Groundwater resources development in hard rock terrain - an approach using remote sensing and GIS...

JAG l Volume 2 - Issue 3/4 - 2000

Groundwater resources development in hard rock terrain - an approach usi,ng remote sensing and GIS techniques

Jagannathan Krishnamurthyl, Arul Man?, Venkatakrishnan Jayaramanl and M ManiveP

1 Indian Space Research Organisation Headquarters, Antariksh Bhavan, Bangalore - 560 094, India (fax: 080-341-38-06/341-74-55; phone: 080-307.23-60/341-73-59; e-mail: jkrishnamurthyQhotmail.com)

2 School of Earth Sciences, Bharathidasan University, Tiruchirapalli - 620023, India

KEYWORDS: artificial recharge, categorisation, drainage

density, hydrological soils, Indian Remote Sensing

Satellite, integration, landforms, landuse, lithology, lin-

eaments.

ABSTRACT

To demonstrate the capabilities of remote sensing and Geographic

Information System (GIS) techniques for groundwater resources

development in hard rock terrains, specifically for the demarcation

of suitable sites for artificial recharge of groundwater aquifers, a

study was carried out in the Kallar Basin, which is located in parts

of the Salem and Tiruchirapalli districts, Tamil Nadu, India. Thematic

maps defining lithology, lineaments, landforms, landuse, drainage

density, thickness of weathered zone, thickness of fractured zone,

hydrological soils, and well yield were prepared from data collected

by the Indian Remote Sensing Satellite (IRS) -1 C and by convention-

al methods. All the thematic layers were integrated using a GIS-

based model developed specifically for this purpose, enabling a

map showing artificial recharge zones to be generated. The exact

type of artificial recharge structure, eg, check dam, nallabund, gully

plugging and percolation pond, suitable for replenishing groundwa-

ter was identified by superposing a drainage network map over an

artificial recharge zones map. The GIS-based demarcation of artifi-

cial zones developed in the study was based on logical conditions

and reasoning, so that the same techniques (with appropriate mod-

ifications) could be adopted elsewhere, especially in hard rock ter-

rain, where the occurrence of groundwater is restricted and subject

to greater complexity.

INTRODUCTION

Groundwater, unlike surface water, is available in some

quantity almost everywhere. Although it is replenishable,

it is not inexhaustible. The depletion of groundwater lev-

els is not a new story in India, but one that has contin-

ued for at least a decade, when the farmers switched

over from manual method of drawing water from wells

to mechanical pumping for agricultural activites.

Continuous failure of monsoons and indiscriminate with-

drawal of groundwater - out of balance with input into

groundwater aquifer systems - have also added to the

depletion of groundwater resources. Even though these

resources are scarce, comprehensive surveys and - espe-

cially - artificial recharging of aquifers might help to

overcome the problem to some extent. The practice of

artificial recharging is increasingly emerging as a power-

ful tool in water resources management. Check dam,

nallabund, gully plugging, contour trenching, recharge

pits/ponds and farm ponds are some popular artificial

recharge structures. By constructing suitable types of

artificial recharge structures, groundwater resources can

be augmented. Many agencies have produced papers

and reports on the depletion of groundwater levels in

India and the need for artificial recharge of groundwater

aquifers, but only a few of them suggest methods for

selection of sites for that artificial recharge.

Surface and sub-surface hydrological features such as

lithology, geological structure, landforms, drainage den-

sity, water bodies and weathered/fractured thickness of

overburden material play an important role in groundwa-

ter replenishment. But through conventional methods

alone it is not an easy task to study the surficial parame-

ters of a large area to identify suitable sites for artificial

recharge, since many controlling parameters must be

independently derived and integrated, which involves

additional cost, time and manpower. Modern remote

sensing techniques have many advantages over older,

conventional methods due to their synoptic coverage,

improved spatial resolution, and their capabilities for

multi-spectral and multi-temporal analysis. In addition,

unlike conventional methods, remote sensing methods

for demarcation of suitable areas for ground water

replenishment are able to take into account the diversity

of factors that control groundwater recharge.

Many assessments of groundwater conditions made with

remote sensing techniques have been reported

[Anonymous, 1979; Baldev et a/, 1991; Basappa Reddy &

Gaikwad, 1985; Chaturvedi et a/, 1983; Krishnamurthy

et al, 1992; Krishnamurthy, 1993; Krishnamurthy, J. et

al, 1992. Krishnamurthy & Srinivas, 1995; Manavalan et

al, 1993; Raj & Sinha, 1989; Ranna, 1998;

204

Groundwater resources development in hard rock terrain

Thillaigovindarajan, 1999; Venkateswara Rao, 19981.

