effects of global climate warming on water quality characteristics and fish habitats in lakes of the...
Post on 23-Jan-2016
215 Views
Preview:
TRANSCRIPT
Effects of Global Climate Warming on Water Quality Characteristics and Fish Habitats in Lakes of the
Contiguous USA
Xing FangPh.D., P.E., D.WRE, Associate Professor
Department of Civil EngineeringAuburn University
Auburn, Alabama 36849, USA
Acknowledgements
• Thanks for NIER’s invitation and arrangement on attending the
international seminar.• Thanks for the support from US EPA to conduct research projects
on the topic presented here.
Presentation Outline:
• Model overview (MINLAKE96)
• Database for model simulation
• Impacts on water temperature characteristics
• Impacts on snow and ice cover characteristics
• Impacts on dissolved oxygen characteristics
• Impacts on fish habitats in lakes
• Conclusions
1. Model Overview - MINLAKE96• MINLAKE96 uses a mixed-layer approach to
simulate water temperature and dissolved oxygen distribution day by day. It is a one-dimensional model. It simulates water temperature and dissolved oxygen in open water season and ice cover period.
• The model can be run continuously for number of years with algorithm to model ice formation date, snow accumulation and melting, ice growth and decay, and ice melting date.
Schematic of a stratified lake with a 10 m sediment layer showing heat transfer components and water/sediment temperature
profiles in the open water season and during the ice cover period
Water Temperature Modeling p
wwz
w
c
H
z
TAK
zAt
T
1
Dissolved Oxygen Modeling
Check one-
dimensional
assumption
using DO and
temperature
measurements
in Fish Lake
(Minnesota)
Year-round
lake model
development
and
applications
Simulated and observed water temperature profiles in winter period for Thrush Lake, MN
Simulated and observed snow and ice thickness in winter period for Thrush Lake, MN
Model PerformanceQuantitative error measurements (between measured
and simulated values in 9 lakes) of the model are
Standard errors between simulated and observed ice thickness and snow depths for three lakes (128 data points over 8 years) are 0.07 m and 0.12 m, respectively.
Nine lakes are Fish Lake, Cedar Lake, Lake George, Lake Orchard, Lake Riley, Square Lake, Thrush Lake, Lake Wabasso, and Lake Waconia with total of 5,976 data pairs.
Error Parameter Temperature (o C) DO (mg/l)
Standard error of estimate 1.43 (0.5 for winter) 1.93
R2 0.92 0.71
2. Modeling Database: Regional Lake Designation
Frequency distributions
of lake surface area,
maximum depth, and
Secchi depths for
3002 Minnesota
Lakes.
• Past climate data – 209 weather stations from 1961 to 1979 (air temperature, dew point temperature, wind speed, solar radiation, sunshine percentage, rainfall and snowfall.
• Future climate scenario – The second generation Canadian Climate Centre Global Circulation Model (3.75o x 3.75o), apply for monthly increments or ratios.
Projected air temperature increase due
to climate warming
Past (1961-1979) and projected 2xCO2 climate scenarios (monthly averages) at Duluth, MN.
3. Impacts on Snow and Ice Cover Characteristics
Parameters studied: frequency of occurrence and duration of ice cover, dates of ice-in (freeze-over) and ice-out
(melting), maximum ice and snow thickness.
Simulated earliest ice-out
date under past
(1962 – 1979) and
future (2xCO2) climate
scenario
Simulated annual cumulative days of ice cover on small, medium-
depth lakes under past
climate conditions
Projected difference of
annual cumulative days of ice cover
on small, medium-depth lakes
4. Impacts on Water Temperature Characteristics
Parameters studied: maximum and minimum surface and bottom water temperatures, .
Strongly dependent
on geographic
location
More or less independent of lake types
Regional Lake Types for Contiguous USA Study
Simulated maximum bottom water temperature under the past climate conditions
Simulated maximum temperature difference between lake surface and bottom
Simulated change or difference (GCM- Past) on seasonal stratification ratio (during open water
season) for deep medium lakes
5. Impacts on Dissolved Oxygen
Characteristics
Parameters studied: minimum surface and
hypolimnetic DO during open water
season and ice cover period, number of dates
and percent lake volume with anoxic
conditions.
