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American Journal of  
Geospatial Technology (AJGT)

Monitoring of  Coastal Geo-Environment for Hazard Mitigation: A Case Study of  
Machilipatnam Region, Andhra Pradesh, India

        M.V. Ramana Murty1*, Ch. Ravi Kumar1, K. Srinivasu1, R. Kannan1, B. Sundar1

Volume 1 Issue 2, Year 2022
ISSN: 2833-8006 (Online)

DOI: https://doi.org/10.54536/ajgt.v1i2.1381
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Article Information ABSTRACT

Received: March 11, 2023

Accepted: April 05, 2023

Published: April 14, 2023

The coastal zone is highly dynamic, which responds in various ways to human interventions 
and extreme weather events. Tropical storms cause enormous damage to the coastal 
region and its communities during landfall. Many of  the world’s largest deltas are densely 
populated and are increasingly vulnerable to natural disasters. The Krishna district within 
the river delta, is amongst the few districts with very high proneness to cyclone hazards. 
Machilipatnam in Krishna district is one of  the oldest coastal towns in Andhra Pradesh, 
situated on a series of  ancient beach ridges. Two major storms struck this region in the 
last half-century causing large scale devastation. The extent of  inundation from multiple 
flood events can be a very good indicator for flood hazard zonation. The lateral expansion 
of  Machilipatnam town is analysed in GIS environment based on time series satellite data. 
The developmental activities in the near shore zone are modifying the pristine coastline 
configuration. This is evident from shoreline monitoring. It is observed that there is a net 
increase in the extent of  mangroves, indicating a better protection to the town against 
tropical storms. The unplanned growth of  aquaculture may be an amplifying factor for 
coastal flooding, particularly if  it is interfering with the drainage system. In addition to 
the existing flood protection measures, the areas suitable for shelter belt plantation and 
mangrove regeneration are identified for coastal vulnerability reduction.

Keywords
Aquaculture, Coastal Flooding, 
Delta, Mangroves, Shoreline

1 Andhra Pradesh Space Applications Centre (APSAC), Labbipet, M.G. Road, Vijayawada, India  
* Corresponding author’s e-mail: moidavrm64@gmail.com

INTRODUCTION
Coastal zone is one of  the most complex environments, 
where continuous interactions exist between land, ocean, 
and air. Further, a wide range of  human activities in 
this coastal zone altered the natural environment. In 
spite of  various benefits being offered to humans, man-
made activities are exerting tremendous pressure in the 
coastal zone. The population explosion in the coastal 
zone is negatively impacting the bio-geo environment. 
Depending on the degree of  human interventions in the 
coastal zone, irrespective of  population size, indirectly 
leads to increased coastal erosion, soil salinization, saline 
water intrusion in newer areas, amplified coastal flooding, 
etc., due to unhealthy land use practices (Patel et al., 2022; 
Thiam et al., 2021; Sukumaran, 2020). Flooding due to 
tropical storms and tsunamis are adversely affecting the 
coastal population and infrastructure. 
The poorest of  the poor are the worst affected, as they 
are compelled to settle in low lying flood prone areas. 
In order to mitigate the effects of  the natural disasters, 
both structural and non-structural methods are adopted 
(Yang & Liu, 2020). Over the years, storm forecasting has 
significantly improved even in the tropical region. The 
advance forewarning in most of  the places provide ample 
time to evacuate the vulnerable population. Various 
parameters are used to assess the vulnerability of  the 
region. Mahapatra et al., (2015) attempted an integrated 
coastal vulnerability index for the South Gujarat coast using 
five physical variables (coastal slope, coastal landforms/
features, shoreline change rate, mean spring tidal range, 
and significant wave height), and four socioeconomic 

variables (population density of  adjacent coastal villages, 
land use/land cover, proximity to road network and 
settlement). Ramana Murty et al., (2023) analyzed the 
inundation based socio-economic vulnerability in the 
Krishna river delta region by considering five variables 
(women population, children, aged, literacy, and non-
workers). The usefulness of  remote sensing data, insitu 
observations, numerical modeling, and GIS analysis tools 
serve as a broad indicator of  a threat to people living 
in the coastal zone (Srinivasa Kumar et al., 2010). They 
developed the coastal vulnerability index for Orissa state 
using eight relative risk variables. Pramanik et al., (2016) 
constructed the coastal vulnerability index due to the sea 
level rise in Krishna–Godavari delta region to enhances 
the subjective attributes, and its useful in summarizing 
the vulnerability assessment results with the stakeholders 
and decision makers.  Based on the socioeconomic and 
infrastructural vulnerability indices, the highly vulnerable 
districts are identified, which are expected to face 
substantial amount of  challenges in coping with cyclones 
(Mazumdar & Paul, 2016). 
The resultant scenario of  both physical and human-
induced changes is important from a sustainable 
development perspective. The study on spatial patterns 
in the framework of  past and present scenarios may 
lead to better understanding of  social and economic 
developments. Mapping is an essential tool for monitoring 
and managing human activities in the coastal zone. The 
effective management practices depend on the knowledge 
of  coastal zone and suitable response by concerned 
government agencies (Nayak, 2017). The information on 

