waterlogging in guwahaty city- disaster or problem

7/25/2019 Waterlogging in Guwahaty City- Disaster or Problem

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AICTE-NEQIP sponsored two daysInternational seminar at Guwahaty onDiaster Management issues and challengesGUWAHATY CITY WATERLOGGING -DISASTER OR PROBLEM?

CONFERENCE PAPER NOVEMBER 2015

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1 AUTHOR:

Prashanta Bordoloi

Kaziranga University

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AICTE-NEQIP sponsored two days International seminar at Guwahaty on Diaster Management issues and

challenges

GUWAHATY CITY WATERLOGGING - DISASTER OR

PROBLEM?by

Prashanta Kumar Bordoloi,Professor, Civil Engineering department,

Assam Kaziranga University, NH37, Karaikhowa, Jorhat, Assam, India 785006,[email protected]

AbstractWaterlogging in Guwahaty city is a common sight after a heavy shower in the summer

monsoon season of south west monsoon, apparently with no solution at sight. Multiplegovernment departments are involved in mitigating this disaster, with varying degree of

success, yet Guwahatian life coming to a standstill because of this flooding, and it is a recurringphenomenon. Augmentation of the pumping capacity at Bharalumukh, provides some relief,

but is not enough. It is largely believe to be a natural calamity, and has to be absorbed by the

society. Disaster cannot be done away with; only loss can be minimized through preparedness.This paper attempts to ponder, Guwahaty waterlogging is not a disaster in entirity; it is a

problem and thus has solution. The approach should be multi-disciplinary, including

participation of civil society; not multi-departmental, engaged in de-silting and partial streamrejuvenating centric solution practice. In the absence of requisite information required for

conducting this study, the problem was studied with high resolution Digital Globe synoptic

recent data on a GIS platform collating with limited pertinent data available in public domain.

Key WordsCommunity participation, multidisciplinary approach, soil and Water Conservation,watershed delineation and development

Dimension of Waterlogging in Guwahati City

Introduction : Inundation owing to water-logging is has been a major catastrophefaced in several wards of Guwahati Municipal Corporation Area during the rainyseason after every medium or heavy downpour. The public and the authority areequally concerned as it brings life to standstill and there has been several initiatives tosolve the vexed issue, involving multi-departmental participation with tall claims andthe situation remain grim which lead to even loss of human lives. The author was

helping a French researcher in introducing the situation and used GIS toolssupplemented with reconnaissance study, limited field data available in public domainto study the inherent limitations leading to deterioration of storm water evacuatingcongestion and spatial pattern of the inundation in the GMC area. Layers of thematicinformation was integrated on a GIS, involving drainage, slope (limited data), andlanduse pattern to use as a tool for the decision makers to address the issue. Thestudy was based on primary data gathered from public opinion voiced in print andelectronic media, and secondary data was collected from various governmentagencies made available in public domain , research centres and concernedindividuals. All data were finally integrated in GIS environment using ERDASIMAGINE for generation of hazard map. Rapid urbanization with increased housing

and construction activities in the city has lead to more rooftops, driveways, streets andother impervious or hard surfaces (CDP, 2006). This rapid development of thewatershed areas decreases infiltration capacity of the land giving rise in runoff losses,


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drainage system had been the yardstick to appreciate the level of civilization of oldcities like Mahenjodaro and Harappa , by that token with nature gifted three stormwater disposal and balancing system Bharalu, Bonda jan and Deepor Beel, and itsdeteriorating environment does not speak the civility of the dwellers in the GMC area,

and blame game is widely displayed as public and authority are equally responsible.Guwahati waterlogging, as we found, is no disaster but is a problem hence there aresolutions, if approached in a systematic way, not whimsically as is practised now.

