Browsing by Author "Janke, Ben"

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All-Weather Ground Surface Temperature Simulation
(St. Anthony Falls Laboratory, 2006-09) Herb, William R.; Janke, Ben; Mohseni, Omid; Stefan, Heinz G.
Thermal pollution from urban runoff is considered to be a significant contributor to the degradation of coldwater ecosystems. Impervious surfaces (streets, parking lots and buildings) are characteristic of urban watersheds. A model for predicting temperature time series for dry and wet ground surfaces is described in this report. The model has been developed from basic principles. It is a portion of a larger project to develop a modeling tool to assess the impact of urban development on the temperature of coldwater streams. Heat transfer processes on impervious and pervious ground surfaces were investigated for both dry and wet weather periods. The principal goal of the effort was to formulate and test equations that quantify the heat fluxes across a ground surface before, during and after a rainfall event. These equations were combined with a numerical approximation of the 1-D unsteady heat diffusion equation to calculate temperature distributions in the ground beginning at the ground surface. Equations to predict the magnitude of the radiative, convective, conductive and evaporative heat fluxes at a dry or wet surface, using standard climate data as input, were developed. Plant canopies were included for surfaces covered by vegetation. The model can simulate the ground surface and subsurface temperatures continuously throughout a specified time period (e.g. a summer season) or for a single rainfall event. Ground temperatures have been successfully simulated for pavements, bare soil, short and tall grass, trees and two agricultural crops (corn and soybeans). The simulations were first run for different locations and different years as imposed by the availability of measured soil temperature and climate data. Data came from sites in Minnesota, Illinois and Vermont. To clarify the effect of different land uses on ground temperatures, the calibrated coefficients for each land use and the same soil coefficients were used to simulate surface temperatures for a single climate data set from St. Paul, MN (2004). Asphalt and concrete give the highest surface temperatures, as expected, while vegetated surfaces gave the lowest. Bare soil gives surface temperatures that lie between those for pavements and plant-covered surfaces. The soil temperature and moisture model appears to model surface temperatures of bare soil and pavement with RMSEs of 1 to 2°C, and surface temperatures of vegetation-covered surfaces with RMSEs of 1 to 3oC. The plant canopy model used in this study, based on the work of Best and Deardorff, provides an adequate approximation for the effect of vegetation on surface heat transfer, using only a few additional parameters compared to bare surfaces. While further simplifications of the model are possible, such simplifications do not reduce the number of required input parameters, and do not eliminate the need for estimating the seasonal variation of the vegetation density. A model for roof temperatures was also developed, based on the surface heat transfer formulations used for pavement. The model has been calibrated for both a commercial tar/gravel roof and a residential roof. Compared to pavement, the roof surface reach similarly high maximum temperatures, but reach lower minimum temperature at night cool due to their lower thermal mass.
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.
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 G.
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.
Characterization of streams and rivers in the Minnesota River Basin Critical Observatory: water chemistry and biological field collections, 2013-2016
(2017-09-06) Dolph, Christine, L.; Hansen, Amy, T.; Kemmitt, Katie, L.; Janke, Ben; Rorer, Michelle; Winikoff, Sarah; Baker, Anna; Boardman, Evelyn; Finlay, Jacques, C.; dolph008@umn.edu; Dolph, Christine, L.
This dataset was collected to inform the Water, Sustainability and Climate Minnesota River Basin Observatory, and was supported by the National Science Foundation under Grant No. 1209402 Water, Sustainability and Climate (WSC) – Category 2, Collaborative: Climate and human dynamics as amplifiers of natural change: a framework for vulnerability assessment and mitigation planning. The dataset contains point locations, watershed areas and water quality information for 231 ditch, stream, river and wetland sites located in the Le Sueur River, Chippewa River, Cottonwood River, Cannon River, Wantonwan River and Blue Earth River basins of Minnesota. Study sites ranged in size from 1st order ditches and streams to an 8th order river. Each of these sites was sampled at least once between 2013-2016 (most sites were sampled multiple times) for one or more of the following parameters: 1) water chemistry (total dissolved nitrogen, nitrate-N, nitrite-N, ammonium-N, particulate nitrogen, soluble reactive phosphorus, total dissolved phosphorus, particulate phosphorus, total phosphorus, dissolved organic carbon, dissolved inorganic carbon, particulate carbon, chlorophyll a, total suspended solids, volatile suspended solids, delta-H-2 and delta-O-18 stable isotopes of site water, specific UV absorbance (SUVA) of site water, fluorescence index (FI) of site water); 2) stable isotopes (delta-C-13, delta-N-15, delta-H-2) of invertebrate consumers, particulate carbon and potential food sources; 3) denitrification rates and characteristics of benthic sediment in agricultural drainage ditches; and 4) stream discharge. This dataset also includes spatial data files containing study site locations and watershed areas delineated for each site.
