in cross-sectional area by raising the invert by several feet resulted in a significant reduction in grit deposition. Complete elimination of grit deposition appears possible with further reductions of duct width.
Collector Well Study For The Cooling Water Intake System Of The James H. Campbell Electric Power Generating Plant, Unit No. 3
(Saint Anthony Falls Laboratory, 1978-11) Stefan, Heinz; Fu, Alec
A 1:24 scale model of the collector well, the central structure of the projected cooling water intake for the James H. Campbell Power Generating Plant, Unit No. 3, on the eastshore of Lake Michigan was built and operated to determine the hydraulic characteristics of the structure. Piezometric pressure distributions and total energy headlosses were measured. Flow patterns and air evacuation characteristics were observed. The total headloss in the 22 ft diameter collector well was determined to be on the order of 4.5 in. for the design flow of 824 cfs. The height of the collector well cover above tbe header axis had to exceed 6 ft in order to avoid formation of a strong vortex in the well. At a height of 11 ft the well performed satisfactorily. Flow rates in the four headers feeding into the collector well deviated by less than 2 per cent from the average. Air entrapped in the dome was evacuated by the £low. Flow from only two headers through the collector was also investigated.
Cooling Water Intake Manifold (Header) Study For The James H. Campbell Electric Power Generating Plant, Unit No. 3
(Saint Anthony Falls Laboratory, 1979-01) Stefan, Heinz; Shanmugham, Chitra; Dhamotharan, Dhamo S.
A seven-junction cooling water intake manifold was studied in a physical model and by hydraulic analysis. The manifold, also referred to as a "header", is one of four to be embedded in the bottom of Lake Michigan approximately 3500 ft offshore from the James H. Campbell Plant. Each header supports and collects water from seven dual screen intake risers (subject of a separate study). The primary objective of the study was to determine flow contribution from each of seven risers and piezometric pressures along the header. It was found that the flow rates ranged from 92 percent to 112 percent of the average flow per riser. To achieve a higher degree of uniformity, an analysis was made to determine how much additional headloss had to, be generated in each intake riser in order to produce identical withdrawal rates in all seven risers. A similar study was. Made for a partially balanced system where withdrawal rates would not fall outside the 95 to 105 percent limits. In that case, headloss generators were required in the two most downstream risers. Sharp edged nozzles were designed for Risers 6 and 7, and experimentally tested. The total piezometric pressure change through the partially balanced riser-manifold system at a total withdrawal rate of 206 cfs was determined to be 13.8 inches of water relative to the lake. The total energy headloss between the lake and the downstream end of the manifold was determined to be 10.7 inches of water.
Dechlorination Basin Hydraulics
(St. Anthony Falls Hydraulic Laboratory, 1986-10) Stefan, Heinz; Johnson, Thomas
Dechlorination of municipal wastewater with sulfur dioxide was found to be incomplete at the Minneapolis-St. Paul Metro Wastewater Treatment Plant (WWTP). Residual chlorine was found intermittently in the dechlorination basin effluent. The purpose of this study was to define and remedy dechlorination basin hydraulics and thus performance.
Environmental controls of wood entrapment in upper Midwestern streams
(2010-07-20) Merten, Eric, C.; Finlay, Jacques; Johnson, Lucinda; Newman, Raymond; Stefan, Heinz; Vondracek, Bruce
Wood deposited in streams provides a wide variety of ecosystem functions, including enhancing habitat for key species in stream food webs, increasing geomorphic and hydraulic heterogeneity and retaining organic matter. Given the strong role that wood plays in streams, factors that influence wood inputs, retention and transport are critical to stream ecology. Wood entrapment, the process of wood coming to rest after being swept downstream at least 10 m, is poorly understood, yet important for predicting stream function and success of restoration efforts. Data on entrapment were collected for a wide range of natural wood pieces (n D 344), stream geomorphology and hydraulic conditions in nine streams along the north shore of Lake Superior in Minnesota. Locations of pieces were determined in summer 2007 and again following an overbank stormflow event in fall 2007. The ratio of piece length to effective stream width (length ratio) and the weight of the piece were important in a multiple logistic regression model that explained 25% of the variance in wood entrapment. Entrapment remains difficult to predict in natural streams, and often may simply occur wherever wood pieces are located when high water recedes. However, this study can inform stream modifications to discourage entrapment at road crossings or other infrastructure by applying the model formula to estimate the effective width required to pass particular wood pieces. Conversely, these results could also be used to determine conditions (e.g. pre-existing large, stable pieces) that encourage entrapment where wood is valued for ecological functions.
