5. BGJ_Vol-20_2014_Ovi_P_53_69

Authors Addresses: SAYEDA ALBINA HAQUE AND A.T.M. SHAKHAWAT HOSSAIN, Dept. of Geological Sciences,Jahangirnagar University, Savar, Dhaka- 1342, Bangladesh. E-mail: [email protected]

Short Term Rainfall Induced Hydro-meteorological Hazards on theWest Bank of Jamuna River, Bangladesh- Balighugri,

A Case Study

SAYEDA ALBINA HAQUE*, A. T. M. SHAKHAWAT HOSSAIN & MD. MEHEDI HASAN OVI

Abstract

Bangladesh is a low lying riverine country located in the South Asia. The Jamuna isone of the major rivers of Bangladesh and is suffering from severe erosional and bankstability hazards. Recent change of climate, mainly short term rainfall patterns hassignificantly increased the Jamuna river bank failure. Thousands of families becomeenvironmental refugees each year due to this hazad. In this paper an attempt has beenmade to see the influence of short term rainfall patterns on the bank stability byconsidering different scenarios. Transient seepage and stability modeling works werecarried out using Seep/W & Slope/W for finite element software (2007) to see theinfiltration mechanism, pore water pressure development and influence of short termrainfall on the river bank stability. From the analysis, it is clearly established that rainfallpatterns can significantly influence on the bank stability and failure mechanism atBalighugri. A variation of the factor of safety values with respect to time is also observedwhen an antecedent rainfall of 13 days is distributed uniformly, a significant drop offactor of safety (Fs) value is observed after 13 days. On the other hand, when 157 mm.single day major rainfall data distributed separately on the bank slope, then the factor ofsafety value is dropped as well. The sequence of dropping of factor of safety values areobserved from initial to 0.218 after 6 hours, 0.198 after 12 hours, 0.185 after 18 hoursand 0.172 at the end of the day. These variations of factor of safety values with timeclearly suggest that short term rainfall is one of the major variable component of theclimate that influence on the Jamuna river bank stability at Balighugri.

Keywords: Rainfall; Hazards; Stability & Seepage.

Introduction

The Jamuna River originates in Tibet as the Yarlung Zangbo Jiang and flows throughArunachal Pradesh of India as Brahmaputra and then it enters into Bangladesh, meets withTista and follows with the name of Jamuna. Before entering into Bangladesh, length of theriver is about 2,850 km. and a catchment area of the river is about 583,000 sq. km. InsideBangladesh, The Brahmaputra-Jamuna River is about 280 km. long and extends fromnorthern Bangladesh to its confluence with the Ganges. The catchment area of Jamuna inBangladesh is about 2,200 sq. km. The average discharge of the river is about 20,000 cubicmeter per second with average annual silt load of 1,370 tons/sq. km. In Bangladesh, theriver is a multichannel system with an overall braided appearance (COLEMAN 1969). In the

BGJISSN 1028-6845

BANGLADESH GEOSCIENCE JOURNAL, VOL. 20, P. 53-69, 2014

54 SAYEDA ALBINA HAQUE, A. T. M. SHAKHAWAT HOSSAIN & MD. MEHEDI HASAN OVI

study area around Sirajganj, the width of the river varies from about 3 km. to 18 km.Maximum channel depth is 40 m. and mean channel depth is around 5 m, although thisdepth varies along with stage fluctuations which are around 7-8 m. per annum. Thesechanges in the stage fluctuation are due to monsoon climate in the region and snow melt inthe Himalayan Mountains (BRISTOW 1993).

Fig. 1. Consequences of Jamuna river bank erosion.

Now a days, Jamuna bank erosion is considered as the Silent disaster of Bangladesh.Many researchers including FUKUOKA 1980; GASMO et al. 2000; CHO & LEE 2001; TOLL 2001& HOSSAIN & TOLL 2013 carried out research on rainfall induced failures in soils, infiltrationmechanism and instability of soil slopes. But research work on Jamuna river bank stabilityhazard is limited.

