Cs Ken Betwa

Geological Survey of India

Contributed by R. L. Sahu, Central Region

KEN-BETWA LINK PROJECT – A CASE STUDY

INTRODUCTION

The fast growing population has put tremendous pressure on earth’s natural resources

including water. Water is an important input for survival and sustenance of life. The demand of

this natural gift has been increasing exponentially. Major source of water in any region is a

network of rivers fed either my monsoon rain or snow melt during summer. Based on various

geo-environmental factors, monsoon rain does not seem to be uniformly distributed in space

and time. This results in regional imbalance and maldistribution of water severely affecting the

socio-economic and political scenario of the area. For optimum utilization of available water

resources, the concept of interlinking of rivers was put forth from time to time for rational

distribution and transfer of surplus water available in some regions to water deficit areas. But

due credence was not given by the Government on techno-economic reasons. However, the

same idea again gained momentum in recent years leading to adoption of National Water Policy

(NWP) by the Union Government emphasizing the need for inter-basin transfer of water in view

of the presence of several water surplus and deficit areas with in the country.

Thirty (30) interlinking river schemes have been identified in the Indian territory (Fig.1).

On completion of all these, additional irrigation potential of about 35 million hectare would be

added over the existing 140 million hectare part from the benefits of additional hydropower,

flood control, water supply, fisheries, navigation, salinity and pollution control etc. Of these, Ken-

Betwa link and Parbati-Kalisindh-Chambal link schemes fall in M.P. and the adjoining areas of

U.P. and Rajsthan respectively

The Ken river, which originates at an elevation of 550 m from the Kaimur Range near

Ahirgawan village in Jabalpur district (M.P.) flows northwards for a total length of 427 km and

joins the Yamuna river near Chilla village in U.P. at an elevation of 95 m with a number of sub-

tributaries on both the flanks. The total length of the river is 427 km, of which 292 km lies in

M.P., 84 km in U.P. and 51 km forms the common boundary between the two states. Out of the

total catchment area of 28058 sq km, 24472 sq km lies in M.P. and the remaining 3586 sq km in

U.P. The river valley has many favourable sites for construction of dams / barrages and power

houses. The Betwa river is one of the major rivers of the State, originating from Barkheda village

in Raisen district, M.P. Rising at an elevation of about 576 m, it flows in a north easterly



direction and joins the Yamuna river near Hamirpur in U.P. at an elevation of 106 m. The total

length of the river is 590 km of which 232 km lies in M.P. and the balance 358 km in U.P. The

river drains a total catchment area of 43895 sq km of which 30217 sq km falls in M.P. and the

remaining 13678 sq km lies in U.P. For harnessing the vast potential, several multipurpose

projects have been commissioned in its middle reaches both in M.P. and U.P. (Fig. 2).

LAYOUT AND SALIENT FEATURES

On the instance of the nodal agency – National Water Development Agency (NWDA),

under the Ministry of Water Resources, Geological Survey of India, Bhopal was associated with

geological investigations of KB Link Scheme for the preparation of DPR. Proposed in the

Bundelkhand region of M.P. & U.P. (Fig.2), the scheme envisages trans-valley diversion of a

surplus yield of 1020 M cu m of the Ken river to the Betwa river for the development of the

command area (about 3.70 lac ha) enroute of the main canal and also proposed under the Ken

multipurpose project (KMPP) on the left flank of the Ken river in Chhatarpur district of M.P. and

Banda district of U.P. besides domestic and industrial water supply and also to enrich the

capacity of the Parichha weir across the Betwa river at the fag end of the main canal.

The project broadly comprises (i) a 73.80 m high and 2040 m long composite dam

across the Ken river near Daudhan village (TS No. 54 P/14) in Chhatarpur district to hold

storage of about 2775 M cu m of water at FRL (287 m), (ii) a toe power house of 60 MW

installed capacity, (iii) a 2 km long upper level diversion tunnel to transmit the designed head

discharge of 72 cumecs of water for irrigation, (iv) a 1.2 km long lower level tunnel with a power

house of 12 MW installed capacity at the exit end and (v) 231.45 km long left bank main canal

with a total of 59 cross drainage structures to facilitate enroute irrigation of about 47000 ha area

in Chhatarpur and Tikamgarh districts of M.P. and Banda, Hamirpur and Jhansi districts of U.P.

