INTEGRATION OF REMOTELY SENSED DATA&GISTECHNIQUES TO STUDY LESSER ZAB RIVER BASIN.

Abstract

The Lesser Zab River Basin (L.Z.R.B) is a part of Iraqi and Iranian territories. The L.Z.R.B lies in the northeastern part of Iraq within Erbil, Sulaimaniy and Kirkuk governorates. The whole area of the L.Z.R.B covers 19190 Km2, 14276.5 km2 is inside Iraq, with percentage 75.4% and 4913.5 km2 is inside Iran, with percentage (24.6%). The main aims of this study are studying morphometric characters, preparing digital map of the drainage system network of the river basin, structural analysis of lineament, and Land Use – Land Cover map, and then to combine all these information to find out suitable area for surface water storage and/or feeding ground water by suggesting some dam locations using remote sensing data and GIS applications.

In the present study, remote sensing techniques were applied like supervised classification; using Maximum Likelihood Classification (MLC), viewing of color composite in band combination, extraction and analysing drainage network and morphometric analysis, drainage density analysis, display DEMs as shaded relief images, Ambient Light Technique, automatic lineament extraction algorithm, density lineaments analysis, lineaments length classification, and digital directional analysis of the lineaments.

ERDAS Imagine 9.1 was used for images analysis; PCI Geomatica software was used for lineaments extraction and Arc GIS 9.3 software was used for drainage delineation and layouting the final results. There are three kinds of satellite images were used; Landsat (TM5) Image, QuickBird satellite Image and ASTER Global Digital Elevation Model (GDEM).

The supervised classification operation was applied on Landsat TM image to recognize Land Use – Land Cover (LULC) classes; The classification of L.Z.R.B resulted in dividing the area into five classes, these are: Urban and Built-up Land, Vegetated Land, Agricultural non-Vegetated Land, Water body and Barren Land. The Agricultural Land non-Vegetated class is subdivided into Cultivated Land, Idle cropland and Burn land subclasses. The Barren Land Class is subdivided into Bare Exposed Rock and Mixed Barren Land subclasses. Bare Exposed Rock subclass is subdivided into Conglomerate, Clastic rocks, Carbonate rocks, Mafic rocks and Ultramafic rocks. The Overall classification Accuracy is 95.50% and a kappa coefficient is 0.9509, which represents very good accuracy.

The morphometric parameters are computed using Arc GIS 9.3 software. The drainage pattern of L.Z.R.B is dendritic to sub-dendritic with 8 stream orders. Drainage density value is 1.79 km/km2 suggesting course to moderate drainage texture. The change in values of stream length ratio indicates their late youth stage of geomorphic development. The values of bifurcation ratio range from 4.46 to 6, it's indicating that all the basin fall under normal basin category. The value of form factor is 0.30 and circulatory ratio is 0.13, which suggest that the L.Z.R.B is elongated and the elongation ratio is 0.35, therefor, the basin is less circular in shape. Elongation ratio indicates that the basin associated with moderate to high relief and steep ground slopes. It is concluded that remote sensing and GIS techniques have been proved efficient tools in drainage delineation and updation.

Studies of lineaments, as one of the most important factors in geological and structural analysis, gave indications about the locations of ore deposits, landslides, and groundwater movements. Shaded relief images were created from digital elevation models (DEMs), it is helpful in identifying lineaments in different distinct relief and topography. This method can enhance lineaments at different orientations by simulating topographic illumination under varied light directions, by useing different azimuth directions and sun angles. The combining of four shaded relief images into a final image leads to enhancing the lineaments within the four sun azimuth directions. Two shaded relief images with multi-directional light were created: The first image is with the four azimuth angles of the light sources, which are 0°, 45°, 90° and 135°, and the second image also is with the four azimuth angles of the light sources: which are 180°, 225°, 270°,and 315°. Both images were used for automatic lineament extraction using PCI Geomatica software. The extraction lineaments of the first image are showed that the most automatic lineaments represent positive lineaments and the automatic extraction lineaments of second image represent negative lineaments of the L.Z.R.B. The main trends of the extracted lineaments for both images are NW–SE, N–S, E–W and NE–SW. The total number of the automatic lineament extraction using DEMs is 7811; for positive lineaments and 9108; for negative lineaments. The average length of the positive lineaments is 1.854 km and the negative lineaments is 1.846 km, the total length of the positive lineaments is 14488.563 km and the negative lineaments is 14688.370 km.

Intersect between lineament and drainage densities maps are used to find out suitable area for groundwater recharge and/or surface water storage. Five dams can be suggested in the L.Z.R.B depending on the acquired data in the present study.