1. Guwahaty Municipal Area and its environ

1.1 As the legend goes : Brief History of the Town

The city that radiated the light of knowledge since the dawn of civilization is thehodonomy Guwahati city referred as the legendary Pragjyotishpur (Dr BhupenHazrikain the song Mor Lakhya sthan hol Tezpur). Dighali Pukhuri the grand tankwas widely believed to be excavated on the occasion of a swayambara leading to

Duryyodhana marrying Bhagadattas daughter in Mahabharata day, the city enjoys arich history and finds frequent mention in medieval historical sources, and also inthe epics Mahabharata, Ramayana and Raghuvansham of Kalidasa. In 640 AD, thelegendary Chinese pilgrim Yuen Chawan graced the city in Kumar BhaskarBarmans reign. The emergence of modern Guwahati started around 1826, after thepact at Yandabu, and in 1890 the city was connected to the rest of India via arailway line. Guwahati experienced phenomenal growth after independence of thecountry following the establishment of major institutions of higher education likeGuwahati University, Engineering College, and Medical College. The Guwahati OilRefinery was established in 1961. In 1972, after the reorganization of the State ofAssam, the capitol was virtually shifted overnight from Shillong to Dispur (Guwahati),

whereby the city gained enough political importance. Since then, the city has grownenormously in terms of population and development of commercial activities. Floodgate for settlers in Guwahati was thus opened.

1.2 Geography

Situated by the banks of Brahmaputra with its cardinal points being 26110N and91440E. Guwahati is located towards the south-eastern side of Kamrup district,which is surrounded by the Nalbari district in the North, the Darrang and Marigaondistricts in the East, the Meghalaya State in the south, and the Goalpara and Barpetadistricts in the West. The GMC area is sandwiched between the mighty Brahmaputraon the north and the Meghalaya hills on the south, dotted with small hills and hillocksseparated by flat velleys. Interestingly, the northern limit is separated from theBrahmaputra, the ultimate city storm discharge system, by the hills of Kharghuli-Nabgraha, Kamakhya, with separation from Uzan Bazar to Bhralumukh, and atBonda through which escapes the two brooks Bharalu and Bondajan snakingthrough the intervening flat terrain. Runoff from Basistha, Khanapara, Koinadhara,Panjabari, Nrengi, Birkusi, Bonda, Nunmati, Chunsali, Jyotinagar, Kharghuli,Neelachal (kamakhya), Jhalukbari, Fatasheel, Sonaighuli, Kahilipara, Japorighog,Henegerabari, Geetanagar, Garbhanga Narkasaur, Nabagraha, Saraniya, covering3455 ha thus traverse through the flat valley of the city 49 to 56 m above Mean SeaLevel (MSL) and Danger level of the Brahmaputra at Pandu at 49.66m add todrainage congestion owing to low relief. In this year, difference of Bharalu and the

Brahmaputra water level was barely 23cm lasting for few hours speak of the gravityof the situation, which warrants forced evacuation.


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Figure 1.1, 1.2 shows the physical environment, morphology of the city and ZonalMap of Guwahati. Zone 1 with Bharalu.the lone storm water disposal channel

1.3. Topography

The stretch of Bharalu and Bahini which traverses through the densest areas ofGuwahati is approximately 16 km long (Table 1-2) with a catchment area thatis almost equally divided between the hilly regions and the plains. Specifically, thehilly upstream section of the Bharalu has a catchment area of 60 km2 (where it is

known as Bahini), and a catchment area of 40 km2 in its d ownstream stretchpassing through Guwahati (Figure 1-4).


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Table 1-1: Description of the Course and Length of Bharalu, Bahini, Basistha,Morabharalu and Pamohi

River Description of the Course of River Length TotalLength

BharaluSplit from Bahini at the Indian Oil Refinery drain toBharalumukh where it drains into Brahmaputra River

7

16

BahiniSplit from Basishta to its downstream point at the Indian OilRefinery drain where it is known as Bharalu

9

Basistha

From its origin in Meghalaya Hills to confluence point withDead Bharalu or Morabharalu

19

27After the confluence point with the Dead Bharalu orMorabharalu up to Deepor Beel

