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12. Saxena, V. K. and Ahmed, S., Dissolution of fluoride in groundwater: A water–rock interaction study. Environ. Geol., 2001, 40,
1084–1087.
13. Handa, B. K., Geochemistry and genesis of fluoride-containing
ground waters in India. Ground Water, 1975, 13, 275–281.
14. Jacks, G., Bhattacharya, P., Chaudhary, V. and Singh, K. P., Controls on the genesis of high-fluoride groundwaters in India. Appl.
Geochem., 2005, 20, 221–228.
15. Hem, J. D., Study and Interpretation of Chemical Characteristics
of Natural Waters, Scientific Publishers, Jodhpur, India, 1991, p.
339.
16. Karanth, K. R., Ground Water Assessment, Development and Management, Tata McGraw-Hill, New Delhi, 1997, p. 720.
17. Subba Rao, N., Krishna Rao, G. and John Devadas, D., Variation
of fluoride in groundwaters of crystalline terrain. J. Environ. Hydrol.,
1998, 6, 1–5.
18. Subba Rao, N. and Rao, A. T., Fluoride in groundwater in a developing area of Guntur district, Andhra Pradesh, India. J. Appl. Geochem., 2003, 5, 94–100.
19. Apambire, W. M., Boyle, D. R. and Michel, F. A., Geochemistry,
genesis, and health implications of fluoriferous groundwater in the
upper regions of Ghana. Environ. Geol., 1997, 33, 13–24.
20. Kruse, E. and Ainchil, J., Fluoride variations in groundwater of an
area in Buenos Aires Province, Argentina. Environ. Geol., 2003,
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21. Liu, Y. and Zhu, W. H., Environmental characteristics of regional
groundwater in relation to fluoride poisoning in North China.
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of high-F groundwaters, Southern India. Appl. Geochem. (Suppl.),
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23. Agrawal, V., Vaish, A. K. and Vaish, P., Groundwater quality: Focus on fluoride and fluorosis in Rajasthan. Curr. Sci., 1997, 73,
743–746.
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the dissolution of fluoride in groundwater. Environ. Geol., 2003,
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environment: A review. Gondwana Geol. Mag., 1995, 9, 1–20.
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ACKNOWLEDGEMENTS. We thank the Regional Director, CGWB,
Central Region, Nagpur for providing necessary facilities, encouragement and permission to publish this paper. Thanks are due to the anonymus reviewers for their critical and valuable suggestions to improve
the quality of the manuscript.
Temporal and spatial variations in
water flow and sediment load in the
Narmada river
Harish Gupta and G. J. Chakrapani*
Department of Earth Sciences, Indian Institute of Technology Roorkee,
Roorkee 247 667, India
Rivers are an integral part of the hydrologic cycle and are
the major geologic agents which erode the continents
and transport water and sediments to the oceans. Thus
rivers constitute an important link between continents
and oceans. A number of natural and anthropogenic
factors influence the water and suspended sediment
flux of a river basin along its pathway. Some important key factors are: area of drainage basin, relief, geology of basin, climate including rainfall and its intensity,
run-off, vegetation, tectonics, land-use patterns and
presence of reservoirs/dams. Any or all of these factors can be important in a particular river system. We
recognize three key factors that influence water and
suspended sediment load of the Narmada river, namely
basin geology, rainfall and presence of reservoirs/dams.
In the present study, water flow and suspended sediment load data in the Narmada river have been assessed
based on 20 years of monitoring at various gauging
stations. Most of the water flow in the river is during
the monsoon season, except in some tributaries, where
groundwater flow to the river during non-monsoon is
significant. The suspended sediment flux is significantly
lowered by the construction of dams and reservoirs
along the river course.
Keywords: Narmada river, reservoirs/dams, sediment
load, water flow.
T HE Narmada river basin, lies in the central part of India,
between 72°32′E–81°45′E long. and 21°20′N–23°45′N
lat., with a drainage area of 98796 sq. km and a mean
elevation of 760 m, higher than other peninsular rivers1 .
