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GLERL 2000 Milestone Reports
GOAL: SUSTAIN HEALTHY COASTS
OBJECTIVE 2: PROMOTE CLEAN COASTAL WATERS TO SUSTAIN LIVING MARINE RESOURCES AND TO ENSURE SAFE RECREATION, HEALTHY SEAFOOD, AND ECONOMIC VITALITY
PM: Number of coastal and Great lakes states provided with improved predictive capabilities and understanding of environmental processes.
Milestone: Develop Improved water-level statistics that reflect:(1) existing hydrologic and hydraulic conditions; (2) the long lag response of the lakes to meteorological variability; (3) changes in climatic regimes; and (4) the needs of diverse Great Lakes decision-makers.
Scientist: F. Quinn
Purpose
Extreme Great Lakes water levels (high and low) periodically cause major social, economic and ecosystem disruption throughout the Great Lakes system. Reliable lake level frequency distributions are a critical component of any comprehensive strategy for coping with lake level fluctuations. Historical records of daily and monthly lake levels reflect secular changes in connecting channel hydraulics, watershed hydrologic response, and climate. The objective of this research is to develop improved water level statistics that reflect l) existing hydrologic and hydraulic conditions, 2) the long lag-response of the lakes to meteorologic variability, 3) secular changes due to changing climatic regimes, and 4) the needs (e.g., varied planning horizons, understanding the limits of lake level statistics) of diverse Great Lakes decision makers. The focus of this milestone is the assessment of secular changes in the Great Lakes seasonal water level cycles. This project will contribute to the NOAA Strategic Plan by assessing changes in the seasonal cycles which improves both our understanding of environmental processes and our predictive capabilities, leading to improved resource management decisions.
Efforts
A study of secular changes in the seasonal cycle of the Great Lakes from 1860 through the present is being conducted to assess possible changes in seasonal water levels due to changing climatic regimes or anthropogenic activities. The Great Lakes water levels Figure 1) constitute one of the longest time series of hydrometeorological data in North America. The seasonal lake levels (Figure 2) are obtained by filtering the monthly water level time series with a centered 12 month moving average to remove the interannual variability. Seasonal statistics generated from the seasonal time series include maximums, minimums, ranges, and timing. Changes in the time series were assessed relative to known changes in the hydraulic regimes of the system.
Figure 1. Lake Erie monthly water levels, 1860-1999.
Figure 2. Lake Erie
Seasonal water levels, 1861-1998.
Customers
There are a broad range of customers for this data. The results have been disseminated by providing the basic and analyzed data through symposia and panel discussions at professional meetings, interest group meetings, Congressional Briefings, requests for information, and the media. Major customers include the US Army Corps of Engineers, the International Joint Commission, Great Lakes Sea Grant extension agents, Environment Canada, the Lake Carriers Association and other port and navigation interests, the eight Great Lakes States, the provinces of Ontario and Quebec, and other diverse groups including marina operators, urban planners and land developers, and insurance companies. Finally, native groups and environmental and wilderness groups within the region have professional and recreational interests that depend significantly upon the water resources of the Great Lakes basin.
Significance
This is the first study to assess secular changes in Great Lakes seasonal cycles. Prior studies have focused almost entirely on interannual variability. The study found particularly significant changes in the seasonal cycles for Lakes St. Clair and Lake Erie (Figures 3 and 4). It is hypothesized the changes are due to reduced ice jams in the St. Clair River due to the construction of a new navigation cutoff channel between 1956 and 1961 and increased Coast Guard ice breaking activities and in the Niagara Rivers due to the construction of an ice boom in the mid 1960's. Also the seasonal range of Lake St. Clair water levels was reduced by about 1/3 in the early 1960's (Figure 5) which could impact wetlands and fish habitat. The seasonal range was also found to be uncorrelated with the lake level regime. Changes were also found to occur in Lake Ontario concurrent with the construction of the St. Lawrence Seaway and subsequent lake regulation. This study also demonstrated the role of ice in the Great Lakes connecting channels on the natural regulation of the Great Lakes.
Figure 3. Lake Erie seasonal cycle
Figure 4. Lake St. Clair seasonal cycle.
Figure 5. Lake St. Clair Seasonal range, 1901-1998.
Success
This analytical work for this project was successfully completed in December of this year and is currently being used as a major information source for the recent record drop in Great Lakes water levels and possible outcomes during the coming winter and spring. A journal article documenting the changes in the seasonal cycle should be published during 2000. This project contributed to the NOAA Strategic Plan by assessing changes in the seasonal cycles which improves our understanding of environmental processes and our predictive capabilities leading to improved resource management decisions.
Next Steps
The data from this study will be used for water resource impact assessments and for the assessment of alternative lake regulation plans for the Great Lakes basin under the auspices of the International Joint Commission.
Last updated: June 10, 2002 mbl