8

Dead Bharalu Between Bharalu and Basishta 13

Pamohi Between Deepor Beel and Brahmaputra River 7

Covering an estimated area of 11 km2in the heart of Guwahati, the catchment area

has seen rapid urbanization from economic and demographic developments. FromBasistha Chariali, the Bharalu River runs for about 17 km till Bharalumukh with anaverage channel width of 5 to 9 m. The average water depth in the channel is 3 m,although it varies considerably as a result of different flow volumes and ever-increasing piles of garbage. Based on earlier estimates, the velocity of flow is 0.76m/sec for the stretch between Basistha and R.G. BaruaRoad, and on average 1.2m/sec for the rest of the course. The Brahmaputra has a water depth ofapproximately 47 m in the Guwahati area. The Bharalu is the main drainagechannel of the Guwahati Municipality area. It discharges into the Brahmaputra at

Bharalumukh. After flowing a few kilometres, the original channel bifurcates into tworivulets. One rivulet is known as the Basistha River, which courses towards DeeporBeel. The other rivulet (initially called Bahini and later Bharalu) passes though thecity draining the areas of Basistha cantonment, Beltola, Rukrninigaon, MathuraNagar, Dispur, Hengrabari, and Ganeshguri, and then passes along the R.G.Baruah Road resembling a manmade drain. This rivulet known as the Bharalumeets a major drain (carrying storm water and waste water run-off from the publicsector Guwahati Refinery, of Indian Oil Corporation Limited; and domestic wastewater from large areas in the eastern part of the city) near the Assam State Zoo andthereafter the combined flow turns to the western direction, crossing the R.G. BaruaRoad and flows through a densely populated residential neighbourhood of NabinNagar and Anil Nagar which hit the media during monsoon season for worst of the

waterlogging, then along Rajgarh Road. It then crosses the G.S. Road atBhangagarh and flows towards Ulubari, Fatasil and Kumarpara prior to joining theBrahmaputra at Bharalumukh. The southern and eastern sides of the city aresurrounded by hillocks. Apart from the hilly tracts, swamps, marshes, water bodiessuch as Deepor Beel, Silpukhuri, Dighali Pukhuri, Borsola Beel and Silsakoo Beelare also within the city most of which pays the role of balancing reservoir.

The GMC falls within the climatic Zone 1 which comprises northern and north-eastern India as well as adjoining parts of Nepal, Bhutan, Bangladesh and NorthMyanmar. In this zone, rainfall generally occurs in the monsoon months from Juneto September while the months from November to February are generally dry withoccasional winter rains. In this basin, four meteorological conditions are mainlyresponsible for heavy rainfall and subsequent floods:

1. Movement of a monsoon trough to the northeast from the Bay of Bengal to


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3. Formation and movement of lowlands or land depressions over North-EastIndia.4. Circulation of cyclonic upper air over North-East India.

Figure 1-3: The Bharalu River System

1.4 Climate

Figure 1-4: Elevations of the Bharalu River Catchment Area (in metres above MSL)The annual rainfall in Guwahati was on average 1 681 mm and 147 rainy days from


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5% during the post-monsoon months (October to November), and 1% during winter(December to February). This uneven distribution of rainfall is the primary cause ofdrainage congestion in the abated by unplanned urbanization, as it generates higherrunoff. Unplanned expansion of the city to accommodate increasing population has led

to severe encroachment in the wetlands, low lying areas, hills and shrinkage of forestcover (Thakur and Goswami, 1993). Denudation of the hills and loss of wetlands thuslead to water logging. Immediately after every down pour the city drains gets silted upwith silts coming with storm water running down the hills flooding the streets (SoilConservation Dept., Govt. of Assam, 2003). The wetlands also cannot cope up withthe excess storm water of the city. With other physiological factor remain un-altered,changing of environment and landuse pattern have profound impact on storm waterdrainage which was unheard of in the sixties.