Rather than using a single technique, combinations of

different techniques have provided more dependable

information for developing suitable plans of action for

development. Such studies have integrated various surfi-

cial features derived from remote sensing data in a GIS

environment [Chi & Lee, 1994; Gustafsson, 1993;

Jeyaram, 1997; Krishnamurthy et al, 1996; Murthy,

2000; Padmavathy et al, 1993; Saraf & Jain, 1996; Saraf

& Choudhury, 1998; Shahid et al, 2000; Sohani et a/,

19981. However only a limited number of studies have

taken the approach of specifically locating artificial

recharge zones using remote sensing and GIS tech-

niques. Researchers have adopted different GIS-based

models while demarcating areas suitable for artificial

recharge, and as such there is no standard model avail-

able. Also, most of the models normally give importance

to the mathematical relations rather than local ground

truth. Hence it was decided to design and test a GIS-

based model for demarcating artificial recharge zones in

hard rock terrain that could be put to operational use.

This study therefore demonstrates the utility of remote

sensing and GIS techniques for demarcating areas suit-

able for artificial recharge, especially the identification of

suitable sites for artificial recharge of groundwater

aquifers in hard rock terrain, where groundwater is typi-

cally scarce.

The aim of this study was to demonstrate the potential of

remote sensing and GIS techniques for selecting suitable

areas for artificial recharge of groundwater aquifers. The

specific objectives of the study were:

Preparation of various thematic maps that are relevant

for demarcation of artificial recharge zones. Thematic

maps that can be prepared from remotely sensed data

may include, for example, lithology, lineaments, land-

forms, surface water bodies and landuse. Thematic maps

that can be prepared from data collected by convention-

al methods may include drainage density, hydrological

soils, weathered zone thickness, fractured zone thickness

and well yield.

Development of a GIS-based model for integration of

thematic maps specifically to demarcate artificial

recharge zones for groundwater development.

Identification of suitable areas/zones for artificial

recharge of groundwater through integration of themat-

ic maps by using the GIS-based model developed.

Definition of suitable artificial recharge structures for

potential recharge zones identified.

DATA SOURCES

STUDY AREA

Because the present study was aimed at generating a

package to demonstrate the potential of remote sensing

and GIS techniques for selecting suitable areas for artifi-


cial recharge of groundwater aquifers, it was decided to

use a study area that was actually having problems with

groundwater availability, thus requiring a suitable plan of

action for groundwater development. From develop-

ments in groundwater status, the Public Works

Department (PWD) of Madras classified the entire Tamil

Nadu region as either “Dark areas” “Grey areas” and

“White areas” for 1994 and 1997 (projected) [Public

Works Department, 19941. “Dark areas” are those areas

in which groundwater extraction is greater than the

input (augmentation is required to maintain groundwater

balance). In contrast, areas classified as “White areas”

are those areas that are recommended for groundwater

exploration since adequate groundwater is available.

After consultation of the PWD’s groundwater develop-

ment status report, the Kallar Basin, located in parts of

Salem and Tiruchirapalli districts in Tamil Nadu, was cho-

sen for the study (Figure 1). Parts of the Kallar sub-basin

had been categorised as “Dark areas” and other parts as

“Grey areas” and the basin required a suitable plan for

groundwater development.

FIGURE 1 Location of the study area

The study area lies between latitudes 11 o 16’ - 1 I0 30’ N

and longitudes 78’ 18’ - 78” 56’ E and it covers approx-

imately 930 km*. The Kallar Basin is surrounded and

partly covered by the Kollai hills in the west, the Pachchai

hills in the north and the Paithur hills in the south. The

terrain is flat and gently undulating in the east and

northwest. The maximum and the minimum elevations of

the study area are 1415 m and 257 m AMSL, respective-

ly. In general, all the hill regions of the basin are covered

by forest, while agriculture is practised on gently undu-

lating terrain. Most of its major streams are controlled by

lineaments.

DATA INPUTS

The detailed data bases used in the study were:

IRS -lC LISS-Ill False Colour Composite photographic

products on 1:50,000 scale and 1 :I 25,000 scale acquired

205


on 24 May 1996.

Survey of India topographical sheet No. 58 I on

1:250,000 scale and No.s 58 l/6, 58 l/7, 58 VI 0, 58 l/l 1

and 58 l/l 5 on 1:50,000 scale.