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the varied aspects of  the coastal zone and their impacts 
can be obtained from space borne sensors. Reshma and 
Mani Murali (2018) studied the decadal change using 
remote sensing and Geographic Information System 
(GIS) techniques in Krishna-Godavari delta region in the 
east coast of  India from 1972 to 2014. They observed 
that high erosion in northern part of  the Krishna delta is 
due to the reduction in size of  the spit.
Since prehistoric times the coast has provided people 
with habitat, food, trade ways, and facilitated socio-
economic networking (Harff  et al., 2019). The coastal 
areas are amongst the most preferred regions for 
various activities leading to population concentration. 
Settlements are concentrated within 5 km of  coastlines 
worldwide, whereas average population densities are 
higher at elevations below 20 m throughout the 100 km 
width of  the near-coastal zone (Small & Nicholls, 2003). 
With the major technological development in the recent 
past, people began to influence the geo-environment 
actively. Hence, the human population of  the coastal 
zone is expected to experience increased threats caused by 
natural and anthropogenically accelerated changes. Urban 
areas in the delta are expanding more rapidly than rural 
areas. This trend is expected to continue in near future, 
unless necessary infrastructure and suitable employment 
facilities are created in rural areas. 
The global dataset show that 339 million people reside in 
river deltas and 89% of  them live in the same latitudinal 
zone of  the most tropical cyclone activity (Edmonds et al., 
2020). They further calculated that 41% (31 million) of  
the global population exposed to tropical cyclone flooding 
live on deltas, with 92% (28 million) in developing or least 
developed economies. The population of  87 mandals of  
Krishna river delta region constitutes about 83,23,072 
(Ramana Murty, 2021). The region’s vulnerability further 
increases due to the impact of  the tropical storms, if  they 
are sediment starved, as in the case of  Krishna river delta. 
Amongst the thirty three major deltas of  the world, 
Krishna delta is affected mainly due to reduced 
aggradation and accelerated compaction (Syvitski et al., 
2009). They further estimated that the flood vulnerable 
in deltas could increase by about 50% under the current 
projected values for sea-level rise in the twenty-first 
century. 
This figure could increase if  the capture of  sediment 
upstream persists and continues to prevent the growth 
and buffering of  the deltas. Rao et al.’s (2010) indicated that 
predominant erosion along the sediment-starved coast 
during the past five decades, is due to the construction of  
dams in the upstream of  Krishna delta. The vast amount 
of  material added till the construction of  dams and 
reservoirs resulted in formation of  bars and barrier spits 
close to the Krishna river mouths (Rao, 1985). Similarly, 
the Mahanadi delta was once a prograding delta of  the 
Holocene is now retreating due to sediment starvation 
and sea-level rise, and experiencing decline in income 
from agriculture or fisheries, degradation of  mangroves 
with loss of  biodiversity and human migration (Hazra et 

al., 2020). This problem will disproportionately impact 
people on river deltas, particularly in developing and 
least-developed economies. Furthermore, 80% (25 
million) live on sediment-starved deltas which cannot 
naturally mitigate flooding through sediment deposition. 
In recent years, intensive development activities together 
with sea-level rise, and groundwater abstractions among 
other activities have seriously threatened the sustainability 
of  many deltas and their estuaries (Loucks, 2019). Most 
of  the coastal ecosystems exhibit extreme variations in 
areal extent, spatial complexity, and temporal variability 
(Klemas, 2011). Protecting them requires the ability 
to monitor their biophysical features and controlling 
processes spatially over time.