The total length of the river is 1312 km. The catchment area
of the river extends in the administrative States of Madhya
Pradesh (MP; 86.18%), Gujarat (11.6%), Maharashtra
(1.5%) and Chhattisgarh (0.72%) 1 . In contrast to the other
peninsular rivers in India, the Narmada along with the
Tapti, drains westward into the Arabian Sea. The Narmada
river has its origin at Amarkantak, on the eastern fringe of
the Maikala plateau, of Satpura range, Anuppur District,
MP and empties into the Arabian Sea near Bharuch (Figure 1). The basin is bounded in the north by the Vindhyans, in the east by the Maikala range, in the south by the
Satpuras and in the west by the Arabian Sea. The river
has 41 tributaries of which 22 are on the left bank (south)
and 19 on the right bank (north)1 , although only Burhner,
Received 20 February 2006; revised accepted 28 September 2006
*For correspondence. (e-mail: [email protected])
CURRENT SCIENCE, VOL. 92, NO. 5, 10 MARCH 2007
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Banjar, Hiran Tawa, Chota Tawa, Orsang and Kundi are the
major tributaries, with catchment area of more than
3500 sq. km. Approximately, 35% of the basin area is under
forest cover, 60% under arable land and 5% is grassland,
wasteland, etc1 . The Narmada river flows along the ENEWSW trending Narmada–Son Fault (NSF), a well-known
seismo-tectonic feature. The NSF is laterally traceable for
more than 1000 km and parallels the Satpura orogenic
belt 2 . It demarcates peninsular India into two geographically distinct provinces, the Vindhyan–Bundelkhand province
to the north and the Deccan province to the south. The
Narmada and the Tapti rivers follow these tectonic trends
throughout their course3. The climate of the basin is humid
tropical, although at places extremes of heat and cold are
often encountered. Average rainfall of the basin is 1178 mm,
Figure 1.
Location map showing various gauging stations and reservoirs in the Narmada basin.
Table 1.
Location
Dindori
Manot
Jamtara
Barmanghat
Sandia
Hoshangabad
Handia
Mandleshwar
Rajghat
Garudeshwar
whereas annual rainfall for the entire basin varies from
800 to 1600 mm. A major portion of the precipitation in the
basin takes place during the southwest monsoon (July–
September), which accounts for about 85 to 95% of the
total precipitation 4 . The hydrological parameters of the
Narmada river at different locations are presented in Table 1.
Throughout the Narmada basin, water discharge and
suspended sediment loads are measured at a number of
locations by State and Central Government agencies, such
as the Central Water Commission (CWC). In the present
study daily water discharge and suspended sediment load
data measured by CWC at two gauging stations (both from
the lower Narmada basin), one upstream of the Sardar Sarovar
dam (Rajghat), which is the largest man-made structure
on the river, and another downstream of the dam (Garudesh-
Hydrological characteristics of the Narmada river at various locations
Latitude
Longitude
Basin area
(sq. km)
22°57′
22°44′
23°05′
23°01′
22°50′
22°46′
27°29′
22°10′
22°04′
21°53′
81°05′
80°31′
79°57′
79°00′
78°21′
77°43′
77°00′
75°39′
74°51′
73°39′
2,292
4,467
17,157
26,453
33,954
44,548
54,027
72,809
77,674
87,892
Length of river
(km)
95
218
389
504
594
676
747
852
982
1169
Water discharge
(km3 yr–1)
Sediment load
(10 6 tons yr –1 )
1.24
3.31
9.27
12.56
15.22
22.25
26.16
33.21
34.87
35.44
N/A
5.82
3.32
11.94
11.66
23.36
31.09
36.32
41.54
28.93
N/A, Not available.
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RESEARCH COMMUNICATIONS
war) on the Narmada mainstream, are being used. The
downstream locations are chosen because these would reflect cumulative effects of all of the processes along the river
course. Suspended sediment observations are conducted
simultaneously once a day (irrespective of peak or low
discharge), starting at 0800 h (except Sunday and holidays),
from various vertical marks along the cross-section of the
river at the gauging stations using boats or specially designed instruments. The observations are conducted at
station gauge line under normal conditions. Suspended
sediment samples are collected at 0.6 m depth from each
vertical where velocity observation is made for computation
discharge, provided depth of flow is 0.3 m. Punjab bottletype sampler is commonly used for collection of suspended
sediment samples for analysis. The suspended sediment
concentrations are obtained by filtering known volumes
of water samples through 0.45 µm filter paper and weighing
the difference in dry filter paper before and after filtration.
The suspended sediments are separated into three size
grades, coarse (> 0.2 mm dia), medium (0.2–0.075 mm dia)
and fine (< 0.075 mm dia) by wet sieving. The daily suspended sediment observation is made during monsoon season,
whereas during non-monsoon ten daily observations are
made. Normally, the monsoon season is assumed to be
between June and November, and non-monsoon between
December and May. For determining suspended sediment
load (the amount of suspended sediment passing a given
cross-section of a river per unit time), all particle sizes
(sand + silt + clay) were considered. The discharge-weighted
suspended sediment load, in tons day–1 , for the river
cross-section is obtained by multiplying the concentration
(g l –1 ) by the discharge (m 3 s–1 ) on a particular day, and it
further used to estimate the annual load1,5. Extremely high
accuracy is maintained during all the procedures followed
for measurements pertaining to water discharge and suspended sediment concentration 1,5 .