Development of Techniques to Quantify Effective Impervious Cover
(St. Anthony Falls Laboratory, 2011-07) Janke, Ben; Gulliver, John S.; Wilson, Bruce N.
Practitioners responsible for the design and implementation of stormwater management practices rely heavily on estimates of impervious area in a watershed. However, the most important parameter in determining actual urban runoff is the ‘effective’ impervious area (EIA), or the portion of total impervious area that is directly connected to the storm sewer system. EIA, which is often considerably less than total impervious area and can vary with rainfall depth and intensity, is likely not determined with sufficient accuracy in current practice. A more accurate determination of EIA in a watershed would benefit a wide range of organizations involved in the design of stormwater management, pollution prevention, and transportation structures. This study investigated two existing methods of estimating EIA in a watershed: (1) analysis of large rainfall-runoff data sets using the method of Boyd et al. (1994), and (2) overlay analysis of spatial (GIS) data, including land cover, elevation, and stormwater infrastructure, using the method of Han and Burian (2009). The latter method provides an estimate of connected pavement, but requires the user to input the value of connected rooftop to determine the actual EIA value, which is the sum of these two quantities. The two methods were applied to two urban catchments within the Capitol Region Watershed in St. Paul, MN; one was a small (42-ac), relatively uniform residential neighborhood, and the other was a large (3400-ac), highly-urbanized catchment with a variety of land uses present. The results were used to evaluate the potential of each method and make recommendations for future studies. In summary, the data analysis technique (Boyd et al., 1994) has the advantage of being quick and relatively simple to implement, as it did not require familiarity with specialized software tools (e.g. ArcGIS) and could be completed with any spreadsheet program with graphing capabilities (e.g. Excel). The EIA estimates from the data analysis are the most accurate, but the technique is unable to determine where in the watershed the EIA is located, and cannot be used if runoff discharge and local precipitation data is unavailable. By contrast, the GIS method (Han and Burian, 2009) has the advantage of being applicable to un-gauged watersheds, and also provides the location of EIA in the watershed. This latter feature makes it particularly attractive for honing the development and placement of BMP’s in a watershed. Unfortunately, the accuracy of the GIS method is completely dependent on the ability to faithfully represent the amount of roof connection in a watershed, a process that can add significant time and expense to the EIA estimate.Future work should be focused primarily on two general areas: (1) improving the GIS-based estimation technique, and (2) expanding the application of both techniques to additional sub-watersheds, with particular emphasis on newer development and on catchments with more homogenous land uses. The GIS method could be improved considerably by developing techniques to improve roof connectivity estimates, e.g. through the use of land use-specific site surveys or through some novel partitioning scheme based on age or type of rooftop. An improved method for handling canopy shading of impervious surfaces than that used herein could also be investigated. Insight on both of these areas of improvement could be supplied by application of both the data analysis and the GIS-based techniques to additional watersheds. Furthermore, additional analyses could potentially allow EIA values to be correlated to land cover characteristics such as roof type, canopy shading, age of construction, lane-miles of road, BMP presence, etc. or even to rainfall characteristics such as intensity, duration, or antecedent rainfall depth. This type of generalized information would be valuable to practitioners in applications such as stormwater management, transportation design, or water quality protection.
Development of Techniques to Quantify Effective Impervious Cover
(Center for Transportation Studies, University of Minnesota, 2011-09) Janke, Ben; Gulliver, John S.; Wilson, Bruce N.