Study Area
Masulipatnam (now Machilipatnam) is one of  the ancient 
coastal towns along East coast of  India. The ancient 
inscription on a pillar of  the mandapam in Ramalinga 
temple, Masulipatnam dates back to twelfth century 
(Mackenzie, 1883). The Kistna (now Krishna) district 
manual also indicates that the great storm of  13th 
October 1779 caused damage to the factory buildings in 
Masulipatnam. Another storm of  1st November 1864 
washed away several people and a 12 feet deep inundation 
recorded in a Dutch factory. The farthest extent of  
deluge due to storm surge was reported to have reached 
17 miles inland, with an estimated human loss of  about 
30,000. Another severe cyclone of  the last century that 
hit Machilipatnam coast on 23rd October 1949, had a 
maximum wind speed of  about 130 kmph. During this 
storm, about 750 lives were lost and about 30,000 cattle 
perished. 
A devastating tropical cyclone that crossed the coast 
near Chirala in Andhra Pradesh on 19th November 
1977 had claimed over 10,000 human lives. As a result 
of  this event, a peak storm surge occurred on the right 
of  landfall point with a height exceeding over 15 feet 
near Sorlagondi, and spreading beyond 40 miles inland 
(Subbaramayya et al., 1979). The cyclonic storm that 
crossed the coast near Machilipatnam on 9th May 1990 
caused enormous damage to the delta region (Rao, 1994). 
Machilipatnammandal(Figure-1)happens to the largest 
mandal of  the district, with 29 villages experiencing 
recurring storms. It is one of  the four coastal mandal with 
significant human population associated with extensive 
mangrove vegetation. Machilipatnam town is not only 
the headquarters of  the mandal but also for the Krishna 
district.The proneness of  this region due to frequent 
inundation caused by the series of  cyclonic storms, and 
degradation to bio-geo-environment is examined spatially 
within the Machilipatnam mandal.

METHODOLOGY
In the present study, Machilipatnam town in particular 
and the mandal in general are studied from the coastal 
inundation perspective using multi-temporal satellite 
imagery and topographic maps. The degree of  coastal 

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inundation is assessed based on three different flood 
events (May, 1990; October, 2005; and September, 2016). 
The areas which are under deluge in all the flood events 
is categorized as extremely vulnerable compared to 
the areas which are inundated in any one of  the events 
(Figure 2). The spatio-temporal extents are significant 
from an inundation point of  view. The extent of  
aquaculture and mangroves in the mandal is important 
from environmental perspective. The coastal zone of  
Machilipatnam constitutes sandy beaches, river deltas, 
wetlands, coastal plains, beach ridges, and other coastal 

features. The changes in the shoreline configuration are 
studied from temporal data-sets. The lateral expansion 
of  Machilipatnam town is analysed in GIS environment 
based on time series data from topographical maps (1938-
41 and 1969), satellite images (1990, 1999, and 2010) 
including the latest Sentinel imagery of  14th June 2022. 
The population of  the mandal during the year 2011 is 
compared with 2001 census. Finally, based on the existing 
flood protection measures (natural and structural), 
resultant changes, etc., new areas are proposed for 
mitigating the impact of  coastal flooding.

Figure 2: Methodology adopted for flood alleviation

Figure 1: Location map

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RESULTS AND DISCUSSIONS
Machilipatnam and its environs in the Krishna river delta 
is considered to be the rice bowl of  the State. This fertile 
region of  the delta constitutes a well distributed drainage 
network coupled with timely releases from canals for 
irrigation enabling better agricultural productivity. 
This region is morphologically even without much 
undulations. The maximum elevation in the mandal is 
about 3.5m. Flat topography, frequent storms, land use 
changes, etc. necessitates a detailed investigation on 
the present geo-environmental status in relation to the 
past. Inundation based flood hazard; distribution of  
mangroves & aquaculture; geomorphology & shoreline 
changes; spatio-temporal variations of  Machilipatnam 
mandal and town; population; and existing/ proposed 
flood reduction measures are discussed. 

Inundation based flood hazard 
The temporal satellite datasets/ layers are obtained from 
NRSC and through open source for the three flood events 
(i.e., Landsat TM of  18th May 1990; IRS LISS-III imagery 
of  22nd September 2005; and Microwave SAR data of  23rd 
/ 25th / 27thSeptember 2016) for Machilipatnam mandal. 
The maximum extent of  inundation during each of  the 
three flood events is observed to be about 159 km2 (May 
1990), 198 km2 (October 2005), and 26 km2 (September 
2016). The extent of  flood inundation is extracted from 
the satellite data/ layers during three different flood 
events and integrated in GIS environment. The integrated 

