USING GIS IN GEOMORPHOLICAL STUDIES

Background Need for dealing with massive data. GIS: – Visualize and analysis of spatial data. GIS can assist in carrying out geomorpholocial study in easier and more accurate manner.

Objective To develop a GIS-based systematic approach for conducting a geomorphological study and its relevant analysis procedures. Methodology: – Assessing existing manual approaches. – Identifying the main steps of building GIS for geomorphological studies. – Highlighting the main advantages of GIS-based approach compared to manual ones.

Manual approach Data collection: – Topographic maps – Aerial photographs – A filed survey Build a number of base maps: – Geological map – Drainage map (Network) – Contour map Data calculation and tabulation. Data analysis. Producing final maps and graphs.

GIS-Based Approach Definition required data Data collection from secondary source of data Field survey Maps Previous studies Map digitizing Construct topology Check errors Map registration Correct errors Errors No errors Transformation of AutoCad drawing files Data analysis and output Data analysis Data visualization and output Building Data base Spatial data editing Data entry AutoCad ArcInfo ArcView

Maps Topographic map Geologic map

Map digitizing

Building data base TypeNameFeature PolygonGeologyGeologic units LineStructure PolygonBasinWatershed LineNetworkDrainage PointLevelLevels points LineRoadTransportation roads PointWellWater wells PolygonStudy areaStudy area border

Spatial data editing

Attribute data entry

Analysis capabilities Inquiry functions. – Table – View (Map) Surface analysis: – Building DEM – Creating contour map – Carrying out most morphometric analysis Overlap functions: – Interrelationships between various factors.

Inquiry function

DEM and Contour Map DEMContour Map

Morphometric analysis Network Watershed Select a basin Watershed Select a basin Overlap Identify streams of the selected basin Overlap Identify streams of the selected basin Inquiry Number and length of streams 1st, 2nd, 3rd, 4th order Inquiry Number and length of streams 1st, 2nd, 3rd, 4th order Editing attribute table of watershed Editing attribute table of watershed Frequency = Drainage density = (stream length/ drainage basin area) Stream bifurcation=

Manual Vs. GIS-based approach GIS-Based approachManual approachItem Requires less timeConsuming time processTime Hard work in building the systemHard work process in all stagesEfforts More accurateLess accurateAccuracy ApplicableNot applicableAmendments Moreover, GIS-based approach has more advantages:  High analytical capabilities.  Producing maps and charts.  Providing database for further research and application

Conclusion GIS is not a system for producing maps. The analytical capabilities is the most important characteristics of GIS The great potentials of GIS-based approach to be applied in geomorphological studies. The efficiency of the suggested approach requires: – Capacity buildings activities Training Networking – More arguments on morphometric analysis