ACTIVE TECTONIC ASSESSMENT OF MANDILI WATERSHED USING GIS TECHNIQUE
Geomorphic indices such as Asymmetry Factor (Af), Stream Length Gradient ratio (Sl), Hypsometric integral (Hi), Valley floor width to height ratio (Vf), Basin shape factor (Bs) and Mountain front sinuosity (Smf), are particularly useful in tectonic studies, because they can be used for rapid tectonic evaluation of large areas, and the necessary data often can be obtained easily from topographic maps and aerial photographs.
Geographic Information system (ArcGIS V-9.3) and Digital Elevation Model (DEM) with resolution of 30 m have been used to extract the stream network watersheds of Mandili Quadrangle, sheet No. NI-38-11, scale of 1: 250 000, east of Iraq.
Mandili Quadrangle is chosen to analyze the relationships between the morphometric characteristics and the active tectonics. The area concerned is located at the western edge of the well-known Zagros mountainous belt, which is a well-known tectonically active area.
Ten sub-basins were extracted by DEM and the above mentioned morphometric indices. In addition relative active tectonics were calculated to evaluate the tectonic history of the area.
The results show that the active tectonic effects on Mandili area range between inactive (low) to moderately active, which may be due to the soft and weakly resistant sediments that cover almost all the area concerned or due to prevailing climatic conditions in a tectonic quiescence.