Fig. 2. Location map of the study area.

Short Term Rainfall Induced Hydro-meteorological Hazards on the West Bank of Jamuna River, 55

The Padma, Jamuna and Meghna are the major rivers of Bangladesh which erodeseveral tens of square kilometers of floodplain making thousands of people landless andhomeless every year in erosion prone areas. In recent years, river bank stability problem isaggravated along the west bank of Simla, Balighugri, Bahuka, Kazipur area (Fig.1). A casestudy was conducted to see the influence of short term rainfall on the west bank of JamunaRiver. The study area lies between 8940 to 8946 E longitude and from 2434 to 2439 Nlatitude as shown in Fig.2. Results are compared, evaluated and analyzed to see theinfluence of pore water pressure development, infiltration mechanism and factor of safetyvalues on the stability.

Materials and Methods

A site investigation was carried out in accordance with B.S. 5930 and IAEG (1981) inthe investigated area to investigate the site from geological point of view. Light cableprecession drilling technique combined with wash boring method was used to collectsubsurface samples. Geo-engineering properties were determined according to B.S. 1377(1990). The soil deposits of the study area is characterized by very loose to loose sandy,medium to fine sand, trace mica at the bottom layer which is underlined by medium denseto dense silty fine sand. A stiff to stiff clayey silt with fine sand are present at the top layer(Fig. 3).

Fig. 3. Observed stratigraphy at the river bank sediment along the Western bank of Jamuna.

A 45m. bore hole was drilled in the study area between 2433 N and 8940 E withthe technical assistance of the consulting firm Delta Soil Engineers to collect samples. SPTnumbers were recorded in the log sheets to interpret the ground condition. Both disturbedand undisturbed samples were collected for laboratory tests. Borelog data suggest that fourdifferent soil layers exist below the ground. Slope geometry is measured during the siteinvestigation. The height of the analyzed slope at Balighugri is 28m. high and inclined at anangle of 72. The strength parameters of the collected samples were determined accordingto B.S. 1377, 1990. The material properties of the analyzed samples are listed in Table 2. It


can be seen from the analysis that the rate of infiltration in different soil layer is differentbecause variation of soil characteristics.

There is no unique measurement of Rainfall Data analysis technique to determine thedirect effect of rainfall on slope failure. Rainfall data of Bogra (1980 to 2012) and Tangaildistrict (1987 to 2012) collected from BMD (Bangladesh Meteorological Department) wereanalyzed to identify the climatic influence on bank stability. Data series approaches wereapplied for linear trend, so that data should be consistent for 20-30 years period. Seep/Wand Slope/W numerical finite element software (2007) have been used to see the influenceof short term rainfall pattern on the Jamuna River bank seepage and stability conditions,pore water pressure (PWP) development and their influence on the factor of safety.

Results and Discussion

An attempt has been made to evaluate the Jamuna river bank stability hazards byusing Seep/W and Slope/W (2007) to see the influence of short term rainfall on a bank slopeat Balighugri area, Sirajganj district. Some primary results of this research work arepublished by HOSSAIN & HAQUE (2015). The grain size distribution curves are shown infigure 4. The authors mentioned that bottom sand layers in the study area are uniformlygraded. Very loose medium to fine sands with some silts and the upper clay soils can beclassified as intermediate plasticity silty clay (CI). The material property of the soil layers atBalighugri area is shown in Table. 2.

Fig. 4. Grain size distribution for the seven sand samples of the study area (HAQUE, 2015)

According to GLOBAL FACILITY FOR DISASTER REDUCTION AND RECOVERY (2011),Bangladesh lies in a humid, warm climate, influenced primarily by monsoon and partly bypre-monsoon and post-monsoon circulations and frequently experiences severe cyclones,local storms and tornadoes. The average temperature is about 26.1C, but it can vary


between 15C and 34C throughout the year. The warmest months coincide with the rainyseason (March-September), while winter (December-February) receives less rainfall. Rainfall,in this country is driven by the south-west monsoon, which originates over the Indian Oceanand carries warm, moist, and unstable air, beginning approximately during the first week ofJune and ending in the first week of October.