Factors influencing wood mobilization in streams
(2010) Merten, Eric; Finlay, Jacques; Johnson, Lucinda; Newman, Raymond; Stefan, Heinz; Vondracek, Bruce
Fairmont Lakes Study; Relationships Between Stratification, Phosphorus Recycling, and Dredging
(Saint Anthony Falls Laboratory, 1979-12) Stefan, Heinz; Hanson, Mark
The City of Fairmont in Southern Minnesota has used several different strategies to reduce algae blooms in its five lakes (Amber, Hall, Budd, Sisseton, and George Lakes). Among these are treatment with copper sulfate and diversion and treatment of municipal sewage effluent. Since 1965, the city has been pursuing a dredging program.
Field Investigations of Water Temperature Stratification and Wind Effects on Dissolved Oxygen in Pool No. 2 of the Mississippi River
(St. Anthony Falls Hydraulic Laboratory, 1976-12) Stefan, Heinz; Wood, Addison
Dissolved oxygen, water temperatures, Secchi depth, and surface drift currents were measured in pool No. 2 of the Mississippi River during very low flow conditions from August 24 through September 25, 1976 on eleven different days and under significantly varied weather conditions. Water quality parameters were found to vary, both in time and space and in direct relationship to prevailing weather, particularly wind and sunshine. With total river flows from approximately 1000 to 2000 cfs, the measured D.O. distributions, water temperatures, and transparencies were predominantly typical of a series of interconnected lakes and to a lesser degree typical of a river. Natural convection, density currents, and wind drift were found to be of great importance. Recovery from low dissolved oxygen levels due to the effluent from the Metropolitan Waste Treatment Plant occurred in the pool upstream from Dam No. 2 mainly as the result of photosynthesis, surface aeration, and the hydrodynamic exchange processes between different regions of the pool.
A flow and temperature model for the Vermillion River, Part I: Model development and baseflow conditions
(St. Anthony Falls Laboratory, 2008-08) Herb, William; Stefan, Heinz
Stream temperature and stream flow are important physical parameters for aquatic habitat preservation in river and stream systems. Water temperature is particularly important for coldwater stream systems that support trout. Summer base flow conditions with low flows and high water temperatures can be critical for maintaining trout habitat. Surface runoff from rainfall events can lead to increases in stream temperature, particularly in developed watersheds. To better understand the interactions between stream temperature, land use, and climate, an unsteady stream flow and temperature model has been developed for the Vermillion River. The model includes the main stem from Dodd Avenue to Goodwin Avenue and a number of tributaries, including South Branch, South Creek, North Creek, and Middle Creek. The EPDriv1 package was used to simulate stream flow, including distributed groundwater inputs. Simplified stream channel geometry was required to obtain converged flow solutions for unsteady low flows. A stream temperature model has been assembled based on previous work at SAFL. The stream temperature model uses flow and flow area from the flow solver, along with observed climate data to calculate surface heat transfer. Groundwater inflows are an important component of both the flow and temperature model. For the Vermillion River, groundwater inflow rates were estimated from flow gaging sites, while groundwater temperatures were estimated by calibrating the stream temperature model. The calibrated combination of groundwater flow and temperature results in a good match of simulated and observed stream temperature, with RMSEs in the range of 0.75 to 2 ºC. The assembled flow and temperature model for the Vermillion River has been calibrated for baseflow conditions, and provides a starting point for future analysis of surface runoff inputs during rainfall events.
