Studies on Twin Micro-Watersheds, Melekote and Rajagatta Dodballapur Taluk, Bangalore Rural District, Karnataka State through Morphometry, Land Formation and Water Quality

doi:10.4236/jwarp.2012.412123

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Journal of Water Resource and Protection, 2012, 4, 1071-1078

http://dx.doi.org/10.4236/jwarp.2012.412123 Published Online December 2012 (http://www.SciRP.org/journal/jwarp)

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

Email: [email protected]

Received September 28, 2012; revised November 1, 2012; accepted November 10, 2012

ABSTRACT

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

SOHCO



. 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),

S. G. RAMACHANDRAIAH ET AL.

1072

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.

S. G. RAMACHANDRAIAH ET AL. 1073

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

S. G. RAMACHANDRAIAH ET AL.

1074

Figure 2. Water bodies and lineaments.

S. G. RAMACHANDRAIAH ET AL. 1075

Mean stream length (Lm)

Lm=

0.802e

0.175U

=0.76

1 2 3

Stream order

Figure 3. Regression of log. of mean stream length V/s

stream order.

Stream order

100

Number of stre am s eg me nts

u=23

9.0e

-1.29U

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

S. G. RAMACHANDRAIAH ET AL.

1076

Table 2. Linear characteristics of watersheds.

Stream Order No. of

Segments Total Length

(km) Bifurcation

Ratio Mean Length

(km) Length Ratio Drainage

Density

(km/sq km)

Stream

Frequency

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

NO

SOHCO

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

NO

S. G. RAMACHANDRAIAH ET AL. 1077

Figure 5. Piper tri-linear diagram showing the chemical composition of ground water during post monsoon.

Table 3. Hydro-chemical assessment.

Minimum-Maximum

Bore Well Dug Well

Physico-Charasterestics

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

S. G. RAMACHANDRAIAH ET AL.

1078

suitable range of constituents for irrigation.

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