From climatic data analysis, four distinct seasons are recognized. The Pre-MonsoonSeason (March - May), where high temperatures dominate at an average maximum of36.7C, with very high rates of evaporation, and erratic but occasional heavy rainfall fromMarch to June. In certain areas temperatures occasionally rise to over 40C. The peak ofmaximum temperatures is usually observed in April, the beginning of pre-monsoon season.In pre-monsoon season, the mean temperature gradient is oriented in southwest to northeastdirection with the warmer zone in the southwest and the cooler zone in the northeast.

Fig. 5. Seasonal variations of rainfall data from 2000-2012 in Bogra district.

The identified Monsoon Season (June - September) is typically hot and humid, withheavy torrential rainfall contributing to most of the years rainfall.

Fig. 6. Seasonal variations of rainfall data from 2000-2012 in Tangail district.

Mean monsoon temperatures are higher in the western districts compared to those ofthe east. Warm conditions generally prevail throughout the season, interspersed with cooler


days during heavy downpours. The Post-Monsoon Season (October - November) is a shortseason characterized by less rainfall and lower temperatures, particularly in the evenings.The Winter Season (December-February) is typically relatively cooler and drier, with anaverage temperature ranging from a minimum of 7.2 to 12.8C and a maximum of 23.9 to31.1C.

The rainfall trend analysis of the region suggests that there is an overall increasingtrend of rainfall in monsoonal period in Bogra and Tangail (Fig. 5 & 6). The rainfall data(1980-2012) analysis also suggests that highest amount of precipitation generally takes placeduring monsoon period. Therefore, monsoonal climate can play a vital role on the bankstability. It is also clearly established that highest amount of rainfall is observed in 2011(Fig. 7 & 8) in Bogra and Tangail area.

Fig. 7. Increasing annual Rainfall trend in August from 2005-2012 (Bogra).

Fig. 8. Increasing annual Rainfall trend in August from 2005-2012 (Tangail).

An attempt has been made to see the overall rainfall pattern for years (2005-2012) forthe months of June to August separately. From the analysis, it is clearly established that anoverall increasing rainfall trend in August i.e. monsoonal period is observed in Tangail andBogra district (Fig. 7 & 8). Therefore, August 2011 short term rainfall data is used as inputparameter in the Seep/W software to see the influence of short term rainfall on bankstability. Different distribution of the rainfall applied on the slope is shown in Table 1.


Table 1. Different distributions of the rainfall applied on the slope

Antecedent Rainfall (mm.) Major Rainfall (mm.)

AntecedentCycle

Total amount ofantecedent

rainfall (mm.)

Duration(Hours)

Intensity(mm./day)

Intensity(mm./hr.

)

Total amount ofmajor rainfall

(mm.)

Duration(Hours)

Intensity(mm./hr.)

Cycle 1 473312

(13 days)36.38 1.52

15724

(1 days)6.54

Cycle 2 21896

(4 days)54.5 2.27

It is clearly established that there are two (2) antecedent cycles and one (1) majorcycle of rainfall in August 2011 both in Tangail and Bogra district (Fig. 9). In Bogra, the firstantecedent cycle (cycle 1) with total amount of 492 mm. rainfall continued from 2nd to 11th

August, 2011 and 2nd antecedent cycle (cycle 2), from 14th to 19th August, 2011 with 97mm. A major rainfall of 215 mm. was also observed on 11 th August, 2011.

Fig. 9. Days of month versus rainfall curve in August 2011 (Bogra and Tangail).

From the rainfall data analyses, it is anticipated that all of these antecedent cycles andmajor event was responsible for slope failure in the study area. In Tangail, the firstantecedent cycle (cycle 1) sustained from 2nd to 14th August 2011 with a total amount ofrainfall of 473 mm. and 2nd antecedent cycle (cycle 2) from 22th to 25th August 2011 with218 mm. rainfall. A major rainfall event was also observed on 17 th August with 157 mm.rainfall.

