Spatial resolution of Digital Elevation Model and its impact on the morphometric measurements- Pendawi basin a case study

The efficiency of morphometric analysis of basins depends on the accuracy of the used data and analysis technique. The Penduya basin which lies in northern Iraq was selected because it is one of the small basins with an area of about 157.32 square kilometres. The morphometric analysis can be repeated several times for the purpose of comparing the variation in the morphometric features. The current study aims at analysing the morphometric measurements in the Penduya basin by adopting typical spatial resolution of the digital elevation models i.e., (30 and 90 meters). The analysis was carried out by adopting the GIS technique and its modifications in the field of morphometric analysis, i.e., morphometric toolbox, to check which of the morphometric parameters will be affected more than the others and their impact on the development and planning in the region. The results have shown that most of the morphometric parameters of the basin, which are related to the number, length and density of the drainage lines, have a clear and significant difference in the value of these parameters. The morphometric measurements calculated using the digital height model (30) meters (1 arc second) values differ from those calculated based on the DEM of (90) meters (3 arc second).The results show that, the measurements from the first model (30 meter) show an increase in the number of drainage lines, their lengths and basin perimeter by up to five times in comparison with the second model (90 meter) by various values for the other geometric and areal measurements. The results of the study have shown that the digital height data should be selected according to the required morphometric details.