The Dying Dead Sea

Assessing the decline of the Dead Sea area in relation to irrigated agriculture

Noel Peterson and Zach Tagar

FR 5262

Off basin Water

diversion since 1960’s

Israel’s National Water Carrier – one of several causes for the decline of the Dead Sea

Water level 1900

The dying of the Dead Sea

The dying of the Dead

Sea

Measuring Surface Area Change

• Based on Landsat band 4 (near-IR)

• Examined histograms in ArcMap to determine cutoff for water: bimodal distributions.

Measuring Surface Area Change

• Using cutoff values determined by histograms, we created binary images using ArcMap’s Reclass tool.

• Output clipped to Dead Sea area to remove misclassified shadows.

Measuring Surface Area Change

• Converted rasters to polygons and removed the rest of the misclassified spots.

• By putting polygon features in a geodatabase, areas are calculated automatically.

Results

Year Full Area (km^2) North Area (km^2)

1900 880.9234 874.5845

1984 901.1682 682.2036

1985 895.1553 680.6817

1989 884.7729 665.4978

1990 884.1348 662.5881

1998 894.8385 650.3202

2003 867.0753 641.1735

2009 858.9582 622.0044

Note: 1900 values calculated by reclassifying SRTM DEM (90m spatial resolution) with an historical surface elevation measurement instead of satellite imagery and histogram values.

Results

Assessing extent of (irrigated) agriculture(Data: Landsat 5 2003/2009)

Try 1: NDVIBand 4 NDVI

No variability between classes

Try 2: unsupervised classification (40 classes)

Same class for agriculture and nature

Try 3: supervised classificationDefining AOI’s across the country (430 - 480)

(Ag, natural vegetation/desert; water; urban)

Stats…

Try 3: supervised classification

Sort of working!

Classification 1 Classification 2

Accuracy Assessment - no reference map!

200 random points from ArcMap …

… to Google Earth (import shapefile in Google Earth Pro Trial version)

Manual inspection…

Manual inspection…

Manual inspection…

Results:

classification 4 Reference      

    Agriculture Natural vegetation Urban Water

Agriculture 42 28 7 7 0

Natural vegetation 94 22 55 17 0

Urban 13 1 2 10 0

Water 34 1 1 0 32

            125

  183 52 65 34 32

• % correct: 68.31%

• Error of Omission (ag): 33.33%

• Error of Comission (ag) 46.15%

• No. of pixels: 6,233,765

• 30 m resolution; 900 sq/m

• Total area ag: 5610.389 sq/Km