flood extents are re-classified into three categories based 
on the frequency of  inundation. The Very Highly Flood 
Affected Areas (VHFAA) includes those areas which are 
under inundated during all the three flood events of  May 
1990, October 2005 and September 2016 (Figure 3). The 
Highly Flood Affected Areas (HFAA) are those regions 
that are under inundation in any of  the two flood events; 
and Moderately Flood Affected Areas(MFAA) are under 
inundation during only one of  the three flood events. 
The extents of  flood hazard classes in Machilipatnam 
mandal i.e., VHFAA, HFAA, and MFAA are about 
18.63 km2 (5%), 63.65 km2 (16%), and 176.56 km2 (43%) 
respectively. 
The extent of  unaffected or least affected area in 
the mandal constitutes about 148.67 km2 (36%).The 
significant extent of  inundation in all the three flood 
events is observed mostly in the east of  Machilipatnam 
town in the reserved forest area near P.T.Palem, and 
Polatitippa. Peddapalem villages in north-eastern parts 
of  the mandal is also identified as VHFAA. The HFAA 
is observed mostly in the east, south and south east of  
Machilipatnam town. The MFAA is also observed mostly 
in the southern half  in comparison to the northern half. 
The unaffected or least affected areas in the mandal are 
observed in the north and NE parts of  Machilipatnam. 
Most of  these least affected areas are associated with 
landforms like beach ridges or ridge & swale complex. 
Further, flood receding/ infiltrating from these areas are 
relatively faster.

Figure 3: Combined inundation from three flood events

Mangroves zonation and Aquaculture
One of  the important features of  coastal ecosystem 
includes mangroves. These mangroves are significant 
for mitigating the adverse effects of  natural disasters, 

particularly coastal flooding and erosion. Empirical studies 
of  storm surge and tsunami protection by mangroves 
have historically been difficult, but the development 
of  remote-sensing and GIS technologies is making it 

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easier to assess damage after natural disasters (Marois & 
Mitsch, 2015). Through the natural processes, mangroves 
essentially contribute in land accretion. The temporal 
changes in extents of  mangroves and aquaculture are 
monitored based on the image data of  1990, 1999, 2010, 
and 2022 (Figure 4). It is observed that the net extent 
of  mangroves gradually increased between the years 
1990 and 2022 from 2,995 ha. to 5,266 ha. This increase 
in mangroves is a positive indication for protection of  
town in minimizing the impact from tropical storms. 
This geospatial gain/ loss can be extracted easily using 
union function in ArcGIS. It is observed that there is a 
natural regeneration/ plantation between 1990 & 1999, 
1999 & 2010, and 2010 & 2022 to the extent of  about 
1698 ha., 1609 ha., and 1822 ha., respectively. In spite of  
the net increasing trend, there is a loss in the extent of  
mangroves between 1990 & 1999; 1999 & 2010; and 2010 
& 2022. It is observed that there is a minimum loss of  
about 799 ha. between 2010 & 2022; and a maximum loss 
of  about 1050 ha. during 1990 & 1999. 
The causative factors in loss of  mangroves are important 
from management and conservation perspective. Effective 
governance structures, better planning for rehabilitation 
of  degraded mangroves, education and awareness building 
in local communities are needed to conserve, protect and 
restore the valuable mangrove wetland ecosystems (Sahu et 
al., 2015). Proactive engagement with governments and the 
public in these potential regions of  mangrove expansion 

may help with conservation efforts (Romañach et al., 2018).
Mangroves and brackish water aquaculture are two 
competing land use/land cover classes. The shrimp 
aquaculture is accountable for the large-scale changes in 
the mangrove lands of  Andhra Pradesh (Jayanthi et al., 
2022). 
The bio-geo environmental conditions for mangroves 
and brackish water aquaculture are very similar. It is also 
observed (Figure 4) that there is a huge increase in the 
extent of  aquaculture from just 981 ha. in the year 1990 to 
about 10,066 ha. in the year 2022. The aquaculture tanks 
are significantly concentrated in south and south-eastern 
parts of  Machilipatnam town. Pedayadara village in NE 
of  the mandal is completely occupied with aquaculture. 
In the process of  expansion, environmental aspects are 
compromised. Indiscriminate growth of  aquaculture 
within and around the lake is observed to be increasing 
the flood hazard (Ramana Murty & Mruthyunjaya 
Reddy, 2010). Further, these ponds are interfering with 
the natural creeks/ drains and may causes hindrance 
to natural flood flow leading to increased area under 
inundation. Such aquaculture ponds are observed near 
north-west of  Rudravaram, east of  Ranganayakulapeta, 
south-east of  Pallepalem and south-east of  Chinnapuram 
village. In addition to this, longer duration of  flooding 
and increased depth of  inundation can be experienced. 
Hence, the impact of  storms shall be severe in regions of  
unplanned expansion of  aquaculture.