This main canal would release its unused discharge (659 M cu m) into the Barua Sagar at its tail

end which, in turn, would be diverted into the Betwa river through a natural stream leading to

Parichha weir (Fig.2). This 659 M cu m of supplemented water will be utilized for irrigation in

about 1.27 lac ha area in the upper reaches of the Betwa river falling under the command of 4

proposed barrage projects, namely Makoriya, Richhan, Barari and Kesari by way of substitution

(Fig.2).



GEOLOGICAL SETTING

Regional Geology : The KB link project is located in the Bundelkhand region of M.P. and U.P.

which is characterized by highly rugged and undulatory topography comprising extensive plains,

linear long ridges and clusters of isolated hills ranging in height from 400 m to 600 m and

dissected bad land along the river course. The general gradient of slope is towards north.

The region is flanked by the great Indo-Gangetic alluvial plains in the north and the

Sone-Narmada-Tapti Lineament zone (SONATA) in the south and south east (Fig.1&2). It is

occupied by litho-assemblages of various geological formations ranging in age from the

Archaean to Quaternary period. The major part of the area is composed essentially of

variegated granite and granite gneisses with enclaves of metasediments and metabasics

belonging to the Bundelkhand Granitoid Complex. These are intruded by NNE-SSW to N-S

trending huge quartz reefs and dolerite dyke swarms. The gneissic-granitic suite of rocks are

overlain by ENE-WSW trending volcano-sedimentary sequence of the Bijawar Group and

intracratonic, platformal, orthoquartzite-carbonate sequence of the Vindhyan Supergroup in the

southern and western parts. The lacustrine Lameta Group of rocks and the overlying flood

basalt of the Deccan Trap Province cover the Bijawar-Vindhyan rocks at various levels. Soil and

alluvium of the Quaternary-Recent period is mostly confined along the banks of the major rivers.

The stratigraphic succession in the project area is given in Table-1.

Table-1 Stratigraphic succession in Ken-Betwa link project

Stratigraphic status Major lithology Age Project / Components

Unclassified Alluvium / Laterite Quaternary –

Recent

Entire Project

Deccan Trap Complex Basaltic flows, intrusives

and intertrappean beds

Upper Cretaceous Barari and Kesari

barrages

Lameta Group Sandstone, shale,

limestone, claystone and

marl

Upper Cretaceous -

Vindhyan

-Bhander

Group

-Rewa

Group

Sandstone, shale and

limestone

Sandstone and Shale

Neoproterozoic

Daudhan and Makoriya

dam site and the entire

submergence area,

Power House No.1 and



Supergroup -Kaimur

Group

-Semri

Group

Conglomerate, sandstone

and shale

Conglomerate, quartzite,

sandstone, limestone,

porcellanite and shale

Mesoprotelrozoic tunnels

Bijawar Group

Phosphorite.

Chert breccia, shale and

dolomite.

Basal volcanics,

conglomerate, quartzite

and slaty shale.

Palaeo – Meso

Proterozoic

Power House No.2 and

main link canals, Tunnels.

Bundelkhand Granitoid

Complex (BGC)

Basic dykes

Quartz reef, pegmatite

veins

Granites in multiple

phases

Gneissic complexes with

enclaves of

metasediments and

metabasics.

Archaean to

Palaeoproterozoic

Entire LBC link canal and

the command area.