Flow Establishment and Initial Entrainment of Heated Water Surface Jets
(St. Anthony Falls Hydraulic Laboratory, 1975-01) Stefan, Heinz; Bergstedt, Loren; Mrosla, Edward
Mathematical models to predict water temperature distributions resulting from heated water surface discharges usually consider three subregions of the flow field: (a) an outlet region or zone of flow establishment (ZFE), (b) a zone of fully established jet flow, and (c) a far field with mostly passive dispersion. Of these three regions, zone (b) can be treated mathematically most readily using integral techniques; zone (c) requires input specifying mean flow and turbulence of the ambient flow field; and zone (a) depends essentially on the geometry of the outlet and the discharge characteristics in terms of the velocity and temperature of the water. The results of an experimental study dealing with zone (a) are reported. The discharge channel had a rectangular cross section and led into a deep, wide reservoir. The aspect ratio (width-to-depth ratio) of the channel, the volumetric discharge rate, and the discharge temperature were varied. A cross-flow was imposed in some of the experiments. The length of the zone of flow establishment, Xo or So, was measured in terms of mean excess temperature, mean velocity, and turbulence intensity along the trajectory. The length, Xo or So, was related to channel aspect ratio A, outlet densimetric Froude number Fo, and cross-flow-to-jet velocity ratio R. Total volumetric flow rates during flow establishment were established as a function of distance along the jet axis and related to A and Fo. The results are useful either for extension of existing mathematical models of fully developed heated water surface jets or for verification of mathematical models of the zone of flow establishment.
Heat Export and Runoff Temperature Analysis for Rainfall Event Selection
(St. Anthony Falls Laboratory, 2007-04) Herb, William; Mohseni, Omid; Stefan, Heinz
Thermal pollution by surface runoff from urban areas can contribute to the degradation of coldwater ecosystems. The hydrothermal characteristics of surface runoff from rainfall are therefore of interest. Three hydrothermal parameters of surface runoff have been studied: runoff temperature (oC), heat flux (W/m2) and total heat export (J/m2). Heat fluxes were defined above a reference temperature of 20oC. The results can be used to identify storm events that have the potential for the largest heat export from a watershed and consequently the strongest thermal pollution of a receiving coldwater stream. In this study, records of rainfall events and weather data are used to estimate the three hydrothermal parameters by model simulation. The model for predicting rainfall runoff temperatures and rates from an impervious surface (parking lot) has been described in Project Report No. 484 from the St. Anthony Falls Laboratory, University of Minnesota (Herb et al 2006). The weather data came from the MnROAD test site in Albertville, MN, and from the SAMSON data set. Runoff temperatures and heat export were calculated for a 100x100m paved surface using 6 years of 15 minute weather data or 30 years of 1-hour weather data. The 6-year data set contained 280 rainfall events from April through October. The 280 values of the three hydrothermal parameters were related to basic rainfall event parameters such as total rainfall, duration, and rainfall temperature (dew point). Average runoff temperature was found to be well correlated to dew point temperature during the storm, and air temperature and solar radiation prior to the storm. 20 extreme values of the hydrothermal parameters were ranked and also related to basic rainfall parameters. Partial duration series of hydrothermal parameters were analyzed separately for frequency of occurrence (return periods).
Ice Formation On Minnesota Lakes: Use Of Landsat Imagery And Weather Data, To Predict Freeze-Over Dates
(Saint Anthony Falls Laboratory, 1979-07) Stefan, Heinz; Fu, Alec
LANDSAT images taken in the fall of 1972, 1973, 1974 and 1975 were analyzed to estimate dates of ice formation on Minnesota lakes. Lakes located in the northern, central and southern parts of Minnesota were studied. Lake surface areas and depths were identified from a lake inventory. The observations derived from the satellite images were compared to theoretical prediction of freeze-over dates based on seasonal heat budget cycles and water temperature cycles. The theory was then applied to all of Minnesota to provide an estimate of average annual freeze-over dates of lakes located in different parts of the state and having different depths. LANDSAT images taken in the Spring of 1976 were analyzed to determine ice break-up dates.
