Journal of Water Resource and Protection, 2012, 4, 1071-1078 Published Online December 2012 (
Studies on Twin Micro-Watersheds, Melekote and
Rajagatta Dodballapur Taluk, Bangalore Rural
District, Karnataka State through Morphometry,
Land Formation and Water Quality
S. G. Ramachandraiah1, M. Inayathulla2, P. S. Nagaraj2, G. Ranganna3, R. Druvashree4
1Faculty in Civil Engineering, Dr. Ambedkar Institute of Technology, Bangalore, India
2Faculty in Civil Engineering, University Visvesvaraya College of Engineering, Bangalore, India
3UGC-CAS in Fluid Mechanics, Bangalore University, Bangalore, India
4University of Agricultural Sciences, Bangalore, India
Received September 28, 2012; revised November 1, 2012; accepted November 10, 2012
The paper discusses assessment of various chemical cons tituents present in groundwater besides morphology, and land
form characteristics of twin micro-watersheds (viz., Melekote and Rajaghatta) Dodballapur Taluk, (Karnataka) coming
under semi-arid climatic zone. Farmers who are mainly depending on agricultural yields for their living are disap-
pointed due to vagaries of monsoons and undependable rainfall. This is particularly so in arid and semi-arid regions.
These regions suffer from water scarcity, soil degradation, low crop yield, high soil erosion and gradual depletion of
soil fertility. All these factors culminate in planning for conservation and sto r age of water in small watersheds fo r future
needs, i.e., during drought con ditions. In many areas, it is observed that the water table levels are declining resulting in
problems of increased concentration of solutes and deterioration of groundwater quality. All aspects of hydrological
studies are covered in relation to watershed management in order to formulate strategies for sustainable agricultural
development. Morphometry, landform and topography play an important role in understanding the hydrological re-
sponse of any watershed. Quantitative morphometric analysis has been carried out on the watershed along with land-
form and topographical study.
Keywords: Water Quality; Morphometry; Groundwater; Land Form
1. Introduction
The behavior of any watershed depends on interactions
between the flow of matter and energy moving within
limits and resistance to topographical surface [1]. There
is need to bring together science, engineering, social sci-
ences and humanities to achieve the goal of equitable
water management. Here, our work concentrates on
field-cum-office work concerning twin micro-watersheds
falling within Arkavati river basin which originates from
the foothills of Nandi hills. An attempt is also made to
suggest steps to carry out economic management of
available water, taking into consideration parameters of
hydrology, soils and water. The rapid growth in water
demand is due to the increasing reliance on irrigation to
offset food security and increasing use for domestic pur-
poses. Irrigated agriculture takes abou t 70 percent of wa-
ter withdrawals and the figure rises to 90 percent in the
dry tropics. This generally has low water use efficiency.
The interrelation between morphometric parameters,
landform and topography governs the existence and re-
sponse of watershed to the surface as well as ground wa-
ter movement [2]. Groundwater is an integral part of the
hydrologic cycle. Ground water often consists of seven
major chemical constituents namely: Ca2+, Mg2+, Cl,
, Na+, K+ and 4
. The chemical parameters of
groundwater play a significant role in classifying and
assessing the water quality. Considering the individual
and paired ionic concentration, certain indices are pro-
posed to determine the alkali hazards. Residual sodium
carbonate (RSC) can be used as a criterion for finding the
suitability of irrigation waters. Ten tiny dams with a
catchment of 1 ha each will collect much more water
than a larger dam with a catchment of 10 ha [3]. Several
studies conducted in India also show a clear relationship
between the size of catchment and amount of runoff that
can be captured [4]. The two watersheds fall within the
geographical bound ary of Dodballapur taluk (792 sq km),
opyright © 2012 SciRes. JWARP
one of the four taluks in Bangalore rural district.