Table 1-2: Monthly Rainfall (mm) in Guwahati from 2008 to 2012

MonthYear Annual

MeanPercent of

Annual Mean2008 2009 2010 2011 2012

January 34 0 9 5 10

February 10 2 23 8 9

March 139 60 124 54 23 80

April 159 112 370 101 382 225

May 143 200 356 225 181 221

June 354 190 483 88 396 302

July 236 363 251 373 344 313

August 281 287 234 204 310 263

September 126 100 223 256 180 177October 116 119 76 0 58 74

November 0 4 5 15 0 5

December 2 4 1 1 5 2

Annual Total 1,600 1,440 2,122 1,350 1,892 1,681

JuneSept. 997 940 1,190 921 1,230 1,056 63%

Oct.Nov. 116 123 81 16 58 79 5%

Dec. - Feb. 46 6 1 34 18 21 1%

MarMay 441 372 850 380 587 526 31%

1.4 Population within the Project Area

The State of Assam has consistently witnessed a steady growth in population.Assam accounts for more than 70% of the population of the North-East (Census2001). The Kamrup District is one of the most densely populated regions inAssam.Guwahati is a fast growing metropolis and the most important city of the region.The city with a population of 8.9 Lakhs (Census 2001) is by far the largest settlement,while Shillong and Imphal, with population sizes of only 2.7 and 2.5 lakhs, respectively,are the second and third largest cities in the north-eastern region. With a substantialincrease in population in the last few decades, the city needs a well-structureddevelopment plan in its infrastructure to sustain its rapid growth.


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The population of the GMA has grown almost 6.5 times between 1971 and2001. The municipal limit of the city during the period increased from 44 km2in 1971 to217 km2in 1991 (Tables 1-3 and 1-4; Figure 1-5).

Table 1-3 Population Growth in Guwahati vis--vis India, Assam and Kamrup

Name

1971 1991 2001

Population(in million)

Population(in million)

Average DecadalGrowth Rate

Population

(in million)Average Decadal

Growth Rate

India 548 846 24% 1,027 21%

Assam 14.6 22.4 24% 26.6 19%

Karup 1.2 2.0 29% 2.5 26%

GMA 0.29 0.65 48% 0.89 38%

GMCA 0.12 0.58 117% 0.81 39%

Table 1-4 Population Growth in Guwahati (1951 and 2001)Year Population in

GMCADecadal

Growth (%)GMA excluding

GMCADecadal

Growth (%)GMA Decadal

Growth (%)

1951 43,615 53,774 97,389

1961 1,66,273 2.81 33,209 -0.38 1,99,482 1.05

1971 2,51,642 0.51 40,387 0.22 2,92,029 0.46

1991 5,84,342 1.32 61,827 0.53 6,46,169 1.212001 8,09,895 0.39 80,878 0.31 8,90,773 0.38

2011 9,68,549 0.09

Figure 1-6: Population Growth of Guwahati Metropolitan Area (1951 to 2001)

As a representative sample of economic status of the poplation, which has adirect bearing on sewage, Bharalu sub-basin consists of the Kamrup metro district ofAssam in the plain portion and Ribhoi district of Meghalaya in the hilly catchment. Theplain catchment of the sub-basin, which is covered by greater Guwahati City, is

densely populated compared to the southern hilly portion of the catchment. Thepopulation statistics of the Bharalu sub-basin are shown in Table 1-5.


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Table 1-5: Population Statistics of Bharalu Sub-basin

2.0 Total Waste Water Generation

Quantification of the industrial waste reaching the Bharalu is not presently available.At present, the city of Guwahati does not have an integrated sewerage systemexcept for select residential areas such as the Railway Colonies, the Oil Refinerycolonies and residential areas under defense establishments which have their ownsewerage and treatment facilities. The only collection and treatment processfollowed is use of septic tanks. Therefore, much of the waste water generated in thecity is being disposed of into rivers without treatment (Tables 2-1 and 2-2).

Table 2-1: Waste Water Generation in Guwahati

TotalHouseholds in

the City

Total WastewaterGenerated in the City

(m3)

Total HouseholdsConnected to Septic

Tanks

Total WastewaterCollected in the Septic

Tanks (m3)

2,30,7691 1,03,932

2 1,38,427

3 17,442

4

Notes: 1 As per Census data 20112 Assumption being 80% of 135 lpcd water supplied to 9,62,334 people 3 As per secondary dataobtained from GMC4 Assuming average household size of 4.2 (as per Census 2011) and 30 lpcd of wastewater

Table 2-2: Calculation of per Capita Sewage Generation

Description DemandNet per capita water demand for South Guwahati (proposed in Water Supply Project) 135