Figure 4: Extents of  Mangroves and Aquaculture during 1990 and 2022

Flood Geomorphology and Shoreline Changes: 
Geomorphological understanding of  floods derives from 
geological tradition of  studying indices of  real processes 
operating in the past, instead of  using mathematical 
(model) manipulation of  idealized parameters that are 
assumed to have flood-like properties (Baker, 1994). 

Coastal geomorphology is one of  the popular ways 
of  assessing flooding. Different landforms respond to 
flooding in different ways (Ramana Murty et al., 1993). 
In the present study, three different geomorphic units of  
different origin i.e., marine, fluvial, and fluvio-marine are 
identified (Figure 5). Sandy Beach, Bar, Tidal Flat, Tidal 

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Figure 5: Geomorphology of  Machilipatnam Area

Creek, Mangrove Swamp, Mud Flat, Saline Plane, Coastal 
Plain, Ridge &Swale Complex, Beach Ridge, Swale, 
etc., are included under marine landforms; Flood Plain, 
Point Bar, Palaeo channel, etc. are included under fluvial 
landforms; and Lower Deltaic Plain under fluvio-marine 
landforms. The range of  a coastal flooding is a result of  
the elevation of  floodwater that penetrates inland which is 
controlled by the topography of  the coastal land exposed 
to flooding. Coastal flooding is mainly a natural event, 
but due the human intervention in the form of  land use 
changes to the coastal environment can aggravate the 
situation.
Coastal landforms are moderately modified by diurnal, 
and seasonal variations; and extremely altered by severe 
storms. The shoreline, particularly the beaches, generally 
undergoes constant adjustment towards a dynamic 
equilibrium. However, anthropogenic changes along the 
coast may alter the stability to such a degree that it never 
reaches coastal stability. The 44.40 km long shoreline 
of  Machilipatnam mandal is analysed based on 1938-41 
and 2022 satellite images (Figure 6). It is observed that 
in a span of  81 years about 26.33 km long shoreline is 
under accretion, and about 18.07 km long shoreline 
is under erosion. The Shoreline changes are classified 
into eight categories based on the width of  erosion/ 
accretion. They include: Very High Accretion (VHA); 
High Accretion (HA); Moderate Accretion (MA); Low 
Accretion (LA); Severe Erosion (SE); High Erosion 
(HE); Moderate Erosion (ME); and Low Erosion (LE). 
The lengths of  different accretion classes include: VHA: 
5.86 km; HA: 6.73 km; MA: 5.11 km; and LA: 8.63 km 
(Table-1). The lengths of  four erosion classes include: SE: 
7.21 km; HE: 4.09 km; ME: 2.35 km; and LE: 4.42 km. 

The combined stretch of  Severe Erosion (SE) and High 
Erosion (HE) having width of  over 750m, constitutes 
over 25% of  total shoreline is of  immense concern. The 
united lengths of  Low Accretion (LA) and Low Erosion 
(LE) having widths less than 500m., comprising of  about 
29.4% can be considered as stable shoreline. The South-
Eastern part of  the mandal is under different degree of  
erosion, while the North-Eastern part is mostly accretion. 
Erosion immediately north of  northern distributary of  
river Krishna can be attributed reduced sediment supply 
due to the construction of  dams in the upstream (Rao et 
al., 2010). 
This eroded material is carried away by the northeast 
flowing littoral currents, and depositing in the north and 
northeast region. The Odissa coast is also exhibiting unique 
reasons for erosion with various degrees of  combinations 
of  sediment depletion, human activities, high frequency 
of  cyclones and floods, sea level rise, etc. (Murali et al., 
2015). With the completion of  Machilipatnam Deep Sea 
Port project in this region, the shoreline scenario is likely 
to change further.
The union operation on polygon feature in GIS 
environment enables measurement of  spatial changes in 
the coastal zone. The total area gained and lost constitutes 
about 18.01 sq km and 16.05 sq km respectively. There 
is net gain of  about 1.96 sq km. It is observed that 
mangroves, tidal creeks and tidal flats along the southern 
coast are subjected to Severe Erosion (SE); sandy beach, 
tidal creeks and tidal flats constitute part of  HE, ME, 
and LE classes. Apart from erosion, the land added in the 
process of  accretion in a span of  about eight decades is 
observed to be transformed into different land use/ land 
cover classes. Sandy beach, tidal creeks and plantations 

Figure 6 : Shoreline changes between 1938-41 and 2022

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are predominant under Very High Accretion (VHA); 
mangroves, plantations, creeks, spit, aquaculture, tidal 
flat, beach  classes are under HA; mangroves, plantations, 
creeks, bar, beach  are under MA; and beach, plantation, 
mudflat and tidal flat are under Low Accretion (LA). 