Practitioners responsible for the design and implementation of stormwater management practices rely heavily on estimates of impervious area in a watershed. However, the most important parameter in determining actual urban runoff is the "effective" impervious area (EIA), or the portion of total impervious area that is directly connected to the storm sewer system. EIA, which is often considerably less than total impervious area and can vary with rainfall depth and intensity, is likely not determined with sufficient accuracy in current practice. A more accurate determination of EIA in a watershed would benefit a wide range of organizations involved in the design of stormwater management, pollution prevention, and transportation structures. This study investigated two existing methods of estimating EIA in a watershed: (1) analysis of large rainfall-runoff data sets using the method of Boyd et al. (1994), and (2) overlay analysis of spatial (GIS) data, including land cover, elevation, and stormwater infrastructure, using the method of Han and Burian (2009). The latter method provides an estimate of connected pavement, but requires the user to input the value of connected rooftop to determine the actual EIA value, which is the sum of these two quantities. The two methods were applied to two urban catchments within the Capitol Region Watershed in St. Paul, MN. The results were used to evaluate the potential of each method and make recommendations for future studies. In summary, the data analysis technique (Boyd et al., 1994) has the advantage of being quick and relatively simple to implement, as it did not require familiarity with specialized software tools (e.g. ArcGIS) and could be completed with any spreadsheet program with graphing capabilities (e.g. Excel). The EIA estimates from the data analysis are the most accurate, but the technique is unable to determine where in the watershed the EIA is located, and cannot be used if runoff discharge and local precipitation data is unavailable. By contrast, the GIS method (Han and Burian, 2009) has the advantage of being applicable to un-gauged watersheds, and also provides the location of EIA in the watershed. This latter feature makes it particularly attractive for honing the development and placement of BMP?s in a watershed. Unfortunately, the accuracy of the GIS method is completely dependent on the ability to faithfully represent the amount of roof connection in a watershed, a process that can add significant time and expense to the EIA estimate.
Estimation of Groundwater Inflow to the Vermillion River from Observations of Stream Flow and Stream Temperature
(St. Anthony Falls Laboratory, 2009-11) Janke, Ben; Herb, William R.; Mohseni, Omid; Stefan, Heinz G.
A model has been developed for estimation of groundwater inflow to a stream reach from observations of stream temperature, groundwater temperature, stream flow rate, and standard weather parameters. The purpose of this model is to provide an estimate of groundwater inflow rate for stream reaches where groundwater inflow is significant. This information is useful for management of fisheries and urban development in watersheds where stream temperature is a concern. In particular, the model was developed for use in the Vermillion River, which has designated trout stream reaches that may be impacted by development in the watershed. The model estimates groundwater inflow rate from a stream reach heat budget, which takes into account atmospheric heat flux, sediment-water heat exchange, and groundwater inflow. The model requires the following data as input: stream temperature at the upstream and downstream ends of the stream reach, stream flow at either end of the reach, standard weather data, and no significant tributaries or inflows between the ends of the reach. The model was applied to six reaches in the Vermillion River watershed. Estimated groundwater inflow rates showed considerable spatial and temporal variability, both seasonally and between the two years simulated (2006 and 2007). In North Creek, groundwater inflow rate was 0.45 to 1.30 cfs/mile in 2007; in the upper Vermillion River main stem for the same period estimated inflow rates ranged from 0.15 to 3.87 cfs/mile. In the middle Vermillion River main stem, estimated inflow rates were unnaturally large and more variable (0.39 to 11.1 cfs/mile); these estimates include significant tributary inflow, which is lumped with groundwater inflow in the model. This, along with the failure of the model for reaches or periods involving high stream flows, is the likely source of the over-predicted groundwater inflow values. Simulations for lower South Creek showed negligible groundwater inflow for 2006; results for lower South Branch were very typical of a groundwater-fed stream, with relatively constant groundwater inflow (around 1.0 cfs/mile) that fluctuated only slightly during periods of heavy rainfall. A comparison of predicted groundwater inflow rates throughout the watershed for both dry (baseflow) and high-flow conditions suggest the presence of shallow groundwater, particularly in the lower reaches of the watershed. The significant variability in groundwater inflow rate predicted by the model can be traced to a number of factors, including data quality and sensitivity of the model to groundwater temperatures, stream shading/sheltering, and especially to stream flow. An extensive sensitivity analysis of the model is presented in this report, as well as an analysis of available data, in particular, groundwater temperature. Limitations of the heat budget approach to modeling groundwater inflow rate are also discussed and criteria for application of the model are developed from the results of sensitivity analysis.