Soil map of the study area and its surroundings on

1:63,360 scale, prepared by Soil and Land Use

Organisation, Coimbatore, Tamil Nadu.

Groundwater yields and bore hole litholog data collected

by the Public Works Department of Madras.

Field observations collected during field checks.

METHOD

In the first phase of the work a number of thematic maps

that reflect factors that directly influence the recharge of

groundwater were prepared from remotely sensed data

and from data collected by conventional field methods.

Thematic maps prepared from remote sensing sources

included: (i) lithology, (ii) landforms, (iii) lineaments, (iv)

landuse, and (v) water bodies from the IRS IC LISS-Ill

Geocoded photographic products. Additional thematic

maps that were developed from the data collected by

conventional field methods included: (vi) base details,

(vii) drainage density, (viii) a soil map of the study area

produced by regrouping soil types on the basis of hydro-

logical characteristics, (ix) weathered zone thickness, (x)

fractured zone thickness, (xi) and groundwater yields.

Details collected during field checks were incorporated

during the final preparation of thematic maps.

In the second phase of the study, GIS techniques were

used to integrate and analyse the thematic maps and to

prepare a map showing areas suitable for artificial

recharge of groundwater.

By superimposing the drainage network map onto this

artificial recharge map and also by taking terrain charac-

teristics into consideration, the types of artificial recharge

structures suitable for each of the zones, for example, a

check dam, a nallabund, a percolation pond, or a con-

tour trench, were identified. The method used in the

study is shown in a flow chart (Figure 2).

RESULTS

THEMATIC MAPS

Details of thematic maps relevant for demarcation of arti-

ficial recharge zones are given in the following subsec-

tions

Lithology

The lithological map of the study area was prepared from

IRS IC LISS - Ill data (Figure 3) using image characters

such as tone, texture, and drainage pattern. In addition,

details available from published geological maps and

from field information were used to distinguish the dif-


ferent rock units from each other. On the standard FCC

image, Unclassified Gneissic terrain was identified as

areas of the bluish-yellow tone with medium to coarse

texture. Areas of Charnockite were identified on the

image by areas of dark-brown to reddish-brown tone

with fine to medium texture. Identification was supple-

mented by reference to ground checks and the relevant

published geological map. Mylonite ridges were demar-

cated based on typical long and elevated elongated ellip-

tical shapes, greenish-brown in tone and medium in tex-

ture. This unit was observed only in the central portion of

the study area. Dolerite dykes, which mostly traverse

gneissic terrain, were demarcated by their relict topogra-

phy and greyish tone. This unit is prevalent in central and

western portions of the basin.

Landforms

Landforms are important surficial indicators in the search

for suitable artificial recharge sites, since each landform

differs in its physiographic disposition, areal extent, etc.

LlNEAMENT

LANDUSE

t I t t + *

FIGURE 2 Flow chart of the methodology adopted

KALLAR BASIN CHARKOCKITE LlTtloLoaY wcL*ss!FIEo OWlSS SCALE-1176666 YYLOMTE RWE #

-s DYKE m

FIGURE 3 Lithological map of the study area prepared from IRS data

206


Landforms were easily demarcated from the IRS LISS III

image, based on the image recognition elements - eg,

tone, texture, shape, size and association. The following

landforms were mapped from the IRS image: (i) denuda-

tional hills, (ii) residual hills, (iii) linear ridges, (iv) pedi-

ment inselberg complexes, (v) pediments, (vi) pediplains,

(vii) flood plains, (viii) duricrusts, and (ix) valley fills

(Figure 4).

Lineaments

Lineaments, which are linear or curvilinear features, can

play a major role in identifying suitable sites for artificial

recharge of groundwater because they reflect rock struc-

tures through which water can percolate and travel up to

several kilometres. Lineaments present in the study area

can be grouped into four categories: (i) NE - SW trend-

ing lineaments, (ii) NW - SE trending lineaments, (iii) ENE

- WSW trending lineaments, and (iv) E - W trending lin-

eaments (Figure 5). Since areas around lineaments may

play an important role in promoting recharge of water

into the groundwater regime, a zone extending 300 m

around each lineament was considered in our study.