Inventory of Road Salt Use in the Minneapolis/St.Paul Metropolitan Area
(St. Anthony Falls Laboratory, 2007-12) Sander, Andrew; Novotny, Eric; Mohseni, Omid; Stefan, Heinz
In the northern regions of the U.S. and in Canada a water contaminant of increasing concern is chloride. The source of chloride contamination is mostly sodium chloride (NaCl) which is used in large quantities for road de-icing and for water softening. Chloride enters into the environment easily in snowmelt runoff and in wastewater treatment plant discharges. Because it is a fairly conservative material it can travel long distances without assimilation. It affects the quality of aquatic ecosystems. Because of its adverse effects on plants and aquatic animals, MPCA standards of 230mg/L and 800 mg/L have been set for chronic and acute exposure. The Twin Cities Metropolitan Area (TCMA) is one of the regions where salt is used for winter road maintenance and for water softening. The TCMA is an urbanized area with a population of about 2.7 million people. It is located at about 45oN latitude and has a reputation of cold and long winters. The TCMA is traversed by the Mississippi River and several of its tributaries, and claims to have 949 lakes within its seven counties and over 186 cities and townships. There are over 26,000 lane miles of roadways with impervious surfaces in the TCMA. In this report an inventory of the amount of road salt (NaCl) applied in the TCMA each year is given. This study was not aimed at evaluating the effectiveness, suitability or cost of using NaCl as a de-icer. In addition to the total amounts of salt used, it is of interest to identify and quantify the metrics that determine the rates of road salt application. The spatial and temporal scales will be large enough so that the results of this study can be compared to other regions in northern climates. Many sources of information regarding the use of road salt in the TCMA and the state of Minnesota were consulted. In the TCMA, most municipalities and counties purchase salt through contracts offered by the Material Management Division (MMD) of the state of Minnesota. The average amount of reported salt use per winter season (2001 to 2006) was 236,800 tons per year and varied between 243,000 and 274,000 tons per year. Relative to the sum of the contract amounts, the actual reported use was on average 93% for the TCMA. Not all municipalities participate in the MMD contract or keep track of the actual road salt applications. The amount of road salt used by municipalities without information was estimated based on a per capita road salt use rate of 0.045 tons per season per person. The rate was determined from the reported road salt use in the TCMA covering about 90% of the population.
Lake of the Woods Shoreline Erosion: Analysis of Historical Shorelines, Climate and Lake Level
(St. Anthony Falls Laboratory, 2005-03) Herb, William; Mohseni, Omid; Stefan, Heinz
This report summarizes the results of Phase I of a study of erosion of the Minnesota shoreline of Lake of the Woods. The overall objectives of this study are (a) to determine the causes and to estimate the magnitude of the shoreline recession rates in the US shorelines of Lake of the Woods, and (b) to recommend management practices for shoreline protection against erosion. In Phase I, we collected historical data on wind and water levels at Lake of the Woods, flow and suspended sediment input from the Rainy River, and information on the shoreline, including aerial photos, satellite images, and soil surveys. Analyses of aerial photos from 1940 to 2003 show rapid erosion of several undeveloped wetland areas of the shoreline and relatively slow erosion of developed areas along Sandy Shores and Birch Beach. Analysis of Pine and Sable Islands show a combination of erosion, rebuilding, and shifting from 1940 to 2003, so that the present state of the islands may represent either a long term loss or a loss/rebuilding cycle. Since long term wind records for Lake of the Woods were not found, a synthetic wind record was constructed from regional wind records. Analysis of wind and water level data from the 1950’s to the present show a relatively uniform distribution of high wind and high water events. Recent high water events appear as typical events that take place several times per decade. Wind and wave data were also collected at two locations on the southern side of Big Traverse Bay, with record lengths of 4 – 5 weeks. The on-lake wind data and wave data will be useful to calibrate wave models in Phase II, and have been used in Phase I to correlate on-lake wind with local and regional off-lake wind measurements. Field measurements of near-shore bathymetry were made and sediment samples were collected to determine size distribution were also collected in preparation for Phase II. Preliminary analyses of data for the Rainy and the Little Fork rivers do not show distinct trends in flow rate or suspended sediment concentration for the period of record.
Maps of wind-wave height on Minnesota lake shorelines
(2022-01-27) Herb, William; Janke, Ben; Cai, Meijun; Stefan, Heinz; Johnson, Lucinda; herb0003@umn.edu; Herb, William; University of Minnesota St. Anthony Falls Lab; University of Minnesota Duluth Natural Resources Research Institute
This data set provides maps of typical wind-wave height and energy on Minnesota lakes to inform shoreline and near-shore habitat restoration projects. The data set consists of a set of ArcMap shape files which map out simulated wave height and energy parameters for a series of points around the shoreline of 460 lakes in Minnesota, with separate files for annual wave statistics and monthly wave statistics. The wave statistics were calculated for each lake based on airport wind data and the open water distance (fetch) across the lake for each wind direction. Each shapefile contains information on multiple wave statistics, including the mean and significant wave height, the number of days wave height exceeds thresholds, and cumulative wave energy over the time period.

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