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European Journal of Applied Sciences – Vol.10, No.5
Publication Date: October 25, 2022
DOI:10.14738/aivp.105.12641.
Faheed, J. K. P., Yusuf, A., Manjusree, P., & Ansari, Z. R. (2022). Monitoring of Flood Dynamics Using Multi Temporal Satellite Data:
A Case Study of Kerala Floods 2018. European Journal of Applied Sciences, 10(5).443-480.
Services for Science and Education – United Kingdom
Monitoring of Flood Dynamics Using Multi Temporal Satellite
Data: A Case Study of Kerala Floods 2018
Faheed Jasin K. P.
Interdisciplinary Department of Remote Sensing &
GIS Applications, A.M.U., Aligarh
Alia Yusuf
Geology Section, Women’s College
Aligarh Muslim University, Aligarh, U.P., INDIA
P. Manjusree
National Remote Sensing Centre, Deptt. of ISRO
Govt of India, Balanagar, Hyderabad
Ziaur Rehman Ansari
Interdisciplinary Department of Remote Sensing &
GIS Applications, A.M.U., Aligarh
ABSTRACT
India is one of the worst flood affected country in South East Asia and accounts for
one fifth of global death count due to floods. It causes heavy losses to property,
infrastructure, agriculture, land and overburdens the country's budget and
resources. Around 40 million hectares of land in the country are subjected to
floods according to National Flood Commission, and an average of 18.6 million
hectares of land is affected annually. During 2018, Kerala was hit by two flood
events in July and August. In August, 2018, Kerala experienced the worst ever
floods in its history since 1924. The torrential rains triggered several landslides
and forced the release of excess water from 37 dams across the state, aggravating
the flood impact. The devastating floods and landslides caused extensive damage
to houses, roads, railways, bridges, power supplies, communications networks,
and other infrastructure. Satellite Remote Sensing has made substantial
contribution in flood monitoring and damage assessment. The unique capabilities
of satellites to provide comprehensive, synoptic and multi-temporal coverage of
very large areas at regular interval and with quick turnaround time have been
very valuable in monitoring and managing flood dynamics. The microwave region
of the EM spectrum has a greater potential in identification of flooded areas
because of almost all weather capability. In this study, multi-temporal microwave
SAR data from RADARSAT and SENTINEL-1 satellites was used to map the flood
affected areas in Kerala and to capture the dynamics of the spatial flood extent.
The analysis showed maximum flood inundation in the second flood event in
August. A steady recession of flood was observed in the July flood event. The peak
flooding was observed on 18th August 2018. There is a rapid progression of flood
from August 11th to August 18th 2018 after which, a slight recession was observed
from August 18th to 21st ,2018. The flood could be seen slightly progressing in the
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European Journal of Applied Sciences (EJAS) Vol.10, Issue 5, October-2022
Services for Science and Education – United Kingdom
next interval of August 21stto 24th ,2018 after which, again an overall recession in
the spatial flood could be observed by 27th August 2018. Kottayam,
Pathanamthitta and Alappuzha were some of the worst flood affected districts. The
maximum flood affected district is observed to be Alappuzha with a maximum
flood inundated area of 27691hectares on 18 August 2018. In the district of
Alappuzha a steady progression in the flood is observed after 21 August. Whereas
in the other two districts namely Kottayam, Pathanamthitta the flood is found to
be receeding after August 24, 2018.This study demonstrated the potential of
multi-temporal satellite imageries for capturing the flood dynamics in a spatial
domain. The progression and recession maps can be used for relief management
by the disaster managers on the ground.
Keywords: Synthetic Aperture Radar, RADARSAT, SENTINEL-1, Flood Dynamics, Flood
Analysis and Microwave Remote Sensing
INTRODUCTION
With the long term change in weather pattern, incidences of extreme heat and humidity are
rising which manifests itself as global increase in precipitation events and subsequent
riverine and flash flood is the manifestation of climate change [1]. According to Federal
Emergency Management Agency (FEMA) Flood is defined as a general or temporary condition
of partial or complete inundation of normally dry land areas from the overflow of inland or
tidal waters and unusual rapid accumulation or run off of surface waters from any source.