2. General Features of the Study Area
Twin watersheds come under the confluence of Kumu-
davathy river catchment, a tributary to river Arkavati
joining Cauvery river (Sangama, Kanakapura taluk, Ra-
managaram District) downstream. Figure 1 shows Me-
lekote and Rajaghatta together cover an area of 98.5
km2. They fall between 13˚07'41'' and 13˚23'15'' north
latitude and 77˚34'24'' and 77˚40'20'' east longitude.
Dodballapur taluk lies in the semi-arid region, receiving
796 mm of rainfall annually in 58 rainy days. Both the
catchments receive rainfall from south-west monsoon
and the humidity will not exceed 50%. The entire taluk
suffers from scarcity of water, uncontrolled sand mining
and natural resource degradation .
Figure 1. Sub-water she ds.
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3. Methodology
Quantitative analysis of morphometric parameters of the
watershed enables 1) derivation of relationship between
drainage patterns of the same watershed; 2) comparative
studies of different watersheds developed in different
environs and 3) identification of certain useful parame-
ters of watersheds in numerical terms [5]. Within the
boundary of twin watersheds the following are details of
the field work carried out for water quality studies in
Melekote—8 wells. Besides in Rajaghatta another 8
wells are explored for water quality, during three succes-
sive seasons, viz., Pre-monsoon, monsoon and post mon-
soon periods. The collected water samples were trans-
ferred into precleaned polythene containers for analysis
of chemical characteristics. Chemical analyses were car-
ried out for the major ion concentrations of the water
samples collected from different locations using standard
procedures as recommended by APHA-1994. The data
can be used for classification of water for different utility
purposes and for ascertaining various factors on which
the chemical characteristics of water depend.
4. Hydrogeology
Occurrence, movement and storage of groundwater is
influenced by lithology, thickness and structure of rock
formations. Laterites overlying peninsular gneisses also
form good aquifers. Groundwater in the district occurs in
weathered crystalline rocks under unconfined conditions
and in fractured rocks under semiconfined conditions.
Large diameter shallow dug wells are the main ground-
water structures. Due to increased demand for water most
of the dug wells have dried up although some of them are
revitalized by drilling bores at the bottom of the dug
wells (Dug-cum-bore wells). General water table level
has also fallen. Static water levels are recorded in the
observation wells by the Dept. of Mines and Geology,
GoK. By utilizing the data on water levels in the obser-
vation wells, fluctuation of water table can be predicted,
i.e., fluctuation varied from 0 - 55 m to 11.83 m below
ground leve l.
5. Landform and Morphometric Analysis
Morphometric parameters of the study area have been
determined for the two twin watersheds in addition to
general characteristics of the watersheds. The catchment
area consists of dykes, lineaments and water bodies. The
watersheds, form a gently sloping rolling topography
with the slope from north to south amounting to 2.5%.
There are 52 villages inside the catchment boundary and
the population is 45,928 The entire population depends
upon groundwater for domestic needs. The area consists
of one of the oldest rock formations of Archaen age.
Peninsular gneisses cover a large portion of Bangalore
district. They are highly migmatitic in nature. Their
composition is of granodioritic material. Gneisses are
generally grey in color. They are jointed with sheet joints
almost parallel to the ground surface. The granites are
medium to coarse grained, and equigranular in texture.
Dykes are oriented east west as well as north south. The
study area has red loamy soils and they are fairly well
drained. Slopes range from 1 to 3 percent, slightly mod-
erately eroded. The major land use classification is agri-
culture (95%) and forests (2%) and the alluvial deposits
are noticed over a small area. Infiltration rates range
from 8 to 12 mm/hour. Geomorphologically we find re-
sidual hills of granites and charnockites with varying
elevations, aerial extent and dissection. Pediplains are
also found with gently undulating with fairly thick
weathered mantle over granites and gneisses. Pediplains
are also found with gently undulating with fairly thick
weathered mantle over granites and gneisses. Quantita-
tive analysis of morphimetric parameters is done for the
watershed considered for study. The parameters so esti-
mated are presented in Table 1. The adjoining water-
sheds have developed 3rd order streams indicating similar
level of maturity attained. The watersheds area and pe-
rimeter for combined Melekote and Rajaghatta is 95.83
sq km and 43.62 km. The elevation of the Melekote is
968 m and Rajaghatta 911 m above msl. The watersheds
relief ratio is less 0.017 resulting in low relief. The
stream ranking is done on Strahlers [6] system. Table 2
shows that the total number of stream segments of a par-
ticular order are smaller in number than for the immedi-
ate lower order but larger in nu mber of segments than for
the next higher order. Figure 2 suppor ts th e Str ahlers law .
