Soil Erosion and Flood Risk Management

For the field work it is recommended to use ground truth sheets, which can be seen in table 1. The main
streets were digitalised from the WorldView2 satellite image using ArcGIS 9.3 for mapping the land use in
the investigation area (Map 1). It is important to note that the field work took place January, 7th and 8th
2013 and the satellite image was taken January, 23 rd 2012. Differences between the vegetation cover may
occur.
Furthermore a subset of the investigation area was created from the satellite image. This is useful to mark
ground truth information like GPS points. For more details, information photos were taken during the field
work from the areas around the GPS points and other regions.
The collected ground truth data are digitalised using the software ArcGIS 9.3.
4.1.4 Results
The results represent the calculated and collected data from Hotspot 2. First, the unsupervised and supervised
classification is analysed. Subsequently, the ground truth data are digitalised to create a land use map.
Unsupervised classification derived from satellite data
The first result created is the unsupervised classification which can be seen in Map 2. The ISODATA-
algorithm calculated the maximum likelihood attached to all pixels. Two different classes of built up areas
are possible to derive. Two classes of shadow were calculated as well. Furthermore, four different classes of
vegetation and three types of different soils were derived.
Tab. 2: The proportion of classes in ha and the percentage
Class name Area [ha] Percentage [% ]
Unclassified 0.96 0.689
Shadow 14.36 10.314
Vegetation 61.96 44.505
Soil 58.60 42.091
Built up area 3.34 2.399
Total 139.22 100
In table 2 the areas per class can be seen. Vegetation and soil together cover more than 86 % of the
investigation area. Built up areas like the St. Kevin Hills Voi and other houses cover around 2.4 % of
Hotspot 2. The total area covers 139.22 ha.
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