These climate change events occur in India as well on frequent basis. Severe floods occur
almost every year in one or the other part of the country causing tremendous loss of life, large
scale damage to property, infrastructure, agriculture, land and overburdens the countries
budget and resources. Floods mostly occur in the country during the south west monsoon
period spread from June to September, though cyclonic storms are common during October to
December. India is the worst flood affected country in the world after Bangladesh and
accounts for one fifth of global death count due to floods. Around 40 million hectares of land
in the country are subjected to floods according to National Flood Commission and an average
of 18.6 million hectares of land is affected annually. To avoid such catastrophic loss of life and
property it is necessary to map the events of flood in entire country so that better planning for
disaster management can be done.
KERALA FLOODS 2018
A catastrophic flood event which devastated the southern state of Kerala, India took place in
2018 due to unprecedented heavy rainfall from 1 June –18 August 2018. The normal
cumulative rainfall during monsoons in Kerala from June till end of August is around 1795.4
mm, but during 2018 monsoon it got an actual cumulative rainfall more than 2428.9 mm was
reported by Indian Meteorological Department (IMD) and Central Water Commission
(CWC). All of major 35 odd reservoirs storage was close to the full reservoir level (FRL) and
had no buffer storage to accommodate the heavy inflows from 10th August. The continued
exceptional heavy rainfall in August (with 170% above normal) in the catchment areas had
compelled the authorities to resort to heavy releases downstream into the rivers. Such a
scenario that continued for almost a week has caused overflowing of all river banks leading to
widespread flooding almost all over the state. During the week of 9th to 15thAugust the rainfall
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Faheed, J. K. P., Yusuf, A., Manjusree, P., & Ansari, Z. R. (2022). Monitoring of Flood Dynamics Using Multi Temporal Satellite Data: A Case Study
of Kerala Floods 2018. European Journal of Applied Sciences, 10(5).443-480.
URL: http://dx.doi.org/10.14738/aivp.105.12641
was severe and Kerala received 255% extra rainfall (Fig.1). Idukki district in which major
dams are situated received 679mm of rain just during that week, the normal during that
period is only 126 mm, which is 438% extra rain. That leads to the opening of Idukki dam
after 26 years. Wayanad received 536.8mm rainfall which is 299% extra for that hilly district,
the normal rainfall for Wayanad is only 134mm [2]. This incessant rainfall triggered
landslides and snapped road links between Wayanad and rest of Kerala. This catastrophic
disaster had created loss of life and property in a dimension unexpected. About 400 people
were reported dead in the state and over 1 million people moved to relief and rescue camps.
According to the Kerala government, one-sixth of the total population of Kerala had been
directly affected by the floods and related incidents, 13 out of 14 districts of Kerala were
affected by the event.
The Indian government had declared it a Level 3 Calamity or "calamity of a severe nature”.
Thirty-five out of the fifty-four dams within the state were opened, for the first time in history.
All five overflow gates of the Idukki Dam were opened at the same time and for the first time
in 26 years 5 gates of the Malampuzha dam of Palakkad were opened. Heavy rains
in Wayanad and Idukki have caused severe landslides and have left the hilly districts isolated.
Such catastrophic events require immediate attention and hence should be mapped to
understand the dynamics of the river. Earth observation data is very useful and essential tool
for flood monitoring[3], risk assessment [4,5], modelling, prediction and validation for
weather forecasting and rainfall-runoff models. These technologies have been the object of
substantial interest for all countries and bodies concerned with space and in exacting
emergency services and disaster management[6]. Remote Sensing along with has proven to
be very effectively for quick assessment of severity and impact caused by natural disasters.
Observed Rainfall as on 11-Aug Observed Rainfall as on 12-Aug Observed Rainfall as on 13-Aug