Structure and tectonics: The Bundelkhand Granitoid Complex (BGC) in the project area is

characterized by the presence of two distinct structural trends, namely NE-SW and NW-SE

(Fig.4). Several faults, lineaments and ductile shear zones traverse along these structural

grains. Surface trace of these elements is manifested in the form of linear granite plutons,

quartz reefs and basic dykes forming high relief in the area. Major rivers / nallas follow the

above tectonic trends. The overlying Bijawar and Vindhyan basins display a dominant ENE-

WSW to E-W trend. The litho-assemblages in these basins are largely un-deformed except

along the basin margins where syn-sedimentational and post depositional folding, faulting and

steep dips with local inversions due to vertical movements have been noticed. Away from the

basin margins, the dips are very shallow and sub-horizontal. Basal sequences are known to

contain significant proportion of mafic magmatism (dyke swarms in Bijawar basin) and acid

volcanics (porcellanite formation in the Vindhyan basin). The contact between the basement

complex and the cover rocks is unconformable which is marked by polymictic conglomerate /

chert breccia or basic volcanics.



Seismicity and Neotectonism : Seismotectonically, the Bundelkhand area is a stable land

mass with a history of least tectonic disturbance. This is evidenced by the absence of mega

lineaments, regional faults or folds in the project area. The fabrics of intermediate and micro

lineaments present in the area do not have any definite pattern signifying their non-alignment

with the known major tectonic elements of the Peninsular India. None of the lineaments present

in the region is considered to be seismogenic. The Precambrian seismicity (c. 3.6 – 1.6 Ga) is

charcterised by ductile mobility with the initiation of shear zones, mylonitic foliation,

emplacement of granite plutons, quartz reefs and basic dykes and several fabrics of faults /

fractures in the basement rocks while the later reactivations during Bijawar, Vindhyan,

Gondwana and Deccan Volcanism have been in the brittle regime as indicated by initiation of

fault-bound Bijawar, Vindhyan and Gondwana basins and associated clastic sedimentation of

the Lametas.

In regional scale, the proposed lay-out of the KB link project is surrounded by the

SONATA Lineament zone in the south, Aravalli-Delhi mobile belt in the west, Himalayan

orogenic belt in the north and north east and the Indo-Burmese arc in the east. Hence, the

project area has continuously been experiencing the fringe effect of seismic activity taking place

in above areas and seismo-tectonic damage / hazards in accordance with the range of

isoseismals. The isoseismals of the recent Jabalpur Earthquake of 22nd May, 1997 (M6) is

drawn in Fig.4. As per the seismic zoning map of India (1990), the KB link scheme falls under

seismic zone II which signifies low seismic event not exceeding M3 and hence the

seismotectonic hazards would be correspondingly minimum. Site specific studies, carried out by

the earthquake engineering department of the Roorkee University have recommended a

seismic coefficient of 0.11 g in the designs of the structures.

GEOTECHNICAL EXPLORATIONS AND ASSESSMENT

Main dam site : In feasibility stage investigations, number of alternative alignments were

explored for deciding the suitable location of the main dam upstream and down stream of the

existing Gangau weir across the Ken river. On geotechnical considerations, the location of the

main dam was finalized near the Daudhan village 2.5 km upstream of the Gangau weir with

spillway section on the left flank due to availability of foundation grade rock at the surface (Fig.

2&3). In this proposal, the provision of approach and spill channels involving deep cutting of

rocks was not made. In DPR stage investigation, it was therefore considered necessary to

explore the possibility of providing spillway at the centre of the river where maximum depth of



river is available. The central spillway will not need any approach channel. It would also facilitate

in construction of surface power house at the toe of the dam. Finally, it was decided to work out

the techno-economic viability of both the alternatives and choose the best of the two for DPR.

Subsequent exploration by large scale mapping and drilling revealed that the side

spillway proposed on the left flank is preferable to central spillway due to presence of competent

foundation grade strata at much higher elevation with sufficient spread to house the structure

(Fig.5&6). In river bed, by virtue of the dip slope, the same competent rock strata is interpreted

at much deeper depth of 18-28 m. The overlying bed rocks available at shallow depth in the Ken

river section is not sufficiently competent due to frequent shaly intercalations.