Modeling Results

Numerical seepage and stability modeling were carried out to see the effect of shortterm rainfall on the bank stability at Balighugri area under changing hydrological condition.Seep/W is capable of modeling saturated/unsaturated and transient flow in two dimensions(2D). The results of the finite element model can be used to interpret the infiltrationmechanism of the slope, seepage conditions, and effect of hydrologic and climaticconditions on the pore water pressure (P.W.P).


Clay & Sandy Sil t (SM-ML)

Very Loose Fine Sand (SP)

Silty Fine Sand (SM-ML)

Medium to Dense Sand (SP-SM)

1 234

5 6

78910

1112

Distance (m.)0 5 10 15 20 25 30 35 40

Elevat

ion (m

.)

0

5

10

15

20

25

30

Fig. 10. Initial bank slope condition without any rainfall data (Fs=0.892).

HAQUE (2013) noted that rapid changes in precipitation is responsible for instability.Thus it is essential to model the problem as transient. In transient flow, hydraulic headchanges as a function of time. The initial slope geometry assumed for the analyses is drawnas described earlier (Fig. 10). The basic material property of different soil layers are listed inTable 2.

Table. 2. Material properties of soil layer at Balighugri, Sirajganj

Soil layer Soil type/Lithologywet

(KN/m)

c'

(kPa)

'

()

Ksat

(m/sec)

Layer 1 (L-1) Clay and Sandy Silt (SM-ML)

18 20 0.5 1e-5 to 1e-6

Layer 2 (L-2) Very Loose Fine Sand (SP) 18.5 0 27.5 1e-3 to 1e-4

Layer 3 (L-3) Silty Fine Sand (SM-ML) 19 10 17 1e-5 to 1e-6

Layer 4 (L-4) Dense Fine Sand (SP-SM) 18 0 27.5 1e-3 to 1e-4

The initial water level was taken to be at 1 m. depth below the ground at the crest andat the toe, ground water level was taken as 0 m. The initial pore water pressure was assumedto be hydrostatic, i.e. directly proportional to the vertical distance below the ground waterlevel. Longer arrows indicate greater flow. Different distributions of rainfall patterns areapplied on the slope (Table1). Slope stability analyses considering the rain infiltrationprocess were performed using limit equilibrium and the Morgenstern-Price method(Morgenstern & Price, 1965). Predicted pore water pressures (P.W.P) obtained from theSeep/W seepage analyses were used as input ground water conditions for subsequent limitequilibrium analyses. In the seepage analyses, 11 m. triangular mesh was used. The totalmesh consisted of 888 nodes and 1589 elements. Along the left and right edges head


boundary were applied in order to define the initial groundwater level and initial pore waterpressure (P.W.P) profile. A zero nodal flow boundary (Q=0) was applied along the base. Theprecipitation rate was modeled as a unit flux boundary (q) into a nodal boundary (Q) andthen calculated the hydraulic head at each node. If a positive head is calculated at anysurface node, the flux boundary is changed to a head boundary and set to zero and the fluxis determined. The slope stability analyses were carried out to study the different seepagecondition (as predicted by Seep/W) on the factor of safety values. Slope stability analysesconsidering the rain infiltration process were performed using limit equilibrium method. TheMorgenstern-Price method was chosen. Predicted pore water pressure (P.W.P) obtainedfrom Seep/W seepage analyses were used as input groundwater condition for limitequilibrium analyses.

For the numerical analyses only 1st antecedent cycle of rainfall (from 2nd to 14th August2011) and single day major rainfall amount of 157 mm. of 17 th August 2011 from Tangailstation is applied (Table. 1). For the modeling, uniform intensity of rainfall (152 mm. /hr.) isapplied for 13 days. Only 1st antecedent cycle and a major rainfall data were analyzed forbank stability analysis as shown in Fig. 9, where 1st antecedent cycle of rainfall wasoccurred from 2nd to 14th August, 2011 (13 days), and the major rainfall was occurred in 17 th

August.

