Remote Sensing and GIS for the Spatio-Temporal Change Analysis of the East and the West River Bank Erosion and Accretion of Jamuna River ( 1995-2015 ) , Bangladesh

Jamuna River is one of the principal rivers of Bangladesh, changing continuously due to erosion and accretion over the past decades. This analysis evaluates the East Bank and the West Bank erosion and accretion between 1996 and 2015 for Jamuna River. An unsupervised classification algorithm and post-classification change employing skills in Geographic Information System are performed to evaluate spatial and temporal dynamics of erosion and accretion for different points of Jamuna River using Bangladesh. Landsat image (1995, 2005, 2015). The correctness of the Landsat-produced map ranges from 82% to 84%. It has been evidently observed that changes in the proportion of erosion and accretion differ in different points of Jamuna River. The highest eroded area is 3.82 square kilometers (km) during the period of 1995 to 2005 and the highest accreted area is 6.15 square kilometers (km) during the period of 1995 to 2015. The erosion and accretion values fluctuated from place to place. The changing trend of Riverbank is creating many socio-economic problems in the proximate areas.


Introduction
In Bangladesh, natural streams of water of fairly large size, flowing in a diverging and converging channels, are divided into three main rivers.The river Jamuna is one of them.The Old Brahmaputra goes down with the name "Jamuna", and it is the largest braided river that crosses through the low-lying subsided deltaic floodplain of Bangladesh [1].It is the cardinal channel in a braided stream of Brahmaputra river as the circulation commencing from India to Bangladesh.Tibetan plateau is the growth center of the Jamuna River, and 93% drainage of the river lays peripheral to Bangladesh.It merges with the Padma River approaching Goalundo Ghat when flowing south.Then combining with Meghna River near Chandpur, it flows down towards the Bay of Bengal (The study area of Jamuna River in Figure 1).After flowing about 2740 km from its origin and 220 km from the northern borders of Bangladesh, the Jamuna interacts with the Ganges, then the Meghna and at last flows into the Bay of Bengal [1].Jamuna is one of the oldest rivers which has a generation about of almost 250 years [2].Since the beginning of that time period, the Jamuna River has maintained state way, mostly disconnected by small islands or called "chor".Changeable banks and instantaneous rates at edgeways movement characterize Jamuna's braided plan which is the accumulative result of different outflows of water and sediments.Resulting from river bank Erosion, surrounding areas like Tista floodplain soils nutrients status are also modulating under several condition like Tista barrage, water dynamics, water flow rate and fertility status of these zones [3] [4].Millions of people have been dislocated from their original living places because of acute riverbank erosion in Bangladesh.283 places, 85 cities, and outgrowth enter including 2004 km of riverbank line are vulnerable to erosion in Bangladesh [5].The fourth IPCC (Intergovernmental Panel on Climate change) report anticipates that the monsoon rainfall of South Asia will increase highly which will create increasing flow in the rivers.This increased flow will reduce the flood control capacity resulting in the increased bank erosion [6].The Jamuna is provided to have exquisite bank erosion and highest rate of bank line movement [7].The future water ability of Jamuna River will be affected by the running climate change through altering the precipitation pattern.Enhancement of flow has been affected by the Jamuna River over the past years.Future water discharge on Jamuna River will increase with massive rain in the catchment area of the river on the enhancement level with the highest amount of snowmelt because of running global warming situation [8].
The Jamuna is showing adventurous and violent behavior by its bank erosion rate [9] [10].The erosion has significant impact on differential population change on rotated human occupancy and bank line settlements of displaces.The Jamuna River is characterized with various types and size of bars, mega forms and macro forms of a bar from the hierarchical bed from classification [11].
From 1994-1998, 5.63 km long Bangabanndhu bridge was constructed to connect the east and west side of the Jamuna river.Due to water regulation in Jamuna River before 1996, the rate of channel shifting increased in Sirajganj-Bhuyiapur region.The water flow also changed during 1988 & 1998 due to flood and heavy monsoon rain [2].Journal of Geoscience and Environment Protection  The change analysis has been accomplished under the structure of RS and GIS.The processing task of images has been executed using ERDAS image processing tool.GIS analysis has been executed by using ArcGIS 10.2.1.with error of omission & error of commission [15] was performed for reliability measurement.In general, reliability was 82% to 84%.

Data Processing Analysis
By performing these skills, the result was calculated using an unsupervised algorithm with Maximum likelihood technique which improved the outcome.