Dam site geology : At the dam site the Ken river flows in a broad open valley with rising gentle

slope on its flanks displaying elevation between 216 m (lowerst river bed level) and 450 m (right

abutment hill). Large scale geological mapping and results of 26 exploratory drill holes along the

axis of the Daudhan dam have revealed that the dam alignment is occupied by an inter-bedded

sequence of sub-horizontally disposed hard, massive sandstone, siltstone / flagstone and shale

intercalations mapped as litho units 1,2,3 and 4 in stratigraphic succession (Fig. 5&6). A

considerable part of the dam alignment is covered with flood plain deposits forming terraces on

either side of the river (lithounit No.5). These rocks belong to the lower sequence of the Semri

Group of the Vindhayn Supergroup. They exhibit a general ENE-WSW trend with shallow (5-

10°) dips in SSE direction. The above lithounits are traversed by 3 prominent mutually

perpendicular joints trending (i) ENE-WSW, (ii) NW-SE and (iii) NE-SW rendering them blocky /

platy in nature. The beds gradually flatten towards the right flank. The joints which are generally

open and clay filled on surface gradually tend to tighten with depth. They have considerable

influence on the structure of the project.

Reservoir area: Systematic geological / geotechnical studies of about 90 sq km reservoir area

under submergence of the Daudhan dam have suggested congenial condition from reservoir

tightness point of view. Occupied by the Vindhyan sequence, the slopes and escarpments in the

reservoir area are by and large stable due to gentle gradient and favourable disposition of joints.

No landslide, fossil slides, rock falls or debrio slides have been reported in the area. There are

no saddles in the topography for escaping water to the adjoining basin needing auxillary

structure. Similarly, no significant inter-fluve pervious horzon of water divide is present in the

submergence area. Lithocontracts, plane of stratification and frequent joints in the bed rocks are

some of the geological weaknesses which may account for some loss of water but appears to



be within the permissible limit due to above favourable topography. As a result, no significant

leakage / seepage is anticipated through the reservoir rim. No major mineral deposits of

economic value occur in the area. No any archeological site of historical importance has been

reported in the submergence area. The reservoir area falls under seismic zone II which signifies

low seismic shocks not exceeding M3 and hence the seismic hazards would be corresponding

to intensity V and IV. Possibility of occurrence of earthquake of higher magnitude in the life span

of the project can not be ruled out.

Foundation assessment

Daudhan dam : Prevailing geomorphic / geological set up at site strongly favoured the

location of the spillway on the left flank due to occurrence of foundation grade hard, massive

sandstone on the surface with very good geotechnical features (mapped as lithounit No.1). The

overlying lithounits (lithounit No. 2, 3 & 4) having gradational nature occur in the middle and

right side of the Daudhan dam (Fig.5&6) are geotechnically considered to be inferior on strength

characteristics and hence unsuitable for foundation of heavy structures. However, for earthen

embankments they form good foundation media. Permeability tests carried out in drill holes

indicated semi pervious to impervious nature of above lithounits.

The major foundation problems anticipated are presence of shale bands / partings in

massive sandstone unit (litho unit No.1), jointed nature of rock mass, pinching / swelling

character and selective deeper weathering in inter-bedded siltstone / flagstone – shale

sequence of lithounit No.2 occurring in the Ken river section and presence of open,

interconnected cavities in chert breccia with dolomitic intercalations in lithounit No.4 forming the

right abutment hill (Fig. 5&6). These features under impoundment of the reservoir are expected

to pose problems of differential settlement, sliding , leakage, and uplift and piping through the

foundation. To avert these problems, the structure will require provisions of clay blanket,

consolidation and curtain grouting, dental treatment of clay filled joints and shear zones and

suitable drainage arrangements etc. For earthen embankments design of proper slopes and

berms will also be needed.

Power house No. 1: Proposed between RD 700 m and 800 m at the toe of the dam, the

open pit power house and allied structures (HRC, TRC and retaining walls etc.) will be located

in lithounit No.1 (Fig. 3,5&6) by virtue of their position on the left flank. The beds of the lithounit

strike at acute angles with the longer axis of the proposed power house. About 15-50 m thick



explored stratigraphic column of this lithounit comprises hard, well jointed, massive sandstone

with shaly partings. It is geotechnically considered to be competent for the proposed power

house and other structures due to favourable engineering attributes. RMR quality assessment

(RMR 47 – 71) suggests Fair to Very Good category of rock mass.