Add 10% for ICI demand1 @ 10% 13.5

Add ground water infiltration @ 5% 6.75

Sub Total 155Considering 80% for sewage generation 124

USE 125Notes:

1. As the Guwahati is a fast growing city and Industrial, Commercial and Institutional (ICI) activities are taking placeat a rapid pace in some areas of the city, so a 10% provision has been used for ICI demand over the per capitademand of water supply for the whole population. This will eventually cover the need of ICI demand for the city as awhole taking care of unevenness of ICI demand distribution. This also accounts for the floating population which willbe working in the ICI facilities.2. Per capita sewage generation is considered as 125 lpcd for GMDA area.

3. The catchment area of the Bharalu includes 36 wards of the city and a projected 2035 population ofapproximately 870,000. The equivalent waste water generation from the projected population is shown in Table 2-3below (Feasibility report of PCBA on Sewage Treatment)

District Type Male Female Total

KamrupMetropolitan

Urban 5,36,523 5,00,488 10,37,011

Rural 1,11,062 1,05,865 2,16,927

Total 6,47,585 6,06,353 12,53,938

Ribhoi

Rural 1,18,705 1,14,882 2,33,587

Urban 13,826 11,427 25,253

Total 1,32,531 1,26,309 2,58,840


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Table 2-3: Projection for Total Waste Water Generation for Bharalu Catchment Area

RiverPopulation Sewage

Contribution(lpcd)

Sewage Generation inMLD

2020 2035 2050 2020 2035 2050

Bahini 3,97,166 6,08,842 11,80,661 125 44 58 137

Bharalu 2,75,644 3,97,984 4,09,605 125 25 33 38

Total 6,96,916 10,06,826 15,90,266 69 91 175

2.1Surface water scenario of the study area

The existing natural drainage of Guwahati comprises the Brahmaputra and its

minor tributaries such as the Bharalu, Mora Bharalu, Khanajan, Basistha and

Bondajan. The Brahmaputra which flows in an east-west direction along the

northern fringe of Guwahati is only 1.5 km wide near the city. In addition to the

above mentioned tributaries, Digaru, Bonda, Amcheng, Barapani are some of the

other major streams that flow through the city; Digaru along with other tributaries like

Bonda and Amcheng form small plains in between the hill ranges in the east and

south-eastern part of the city. The three tributary basins of Guwahati, viz. the

Bondajan basin, the Bharalu basin and the Khanajan basin have contrasting

characters with a 9 degree, 6 degree and 3 degree slope respectively. This shows

that the average slope of the study area falls while traversing from the eastern to the

western, with exception of inter-basin separation. Khanajan in the western most part

of the city connects Deepor Beel (wetland) with the Brahmaputra. As the legend

goes, this was a river transport channel developed by the Mughal invaders to enter

into the Deepor Beel from the Brahmaputra. It makes sense, as the manmade

channel would have not developed against the lie of the land, had it been for storm

water drainage. Mora Bharalu is a small channel linking Bharalu with Basistha

stream on the south and south-eastern part of the city and flows to the Deepor

Beel.The city of Guwahati is dotted with numerous surface water bodies comprising

of wetlands and ponds. These water bodies play a significant role of balancing

reservoir of rainwater. But unplanned rapid urbanisation and development activities

have truncated these water bodies. At present, the city can boast of only six

wetlands, viz., the Deepor beel, Hahsora beel, Silsako beel, Narengi beel, Borsola

and Sarusola beel. The Deepor beel is the largest one and is also a Ramsar site.

The Borsola and Sarusola beels are located in the central part, while the Hahsora,Narengi and Silsako beels are located in the eastern part of the city. Apart from the

various natural water bodies, there are a number of historic water tanks or ponds

within the city. These tanks which include Dighalipukhuri, Silpukhuri, Joorpukhuri,

Nagputapukhuri, Kamakhyapukhuri, etc. play a critical role in maintaining surface

water repositories of the city. These surface water bodies sustain water flow

dynamics between the high


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Fig. 2. 1 : Guwahati city showing Municipal Ward Boundaries

land and low land of the citys landscape, function as storm water reservoir and act aspotential sites for natural recharge of the sub surface water.