Effect of 1st Antecedent Rainfall Cycle (13 days data) on River Bank Failure

The 1st Antecedent Rainfall Cycle (13 days data) from 2nd to 14th August, 2011 is used inthe analysis. Total amount of rainfall for 13 days was 473 mm. the intensities and rainfalldistribution patterns are listed in Table 1. P.W.P profiles generated by Seep/W and Slope/Win each case were used to evaluate the stability conditions. The initial steady state seepagecondition of slope and natural geometry of bank slope analyzed using Morgenstern-Pricemethod are shown in Fig. 11 (A & B) respectively. Before applying any rainfall data bankslope analyzed by Morgenstern-Price method provides a factor of safety (Fs) value 0.892 forthis slope which indicate very unstable condition (close to 1) of the bank slope. Thisunstable condition of bank slope was also justified during field investigation with very loosenature of fine sandy soils. The initial slope condition without rainfall data and developedpore water pressure contours for this bank slope without raining are shown in Fig. 11 (C &D) where the critical failure surface of the bank slope is marked by circular red shaded zone.From Fig. 11 (E) it can be see that the seepage condition of the bank slope where maximumnegative pore water pressure was -100kPa built up below the crest after applying one dayrainfall data of 1st antecedent cycle.


Fig. 11. Seepage and slope stability condition for 1st antecedent cycle.


Fig.12. Seepage and slope stability condition for 1st antecedent cycle (A-C) and (D-H) for major rainfalldata.


The infiltration capacity and permeability of different layers are not same because ofdifferent material properties shown in Fig. 11 (E). From Fig. 11 (F) it is clearly observed thatafter one day rainfall the Factor of safety is dropped to 0.218, which is indicating a veryunstable bank slope condition. During analysis, it is also observed that the factor of safetyvalue (Fs=0.218) remaining same up to the 4th days of raining and there is no change offactor of safety value up to the day 4. After day 5 of 1st antecedent cycle the factor of safetyvalue again reduced and dropped to 0.198 (Fig. 11 G) and remains constant up to the 8th

day of the antecedent rainfall. Critical failure surface for this slope is indicated by redshaded zone (Fig. 11 G). Factor of safety value again decreases to 0.185 after applyingrainfall data of day 9 (Fig. 11 H) and this factor of safety value remains same up to day 10.During the 11th days of raining of 1st antecedent cycle factor of safety value is dropped to0.175 (Fig. 12 A) and remains same value (Fs=0.175) up to the end of the test and indicatinga vulnerable condition for the bank slope. Fig. 12 (B) showing the seepage condition of thebank slope at the end (day 13) of 1st antecedent cycle of rainfall. It can be seen from this Fig.12 (B) that the pore water pressure contour change its position as observed in figure 11 (E).At the end of the test (day 13) the factor of safety value reduced to 0.172 (Fig. 12 C) anddirectly indicates that the dropping value of factor of safety from 0.218 (after applying day 1data of rainfall) to 0.172 (at the end of the test) may be due to variation of rainfall patternwith time. An attempt has been made to follow the development of factor of safety for thebank slope through the analysis where a uniform intensity of rainfall 1.52 mm./hr is appliedfor 13 days. It is interesting to note that the factor of safety values with different time steps(2nd to 14th August), is gradually decreased. The change of Fs values with different time steps(2nd to 14th August) is shown in Fig. 14. Initially a significant drop and then a smallfluctuation between the Fs values are observed with time during raining. However, it is clearfrom figure 14 that before starting antecedent raifall cycle the Fs value was 0.892 and duringraining from 1st to 4th August the Fs value was same and reduced from initial value 0.892 to0.218 with increasing time. Again the Fs is dropped to 0.198 (Fs=0.198) and without anysignificant change it continued up to day 8. The factor of safety value is dropped to 0.175(Fs=0.175) in day 11 to day 12 without any significant variation. At the end of theantecedent cycle (day 13) the factor of safety value is dropped to 0.172. The dropping valueof factor of safety with time clearly indicating the influence of Short term rainfall on the bankstability. The sequence of factor of safety value dropping from initial value 0.892 to 0.218for 4 days (from 1st up to 4th August), 0.198 for 4 days (from 5th up to 8th August), 0.185 for 2days (from 9th up to 10th August), 0.175 for last 3 days (from 11th up to 13th August. Changeof factor of safety values clearly indicate very unstable condition of the bank slope. It infersthat the antecedent rainfall event played role in reducing the bank slope stability.