Major foundation problems apprehended are presence of frequent shaly partings, open,

clay filled joints in mutually perpendicular orientation and selective deeper weathering in the

rock mass. These adverse features are expected to cause three-fold problems of leakage and

piping, settlement and sliding along potential planes filled with clayey-gougy material

necessitating site specific remedial measures for improvement in the bearing capacity and

modulus of elasticity. Deep rock cutting for power house pit, HRC and TRC would generate a

number of slope faces requiring their stability by adopting suitable slope angles and berms at

regular heights supported by strengthening measures of rock bolting and shotcreting etc.

Power House No. 2 : The power house No. 2 is located at the exit end of lower level

tunnel which happens to fall at the foot of the east-west trending ridge. The proposed area is

mostly covered by scree and slope wash materials with elevations varying between 240 m and

260 m. Scanning of data gathered through geological mapping and exploratory drilling has

revealed that the proposed site is occupied by an inter-bedded sequence of slaty shale and

quartzitic sandstone belonging to the Bijawar Group of rocks. They exhibit a general east-west

trend with moderate (15-30°) dips towards south. These rocks are traversed by 5 – 8 sets of

subvertical to vertical joints giving rise to blocky / platy nature to the bed rocks.

Major foundation problems anticipated are on account of (i) presence of inter-bedded

sequence of contrasting bearing strengths with mutually intersecting vertical joints prone to

creep / minor rock slides and gravity falls, (ii) number of shear zones / fracture zones with

selective deeper weathering along them likely to pose problems of seepage and settlement and

(iii) suspected sliding (instability) along the contacts of soft, fissile shale, siltstone and quartzitic

sandstone etc during construction. In view of the above, suitable site specific, preventive

measures may be adopted in the designs against shear failure of the structure.

Upper level tunnel : About 2300 m long and 5 m dia horse shoe upper level tunnel

(elevation between 261 m and 256 m) has been envisaged in the initial reach of the left bank

main link canal to transmit the designed discharge from the Ken river to the Betwa river. The

tunnel has the rock cover varying between 10 m and 120 m. Geological section (Fig.7) revealed



that the tunnel passes through a variety of rocks belonging to the Bijawar Group and the Semi

Group of the Vindhyan Supergroup. The contact between them is unconformable which is

marked by a thick (100 m) conglomerate horizon. From inlet to exit portal, the tunneling media

constitutes hard, thickly bedded quartzitic sandstone followed by the above conglomeratic

horizon covering about half (1170 m) of the length of the tunnel. In downstream direction, it

constitutes hard, foliated quartzite in 80 m tunnel length followed by sheared rock mass with a

very poor geotechnical parameters in a 275 m length of the tunnel, inter-bedded sequence of

red, slaty shale and sandstone covering about 325 m length and hard, foliated quartzite in the

rest of the 450 m length of the tunnel in the exit portal end. The above tunneling grades have

also been assessed on RMR classification for prognosticating excavation methodology and

support requirements.

The Bijawar sequence in view of their foliated to thinly bedded nature, frequent presence

of shear zone / fracture zone with enclosure of clayey / gougy / sheared products and selective

deeper weathering may pose serious problems of leakage, excessive over breaks, and gravity

fall leading to formation of deep cavities /chimneys in the tunnel roof necessitating adequate,

site specific support measures during tunneling.

Lower level tunnel : About 1400 m long and 5 m dia horse shoe lower level tunnel

(elevation between 249 m and 244 m) has been envisaged in the initial reach to transmit the

designed discharge from the Ken reservoir to command area (Fig.2). The rock cover above the

tunnel varied from 20 – 100 m. Geological section revealed that the tunnel passes through the

same formations of the Bijawar Group and Semri Group as interpreted in upper level tunnel.

From inlet to exit portal, the tunneling media includes hard, massive sandstone followed by thick

pebbly conglomeratic horizon both covering about 57% (800 m) length of the tunnel. Further

downstream, it constitutes slaty shale with inter-bands of sandstone and quartzite in the rest of

the 600 m tunnel length in the exit portal end (Fig.8). The above tunneling grades have also

been assessed on RMR classification for prognosticating excavation methodology and support

system. As anticipated, the Bijawars may pose the same tunneling problems requiring suitable,

site specific support measures.