The average annual water flow in the Narmada river
shows significant downstream increase and varies between
1.2 km3 yr–1 at Dindori (upstream) to 35.4 km3 yr–1 at Garudeshwar (downstream). The final flux (mean flux of 20 water
years; 1980–2000) of the Narmada river to the Arabian
Sea is approximately 37 km3 yr –1 . The annual suspended
sediment load of the Narmada river varies from 3.33 × 106
tons to 41.5 × 106 tons, at different locations in the basin.
The mean annual suspended sediment load at the upstream
location (Manot) is close to 5.83 × 106 tons, whereas it is
about 28.9 × 106 tons at Garudeshwar, located closest to the
Arabian Sea. The lowest and highest suspended sediment
loads are observed at Jamtara (3.33 × 106 tons) and Rajghat
(41.5 × 106 tons). Suspended sediment load in the Narmada
mainstream from upstream to downstream shows significant
increase, except at a few locations. Suspended sediment
load at Manot (upstream station) is 5.82 × 106 tons yr –1
higher than that at Jamtara. On the contrary Garudeshwar
(extreme downstream of the Narmada) shows low suspended
sediment load than upstream Rajghat. The water and susCURRENT SCIENCE, VOL. 92, NO. 5, 10 MARCH 2007
pended sediment flux at Rajghat are 34.87 km3 yr –1 and
41.5 × 106 tons yr –1 respectively. The Narmada river annually transports 37 cubic km of water and 30 × 106 tons
yr –1 tons of suspended sediment (mean of 20 water years;
1980–2000) to the Arabian Sea at Garudeshwar, the farthest gauging station on the Narmada river mouth. Based
on the annual water flow and suspended sediment concentration, the erosion rate at Rajghat and Garudeshwar is
calculated to be 533.9 and 329.2 tons km–2 yr –1 . Table 1
presents the average water discharge, suspended sediment
load and physical weathering rates at different stations on
the Narmada mainstream.
Precipitation has been widely understood to have a
predominant influence on river water flow and suspended
sediment discharge6–8 . A major portion of the precipitation in the Narmada river basin takes place during the
southwest monsoon. The date of onset of monsoon in the
basin is 15 June. Nearly 90% of rainfall is received during the five monsoon months from June to October, out
of which about 60% is received during July and August.
Rainfall distribution is not uniform throughout the basin.
While the upstream hill regions receive high rainfall, it
decreases in the mid-stream region. In the upper hilly regions, the annual rainfall is in general more than 1400–
1600 mm. In the upper plains from nearby areas of Jabalpur
to near Indra Sagar dam station, annual rainfall decreases
from 1400 mm to less than 1000 mm with a high rainfall zone
around Pachmarhi, where the annual rainfall exceeds
1800 mm. In the lower plains, the annual rainfall decreases rapidly from 1000 to less than 650 mm around
Barwani 4 . Figure 2 shows the average rainfall distribution
in the basin and annual rainfall for the year 1997–98. Water
flow in the basin varies at different locations and during
different time-span. Irrespective of location, water flow is
highest during July–September, which represents the monsoon season. As a consequence, the annual flow patterns
in the basin are intimately coupled to the monsoon season. Though the monsoon season lasts for five months, on
an average the basin gets rain only for 50–70 days and a
few days during the monsoon make up the bulk of the
Figure 2. Mean annual rainfall (1980–2000) and its spatial distribution during 1997–98 at different stations on the Narmada mainstream.
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Figure 3. Variation in daily flux of water and sediment at Rajghat
and Garudeshwar (monsoon period 1997–98).
Table 2. Average (10 years) water and suspended sediment discharge at
various stations on the Narmada river (per cent annual flow) during
monsoon season
Location
Manot
Jamtara
Barmanghat
Sandia
Hoshangabad
Handia
Mandleshwar
Rajghat
Garudeshwar
Water discharge
92
70
76
77
79
81
83
83
85
Sediment discharge
95
90
94
95
93
97
99
99
99
rainfall receiving more than 10 mm. For example, in the
year 1997–98, Rajghat received 618 mm (total annual
rainfall 644.6 mm) of rainfall in 45 days during the monsoon period (June–October); rainfall during 15 days makes
70% of the total monsoon rainfall. Although most of the
rainfall is confined to the monsoon season, appreciable
rainfall is observed during other times as well. Comparison
of rainfall with water flow in the Narmada basin shows
close correspondence; high rainfall induces high water
flow in the river. This uneven distribution of rain, its intensity and periodicity, cause irregular water discharge and
suspended sediment load patterns at various stations. This
is evident by the water discharge and suspended sediment
load patterns as shown in Figure 3.
