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Description of Study Area

This document summarizes a study that aims to analyze flood inundation areas along the Brahmaputra River network and assess flood hazards in Nagaon District, India by integrating geospatial data using GIS. It describes the study area, data sources including Sentinel-2 satellite imagery and ASTER DEM data, and the tentative methodology which includes producing land use/land cover maps, a road map, drainage maps, and watershed delineation to eventually create flood hazard maps.

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Ijaz Ahmed
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43 views10 pages

Description of Study Area

This document summarizes a study that aims to analyze flood inundation areas along the Brahmaputra River network and assess flood hazards in Nagaon District, India by integrating geospatial data using GIS. It describes the study area, data sources including Sentinel-2 satellite imagery and ASTER DEM data, and the tentative methodology which includes producing land use/land cover maps, a road map, drainage maps, and watershed delineation to eventually create flood hazard maps.

Uploaded by

Ijaz Ahmed
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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The main objective of this study is to analyse the inundation area along the Brahmaputra River

network, and to assess the flood hazard in the Nagaon District by integrating geomorphic,
topographic, and hydrological data using GIS.

Description of Study Area

The geographic location of the district is between 25° 45'N to 26° 45'N latitudes and 89° 45'E
to 96° 15'E of longitudes . Nagaon is the centrally located district of Assam with headquarters
at Nagaon town. It is one of the largest districts of Assam. With an area of 3993 sq.km the
district consists of fertile alluvial plains and thickly forested hills. It is situated 123 kilometres
(76 mi) east of Guwahati. The district is bounded by Sonitpur district & the Brahmaputra River
in the North, Karbi Anglong and North Cachar Hills in the South, East Karbi Anglong and
Golaghat district in the East.

The population of the district according to the 2011 Census Data is 2826000 with a population
density of approx. 711 per sq.km

The district shape vector was buffered by 25 km and the resulting region is considered to be
the study area.

Data Description

 SENTINEL-2 Data

Multi-spectral data with 13 bands in the visible, near infrared, and short wave infrared part of
the spectrum

Bands Central Wavelength Resolution (m) Bandwidth (nm)


(µm)

Band 3 – Green 0.560 10 35

Band 4 – Red 0.665 10 30

Band 8 – NIR 0.842 10 115

A False Colour Composite was created by the combination of these bands upon which training
samples were collected for development of Land Use Land Cover map
 ASTER DEM

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is an


imaging instrument on board Terra, the flagship satellite of NASA's Earth Observing
System (EOS) launched in December 1999.

ASTER has 14 bands of information although bands 4 to 9 are considered for Digital Elevation
Modelling. These bands are captured at 30 m spatial resolution

 Road Data was generated by digitizing a topographic map of the area using ArcGIS
 Population Data collected from Census 2011.
Tentative Methodology

Sentinel Data
Work Flow

 Preparation of Land Use Land Cover Maps

 Preparation of Road Map

Topological Digitization
Creation of
Map added of the road Preparation
shape file
as Base network in of Road
for road
Map in the study Map
network
ArcGIS area
 Preparation of Drainage Map and Watershed

Acquisition of Aster
Determination of
DEM of the study
Fill Sinks in the Data Flow direction using
area and clipping
sink filled data
using area shape file

Preparation of Pour
Preparation of Flow
Point Vector Data Stream Definition and
Accumulation using
from Maximum flow Stream Ordering
Flow Direction data
accumulation points

Development of
Snapping Developed Watershed from
Pour Point Shape attributed pour points.
with Flow Direction

Future Work

 Contour Inundation Mapping (50 m, 100m, and 200m)


 Weighted Sum Analysis thereby combining individual components and resulting hazard
mapping.
Preliminary Results

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