The distribution of the surface water sources, however, is not uniformthroughout the city and is controlled by the landscape patterns along with the riversand streams which originate from the southern and north eastern highlands and flowalong the natural slope gradient of the city. Wetlands are located in the central, southeastern and western parts of the city. These parts are primarily depressed valley areaswith remnants of palaeo-channels of Brahmaputra being traced through variousstudies and surveys. It is observed that natural drainage exists in atleast 30 wards ofthe city with the highest density of about 26 sq. kms. in ward number 46.(Fig 2.2).

Fig. 2.2 : The natural drainage density in different wards of Guwahati city

Moreover, it is evident from figure 2.3 that atleast 8 wards of the city viz, 1,2, 13, 37, 46, 47, 51 and 52 have more than 5 sq. kms. of its area under wetlands andthese wetlands facilitate in maintaining the moisture content of soil in its vicinity and


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Fig. 2.3 : Total area under wetland in different wards of Guwahati city

2.2 Drainage Channel

Bharalu is the master drainage channel of the GMC area which is highlycommercialized and industrialized and drains into the Brahmaputra at Bharalumukh(Figure 2-2). From Basistha Chariali, the Bharalu flows up to Bharalumukh forabout 16 km with an average width of 5 to 9 m. The water depth varies with flowand due to other reasons, but is on average 3 m. The peak discharge of the Bharalu

is about 35 m3/s.Bharalu is the primary drainage course for most of the eastern and southern

part of Guwahati. Bharalu has several storm water drain outfall. The Bharalucatchment area is covered by the G.N. Bordoloi Road in the North from Chandmarito Bharalu, R.G. Baruah Road in the East including the Chandmari flyover, G.S.Road in the South & South West from Dispur to Ulubari and L.P.B. Road up toSabipool and the road along the Bharalu River, reaching Kumarpara Pachali.

Municipal wards covered by this area are mainly Wards 18, 19, 20, 27 to 36and 38 to 44. The topography is fairly flat with very little natural slope. The remainingparts are covered with some hillocks and pockets of low lands. The basin coversvery densely populated areas of Guwahati. To regulate the flow of the river, asluice gate has been constructed by the State Water Resources Department atBharalumukh to prevent reverse flows from the Brahmaputra during high floods.

However, during the dry season, the flow is very low, the primary source beingurban drainage (sewage).

Several obstacles have been identified in the Bharalu between R.G. BaruahRoad Bridge Crossing to outlet. For example, at R.G. Baruah Road crossing,projection of the lower slab of the road bridge together with crossings of servicepipelines have obstructed the flow through the drainage course and reduced itscarrying capacity. Moreover, a large number of temporary wooden foot bridgesalong with a number of old existing bridges (both made of wood/timber andconcrete) at various locations along the Bharalu have obstructed normal flow ofwater during peak hours due to lower deck level and thereby have reduced thetravel time of storm water through the drain considerably. At various locations,

these obstructions have led to water overflowing into the adjoining areas. A numberof shops and commercial establishments made inroad into the waterway of the drainat Fatasil area. The width of the Bharalu ranges from approximately 10 to 18 m

Totalareaunderwetland

sq.

kms.)


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In high stages the Brahmaputra backflows into the Bharalu when exceed thefull supply level (FSL) of the Bharalu. As a precaution a sluice gate was erected atShantipur, backing up with drainage pumps.

There are several prominent secondary drains which serve the Bharalu

catchment area: Pub-Sarania Rajgarh Area Secondary Drain: This is major

secondary covered drain carrying storm water from parts of Chandmari, carryingstorm water from Krishna Nagar and from the foothill of Sarania Hill on the easternside. The drain is divided into two parts; one towards Nabin Nagar-Anil Nagarunderground drain and the other reaching Lachit Nagar underground drain. The totallength of this drain is 3700 m.