Figure 4 shows the relation of rainfall with water flow
and suspended sediment load. This does not show a oneto-one correspondence, while there may be a time lag in
rainfall and river water flow. Peaks and dips in water dis682
charge show spatial variations among the different locations, depending upon rainfall distribution patterns and
other local catchment characteristics (catchment area, soil
properties, topography and vegetation cover). Immediately
after the rains, water flow does not increase, because the
rains initially recharge the groundwater and after it is
saturated, water flow in the river might show increased
values with subsequent rains. The rock types, mostly fractured basalt, act as good aquifers. Similarly, availability of
materials for transport does control the suspended sediment load, rather than just the rainfall intensity or water
flow in the river. This has been observed for many other
rivers of the world9,10, where a functional relationship between water discharge and suspended sediment load does
not exist, because the suspended sediment flux is affected
more by the supply of loose materials for transport than
by the capacity of flow to transport it. Our observation for
a long time period (1990–2000) also demonstrates that
approximately 70–90% of annual load in the Narmada
river is transported during 14–24 days. All of these days with
high suspended sediment load correspond to the monsoon
season and are characterized by high water discharge at
the same time. For example, the water and sediment discharge on 28 July 1996 at Rajghat was 11.7 and 47.4% of
the total annual discharge, whereas the water and sediment
discharge on 27 and 29 July 1996 was 3.2 and 4.8%, and
3.4 and 4.7% respectively. This shows that a threefold increase in water discharge results in tenfold increase in
sediment load. Heavy and excessive rainfall triggers high
water discharge and sediment load. This is also noticed in
the case of sediment discharge at Rajghat on 28 July 1996,
which was 47.4% of total annual load, with the highest
sediment concentration (2874 mg l–1). Total sediment load
during July, August and September in 1996 was about 58,
18 and 19% respectively, which adds up to 95% of the total
annual load. It is observed that a few days in the year
carry > 1% of the annual sediment load. The number of days
with sediment load 1–10% varies between 11 and 23, and
accounts for 34–65% of the annual sediment load. The
days with sediment load > 10% vary between 1 and 3, and
account for 13–15% of the annual load. Heavy and excessive rainfall triggers high water discharge and suspended
sediment load. This shows the effect of a few days in
suspended sediment transport, a trend similar to water
discharge in the basin. Meade and Parker 11 observed in
many rivers of the United States, that a large proportion
of the suspended sediment load is transported in only a
few days, and calculated that more than one half of the
annual suspended sediment load is transported in only 5
or 6 days. This observation is also true for some of the
Indian peninsular rivers such as Godavari12 and Mahanadi13.
The Narmada river allows 70–99% of water and 90–99%
of suspended sediment load to be transported during the
monsoon season, whereas the tributaries transport 85–
99% of water and 95–100% of suspended sediment load
during monsoon (Table 2). Figure 5 shows annual rainCURRENT SCIENCE, VOL. 92, NO. 5, 10 MARCH 2007
RESEARCH COMMUNICATIONS
Figure 4.
Relation of rainfall (mm) with water discharge (10 6 l day–1 ) and sediment load (10 –3 tons day–1 ).
Figure 5. Variation in annual water discharge (km3 yr –1 ), sediment
load (10 6 tons yr –1 ) and rainfall (cm yr–1 ) at Rajghat.
fall, water discharge and sediment load during of 20 years
(1980–81 to 1999–2000) at Rajghat. Though Figure 5 shows
large variations in rainfall, water discharge and associated
suspended sediments over the years, the interrelationship
between all of these elucidates good correspondence.
Another important factor which influences water discharge and suspended sediment load in the Narmada river
is the presence of a number of reservoirs/dams along the
river course, constructed for irrigation, hydroelectric or
flood control purposes. Among all the categories of human
influences on river basins, reservoirs exert the most influence
on altering water and suspended sediment flow patterns.
The natural sedimentary cycle gets enormously altered by
land-use changes, deforestation and soil-conservation
practices. Humans are perennial dam-builders with presentday estimations of more than 45,000 registered dams over
15 m high in operation today worldwide14, which represents
nearly an order of magnitude greater number than in 1950.