Estimation of Runoff Temperatures and Heat Export from Different Land and Water Surfaces
(St. Anthony Falls Laboratory, 2007-02) Herb, William R.; Janke, Ben; Mohseni, Omid; Stefan, Heinz G.
This report describes work to analyze runoff temperatures and runoff heat export rates for a variety of terrestrial land covers and aquatic surfaces. Surface runoff temperatures and heat export have been simulated for ten terrestrial covers, an unshaded wet detention pond, a lake/reservoir, and a vegetated pond. A continuous simulation was run from April 1 to October 31, yielding a total of about 280 precipitation events for six years (1998-2000, 2003-2005). Six years of 15-minute climate data from the weather station at the MnROAD facility in Albertville, MN, were used as model input. In general, the variation in average runoff temperatures from terrestrial land covers and open water surfaces was moderate, from 24.9 °C for concrete to 21.5 °C for a forest. Pavements, commercial rooftops, bare soil, wet detention ponds, and lakes/reservoirs were all found to give runoff temperatures high enough to significantly impact stream temperature. Vegetated surfaces gave substantially lower runoff temperature and heat export than paved surfaces. Runoff temperatures from bare soils were consistently higher than from vegetated surfaces, but lower than from pavements. Residential roofs gave, on average, low runoff temperatures, due to very low thermal mass, while commercial roofs gave high runoff temperatures in some cases. Large water bodies (lakes and reservoirs) generally give very high runoff temperatures, but the quantity of runoff is highly dependent on the water level prior to the storm event. Analysis of a vegetated pond indicates that shading from emergent vegetation can reduce runoff temperature up to 6°C compared to an unshaded pond.
Heating of Rainfall Runoff on Residential and Commercial Roofs
(St. Anthony Falls Laboratory, 2010-01) Janke, Ben; Mohseni, Omid; Herb, William R.; Stefan, Heinz G.
A common assumption in stream water temperature modeling is that rooftops of all types contribute very little heat to runoff from rainfall. In this report we examine the accuracy of this assumption (a) by analyzing temperature data which we recorded on a residential rooftop, a commercial rooftop, and a concrete driveway, and (b) by simulating temperature profiles within rooftops and pavements, and estimating heat transfer from these surfaces to rainfall runoff. Analysis of both wet‐ and dry‐weather temperature data which we recorded over periods of several months allowed us to conclude that a driveway has a far greater capacity for heat storage and release than a rooftop, although the commercial rooftop was able to store and release more heat than the residential rooftop. On sunny days and prior to rainfall, rooftops can reach higher temperatures than paved surfaces, but not much heat is stored, and roof temperatures drop rapidly as cloud cover increases with an approaching storm. Interestingly, weather events leading to the highest dew point (rainfall) and surface temperatures often occurred during late night or early morning hours, contrary to the expectation that the worst‐case runoff heating events would occur during daylight hours. The analysis conducted for three rainfall events showed that the heat export from the commercial rooftop was roughly three times that of the residential rooftop, but only 30%‐90% of the heat export from the concrete driveway. Potential heat export was significantly higher for the driveway than for either rooftop.
Heating of Rainfall Runoff on Residential and Commercial Roofs
(St. Anthony Falls Laboratory, 2010-01) Janke, Ben; Mohseni, Omid; Herb, William R.; Stefan, Heinz G.