Result and Discussion
The Riverbank line has been identified and established at Landsat image of 1995, 2005, and 2015.Histogram Equalized unsupervised image is meaningful for identifying the Riverbank line.By analyzing three distinct Landsat image from 1995 to 2015, it was observed the five-year rate of erosion and accretion of the active channel of Jamuna River.The highest eroded area is 3.81 square kilometers (km 2 ) in the period of 1995 to 2005 and the highest accreted area is 6.15 square kilometers (km 2 ) in the period of 1995 to 2015.Changes of Jamuna River bank erosion (1995-2005) is shown in Figure 6.The erosion and accretion values fluctuated from place to place.The fluctuation of erosion and accretion on the west bank and east bank can be shown on a graph as Figure 6.
It is prominent that the highest erosion amount on the west bank from 1995 to 2005 was about 3.81 square kilometers (km 2 ) when accretion amount was 5.62 square kilometers (km 2 ).On the east bank, the highest amount of erosion was about 2.61 square kilometers (km 2 ) when accretion amount was 2.26 km.So, there are more visible new bank line formation on the west side of the river over this period.The highest erosion amount on west bank from 1995 to 2015 was about 1.99 square kilometers (km 2 ) when accretion amount was 9.14 km.On the east bank, the highest amount of erosion was about 3.63 square kilometers (km 2 )when accretion amount was 1.59 km.Therefor, there is bank shifting from the east side to west due to huge accretion rate on the west bank on these years.The fluctuation of the amount of erosion and accretion on the west bank and east bank can be shown on a graph in Figure 7.As the accretion rate of the west bank is higher than the erosion rate and the erosion rate is higher on the east bank of Jamuna River than the accretion rate, so the course of the River has been shifted towards west direction through this period.
It has been identified that the highest erosion amount on west bank from 1995 to 2005 was about 3.81 square kilometers (km 2 ) when accretion amount was 5.62 km.On the east bank, the highest amount of erosion was about 2.61 square kilometers (km 2 ) when accretion amount was 2.26 km (in Figure 8).The highest erosion amount on west bank from 1995 to 2015 (in Figure 9) was about 1.99 square kilometers (km 2 ) when accretion amount was 9.14 km.On the east bank, the highest amount of erosion was about 3.63 square kilometers (km 2 ) when accretion amount was 1.59 km.The complete table and graph of the fluctuations of the amount of erosion and accretion on the west bank and east bank from 1995 to 2015 has been shown in Figure 8.
As shown in Figure 9, the accretion amount of the West Bank of Jamuna River was higher from 1995 to 2015 than from 1995 to 2005.On the other hand, the erosion amount of the west bank was higher from 1995 to 2005 than from 1995 to 2015.
The graph of the changes of Jamuna River east bank represents the higher

Socio Economic Impact of Jamuna River Erosion
The mighty 127 miles long Jamuna River has eroded almost 30 villages in the past 10 years [16].The consequence of the erosion is not only human displacement but also continuous erosion destroys roads and other communication facilities reducing the chance of getting reliefs quickly.The affected people, who have no other choices, at first, try to copy locally and then migrate to the nearby cities for livelihood and start to live in slums, in the open space on both sides of rail lines or in Govt Khash Lands of the cities [17].Each year, the area of the slum in several cities is increasing and most of the people have come here due to river erosion [6].The condition of social amenities, such as food, shelter, em-

Conclusion
In general, it has been observed that the riverbank shifting of Jamuna occurs continuously each year.This continuous river bank erosion and accretion pro- the erosion rate changed from 58.1% to 54.9% [19].This study has also manifested the effective use of geospatial data and advantage of riverbank mapping.
The study result can be a base for further analysis for future consideration of long-term erosion protection measures in the Jamuna.The result can be made more precise by considering Char lands and with higher resolution professional geospatial data.The identified area can be a valuable source for the expertise to find the optimum place for causeway to protect the river bank.The analysis and the result found from this research can be a model for similar studies on another riverbank management system in Bangladesh.The raster image analysis result How to cite this paper: Hassan, M.A., Ratna, S.J., Hassan, M. and Tamanna, S. (2017) Remote Sensing and GIS for the Spatio-Temporal Change Analysis of the East and the West River Bank Erosion and Accretion of Jamuna River (1995-2015), Bangladesh.Journal of Geoscience and Environment Protection, 5, 79-92.https://doi.org/10.4236/gep.2017.59006

1 .
Data and Software Used For observing and juxtaposing erosion and accretion changes of the west and east bank of Jamuna River, Landsat TM image of 1995 and 2005, and Landsat OLI image of 2015 (Path 138 and Row 42 & 43) shown in Figures 2-4 respectively have been used.Seven reflective Bands for 1995 and 2005 and eleven reflective bands for 2015 have been considered for image classification.Images depict dry time of Jamuna River as those were collected between December to April.

Figure 11 .
Figure 11.Changes of the east and west Jamuna river bank (1995-2005) due to the correlation of erosion and accretion of bank line.

Figure 12 .
Figure 12.Changes of the east and west Jamuna river bank (1995-2015) due to the correlation of erosion and accretion of bank line.

Figure 13 .
Figure 13.Changes of the east and west Jamuna River bank (1995, 2005 & 2015) due to the correlation of erosion and accretion of bank line.