This relation leads to the definition of bifurcation ratio.
Table 1 also shows bifurcation ratio for both the water-
sheds. The average bifurcation ratio obtained for water-
shed is 3.6. The bifurcation ratio is indicative of mild
slope in the watersheds. Figure 3 the mean stream of a
stream channel segment of certain order is a dimension
property, which reveals the characteristic size of a drain-
age network and its contributing basin surface. Figure 4
show that the watershed follows the Horton’s law [7]
with perfect linear relation of all the orders. However
elongation ratio shows the watersheds are attaining ma-
ture and old stage topography. The drainage density in-
dicates an expression of the closeness of spacing of
channels, hence provides quantitativ e measure of averag e
length of stream channel area of the whole watershed.
The drainage density is estimated to be 2.41, which is a
very useful index of catchment characteristics and it af-
fects the magnitude of stream flow from a catchment.
According to [8] the low drainage density is a character-
istic of regions of highly resistant or highly permeable
surface and low relief. High drainage density is found in
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Figure 2. Water bodies and lineaments.
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Mean stream length (Lm)
1 2 3
Stream order
Figure 3. Regression of log. of mean stream length V/s
stream order.
Stream order
Number of stre am s eg me nts
0 1 2 3 4
Figure 4. Regression of log. of number stream segments/s
stream order.
Table 1. Chracterstics of two watersheds representing dif-
ferent envi r o ns.
Basin Characterstics Values
Area of watershed (sq km) 95.83
Perimeter of waters hed (km) 43.62
Width of watershed (km) 11.34
Highest stream order 3
Cumulative length of stream (km) 89.06
Bifurcation rat io 3.66
Watershed shape factor 2.43
Form factor 0.74
Compactness coefficient 0.4
Circularity ratio 2.5
Elongation ratio 0.5
Drainage density (km/sq km) 2.41
Constant of channel maintenance
(km/sq km) 0.41
Stream frequency 0.92
Watershed re l ie f 0.75
Relative relief 0.049
Relief ratio 0.017
Ruggedness number 1.80
regions of weak or impermeable subsurface materials,
sparse vegetation and mountainous relief. In the present
case, the drainage density is (2.41) indicating average
permeability in the watershed. [9] state that in areas of
low relief drainage density may be more indicative of
permeability of surface material and therefore, could be
used as a criterion for the selection of suitable sites for
deep wells. Drainage density also influences run-off pat-
tern and thereby infiltration capacity of the rock material.
The constant of channel maintenance depends on the
rock type, permeability, climate, vegetation cover and
relief [10]. It has been observed that constant will be ex-
tremely low in an area of close dissection. The value 0.41
sq. km/km was obtained for constant of channel mainte-
nance for watersheds. This shows that the watersheds are
controlled by the presence of lineaments. The stream
discharge is influenced by the shape of the basin and the
surface runoff. It has been found that a long narrow
drainage basin with high bifurcation ratios would be ex-
pected to have attenuated flood discharge period but on
the other hand th e round basin with low bifurcation ratio
would be expected to have sharp peak flood discharge
[10] study circulatory ratio, elongation ratio, form factor
and compactness coefficient have been examined. The
value of circularity ratio of 2.5 exhibits catchments ma-
turity and old stage topography.