Lachit Nagar Area Storm Drain (Lachit Nagar Road to BharaluDrainage Channel via B.T. College Road): It is a combination of a pipe conduit(N.P.-3 Hume Pipe) and a concrete box drain. This underground drain carries stormwater from all of Lachit Nagar and the southern part of the Sarania Hill catchment

area through drains meeting it at different locations. This drain starts at the LachitNagar G.S. Road junction and terminates at the Bharalu River through B.T. CollegeRoad. The approximate length of the drain is 1 km.

Railway Open Drain (from Voltas Point near Sadin Office to B.Baruahover bridge): This is an open concrete drain that was constructed in 2004. It carriesstorm water from parts of Nabagraha Hill, Chandmari, Krishna Nagar and Silpukhuriarea. It flows through the railway culvert below the B. Baruah over-bridge andpasses through Hedayatpur and ultimately outfalls at Borosila Beel throughSolapara. The total length of the drain is about 1.3 km.

Underground drain from Ambari via parts of G.N.B. Road to Railwayopen drain at Ambari: This drain carries storm runoff from Lamb Road area,Ambari and parts of Uzan Bazar Area. This drain originates at the Lamb Road area,then meets the railway culvert below B. Baruah over-bridge, and finally outfalls atBorosila Beel.

R.G. Baruah Road Drain (From Zoo Narengi Tiniali to Bharalu Drain):This is an open concrete drain. The origin point of this drain is at Zoo Narengi Tiniali;the outfall is at the Bharalu. This is one of the major open secondary drainscollecting storm/ waste water from the Guwahati Refinery, Noonmati andBamunimaidan area through drains running along the railway line at Bamunimaidan,the Bhaskar Nagar area and ultimately meeting it at Zoo Narengi Tiniali. Water fromNarikal Basti and Ambikagiri Nagar also contributes to this drain. Some of the runofffrom the Rajgarh and Chandmari areas is also contributing to this drain. This drainmeets the Bharalu at Jonali, the confluence between the Bharalu and the Bahini

Rivers. The total length of the drain is about 1 km. Chandmari - Bharalu Secondary Drain (through Bhaskar Nagar,

Rajgarh, Nabin Nagar, Anil Nagar): This drain was constructed by the T&CPDepartment and carries water from parts of the Chandmari area, Bhaskar Nagar,Rajgarh, Nabin Nagar, part from Pub- Sarania and Anil Nagar. The total length ofthis drain is almost 5 km.

Underground drain along the boundary of Nabin Nagar and Anil Nagarto Bharalu (through Anil Nagar): This drain carries storm runoff from the Anil Nagararea. Part of drain flows towards the Chandmari - Bharalu Secondary drain; theremaining part of the drain flows towards the Bharalu primary drain. The total lengthof the drain is 1.4 km.

Extended stretches of several drains are clogged with silt and garbage. Stormrunoff from adjoining hills and the runoff carries huge loads of silt and vegetation,


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and garbage dumping, reducing the storage capacity of the lake.Several of the manholes have been paved over by a layer of bitumen during

road construction. Some of the existing manholes were found to be damaged orbroken. Sometimes, manhole openings are inadequate for manual cleaning.

The major reasons of ineffectiveness of drains are therefore as follows: Deposition of garbage and solid waste that reduce the carrying

capacity of the drain HFL of the drain is higher than the surrounding area causing backflow. Obstruction of flow at the outfall point due to silt deposition. Obstruction in flow due to construction of low level cross structures on

the drain. The outfall of Bharalu is severely clogged owing to silt deposit as well

as the outlet is discharging into the Brahmaputra orthogonally.

Photo 1Outlet of BharaluStagnant Bharalubut Brahmaputra is flowinga point to ponderBharalu is stagnant, but Brahmaputra is flowing. Velocity is a vector, therefore, Bharalu should meet theBrahmaputra as tangentially as possible.

3.0 Solution :Since waterlogging in Guwahati is a problem, and not a disaster, there is

solution to address the problem, if one approach scientifically.Going by the conservation of mass , Inflowoutflow = +/- storageHere inflow is runoff (hills+plains ) + sewage + infiltrated waterOutflow is the outflows of Bharalu, Khanajan and Bondajan.These outlet

needs development with priority. Bharalu outlet should meet the Brahmaputra at anacute angle for augmenting the outflow.