Simulated average
dissolved oxygen (mg/l)
isopleths for a
shallow eutrophic lake (10
km2) near Duluth, MN under past and future
climate scenario
winter fish kill
DO criteria for three fish guilds: cold-water and cool-water fish - 3.0 mg/l; and warm-water fish - 2.5 mg/l
A schematic distribution of survival and growth of fish in a seasonally stratified lake
6. Impacts on Fish Habitats in Lakes
Guild Lower good-growth
temperatureLGGT, (oC)
Upper good-growth
temperatureUGGT, (oC)
Upper lethal temperature
LT, (oC)
Optimum temperature
OT, (oC)
Dissolved Oxygen
DO, (mg/l)
Cold-water1
Mean Range
9.0(6.4-11.8)
18.5(15.5-21.2)
23.4(22.1-26.6)
15.3(11.5-18.7)
3.0
Cool-water2
Mean Range
16.3(13.2-18.2)
28.2(27.7-28.8)
30.4(28.0-32.3)
25.1(24.0-25.7)
3.0
Warmwater3
Mean Range
19.7(17.7-22.5)
32.3(31.3-34.7)
34.5(32.3-36.0)
29.2(27.0-32.0)
2.5
Thermal and dissolved oxygen criteria for cold-, cool- and warm-water fish guilds
1Cold-water species: brook trout, brown trout, chinook salmon, chum salmon, coho salmon, mountain whitefish, pink salmon, and rainbow trout.
Simulated
depth-
time
contour
for
shallow
large
eutrophic
lake near
Duluth,
MN
Simulated
depth-
time
contour
for cool-
water fish
in
medium-
depth
medium-
size
trophic
lake
Fish Habitat Model Validation• Simulated fish habitats were compared with fish
observations in 3002 Minnesota lakes.• Simulated fish habitats agree with observations
in all medium and deep lakes, small and medium-size shallow oligotrophic lakes for cold-, cool-, and warm-water fish guilds.
• Winterkill was simulated to occur in shall eutrophic and mesotrophic lakes. Sensitivity analysis shows that a lower DO limit (<0.5 mg/l) produced better agreement with the fish observation database than higher limits.
Distribution of number of
lake types with
suitable fish habitat
for cold-water fish
at 209 locations in
the contiguous
USA
Distribution of number of
lake types with
suitable fish habitat
for cool-water fish
at 209 locations in
the contiguous
USA
Winterkill
Summerkill
Distribution of number of
lake types with
suitable fish habitat for warm-water fish
at 209 locations in
the contiguous
USA
Conclusion Remarks• Simulated water quality and ice cover characteristics
were related to lake geometric and trophic characteristics and to geographic location.
• The 2xCO2 climate scenario is projected to increase lake surface temperatures by up to 5.2oC when CCC GCM projects an increase of mean annual air temperature up to 6.7oC.
• The duration of seasonal summer stratification is projected to be up to 66 days longer under a 2xCO2 climate scenario, and this leads to longer period of anoxic hypolimnetic conditions that will result various negative environmental and ecological impacts in lakes.
Conclusion Remarks• Projected climate warming has strong impact on
ecological conditions in ice-covered lakes, e.g., later ice formation, earlier ice-out, and short ice cover period (shorten up to 90 days).
• Climate warming is projected to reduce the number of locations in the contiguous U.S. where lakes have suitable cold- and cool-water fish habitat, by up to 45% and 30%, respectively. Summerkill under the projected 2xCO2 CCC climate scenario is projected to have a significant negative influence on cold-water fish in northern lakes and cool-water fish in southern lakes of the contiguous U.S., where suitable habitat existed under historical conditions.
Thank You!
More information and journal papers about the study:
http://eng.auburn.edu/users/xzf0001/
top related