6. Water Quality
Water quality degradation can also cause scarcity of
good quality water. Freshwater bodies also have quality
problems due to pollution stemming from expanding
urban activities industrial application and improper agri-
cultural uses. Conceptually water quality refers to the
characteristics of water supply that will determine its
suitability for a specific use, i.e., how well the quality
meets the need of the user. Groundwater becomes a us-
able resource when the water bearing formations are
permeable enough to yield adequate quantity of good
quality water. Compared to surface water, groundwater is
relatively free from the effect of surface pollutants and is
less susceptible to chang es in quality, chemical composi-
tion and temperature variations. However its salinity
values are relatively higher.
7. Results and Discussion
The watershed has a moderate slop e of 2.5% and a relief
of 0.75 m with a drainage pattern varying from dendritic
to subdendritic. In view of this watershed is more prone
to erosion, and less stable. The lower value of channel
maintenance (0.41 sq km/km) the watershed indicates the
presence of large number of lineaments. Elongation ratio
of the watershed is an indicative o f the attaining maturity
and old age topography. The presence of a large number
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Table 2. Linear characteristics of watersheds.
Stream Order No. of
Segments Total Length
(km) Bifurcation
Ratio Mean Length
(km) Length Ratio Drainage
(km/sq km)
1 66 59.63 0.9034
2 18 23.01 3.6 1.278 0.700
3 5 6.42 3.6 1.284 0.990
2.41 0.92
Total 89 89.06
of lineament sand catchments attribute to impermeable
subsurface. The watershed has a large number of small
water bodies. The minimum and maximum concentra-
tions of various constituents in the water samples col-
lected from the dug wells and bore wells during different
seasons in the study area have been presented in Table 3 .
Observed ranges of different constituents in the well wa-
ter indicate variations. Most of the dug well water pH
values observed are less than the prescribed range of 6.5 -
8.5 for drinking water purpose. High level of dissolved
solids, are reflected from the conductivity values in the
watershed. Concentration of3 N above 3 mg/l (ni-
trate: 13.5 mg/l) in ground water are representative of
orthopogenic sources. High level of nitrate content has
been observed in some of the observation well waters
indicating the possibility of domestic/agricultural wastes
reaching the water sources. Over 75% of the observation
wells in the catchments, especially the dug wells showed
significant level of nitrate during monsoon and post
monsoon periods indicating the possibility of migration
of nitrates to the wells during rainy season. This is from
field observations, such as poor maintenance of the well
surroundings, lack of proper drainage system and poor
sanitary conditions prevailing around the wells. The iron
concentrations in about 80% of the dug well-waters es-
pecially during pre-monsoon and monsoon seasons are
observed to be above the maximum permissible level
(1.0 mg/l), irrespective of the seasons. The common
problems faced by the people due to high iron concentra-
tions are iron taste, staining of pipes, vessels and clothes,
and cooked food gettin g sp oiled fast. Water with condu c-
tivity range between 750 to 2250 µmhos/cm is success-
fully used for irrigation with satisfactory crop growth,
coupled with good management and favorable drainage
conditions. The conductivity levels in the well water of
watershed were found within the recommended range,
with a maximum recorded value of 1700 µmhos/cm dur-
ing summer season. However, water with low conductiv-
ity need not be always suitable for irrigation, since the
presence of significant concentrations of specific ions
such as sodium, magnesium, chloride, bicarbonates, and
sulphate do produce toxicity and lead to crop hazards.
The evaluation of sodium adsorption ratio (SAR) and
residual sodium carbonate (RSC) indices will help in
revealing the safety of water from alkalinity hazard. The
SAR values of the well waters in the study area range
from 9.54 to 48.6 and the RSC level ranges from 0.125 to
0.35 indicating suitability for irrigation.