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The chronically inundated zones are as fillows

The major roads and areas severely affected from flood inundation problem were

identified based on field observation and can be listed as follows:

1) Geetanagar / Hatigaon Charialiupto Narengi

2) G.N.B Road from Guwahati Club

to Noonmati ( Except New Guwahati

Area )

3) R.G Baruah Road

4) Maligaon / Durgasarobar

5) Guwahati College approach road

6) Nabagraha Road and its nearby

areas

7) Along the Kanwachal road ,

particularly the southern part

8) Nabin Nagar / Anil Nagar

/Ambikagiri Nagar / Tarun Nagar

/Lachit Nagar upto Bhangagarh

9) Srimantapur10) Christianbasti area of G.S Road

11) Rukminigaon , Mathura Nagar

and some low-lying area in

Beltola

12) Some areas on the A.T Road

13) SantipurBharalumukh area

14) Fatasil Ambari

15) B.Baruah Road

16) Hedayatpur

17) Lamb Road , Ambari

18) Gandhibasti area

19) B.K Kakoti Road

20) Kachari Garigaon


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Adhering to the principle of catchment planning, by developing the drainage systemcatchment wise this vexed problem can be solved mostly by gravity. Severely waterlogged

Anil Nagar and Nabin nagar might be needing pumping because of its inherent limitation of

relief which can determined with the help of a contour map.Bondajan outlet, which is now totally clogged should be activated throughrejuvenation and as and where necessary internal drainage should be developedconforming to the drainage load for a projected population as stated elsewhere on the basisof a contour survey map. Similarly, there are still possibilities of rectifying the layout of the

Khanajan towards downstream taking advantage of the culvert near Girijananda Chaudhury

Institute of Management and Technology.


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Fig 2.4 Bondajan Development

Fig 2.5 Proposed Khanajan Diversion through Kalmani stream

Present Khanajan outlet


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There are tremendous potential for watershed management in the hill portion of thecatchment where soil and water conservation will play a significant role. With standardpractice of contour bund, afforestation sediment yield can be arrested, through rainwaterharvesting water bodies can be created for multipurpose use of aquaculture, tourism etcand can be commercially exploited from touristic angle. There are tremendous scope formass participation in these efforts.

PicProposed Rainwater Harvesting in situ in Hilly Catchment.


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18

Pospect of Rainwater Harvesting in situ in the hilly cathcment

Proposed Soil conservation measures on the hilly catchment.


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19

4.0 Conclusion : With the application modern technology for surveying a bas map beprepared on priority basis which shall form the basis for drainage planning andinplementation rather than the present practice of improving the drainage in a piecemealway. It should be a holistic approach of catchment planning in the principle of whole tothe parts, in other words starting with outlet development then watershde wise internal

drainage development. Watershed management in the hill cathcment will renderaesthatic beauty to this heavenly city we make dirtier. Bharalu river can be managedwith the sluice gate at Shantipara, as it snaking through the city centre, and can beutilised for developing at floating market round the year, which will add a silver line tothe city of Ancient LorePragjyotishpur.

5.0 References

1 Bapalu, G.Venkata and Rajiv Sinha, 2005, GIS in Flood Hazard Mapping: A Case Study

of Kosi River Basin, India, GIS Development: The Geospatial Resource Portal, pp.1,

2 Correia et al., 1998, Floodplain Management in Urban Developing Areas. Part 2. GIS

Based Flood Analysis and Urban Growth Modelling, pp.27

3 City Development Plan (CDP), Guwahati, Govt. of Assam, July,2006, pp-70

4 Department of Soil Conservation, South Bank Division, Govt. of Assam, 2003, Concept

Paper on Soil Erosion Control for Managing Flash Floods in Guwahati City, Unpublished Report,pp. 4-5.

5 Thakur, A and Goswami, D.C, 1993, Urban Sprawl and Land Suitability Analysis: A Case

Study of Guwahati City and its Environs, Proceedings of National Symposium on RemoteSensing Applications for Resource Management with special emphasis on N.E Region,Guwahati, pp.194-201

6 PCBA report by Louis Berger

waterlogging in guwahaty city- disaster or problem

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