Browsing by Subject "Water temperature"

Now showing 1 - 3 of 3
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    Assessing Impacts of Climate Change on Vulnerability of Brook Trout in Lake Superior’s Tributary Streams of Minnesota
    (University of Minnesota Duluth, 2013) Johnson, Lucinda B; Herb, William; Cai, Meijun
    Water temperature is generally considered one of the primary physical habitat parameter determining the suitability of stream habitat for fish species, with effects on the mortality, metabolism, growth, behavior, and reproduction of individuals. In this study we assessed the potential threats of climate change on stream temperatures and flow regimes in Lake Superior tributary streams in Minnesota, USA. The study included deterministic models for stream flow and temperature of three study streams (Amity Creek, Baptism River, Knife River), and regional (empirical) models for specific flow and temperature parameters to give better spatial coverage of the region. Information on stream flow, stream temperature, and land cover was used to develop a brook trout presence/absence model to understand the current pattern of distribution of brook trout and predict future distributions under future climate. The hydrology of north shore streams is mainly driven by air temperature and precipitation. Historical air temperatures in the region have a significant upward trend, particularly since 1980. Global climate model (GCM) outputs project a continued increasing trend in air temperature, with an increase in mean annual air temperature of 2 to 3 °C by 2089. The historical precipitation data shows an increasing trend for total annual precipitation at Duluth and Two Harbors between 1900 and 2010, whereas Grand Marais and Grand Portage do not have a clear trend. Based on an analysis of daily precipitation totals, there is some indication of an increasing trend in the number of days in summer with high precipitation (10-20 cm). Both the GENMOM and the ECHAM5 GCMs project overall increases in precipitation of about 15%, but differ with respect to the seasonal distribution of the precipitation changes. A significant and relatively certain impact of climate change is a projected shift in precipitation from snowfall to rainfall. While an increasing trend in precipitation leads to increasing streamflow, the increasing trend in spring and summer air temperature tends to reduce streamflow (by increasing evapotranspiration). Available streamflow records for north shore streams suggest there may be a decreasing trend in mean annual flow and summer low flow, but the trends are not statistically significant. Future projections of streamflow based on the GCM output were mixed, with the deterministic models projecting moderate increases in average stream flow and summer low flow, while the regression models for project a moderate decrease in low flow. Stream temperature analyses for the three study streams based on GCM climate output give the result of fairly uniform seasonal increases in stream temperature to 2089 ranging from 1.3 to 1.9 °C for the GENMOM model to 2.2 to 3.5°C for the ECHAM5 model. Application of the GENMOM climate data to the deterministic stream temperature models produced fairly similar stream temperature changes for the three study sites. The empirical stream temperature study found stream temperature in the north shore region to be influenced by air temperature, catchment size, percentage of woody wetlands, latitude, and soil permeability rate. In response to climate change projected by the GENMOM GCM, the regional stream temperature model projects July mean water temperature to rapidly increase by approximately 1.2oC from 1990s to 2060s, followed by a slight decrease to 2089. The temperature increase was predicted to be the largest in the coastal area of middle north shore region. The brook trout presence/absence model found water temperature to have the strongest influence on trout presence. Brook trout were predicted to be at risk for water temperatures above 18.7oC and be extirpated from streams for temperatures over 20oC. Stream flow was shown to have a negative effect on trout presence, though not as strong as water temperature. Overall, these data predict that brook trout may be extirpated from lower shore area, be exposed to increasing risk in middle shore region, and remain present in upper shore streams from the present to 2089. This work would benefit greatly from a number of modifications to the GCM’s, the spatial data used in the development of both the deterministic and empirical models, and implementation of a more detailed, spatially explicit, hydrologic model. Finally, additional fish data, including cool and warm water assemblage data, along with descriptors of landscape structure (i.e., connectivity) would allow us to assess the areas where cold water species may be threatened by the presence or potential presence of coolwater competitors.
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    Data for: The influence of an in-stream thermal gradient on chironomid emergence during winter
    (2019-10-17) Ferrington, Leonard C Jr.; Nyquist, Corrie E; Vondracek, Bruce; ferri016@umn.edu; Ferrington, Leonard C Jr.; Chironomidae Research Group
    Chironomid surface floating pupal exuviae were collected from November 2017 through March 2018 from sites within one head water trout stream, Ike's Creek, and two comparative head water trout streams, Pine Needles Creek and Arcola Mills Stream. Pupal exuviae were identified to genus and species. Relative abundance over time at each site was used to calculate Jaccard’s coefficient of similarity among sites and to observe if there were differences in community composition along the length of a trout stream with longitudinal thermal heterogeneity. Mean daily water temperatures were also collected from November 2017 to April 2018 from each of the sites. Mean daily air temperatures were obtained from November 2017 to April 2018 from the NOAA National Weather Service. This data were collected in order to create air-water linear regressions for trout stream sites over winter. Our goal was to determine if fine-scale thermal heterogeneity exists along a first and second order trout stream and to compare the thermal regime with two other trout streams. The data, here, are released in accordance with the terms of publication.
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    Water temperature as a tracer in karst aquifers.
    (2011-07) Luhmann, Andrew James
    Water temperature at springs generally provides useful information concerning aquifer geometry and recharge. Temperature monitoring at 25 springs and cave streams in southeastern Minnesota has shown four distinct thermal patterns that can be interpreted in terms of heat exchange effectiveness along a flow path and the nature of recharge. The patterns provide information about the size of the flow path, recharge type and duration, and aquifer depth. Water temperature is generally an interactive tracer, where heat exchange rapidly occurs when water and aquifer rock are at different temperatures. In a multi-tracer experiment at Freiheit Spring, MN, uranine, chloride, and δD breakthrough curves were essentially identical and conservative. In contrast, the water temperature interacted with the aquifer as it moved along the flow path, producing a damped, lagged thermal signal at the spring. However, both the conservative and nonconservative tracers provide useful geometrical information. By summing discharge between the initial increase in stage produced by a pressure pulse and the chloride peak, the conduit volume is estimated as 51 m3. Using a heat transport simulation to reproduce the modified thermal signal requires a planar flow path with a hydraulic diameter of 7 cm. Both methods together suggest a bedding plane flow path that is 3.5 cm high by 10 m wide, in agreement with the observed spring geometry. The different tracers provide complementary information and stronger constraints on flow path geometry than could be obtained using a single tracer. Finally, numerical simulations were run to determine variables controlling thermal retardation in karst conduits. The lag of a thermal peak in the water is proportional to a conduit's length; is proportional to the square root of recharge duration, rock thermal conductivity, rock specific heat, and rock density; and is inversely proportional to a conduit's hydraulic diameter, velocity, water specific heat, and water density. These individual relationships were then combined to form one collective function, which, when plotted against thermal peak lag produced a line in log-log space. The relationship between the thermal peak lag and the combined function potentially enables estimates of conduit geometry using thermal peak lag data.