8. Assessments of Water Quality and Types
The piper tri-linear diagram is an effective tool in segre-
gating the analyzed data for critical study with respect to
sources of the dissolved constituents in water, modifica-
tions in the quality of water as it passes through an area,
and related geochemical problems. The analyses of water
samples include physical and chemical tests besides the
nature and magnitude of the impurities present and suit-
ability of water for different purposes [11]. Figure 5 rep-
resent the tri-linear plot will show the essential chemical
characteristics of water according to the relative concen-
trations of its constituents. These diagrams reveal the
analogies, dissimilarities and different types of waters in
the study area. The concept of hydro chemical faces was
developed in order to understand and identify the water
composition in different classes. In the tri-linear plot at
the lower left, the percentage reacting values of three
cations (Ca2+, Mg2+ and Na+ + K+) are plotted as a single
point according to conventional tri-linear coordinates.
The three anion groups (Cl, 4 and 3
) are
plotted likewise in the triangular field at the lower right.
Thus, two points on the diagram, one in each of the two
triangular fields, indicate the relative concentrations of
the several dissolved con s tituents present in groundwater.
The central diamond-shaped field is used to show the
overall chemical characteristics of ground water by a
third single-point, which is at the intersection of the rays
projected from the two plots of the cation-anion pairs that
correspond to the four vertices of the field. These water
sample test wells more or less represent the entire sub-
watersheds of Melekote and Rajaghatta. Ground water
samples were analysed for pH, EC, Phosphate (4
Iron (Fe3+), Sodium (Na+), Potassium (K+), Calcium
(Ca2+) and Magnesium (Mg2+), Chloride (Cl), fluoride
(F), sulphate (4
), and nitrate () as per the
standard analytical procedure. 3
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Figure 5. Piper tri-linear diagram showing the chemical composition of ground water during post monsoon.
Table 3. Hydro-chemical assessment.
Bore Well Dug Well
Pre-Monsoon Monsoon Post MonsoonPre-MonsoonMonsoon Post Monsoon
pH 7.6 - 8.41 6.7 - 8.1 7.0 - 7.3 7.3 7.4 6.8
Electrical conductivity (EC) 1034 - 431 1700 - 2471034 - 161 334 332 230
Total alkalinity (TA) 316 - 36 232 - 34 316 - 36 60 60 32
Total hardness (TH) 383 - 61 372 - 28 383 - 61. 6 80 80 72
Total dissolved solids (TDS) 104 - 664 178 - 1200260 - 746 512 512 150
Chloride (Cl) 121 - 11 143 - 5 121.7 - 11.6 28.7 28.7 34.9
Fluoride (F) 0.74 - 0.11 0 .3 - 0.1 0.5 - 0.04 0.3 0.3 BDL
Sulphate (SO4) 46.8 - 1.8 63 - 7.6 59 - 11.5 22.4 22.4 11.1
Nitrate (NO3) 62.6 - 3.5 33.2 - 3.2 21.3 - 3 19.8 19.8 18.9
Iron (Fe) 0.14 - 0.06 BDL 0.1 - 0.05 0.8 0.8 BDL
Sodium (Na) 62.16 - 14.6 58 - 12 72 - 9 21 21 25
Potassium (K) 6.7 - 0.7 13 - 4 16 - 1 12 12 BDL
Calcium (Ca) 113.6 - 12.2 133 - 8.8 8 2.5 - 11.2 16 16 19.2
Magnesium (Mg) 22.9 - 1.5 30.6 - 1.4 48.6 - 3.8 9.7 9.7 5.8
NB: All values are expressed in mg/l ex cept pH and EC, pH in pH units;EC in micromhos/cm at 25˚C; BDL: Below detectable level.
9. Conclusion
The ground water quality in the watershed region is fairly
good and potable. The variation of chemical concentra-
tion possibility of pollutants from domestic sewage en-
tering the sub-surface, leads to pollution. Inadequate
drainage systems and ill maintenance of the well sur-
roundings are found to be the reasons for contamination.
The results of the chemical analyses of water samples
reveal that there are no abnormalities in them. The two
sub-watersheds are unexplored water stressed region
with regard to water resources. The suitability of water
for irrigation is evaluated based on SAR, % Na, RSC and
salinity hazards. All samples in the watersheds reveal
Copyright © 2012 SciRes. JWARP
suitable range of constituents for irrigation.
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