Spatio-temporal variations of  Machilipatnam mandal 
and town
The spatio-temporal change in the extent of  settlements 
in Machilipatnam mandal is a attempted based on the 
Survey of  India toposheets (1969), and satellite images 
of  years 1990, 1999, 2010, and 2022 (Figure 7). The total 
number of  revenue villages including the Machilipatnam 
town in the mandal is 29. Each of  these revenue villages 
constitutes 3 to 5 hamlets. It is observed that the number 
of  settlements are not uniform in the last five decades. 
The number of  settlements during the years 1969, 1990, 
1999, 2010, and 2022 in Machilipatnam mandal are 96, 
104, 111, 112, and 118 respectively. 
This increase can be attributed to the movement of  rich 
farmers and the associated laborer to establish close to 
the agricultural fields. As this allows the farmers to closely 
monitor, have extra space for agriculture operations, etc. 
The total extent of  these settlements during the year 
1969 is 11.29 sq km; while its 26.87 sq km during the year 
2022. Thus there is an overall increase in the extent of  all 
settlements in the mandal by about 15.58 sq km (@ 29.4 
ha/ year) between 1969 and 2022. However, the rate of  
expansion is not uniform. Based on the available data, 
the rate of  expansion during the initial period is larger 
than the recent. It is observed that the rate of  growth 
is 55 ha per year between 1969 and 1990 within a span 
of  21 years. But between the years 1990 and 2022, the 
rate of  growth is just 13 ha per year. The severe cyclonic 
storm of  May 1990 could be the discouraging factor. 
The area of  Machilipatnam town alone constitutes about 
69%, compared to the extents of  remaining villages in 
the mandal. Hence, the changes in Machilipatnam town is 
analysed separately.
The urban landscape has been changing more rapidly 
than rural areas with time. The geospatial information 
on changes are very important to urban developers and 
planners. Multi-temporal data from historical maps and 
satellite images enable measurements of  spatial variations 

over different period. It is observed that Machilipatnam 
town has grown from 473 ha.(1938-41) to about 1846 ha. 
in the year 2022 (Figure 8). There is clear distinction in 
the expansion of  Machilipatnam town till the year 1990 
and thereafter. It is observed that the town has grown @ 
52 ha. per year during 1938 and 1990; while during the 
years 1990 and 2022 the growth has been significantly 
reduced thereafter to about 32 ha. per year. One of  the 
factors for this reduction could be the impact of  May 
1990 cyclone. In addition to this, the groundwater from 
shallow aquifers of  Machilipatnam mandal is not suitable 
for domestic and irrigation purposes as the values of  EC 
and some of  the chemical constituents are more than 
permissible limits (Krishna, 2013). These two aspects 
could be determining factors for moderate growth of  
the town in the recent time. The development of  town 
is predominantly along the major axis (NE-SW) of  the 
beach ridge & swale complex. The extent of  growth in 
NE (Potlapalem village) is about 3308 m, and by about 
1837 m. is SW direction (Rudravaram village). The growth 

Table 1: Extent of  Erosion/ Accretion between 1938-41 and 2022
Sl. 
no.

Erosion/ Accretion Class Width (m.) of  Erosion/    
Accretion Class  

Length (km.) of  
Erosion/ Accretion  

Erosion/ Accretion 
Area (sq.km.)

1 Very High Accretion  > 1000  5.86  6.41
2 High Accretion  750 - 1000  6.73  6.59
3 Moderate Accretion  500 - 750  5.11  3.37
4 Low Accretion  < 500  8.63  1.64
5 Severe Erosion  > 1000  7.21  9.51
6 High Erosion  750 - 1000  4.09  3.73
7 Moderate Erosion  500 - 750  2.35  1.68
8 Low Erosion  < 500  4.42  1.13

Figure 7: Growth of  Machilipatnam Mandal

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of  settlement perpendicular to this axis, i.e., in NW (along 
National Highway 65) and SE (Kara Agraharam village) 
directions are by about 577 m. and 806 m. respectively. 
The growth in the remaining directions is in the range 
of  0 to 450 m., except along the Pedana road (1161 m) 
in North.In the coming years, the predominant growth 
of  Machilipatnam town is likely to continue in the NE 
direction. This is because of  the favourable geomorphic 

set-up in that direction. Hence, necessary amenities like 
protected water supply, flood proofing infrastructure, etc 
is to be developed in this region. Further, there is need to 
restrict over withdrawal of  ground water from shallow 
aquifers. Else, the sensitive balance between the fresh 
water over the saline water could be disturbed (Seenipandi 
et al., 2019).