Between 1951 and 1982, large dams were being constructed
at a rate of 900 per year 15 . A decrease in suspended sediment load to the river through damming results in an increase in coastal erosion and deterioration of coastal marine
ecosystem. For example, the Aswan Dam was completed
in 1964, and since then the sardine fish catch reduced by
95% and the delta shrank rapidly16 . A number of dams
have been constructed on the Narmada river and its tribuCURRENT SCIENCE, VOL. 92, NO. 5, 10 MARCH 2007
taries. Over 4000 water-related projects of various scales and
purposes have been proposed for the basin. Bargi, Barna,
Indra Sagar, Kolar, Omakareshwar, Maheshwar, Bhagwant
Sagar, Tawa dam and Sardar Sarovar dam are some of the
major projects in the basin. At present three large dams are
in operation on the Narmada mainstream namely, Bargi
(upper), Indra Sagar (middle) and Sardar Sarovar dam
(lower). However, till the water year 1999–2002, only Bargi
and Sardar Sarovar were in operation. Operation of Indra
Sargar commenced only after 2002, and hence our discussion is restricted up to the year 2000. Among the 30 large
dams planned for the Narmada basin, the Sardar Sarovar
is the largest, with a proposed height of 110.64 m and
with a reservoir capacity of 3700 million cubic metres17 .
The Sardar Sarovar dam traps large proportions of suspended sediments being carried by the river. The dam is
located between Rajghat and Garudeshwar and is situated
8 km upstream of Garudeshwar. If we consider the last ten
years’ data (1990–2000), Bargi dam in the upper Narmada
basin shows entrapment of more than 40%, whereas Sardar
Sarovar shows approximately 30% trapping of annual
load carried by the river. Suspended sediment load estimation during the three years (1996–99) indicates large trapping of suspended sediment during the monsoon season, to
the extent of 60–80% of its upstream load, whereas in the
water year 1999–2000, it shows 76% trapping. The presence
of dam reduces 70–90% of coarse and approximately
50% of medium-sized particles on their way downstream,
allowing them to settle in the reservoir. From its source to
mouth, the Narmada river shows significant changes in water
and suspended sediment load, influenced by contributions
from tributaries and reduction in suspended sediments
due to trapping in the reservoirs by damming. Comparative
studies of average suspended sediment load at various locations on the Narmada river for more than two decades,
show overall reduction in suspended sediment load in the
river. Vorosmarty et al. 18 estimated that 30% of global
sediment flux is trapped behind large reservoirs. Several
large basins such as the Colorado and Nile, show nearcomplete trapping of suspended sediments due to large
reservoir construction and flow diversion. Our present estimation of suspended sediment flux by the Narmada river
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RESEARCH COMMUNICATIONS
Figure 6. Comparative study of long-term variability during the last two decades in water flux (km3 yr –1 ) and sediment load
(10 6 tons yr –1 ).
to the Arabian Sea is 30 × 106 t yr –1 , ranking the Narmada
river as the fifth largest after Brahmaputra, Ganga, Indus
and Godavari in India in terms of suspended sediment
transport.
Figure 6 presents the long-term variability during the
last two decades (average of 10 years) in water discharge
and suspended sediment load at different stations on the
Narmada river. It is clear from Figure 6 that water discharge and suspended sediment load patterns of the basin
have been greatly modified. Water discharge shows an
overall increase during 1990–2000, whereas suspended
sediment load at different stations shows different trends.
A few stations (Barmanghat, Sandia, Handia and Mandleshwar) have shown increase in sediment load during the
recent decade, while the rest of the stations recorded a
decrease in load. Increase in suspended sediment load
may be attributed to change in land-use patterns in the basin.
This trend should be followed alike in the basin, but the
large dams present in the basin trap a large proportion of
suspended sediment load and the stations located in the
reservoir catchment and immediate downstream show decrease.
It can be concluded that rainfall and presence of large
dams have significant control over the water flux and
suspended sediment load patterns in the Narmada river.
Rainfall, its intensity and periodicity control both water
flux and sediment load in the basin, whereas the reservoirs act as efficient systems for entrapment of suspended
sediment load.
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(CWC), Narmada Basin Organization Bhopal.
2. Biswas, S. K., Regional tectonic framework, structure and evolution of the western marginal basins of India. Tectonophysics,
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3. CRUMANSONATA, Geoscientific studies of the Son–Narmada–
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sediment to the oceans. J. Geol., 1983, 91, 1–21.
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ACKNOWLEDGEMENTS. We thank the personnel of Narmada
Basin Organization, Central Water Commission, Bhopal and Tapi River
Division, Central Water Commission, Surat for providing necessary
data. H.G. thanks CSIR, New Delhi for the award of a fellowship.
Received 24 May 2006; revised accepted 22 September 2006
CURRENT SCIENCE, VOL. 92, NO. 5, 10 MARCH 2007