Poster Presentation C Thursday, 5:00 � 6:00 pm C Edmund Fitzgerald Exhibit Hall

Use of IKONOS Imagery for Assessment of Lake Water Clarity in Eagan, Minnesota

Leif Olmanson, Marvin Bauer
University of Minnesota
Department of Forest Resources
Remote Sensing and Geospatial Analysis Laboratory
115 Green Hall
1530 Cleveland Avenue North
St. Paul, MN  55108
Leif.G.Olmanson-2@tc.umn.edu

Patrick Brezonik
University of Minnesota
Water Resources Center
173 McNeal Hall
1985 Buford Avenue
St. Paul, MN  55108

IKONOS data with four multispectral bands similar to Landsat TM bands 1-4 and high spatial resolution (4 m multispectral and 1 m panchromatic) is potentially well suited for assessment of small lakes and ponds. To explore the capabilities of IKONOS imagery for lake water quality assessment and monitoring, we acquired an August 23, 2000 IKONOS image for the City of Eagan, Minnesota. Eagan has 375 small lakes and ponds larger than one acre with 44-acre Thomas Lake being the largest. 

Lake signatures were extracted from 19 lakes that had Secchi disk transparency (SDT) measurements within three days of the image date. A regression model was developed using the band 3:1 ratio and band 1 as the independent variables and the natural log of SDT as the dependent variable. The results were very similar to results we have seen using Landsat imagery with an R2 = 0.82 and standard error of estimate (SEE) = 0.369. With the relationship we created a pixel level map of lake water clarity of the small lakes and ponds.

The use of IKONOS data for assessment of water clarity for small lakes at a city scale is promising. The high spatial resolution of the IKONOS data enables the assessment of smaller lakes and ponds than the Landsat 30-meter resolution allows. Only 14 of Eagan�s 375 ponds and lakes were included in our Landsat assessments, while IKONOS data allows for the assessment of all of Eagan�s small lakes and ponds.