Figure 8: Urban Extension and predominant growth direction.

Population
The population census is collected on selected 
demographic and socioeconomic characteristics of  the 
population at a fixed interval (e.g. 1991, 2001, 2011, 
etc). The data collected through the census is useful 
for planning and policy making. In the present case, the 
population census of  Machilipatnam town and mandal 
is collected. As per the census, the population of  the 
Machilipatnam town has increased from 39,507 in the 
year 1901 to 1,69,892 in 2011 (Census of  India, 2011). 
Further, as per the 1901 and 1911 census, the population 
of  Machilipatnam town was more than Vijayawada town 
indicating its importance. There after the population of  
Vijayawada had a rapid rise by about 600% compared 
to the population of  Machilipatnam town in the year 
2011. Various factors leading to the stunted growth 
of  Machilipatnam town includes recurring storms 
leading to frequent inundation, mostly low lying areas, 
limited portable ground water, away from major road/ 

rail connectivity, limited employment opportunities 
to all sections of  population, etc. Above all, the most 
striking observation is reduction in population of  the 
Machilipatnam town from 1,75,305 to 1,68,946 between 
the years 2001 and 2011.
The total population of  the Machilipatnam mandal during 
the years 2001 and 2011 (Census, 2011) is observed to 
be 2,50,521 and 2,38,962 respectively (Figure 9a and 9b). 
There is an overall reduction in the mandal population 
by 11,559 persons. The population of  each village in the 
mandal during 2001 and 2011 is classified into five classes 
(0 to 1000, 1000 to 2000, 2000 to 3000, 3000 to 5000, 
and > 5000). In addition to Machilipatnam town, the 
reduction in village population is observed in Tallapalem 
(-572); and Chinnapuram village (-845). Further, 
Pedayadara village (NE of  Machilipatnam mandal) was 
in the class of   >5,000 in 2001 census has gone down to 
3,000 to 5,000 class in census 2011. Similarly, Rudravaram, 
Gundupalem, and Pedapatnam villages were in the range 

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Am. J. Geo Spat. Technol. 1(2) 27-38, 2022

of  2,000 to 3,000 as per 2001 census, have come down to 
1,000 - 2,000 range in 2011 census. Chilakalapudi village 
in NE of  Machilipatnam Town is the only village in the 
mandal which recorded the population increase by 1356. 
In addition to the factors mentioned for reduction in 
population, changing land use pattern is also observed 

to be one of  the important factors. Large tracks of  
agricultural lands are converted into aquaculture (Ramana 
Murty & Mruthyunjaya Reddy, 2010), not only increasing 
the flood vulnerability but also leading to reduction in 
employment opportunities.

Figure 9a and 9b: Population classes based on 2001 and 2011 census

Existing and proposed flood proofing measures
Recurring storms in the Krishna river delta is resulting in 
loss of  several thousand human lives. In order to protect 
the human population in particular; and livestock, and 
agricultural fields in general, flood/storm protection 
measures are to be adopted. These could be structural 
measures or environmentally friendly non-structural 
measures. Embankment is one of  the popular measures 
adopted to help protect people, livestock, dwellings, 
and croplands from storm surge. Apart from building 
embankment, the other important structural measures 
against tropical storms, includes cyclone shelters, 
improved road links, culverts/bridges, drains, etc. In order 
to protect Machilipatnam mandal from storm surges / 
tidal waves, Kona Tidal Bank (Saline Embankment) is 
made (Figure 10).It is spread between Polatitippa and 
Kammavaricheruvu villages having a stretch of  about 
18.55 km in Machilipatnam Mandal. There are few 
settlements close to this tidal embankment. Apart from 
tidal embankment, there are other embankments along 
river Krishna (16.27 km), and along major drains (10.77 
km) of  the mandal. These other embankments are 
designed to restrict the flood waters to contain within 
either banks of  river/ drain.
The role of  non-structural methods in handling disasters 
has been gradually evolved by the community with the 
traditional knowledge. These have been time tested, 
economical, cost effective, user friendly, and can be 
done by involving local people. One of  the important 

