Environmental Engineering Reference
In-Depth Information
Chapter 3
Methodology
3.1 Introduction
This chapter is first constituted of the conceptual and methodological approaches
leading the research on comparisons between digital elevation model (DEM)
quality control modeling and interpolation techniques. Second, it intends to
explain the input data preparation procedures for hydrodynamic modeling. Then in
the next step, the calibration and modeling approaches for flood hazard assess-
ment, the basic theory for hydraulic and hydrologic models (HEC-RAS and
SOBEK), are described. Following this, the statistical methods applied to ran-
domness, homogeneity, and trend detection in hydrometeorological variables are
described. Finally, in the last part of this chapter, the approaches used to analyze
the land use changes from the past until the present are posed and presented.
Model analysis such as land use change detection and DEM quality control
modeling was mostly done using ESRI software ArcGIS 9.3.1, based on different
extensions and tools such as: Spatial Analyst, 3D Analyst, and Geostatistical
Analysis, Arc Hydro Tools, HEC-GeoRAS, Hawthstools-Sampeling Tools cou-
pled with SAM.
For hydrological simulation, HEC-RAS (1D), developed by the US Department
of Defense Army Corps of Engineers, coupled with the SOBEK (1D-2D) model,
developed by Delft Hydraulics (The Netherlands), were used to analyze flood
hazard scenarios and flow characteristics over time. ArcGIS and ILWIS softwares
were used in the pre- and post-modeling phases of HEC-RAS and SOBEK for data
preparation, visualization, and analysis.
The calculation of trends in climatic parameters was made with SPSS software.
Land use change detection was analyzed in ArcGIS. The scale of all GIS layers was
fixed in ArcGIS using the ''Raster Storage Setting''. From different pyramid
resampling techniques, the ''Nearest Neighbor Method'', which is based on per-
forming a nearest neighbor assignment, was selected because it is a fast interpolation
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