A common assumption in stream water temperature modeling is that rooftops of all types contribute very little heat to runoff from rainfall. In this report we examine the accuracy of this assumption (a) by analyzing temperature data which we recorded on a residential rooftop, a commercial rooftop, and a concrete driveway, and (b) by simulating temperature profiles within rooftops and pavements, and estimating heat transfer from these surfaces to rainfall runoff. Analysis of both wet- and dry-weather temperature data which we recorded over periods of several months allowed us to conclude that a driveway has a far greater capacity for heat storage and release than a rooftop, although the commercial rooftop was able to store and release more heat than the residential rooftop. On sunny days and prior to rainfall, rooftops can reach higher temperatures than paved surfaces, but not much heat is stored, and roof temperatures drop rapidly as cloud cover increases with an approaching storm. Interestingly, weather events leading to the highest dew point (rainfall) and surface temperatures often occurred during late night or early morning hours, contrary to the expectation that the worst-case runoff heating events would occur during daylight hours. The analysis conducted for three rainfall events showed that the heat export from the commercial rooftop was roughly three times that of the residential rooftop, but only 30%-90% of the heat export from the concrete driveway. Potential heat export was significantly higher for the driveway than for either rooftop. In conclusion, the results of the data analysis and heat export simulations support the assumption that residential rooftops contribute very little heating to runoff from rainfall. Commercial rooftops may have a thermal impact on rainfall runoff because of their greater thermal storage capacity. An asphalt pavement, (road or driveway) is expected to have a greater thermal impact than a concrete pavement. Commercial rooftops in addition to asphalt and concrete pavements should be considered when the water temperatures of rainfall runoff from highly urbanized areas are estimated.
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.
MINUHET (Minnesota Urban Heat Export Tool) USER MANUAL
(St. Anthony Falls Laboratory, 2010-01) Herb, William; Janke, Ben; Mohseni, Omid; Stefan, Heinz
MINUHET (Minnesota Urban Heat Export Tool) is a tool used to simulate the flow of stormwater surface runoff and its associated heat content through a small watershed for a rainfall event or events of interest. The main output of MINUHET is a time series of flow rate and temperature at the outlet of the watershed, to enable prediction of thermal impact on receiving streams. MINUHET is event-based, i.e. it is designed primarily to simulate a single storm event. The MINUHET tool includes a database of observed and/or synthetic storm events that have the potential to produce high thermal loading in receiving streams.
MINUHET (Minnesota Urban Heat Export Tool) USER MANUAL
(St. Anthony Falls Laboratory, 2010-01) Herb, William R.; Janke, Ben; Mohseni, Omid; Stefan, Heinz G.
MINUHET (Minnesota Urban Heat Export Tool) is a tool used to simulate the flow of stormwater surface runoff and its associated heat content through a small watershed for a rainfall event or events of interest. The main output of MINUHET is a time series of flow rate and temperature at the outlet of the watershed, to enable prediction of thermal impact on receiving streams. MINUHET is event-based, i.e. it is designed primarily to simulate a single storm event. The MINUHET tool includes a database of observed and/or synthetic storm events that have the potential to produce high thermal loading in receiving streams.
MINUHET (Minnesota Urban Heat Export Tool): A software tool for the analysis of stream thermal loading by urban stormwater runoff
(St. Anthony Falls Laboratory, 2009-03) Herb, William R.; Janke, Ben; Mohseni, Omid; Stefan, Heinz G.
Urbanization affects the temperature of cold water resources, coldwater streams in particular. In Minnesota such streams are typically found in well-shaded watersheds and receive large groundwater inputs. They are ecologically significant because they support coldwater fisheries and other wildlife that would be unable to survive in warmer streams. The conversion of land from existing agricultural use or natural conditions poses a threat to these streams. Urban expansion usually requires removing crops and trees and replacing them with buildings, parking lots, roads, lawns, and parks. These changes affect shading, heat transfer, and hydrology within the watershed. Currently, there are few tools available to project to what extent stream temperatures are influenced by development in the watershed. This report describes a new simulation tool, MINUHET (Minnesota Urban Heat Export Tool). MINUHET is a tool used to simulate the flow of stormwater surface runoff and its associated heat content through a small watershed for one or several rainfall event of interest. The tool includes hydrologic and thermal models for surface runoff, natural and man-made drainage networks, and stormwater treatment ponds. The main output of MINUHET is a time series of flow rates and temperatures at the outlet of the watershed, to enable prediction of thermal impact on receiving streams. MINUHET is event-based, i.e. it is designed primarily to simulate a single storm event. The MINUHET tool includes a database of observed and/or synthetic storm events that have the potential to produce high thermal loading in receiving streams. Verification of MINUHET has been performed at both the component level and the system level. The surface temperature model was verified for a number of different impervious and pervious land surfaces for continuous, multi-month simulations of wet and dry conditions. The runoff model has been compared to other models, including a more complex kinematic wave model and a commercial runoff model (EPA-SWMM), and to observed runoff time series from a parking lot. The pond model component was used successfully to simulate several months of observed water level and temperature data for a wet detention pond in Woodbury, MN. The MINUHET tool has been applied to a 12 acre residential development in Plymouth, MN that was instrumented in 2005. A common application of MINUHET may be to compare the thermal loading of stormwater runoff from an area of land before and after development, to quantify possible increases in thermal loading due to development. MINUHET includes components for developed and undeveloped land parcels (sub-watersheds), pervious and impervious open channels, storm sewer systems, and stormwater ponds. MINUHET does not include a stream temperature model, so that while MINUHET can be used to simulate the heat loading to a stream, it cannot be used, by itself, to simulate the resulting change in stream temperature.
