USING GEOGRAPHIC INFORMATION SYSTEM AS A DECISION SUPPORT SYSTEM by variablepitch344

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									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.

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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

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Data calculation and tabulation.  Data analysis.  Producing final maps and graphs.

GIS-Based Approach
AutoCad

Definition required data Maps Data collection from secondary source of data Previous studies Field survey

Map digitizing

Transformation of AutoCad drawing files Construct topology

ArcInfo
Check errors
Errors No errors

Correct errors

Spatial data editing
Data entry

Map registration

ArcView

Building Data base Data analysis Data analysis and output
Data visualization and output

Maps

Geologic map
Topographic map

Map digitizing

Building data base
Feature Geologic units Structure Watershed Drainage Levels points Transportation roads Name Geology Structure Basin Network Level Road Type Polygon Line Polygon Line Point Line

Water wells
Study area border

Well
Study area

Point
Polygon

Spatial data editing

Attribute data entry

Analysis capabilities


Inquiry functions.
– Table – View (Map)

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Surface analysis:
– Building DEM – Creating contour map – Carrying out most morphometric analysis

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Overlap functions:
– Interrelationships between various factors.

Inquiry function

Order 1 2 3 4 Total

Count 13 4 2 1 20

Length (KM) 8096.65 6288.77 3552.60 978.07 18916.09

DEM and Contour Map

DEM

Contour Map

Morphometric analysis
Network

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

Manual Vs. GIS-based approach
Item Time Efforts Accuracy Amendments Manual approach Consuming time process Hard work process in all stages Less accurate Not applicable GIS-Based approach Requires less time Hard work in building the system More accurate Applicable

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
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

Training Networking

– More arguments on morphometric analysis


								
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