non-structural and environmental friendly measure is 
development of  mangrove forest. Mangroves act as a 
bio-shield for protecting life and property from storm 
surge and strong winds. They also protect the coastline 
from erosion and deposition of  sand. The total extent 
of  existing mangroves as assessed based on the latest 
satellite imagery of  2022 constitutes about 5,266 ha. 
Potential areas for regeneration are identified in degraded 
areas, and generation of  mangroves in suitable areas 
based on the landforms and tidal influence are identified. 
The shelter belt plantation is another important non-
structural measure for protection from stormy winds. 
The total extent of  potential zone constitutes about 478 
ha. These shelterbelts are barriers of  trees planted parallel 
to the shoreline to reduce the wind velocities and protect 
human habitations and agricultural crops from physical 
damage. The shelterbelt is mostly planted with casuarina 
all the sandy stretch of  coastline. 
The total coastline length with shelterbelt plantation 
constitutes about 38.29 km. In addition to this, other 
potential sites, particularly coastal dunes and beach ridges 
are identified for shelter belt plantation. It is observed 
that there is apossibility of  plantation near villages 
Gollagudem, Giripuram, and Pallipalem for an addition 
length of  about 5.66 km. Another important aspect of  
flood impact minimization is drainage improvement. The 
efficient drainage system of  an area can remove the storm 
water with ease without inundating the surrounds for 
longer duration. The total length of  drains in the mandal 

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Am. J. Geo Spat. Technol. 1(2) 27-38, 2022

is about 268 km. The major issue with drains in the river 
delta region are, either they are silted up or choked with 
weeds. It is observed that about 25.5 km of  drain length 
is occupied with aquatic vegetation. Such choked drains 
are observed near the villages Garaladibba and Pallepalem 
which needs to be improved at least to it designed capacity. 
Any hindrance to drains due to aquaculture also needs to 
be identified and necessary alleviation measures may be 
adopted. In the present study, only some of  the feasible 
structural and non-structural measures are discussed. 

Figure 10: Proposed Flood Alleviation measures

CONCLUSION
Coastal flooding results in loss of  human lives and destroys 
livelihoods, infrastructure and other assets. Deltas are 
extremely vulnerable to coastal flooding. Amongst the 
global deltas, the Krishna river delta is identified as one 
with greater peril as there is virtually no aggradation. The 
protection of  human life in deltas against coastal flooding 
is essential component of  disaster minimization. Human 
migration to the coastal zone is a common phenomenon 
elsewhere, but population reversal is observed in most 
of  the villages of  Machilipatnam mandal. Recurring 
tropical storms and natural resources degradation of  
historical Machilipatnam town resulted in stunted growth 
in comparison to the other towns of  the State. The land 
use/ land cover modifications mayfurther increase the 
flood vulnerability of  the region. In order to alleviate 
coastal flooding, adoption of  suitable structural and non-
structural are a prerequisite. The Kona tidal embankment 
between Polatitippa and Malakayalanka villages protects 
Machilipatnam town from coastal flooding. Apart from the 
tidal embankment, there are embankments along Krishna 
river and drain to prevent from overflowing. Regular 
maintenance and strengthening of  these embankments 
is to be taken up before the two main cyclone seasons 
i.e., May, and September-November. In addition to the 

structural measures like flood embankment, multi-
purpose cyclone shelter, all-weather roads, etc. can 
effectively minimise the vulnerability of  the region. There 
is a need for improving the carrying capacity of  drains, 
nalas, etc. The total length of  drains/ nalas in the mandal 
constitutes about 268 km. About 25.5 km of  this drain 
length is observed to be choked with weed, which needs 
clearance. Ecosystems-based approaches, like restoration 
of  mangrove vegetation on coastal mudflats, and shelter 
belt plantation preferably with casuarina on coastal dunes/ 
beach ridges help mitigate the impacts of  storm surge 
and strong winds. There is a need for land use policy to 
protect the mangroves outside the reserved forest areas 
in privately owned lands by allocating alternate resource 
space, and monitoring periodically. The satellite image of  
the year 2022, compared to the imagery of  1990 indicates 
a substantial increase in the extent of  mangroves. Healthy 
coastal ecosystems would support coastal fisheries and 
eco-tourism too. Adoption of  appropriate environmental 
friendly flood protection measures would significantly 
reduce the coastal vulnerability to Machilipatnam towns 
and its environs.

Acknowledgements
The authors express gratitude to Disaster Management 
Support Group of  National Remote Sensing Centre for 
sharing the flood inundation layer of  September 2016 
event. We are extremely thankful to USGS and ESA for 
facilitating free downloads of  optical/ microwave satellite 
data from Landsat, and Sentinel Series. Our thanks 
are due to Office of  the Registrar General & Census 
Commissioner, India, for enabling to use the Census, 
2011 data. We sincerely appreciate the anonymous 
reviewers for reading the manuscript, and offering 
valuable comments and suggestions.

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