Use of Remote Sensing to Characterize Impervious Cover in Stormwater Impaired Watersheds

Transcription

1 University of Massachusetts Amherst Amherst Water Resources Research Center Conferences Water Resources Research Center Use of Remote Sensing to Characterize Impervious Cover in Stormwater Impaired Watersheds Brenda Berasi Ken Hickey Brendan Lennon Scott Stoodley Follow this and additional works at: Berasi, Brenda; Hickey, Ken; Lennon, Brendan; and Stoodley, Scott, "Use of Remote Sensing to Characterize Impervious Cover in Stormwater Impaired Watersheds" (2007). Water Resources Research Center Conferences. 23. Retrieved from This is brought to you for free and open access by the Water Resources Research Center at Amherst. It has been accepted for inclusion in Water Resources Research Center Conferences by an authorized administrator of Amherst. For more information, please contact

2 Use of Remote Sensing to Characterize Impervious Cover in Stormwater Impaired Watersheds Brenda Berasi,, Ken Hickey, Brendan Lennon, Scott Stoodley AMEC Earth & Environmental

3 Introduction The impervious cover model (ICM) uses the percent impervious cover of a watershed as a surrogate TMDL target. A total maximum daily load (TMDL) is the maximum pollutant load that a waterbody may receive and still meet water quality standards and support its designated uses.

4 Impervious Cover Model Source: Center for Watershed Protection

5 Impervious Cover Model 1. Watershed delineation 2. Impervious cover mapping 3. Calculation of % impervious cover of watershed 4. Estimation of annual runoff volume 5. Estimation of pollutant loads

6 Impervious Cover Model 1. Watershed delineation 2. Impervious cover mapping 3. Calculation of % impervious cover of watershed 4. Estimation of annual runoff volume 5. Estimation of pollutant loads

7 Impervious Cover Mapping If landcover data is available, the percent imperviousness may be estimated based on a typical percentage for each landcover class. Refinement may be necessary May be outdated

8 Impervious Cover Mapping Remote sensing can provide an impervious cover map that is: Accurate Recent Frequently updated Site-specific Automated by digital image processing techniques

9 Application: Arapahoe County Objective: To map impervious cover in a study area using high resolution satellite imagery Evaluate the accuracy of two digital image processing methods

10 QuickBird Imagery Acquired 22 July 2005 by Digital Globe 4-band multispectral data (2.40 meter resolution) Panchromatic band (0.60 meter resolution)

11 Methods QuickBird Multispectral (2.40 m) QuickBird Panchromatic (0.60 m)

12 Methods Pan-sharpened to preserve spectral integrity (Wavelet Transform) Pan-sharpened to improve visual interpretation (IHS Transform)

13 Methods Ground truth data was collected in June 2006 at 40 locations where there was spectral confusion in the imagery

14 Results A continuous map was produced in which each pixel was classified as either pervious or impervious

15 Results By overlaying a parcel shapefile, the impervious area per parcel was calculated 25.8% Impervious 19.5% Impervious

16 Accuracy Assessment 100 locations were selected using a stratified random sampling design In the absence of field data, the 2004 aerial imagery was used as ground truth Both processing methods yielded an overall accuracy of 86.0%

17 Accuracy Assessment Multispectral Pan-sharpened

18 Conclusions The accuracy assessment revealed an overall accuracy of 86.0% for both processing methods, with slightly differing user s and producer s accuracies. Neither processing method showed to have any advantages or disadvantages relative to the other.

19 Future Sources of Data WorldView I To be launched no later than mid-2007 Panchromatic (0.45 meter) GeoEye-1 To be launched 3 rd Quarter 2007 Panchromatic (0.41 meter) 4-band multispectral (1.64 meter) WorldView II To be launched no later than 2008 Panchromatic (0.46 meter) 8-band multispectral (1.8 meter)

20 Remote Sensing Benefits Synoptic view Allows for simultaneous regional-scale assessments Frequent and repetitive coverage Allows for easy updating Available archived imagery Allows for examination of historic conditions Worldwide coverage Allows for access to remote locations Low-cost data

21 For More Information: Brenda Berasi Ken Hickey AMEC Earth & Environmental (978)