Vol. 7, Issue 11, Part C (2025)

This study was conducted to assess the state of soil degradation and desertification using the MEDALUS model and the Soil Quality Guide in the semi-arid region located between longitudes 43°54'25" E and 44°03'27" E east, and latitudes 34°05'58" N and 36°04'31" N north, which includes parts of the Kirkuk and Erbil plains within Kirkuk and Erbil governorates, covering a total area of approximately 460,000 hectares. Five pedons were excavated and morphologically described according to Schoeneberger et al. (2012), and samples were taken from representative horizons of each pedon. In addition, thirty-six surface soil samples were collected from areas surrounding each pedon, placed in nylon bags, labeled, and transported to the laboratory for physical and chemical analyses, resulting in a total of sixty samples. Satellite imagery from the American Landsat 7 and Landsat 8 satellites at multiple dates (11/6/2000 and 18/6/2020) was used, and spatial distribution maps were prepared using ArcGIS 10.4.1. The study revealed the following:
A- Assessment of Desertification Using the MEDALUS Model:
Soil Quality Index (SQI):
1- The soil texture index ranged from Class 1 (Good), occurring in some parts of the Daqouq area and small parts of Al-Tun Kubri and Qushtapa, to Class 2 (Moderate), found in major parts of Daqouq, Shuwan, Al-Tun Kubri, Shirawa, and Qushtapa, and Class 3 (Poor), occurring in small parts of Daqouq, Al-Tun Kubri, Qushtapa, and Shirawa. These classes covered areas of 731.54, 455,868.21, and 3,400.25 hectares, representing 0.2%, 99.1%, and 0.7% of the total area, respectively.
As for the indices of parent material, rock fragments, slope, soil depth, and soil drainage, they were classified as Class 2 (Moderate), Class 3 (Bare to Slightly Rocky), Class 1 (Very Level), Class 1 (Deep), and Class 1 (Good), respectively.
The organic matter content index fell within Class 2 (Good) in the Shuwan area and parts of Al-Tun Kubri, and Class 3 (Moderate) in Daqouq, Shirawa, and Qushtapa. The area of Class 2 (Good) was 172,897.40 hectares, representing 37.59%, while Class 3 (Moderate) covered 287,102.6 hectares, or 62.41% of the study area.
The calcium carbonate content index was classified as Class 3 (Poor). The pH index of the study area soils fell within Class 3 (Moderate) in Daqouq and Class 4 (High) in Qushtapa, Shirawa, Al-Tun Kubri, Shuwan, and parts of Daqouq, covering areas of 121,782.76 and 338,217.24 hectares, representing 26.47% and 73.53%, respectively.
Meanwhile, the electrical conductivity (EC) index for the soils of the study area was classified as Class 1 (Low).
2- The Soil Quality Index (SQI) for the study area fell within Class 2 (Moderate Quality).
B- Assessment of Desertification and Degradation Using Remote Sensing Techniques:
1- The imagery resulting from the supervised classification for the period between 2000 and 2020 indicated a change in land cover features, with a clear transformation of large areas of agricultural or arable lands into urban or non-agricultural lands.