Effects of Major Rainfall Patterns on bank slope stability

An attempt has also been made to see the influence of single day major rainfall amountof 157 mm. of 17 August, 2011 on bank slope stability. The major rainfall was distributedover 24 hours with an intensity of 6.54 mm./hr. The major rainfall data of 17 August, 2011was analyzed in four (4) steps at 6 hour interval (Fig. 15). The pore water pressure contoursand seepage condition of the bank slope before applying any rainfall data is shown in Fig.12(D). The seepage condition and stability of bank slope after 6 hr. are shown in Fig. 12 (E)and (F) respectively. From Fig. 12 (E) it is observed that after 6 hr. raining with an intensity of6.54 mm./hr. A negative pore water pressure value (-100 kPa) is developed in the slope andshowed various degree of infiltration and permeability depending on the material properties.


Bank slope stability condition can be observed from Fig. 12 (F) where factor of safety valuedropped to 0.218 which indicates very much unstable slope condition. Critical failuresurface is marked by red shaded zone in Fig. 12 (F). After 12 hour, a change in pore waterpressure is observed (Figure 12 G). The slope stability condition after 12 hour is also shownin Fig.12 (H). The factor of safety value dropped from 0.218 (after 6 hours) to 0.198 (Fig. 12H). From Fig. 13 (A), it can be observed that after 18 hour of raining, the negative pore waterpressure is gradually reduced from -100 kPa in Fig. 12 (E & G) and dropped to -80 kPa,which is clearly indicating the reduced suction. The slope stability condition can beobserved from Fig. 13 (B).

Fig. 13. Seepage and slope stability condition at different intervals for major rainfall data.

The factor of safety value is dropped to 0.185 after 18 hour raining (Fig. 13 B) andindicates unstable condition of slope. At the end of the day of major rainfall event, themaximum negative pore water pressure dropped to -60 kPa from the initial value (-100 kPa)and indicates that the suction values gradually decreasing which might cause slope failure(Fig.13 C). It can be seen from Fig.13 (D), that the factor of safety value is 0.172 at the end ofthe day with an intensity of 6.54 mm./hr. rainfall. From the seepage and slope stabilityanalysis of major rainfall data (157 mm.) of 17 August, 2011, it is clearly established thatduring raining negative pore water pressure gradually reduced and hence soil loses itsstrength which might be responsible for slope failure. It is the clear indication of majorrainfall event on river bank failure.


Fig.14. Variation of Factor of safety values with different time (1st antecedent rainfall data).

Fig.15. Variation of Factor of safety values with different time (Major rainfall data).

The variation of Fs with different time intervals are shown in Fig.14 & Fig.15. From theseseepage and slope stability analyses of 1st antecedent cycle (2nd to 14th August, 2011) and amajor rainfall data of 157 mm of 17th August, it is established that precipitation causes thesuction near the surface to decrease and indeed natural bank slope failures might occur dueto recent climate change of rainfall patterns.

