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Background:Project Background * Work Statement * Relevance Study Area Methodology:Past Studies Data Preparation *? Actual Data Adjustments * - PowerPoint PPT Presentation

Outline Background:Project Background * Work Statement * Relevance Study Area Methodology:Past Studies Data Preparation *? Actual Data Adjustments * Modeling Procedure *? Models:Hydrology Model Lake Thermodynamic Model Water Balance and Routing *

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Background:Project Background * Work Statement * Relevance Study Area Methodology:Past Studies Data Preparation *? Actual Data Adjustments *

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Outline

Background:Project Background *

Work Statement *

Relevance

Study Area

Methodology:Past Studies

Data Preparation *?

Actual Data Adjustments *

Modeling Procedure *?

Models:Hydrology Model

Lake Thermodynamic Model

Water Balance and Routing *

Hypsometric Relations and Outflow Equations *

Validation:Interdependent Lakes: Base Case vs. Historical *

NBS, Levels, & Channel Flows for whole system * * *

Terminal Lakes:Split System & Replace St. Clair Equation *

Consider removal of present-day diversions

Look @ independent lakes NBS only (upstream lakes terminal) *

NBS climate summary *

Look @ interdependent lakes: Outflow climate summary *

Lake Level summary * *


Background

Great Lakes in terminal state about 9000 years ago

Hypothesize climate caused this

Understand extremes of climate closing Great Lakes

NSF proposal with 13 others funded late last year


Background

Great Lakes in terminal state about 9000 years ago

Hypothesize climate caused this

Understand extremes of climate closing Great Lakes

NSF proposal with 13 others funded late last year

Work -- Simulate Great Lakes hydrology under various climates

Use GLERL’s AHPS

includes basin hydrology, overlake precipitation, lake thermodynamics, channel routing

used in climate change impact studies for EPA, IJC, NOAA, & IJC

Adjust lake & connecting channel conditions

outlets with “natural” outflow-elevation relationships and connecting channels

remove French River watershed

use dynamic areas in evaporation

remove existing diversions & consumptions

Use similar methodology here

propose climate characteristics compatible with geologic evidence or GCM simulations

modify meteorological record to reflect proposed climate changes

simulate resulting hydrology & compare to base case

Build WWW interface of project results for other researchers & public


Work (continued)

Model entire interdependent system (Georgian Bay draining into St. Clair)

Model two systems independently

Lakes Superior, Michigan, Huron, and Georgian Bay (used to drain to Hudson Bay)Lakes St. Clair, Erie, and Ontario (no inflow from above)

Look at steady-state closed lake

Steady-state (repeat adjusted meteorological record with initial conditions = ending)

Sufficient to use zero outflow and look at climates giving levels below sill

a) Superior terminal?

b) Michigan-Huron-Georgian Bay terminal, given Superior terminal?

c) Erie terminal?

d) Ontario terminal, given Erie terminal?

Relax constraint of upstream terminal lakes.


Relevance

Increase understanding of Great Lakes sensitivity to climate change

Previously, lake changes attributed to isostatic rebound & shifts in outlet elevation

New findings suggest climate shifts

Understand climate change impacts today


Study Area


Past Studies

Great Lakes have tremendous water & heat storage capacities

Early Great Lakes Climate Change Impact Studies

used simple constant changes in air temperature or precipitation in water balances

GCMs simulate current & 2xCO2 conditions

GCMs used for transient increases of greenhouse gases

EPA in 1984 used hydrology components of GCMs to assess water availability

Recent Similar Great Lakes Climate Change Impact Studies

GLERL-EPA 2xCO2 impacts (1989)

GLERL-IJC 2xCO2 impacts (1992)

Transposed Climate impacts (1998)

US National Assessment in Great Lakes (1999)

IJC LOSLR Regulation study (2004)


Data Preparation

Climate Data

models use daily data 1948—1999

~1800 stations for overland meteorology

~40 stations for overlake meteorology

Thiessen-averaged over 121 subbasins & 7 lakes

Changed Climate

“base case” scenario

apply ratios & differences to historical data

use with models to calculate climate change scenario


Actual Data Adjustments

P’ = P * R

T’ = T + D


Modeling Procedure

Arbitrary initial conditions used with 2-yr initialization simulation period

Estimate “steady-state” conditions

repeat 52-yr simulation with initial conditions equal to end values, until unchanging

Simulate with models on adjusted data sets for all scenarios (including base case)

121 watersheds and 7 lakes

Interpret differences between scenarios & base case as hydrology impacts


NBS Adjustment


Hypsometric Relations


Integrated System

St. Mary’s River

St. Clair River

Detroit River

Niagara River

St. Lawrence River


NBS


Matching MHG Historical Water Balance

For Superior: QS = 824.721 (ES – 181.425)1.5

For Mic-Hur-Geo:QMHG = 185 (EMHG – 166.549)1.5


Negligible Diversions


NBS

S2 – S1 = Inflow + NBS – Outflow


Steady-State NBS As a Function of Climate


Steady-State Outflow As a Function of Climate


Steady-State Water Levels As a Function of Climate


Steady-State Water Levels As a Function of Climate

Terminal Lake Climates:

Superior, 4.7 T + P > 60;Michigan-Huron, 4.5 T + P > 63


Steady-State Outflows As a Function of Climate


Steady-State NBS As a Function of Climate


Steady-State NBS As a Function of Climate


Steady-State Climate Range


Lower Great Lakes Without Upstream Inflows

For St. Clair:

QC= 70.714 (EC – 165.953)2(EC – EE)0.5,EC > EE > 165.953

= 70.714 (EC – 165.953)2(EC – 165.953)0.5,EC > 165.953 > EE

For Erie:

QE = 701.504 (EE – 169.938)1.5,EE > 169.938

For Ontario:

QO = 577.187 (EO – 69.622)1.5,EO > 69.622


Steady-State Water Levels As a Function of Climate

Terminal Lake Climates:

Erie, 4.7 T + P > 51;Ontario, 3.5 T + P > 71


Steady-State Outflows As a Function of Climate


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