Quantifying Wave Energy on Minnesota Lakes
(2022-01) Herb, William; Janke, Ben; Stefan, Heinz; Cai, Meijun; Johnson, Lucinda
Quantifying wind‐wave energy on Minnesota Lakes
(2016-07) Herb, William; Janke, Ben; Stefan, Heinz
Quasi-2D Model for Runoff Temperature from a Paved Surface
(St. Anthony Falls Laboratory, 2006-08) Janke, Ben; Herb, William; Mohseni, Omid; Stefan, Heinz
Thermal pollution from urban runoff is considered to be a significant contributor to the degradation of coldwater ecosystems. Impervious surfaces (streets, parking lots and buildings) are characteristic of urban watersheds. A model for predicting rainfall runoff temperatures and runoff rates from an impervious surface (parking lot) is described in this report. The model has been developed from basic principles. It is a portion of a larger project to develop a modeling tool to assess the impact of urban development on the temperature of coldwater streams. Heat transfer and runoff processes on an impervious surface were investigated for both dry and wet weather periods. The principal goal of the effort was to describe and quantify the heat transfer between a paved surface and storm water runoff during a rainfall event. A kinematic wave scheme was used to predict runoff flow rates as a function of distance and time on a paved surface, and a numerical approximation of the 1-D unsteady heat diffusion equation was used to calculate temperature distributions in the sub-surface. Equations to predict the magnitude of the radiative, convective, conductive and evaporative heat fluxes at a dry or wet surface, using standard climate data as input, were developed. The model can simulate surface runoff (flow) and temperature continuously throughout a specified time period (e.g. a month) or for a single rainfall event. It also predicts the ‘total heat export’ for an event, which is defined as the heat contained in the runoff above a reference temperature. A sensitivity study was performed to investigate the extent to which heat export is affected by antecedent pavement temperature, characteristics of the rainfall event, and physical parameters of the paved surface. In general, it was found that heat export was more sensitive to rainfall intensity, rainfall duration, and antecedent pavement temperature conditions than the physical properties of the paved surface (slope, roughness, length). It was also found that lower-intensity events extracted more heat from the pavement per depth of rainfall than higher-intensity events, and an increase in rainfall duration increased the total event heat export, especially for higher-intensity events. Finally, atmospheric forcing was determined to have a significant influence on runoff temperature and heat export, leading to a reduction in heat export that was a function of rainfall intensity.
Study of De-icing Salt Accumulation and Transport Through a Watershed
(Minnesota Department of Transportation, 2017-12) Herb, William; Janke, Ben; Stefan, Heinz
The accumulation of chloride in surface waters and groundwater from road deicing and other sources is a growing problem in northern cities of the U.S., including the Minneapolis-St. Paul metro area. To inform mitigation efforts, the transport of chloride in surface waters of a metro-area watershed (Lake McCarrons) was studied in this project to characterize chloride transport by surface runoff, the residence time of chloride in surface water, and how variations in weather influence chloride transport and accumulation processes. Monitoring work over three winters showed that the residence time of chloride in small, sewered watersheds varied from 14 to 26 days, depending on winter weather conditions, with 37 to 63% of chloride applied as de-icers exported in snowmelt and rainfall surface runoff. In contrast, a monitored highway ditch exported less than 5% of chloride applied to the adjacent road. Stormwater detention ponds were found to act as temporary storage for chloride, with persistent layers of high chloride content at the bottom. Chloride monitoring data and runoff simulations were used to explore the possibility of snowmelt capture as a chloride pollution mitigation strategy. We found that capturing snowmelt runoff close to source areas (roads and parking lots) yields the highest chloride concentrations and removal potential.

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