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Browsing by Author "Sinokrot, Bashar"

Now showing 1 - 4 of 4
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    Deterministic Modeling of Stream Water Temperatures: Development and Applications to Climate Change Effects on Fish Habitat
    (St. Anthony Falls Hydraulic Laboratory, 1992-12) Sinokrot, Bashar; Stefan, Heinz G.
    The effect of projected global climate change due to a doubling of atmoapheric CO2 on water temperatures in five streams in Minnesota is estimated using a deterministic heat transport model. The model calculates heat exchange between the atmosphere and the water and is driven by climate parameters and stream hydrologic parametera. The model is based on a finite difference solution of the unsteady heat advection-dispersion equation. An energy balance at the water surface accounts for the effects of air temperature, solar radiation, relative humidity, cloud cover and wind speed on the net rate of heat exchange through the water surface. The energy balance at the bottom of the stream requires modeling of diurnal heat exchange between water and streambed. The model was calibrated against detailed measurements to account for seasonally variable shading and wind sheltering shown to be dependent on leaf cover of trees on stream banks. Measurements were made in 5 streams at 2 minute intervals over periods of up to 4 weeks. After calibration, accuracies of hourly and daily water temperature predictions over periods of several weeks are on the order of 0.2 to 1°C. The model is sensitive to each of the aforementioned weather parameters to different degrees. Sensitivity coefficients are calculated by two different methods which gave same order of magnitude results. The mean and/or the standard deviation of each of the weather parameters are combined with the sensitivity coefficients to establish the sensitivity of the model to each parameter. The sensitivity analysis showed that stream water temperature is most sensitive to air temperature and solar radiation. Using climate projections from the GISS (Goddard Institute for Space Studies), GFDL (Geophysical Fluid Dynamics Laboratory) and OSU (Oregon State University) Global Circulation Models (GCM's) as input; stream temperature simulations predict a warming of freely flowing river reaches by 2.4°C to 4.7°C when atmospheric CO2 doubles. In small shaded streams water temperatures are predicted to rise by an additional 6° C in summer if trees along stream banks should be lost due to climate change. These projected water temperature changes have significant consequences for survival and growth of fishes in different temperature guilds (cold-, cool- and warmwater fishes). A model developed by the USEPA, relating fish survival and fish habitat to water temperatures, was applied to make the first assessment. The simulation results obtained with the complete heat budget equations are also used to examine simplified water temperature/air temperature correlations.
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    Impacts of In-Stream Flow Requirements Upon Water Temperature in the Central Platte River
    (St. Anthony Falls Hydraulic Laboratory, 1996-05) Sinokrot, Bashar; Gu, Ruochan; Gulliver, John S.
    This report describes the results of a study to determine the impact of various instream flow criteria upon the number of days that water temperature in the central Platte exceeds 1) the State standard of 32°C, and 2) 35°C. The 35°C level is presumed to be a temperature at which the aquatic biota is more severely stressed than at 32°C. The 35°C level was also justified by Dinan (1992) as a temperature that is close to the "Critical Thermal Maximum" for many fish species found in the river basin. The study involves the application of a computational water temperature prediction model, MNSTREM, to the central Platte River. MNSTREM has been shown to accurately predict stream water temperature on an hourly time scale under highly unsteady conditions (Gulliver, 1977; Stefan et aI., 1980), and has been adapted to incorporate all of the important aspects of natural rivers (Sinokrot and Stefan, 1992, 1993, and 1994). Calibration and verification takes place through the comparison with four years of water temperature record at four stations on the Platte River. The model is then used with the four-year weather record to predict the water temperatures that would have occurred with various minimum instream flow criteria applied to the reach. The impact of these in-stream flow criteria on water temperature is then predicted for the four-year period through comparison, of computer simulations.
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    A Methodology to Estimate Global Climate Change Impacts on Lake and Stream Environmental Conditions and Fishery Resources with Application to Minnesota
    (St. Anthony Falls Hydraulic Laboratory, 1992-03) Stefan, Heinz G.; Hondzo, M.; Sinokrot, Bashar; Fang, Xing
    The effects of global climate were projected on the distribution and growth potential of common freshwater fishes in 5 streams and 27 classes of lakes in Minnesota. The method developed for, this analysis uses laboratory growth and mortality data, and a stream temperature-fish distribution database, to define temperature responses for 32 fish species. Sensitivity to depressed dissolved oxygen concentrations was derived from information presented in the U.S. EPA ambient water quality criteria document on oxygen. Stream and lake water temperatures and lake dissolved oxygen concentrations are simulated by one-dimensional, unsteady heat and oxygen transport models operating on a timestep of one day. Simulations are made for a 25-year historical period (1955.-80) and projected steady-state future climate simulated by general circulation models assuming a doubling of atmospheric CO2• Water temperature and dissolved oxygen (D.O.) concentrations simulated for streams and lakes are then compared to "critical" values for presence (survival ) or "good" growth (time of exposure to temperatures permitting rapid growth) of a fish species or guild. The results project expected impacts on representative Minnesota streams, while the lake results represent a regional analysis for the state as a whole. The following conclusions stand out among the many study results. In wide, essentially unshaded streams, global warming is expected to contribute to elimination of coldwater fishes and some coolwater fishes in many habitats where they were formerly present. Warmwater fishes will gain substantially more potential for good growth than existed previously. Coldwater fishes will have a chance for continued existence only in those streams with adequate shading by riparian trees. Coldwater fishes will have the best chance to survive in deep lakes located in the northern half of the state, but there will be a loss in habitat for good growth. Warmwater fishes will gain habitat for good growth in virtually all types of lakes. Coolwater fishes will gain habitat enabling good growth in most types of lakes. Losses or gains in good growth potential due to global warming are projected to be larger in deep lakes than in shallow ones. The trophic state of the water body will also have an influence on the response of indigenous fishes to climate change. In shallow lakes, trophic state is projected to have little effect on the influence of global warming on habitat suitability for fishes. In deeper, seasonally stratified eutrophic lakes losses or gains of habitat for good growth are projected to be smaller than in oligotrophic lakes of the same size and depth. Lake size and depth are of importance as they affect seasonal stratification of water temperature and dissolved oxygen. Dissolved oxygen limitations are more serious in eutrophic lakes than in oligotrophic lakes. They are also more apparent in deep lakes than in shallow ones. Climate change is projected to worsen availability of habitats for good growth due to oxygen limitations. For the state as a whole, the potentital for good growth of lake dwelling, coolwater fishes is projected to increase by 20 percent and for warmwater fishes by 53 percent. Coldwater species will lose 40 percent of their habitat suitable for good growth. The total habitat for good growth of Minnesota lake fishes, regardless of guild designation, is projected to increase by 6 percent.
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    Performance Studies of the Unocal Pump Sump Hydraulic Model
    (St. Anthony Falls Hydraulic Laboratory, 1989-09-15) Voight, Richard L., Jr.; Wetzel, Joseph M.; Sinokrot, Bashar; Grundhoffer, Jeffery F.
    Stone and Webster Engineering Corporation has prepared a preliminary hydraulic design of the Colorado River Water Supply Project for the UNOCAL Corporation. Of particular concern was the area extending from a proposed pumping station to a proposed grit basin on the Colorado River near Grand Valley. The grit basin is used as a settling pond to remove the sediment carried by the river.