Conclusions

From the grain size analyses it is established that the soils of the bottom part of theinvestigated area are mainly uniformly graded very loose to medium fine sands with somesilts and the upper clay soils (C.I) of intermediate plasticity. From the rainfall data (1980-2012) analysis, it is established that during monsoonal period (June-September) the amountof rainfall showing an increasing trend from 1980-2012 which showing a consistency withextensive bank failure within this period in the study area. From rainfall data of 2002-2012,the highest amount of rainfall is observed in 2007 and 2011 in both Bogra and Tangaildistrict. Short term rainfall data of Tangail district (August, 2011) was selected as inputparameters in software to see the short term rainfall influence on the bank stability. Two (2)antecedent cycles (2nd-14th August and 22th-25th August, 2011) and one major rainfall event(17th August) are analyzed to see the influence of rainfall on bank stability. From the seepageand stability analyses, it is clearly established that 1st antecedent cycle of 13 days rainfall hasdirect influence on the bank slope failure with a drop of factor of safety value from 0.892 to


0.172 at the end of the cycle. Maximum negative pore water pressure and suction valuesgradually decreased and after certain time the factor of safety values dropped to below 1and indicating unstable condition of slope. The 2nd antecedent cycle of 4 days has noinfluence on bank stability. A major rainfall event with 6.54 mm./hr. has no effect on bankstability but in conjunction with 1st antecedent cycle this major rainfall might influence onthe bank slope stability. From these analyses, it is established that the slope are already invulnerable condition (Fs =1) without influence of rainfall water. But after raining the factorof safety values are reduced than the initial condition during 1st antecedent cycle. Maximumnegative pore water pressure value were gradually decreased with time and at the end of the1st antecedent cycle (13 days) the factor of safety value becomes 0.172 which indicates afailed slope. A major rainfall event of 17th August, 2011 when analyzed separately, factor ofsafety also suddenly dropped and finally reached a value of 0.172. This is the clearindication of rainfall event influence on the bank stability. To control bank failure in theinvestigated area some mitigation measures including re-vegetation, placing of geo-sandbags, concrete blocks and green slope toe protection methods are recommended.

Acknowledgements

Financial assistance provided by the Ministry of Science & Technology, Governmentof the Peoples Republic of Bangladesh to complete this research work is gratefullyacknowledged (Grant no: 94 NST Fellowship No.39.012.002.01.03.021.2014-08).

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GASMO, J.M., RAHARDJO, H., & LEONG, E.C., 2000, Infiltration effects on stability of a residual soil slope;Computers & Geotechnics, Vol. 26(02).

GEOSLOPE INTERNATIONAL LTD., 2007, Seep/W for finite element seepage analysis; User Manual, 4,Calgary, Alberta, Canada.

GEOSLOPE INTERNATIONAL LTD., 2007, Slope/W for finite element seepage analysis; User Manual, 4,Calgary, Alberta, Canada.

Global Facility for Disaster Reduction and Recovery (GFDRR), 2011, United States of America.

HAQUE, S.A., 2013, Climatic scenario, stability and liquefaction hazards in some parts of the westernbank of Jamuna River, Sirajganj district, Bangladesh; M.S. Thesis, Department of GeologicalSciences, Jahangirnagar University, Savar, Dhaka, 176 p. (Unpublished Thesis).


HOSSAIN, A.T.M.S & HAQUE, S.A., 2015, Modeling short term rainfall induced hydro-meteorologicalriver bank stability hazards of the west bank of Jamuna River, Bangladesh-Balighugri, a casestudy; Conference proceedings on the International Conference on the Water Crisis in the Asia-Pacific Region, Disaster Management, B2; P. 63-64. edited by ICEDS; Kagawa University,Japan.

HOSSAIN, A.T.M.S & TOLL, D.G., 2013, Climatic Scenario and Suction Controlled Rainfall InducedLandslide Hazards in Some Unsaturated Soils of Chittagong, Bangladesh; 13CIA-2013 Book,AHDPH, P. 851-859.

MORGENSTERN, N. R., & PRICE, V. E., 1965, The Analysis of the Stability of General Slip Surface;Geotechnique, Vol. 15 (4), P. 289-290.

TOLL, D.G., 2001, Rainfall induced landslides in Singapore; Proceedings of the Institute of CivilEngineers, Vol. 149(4), P. 211-216.


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5. BGJ_Vol-20_2014_Ovi_P_53_69