Makoriya dam : The proposed Makoriya dam site is an alternative upstream option of

the discarded Neemkhera dam site across the Betwa river. Located 7 km up-stream, the Betwa

river at dam site flows in a shallow, open valley displaying elevation between 416 m and 445 m

respectively. Geological mapping and results of 7 drill holes have revealed that the bed rocks of



hard, massive sandstone exposed at abutment hills above RL 430 m is covered up to 22 m thick

overburden along the dam axis (Fig. 9). Belonging to the Vindhyan Supergroup, the beds of the

sandstone exhibit sub-horizontal, rolling dips. Besides widely spaced bedding joints, 2 mutually

perpendicular joints trending NW-SE and NE-SW are frequently present rendering blocky nature

to the bedrocks. These joints play significant role in deciding the stability and tightness of the

reservoir.

The 15-21 m explored depth of bed rock below the overburden exhibits continuity of

sandstone with occasional shaly partings. Geotechnically it is considered to be very competent

rock mass for founding major structures. Foundation /cut off grade has been interpreted

between 4 m and 23 m (RL 430.39 – 398.49 m) from the ground surface. Foundation problems

anticipated are presence of shaly partings, jointed nature of rock mass with clayey fillings and

selective deeper weathering in bed rocks. These features are likely to pose problems of

seepage, settlement and sliding of the structure requiring adequate measures in design to

improve rock mass quality as well as drainage arrangements etc.

Other structures : A large number of structures such as Barari and Kesari barrages

downstream of Makoriya dam (Fig.2) and important cross drainage structures like aqueducts,

drainage syphons, railway and road crossings and deep canal sections along the main link

canal and LBC and RBC of Mokariya, Barari and Kesari barrages were also explored by drilling.

Tentative foundation grade and other geotechnical inputs for each structures were deciphered

to cater the needs of the preparatory designs.

CONCLUSION AND RECOMMENDATIONS

The Ken-Betwa link project is one of the important 30 link schemes proposed in the

Indian territory. Located in a geologically stable province of the Bundelkhand Craton, the

scheme envisages construction of 4 storage dams across the Ken and Betwa rivers, 2 power

houses of 72 MW installed capacity and more than 200 km long inter-basin link canal including

more than 3 km of tunneling and a number of cross drainage structures.

Whereas the reconnaissance geological investigations helped to optimize the type and

quantum of explorations for a variety of structures wherever they were proposed, detailed

investigation by geological mapping and drilling proved the suitability of the side spillway of the

Daudhan main dam on the left bank of the ken river by evaluation of foundation media with the



slate of the art and existing practices in geotechniques. Similarly, the spillway of the Makoriya

dam on the right flank section of the structure would be preferable to central spillway on account

of availability of hard, massive sandstone at much higher elevation than the river section. Based

on studies of site specific surface and subsurface geological data of other major components

such as toe power house No.1 down stream of the Daudhan dam, upper level tunnel linking the

Ken lake with that of the inter-basin left bank main canal, lower level tunnel with power house

No. 2 at the exit end, Barari, and Kesari barrages and a large number of CD structures, it can be

concluded that the entire spread of the scheme is geotechnically feasible both on regional and

local geological considerations. However, presence of frequent shaly horizons, local influence of

density and orientation of joints, shear / fracture or fault zones, mechanical behaviour of various

litho units, effect of deeper and selective weathering and ground water condition are some of

the anticipated geotechnical features which govern the safety and stability of the structures

requiring adequate treatment measures in designs during construction.

The optimization in exploratory programme at a number of structures of the scheme and

modifications suggested by GSI in the lay out of the Daudhan and Makoriya dams have been

accepted by the project authorities where DPR stage investigations were continued and

assessment of foundation was made to cater the needs of the designers. This will result in

considerable savings in terms of time and cost involved in deep excavation and back filling both

in the spillway and earthen flank sections on either side

Cs Ken Betwa

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