Landuselland cover

Information on present landuse /land cover provides

important indications of the extent of groundwater

requirements and groundwater utilisation, as well as

FIGURE 4 Landform map of the study area prepared from IRS

W SETTLEYIIT El FOMST Lr.r

KALLAR MUW

CR0Pl.M EJRO~Y lREI m LANDWI

F&Low L1D mW&TER moDy* w-lI7~ooo

m h-v LW WTH 110 .C.~aununDILLTIIQ TERRAI” WrH cuRleR”It m LAO WITH *cwa @

FIGURE 6 Landuseiland cover map of the study area prepared from IRS data

JAG l Volume 2 - Issue 314 - 2000

being an important indicator in the selection of sites for

artificial recharge of groundwater. The role of remotely

sensed data in providing such information has been con-

vincingly demonstrated in many previous studies due to

its capabilities for synoptic viewing and multi-spectral

and multi-temporal coverage. The study area was classi-

fied into different IanduseAand cover classes by visual

interpretation of satellite images (Figure 6): (i) settle-

ment, (ii) crop land, (iii) fallow land, (iv) land with scrub,

(v) land without scrub, (vi) forest, (vii) rocky area, (viii)

water bodies, and (ix) undulating terrain with duricrust.

Drainage density

The drainage density, expressed in terms of length of

channels per unit area (km km-z) indicates an expression

of the closeness of spacing of channels. It thus provides

a quantitative measure of the average length of stream

channels within different portions of the whole basin. In

our study, drainage density was considered as one of the

prime indicators for selection of artificial recharge sites

since it indirectly indicates the permeability and porosity

of the terrain. Figure 7 shows the drainage map of the

study area; the drainage density map is given in Figure 8.

In the Kallar Basin, as many as 21 sub-basins were delin-

eated (without any interbasinal areas between them).

The drainage density values were grouped into five cate-

FIGURE 5 Lineament map of the study area prepared from IRS data

W KALLAR lwuW

FIGURE 7 Drainage map of the study area

207


gories: (i) <I .5 km km-z, (ii) >I .5 to <I .75 km km-z, (iii)

~I.75 to cl.85 km km-z. (iv) >I.85 to ~2.20 km km-z,

and (v) >2.20 km km-z.

Hydrological soils

Soil characteristics invariably control penetration of sur-

face water into an aquifer system and they are directly related to rates of infiltration, percolation and perme-

ability, for example. The hydrological soils map of the

study area was generated by evolution of the soil map

published by Soil Survey and Land Use Organisation,

Coimbatore. Ten different categories of soils were

demarcated (Figure 9) according to their hydrological

characteristics.

Weathered zone thickness

The predominant rocks exposed in the study area are Biotite Gneisses and Charnockites. The intensity of

weathering depends on the composition of the rocks.

Since the weathered mantle permits percolation of water into groundwater aquifers, a map showing the thickness

of the weathered zone was generated (Figure 10). Due to

variation in the compactness of the different rock units,

areas covered by Charnockite rock have relatively less

weathered thickness than Biotite Gneisses. The thickness

of the weathered zone in the study area varies between


7 and 68 m. Based on field observations, the weathered

thickness zone of the study area was grouped into four

categories: (i) <I 5 m, (ii) 15 to 25 m, (iii) 25 to 40 m, and

(iv) >40 m.

Fractured zone thickness

Highly fractured rock columns hold the maximum amount of water and have the highest percolation rate,

so highly fractured zones are considered to be most suit-

able for artificial recharge. Therefore a contour map

showing the thickness of fractured zones in the study

area was constructed (Figure 11). The thickness of frac-

tured zones in the study area ranges between 0 m and

81 m. Based on field observations, the thickness of frac-

tured zones was grouped into four categories: (i) <I 0 m, (ii) 10 to 35 m, (iii) 35 to 50 m, and (iv) >50 m.

Well yield

Well yields in an area depend, for example, upon the per-

meability of the aquifer and the amount of available sub-

surface water in the aquifer system. A contour map was

prepared showing well yields with contour interval of

22.5 litres per minute (Figure 12). The zone of highest

well yield was observed in the western part of the study

area, while the zone of lowest well yield was observed in

the northeastern part of the study area

FIGURE 8 Drainage density map of the study area

FIGURE 10 Weathered thickness map of the study area

FIGURE 9 Hydrological soil map of the study area

Ll!Qu*) KALLAR BASIN

FIGURE II Fractured thickness map of the study area

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Groundwater resources development in hard rock terrain JAG l Volume 2 - Issue 314 - 2000

FIGURE 12 Well yield map of the study area

TABLE I Thematic characteristics used to categorise recharge potential

A G&BASED MODEL

To demarcate areas suitable for artificial recharge of

groundwater, a G&based model was specifically devel-

oped for integrating and analysing different thematic

maps. Details are given in the following subsections.

Categorisation and weight assignment

The thematic layers described the section on thematic

mapping were digitised and all the polygons were

labelled. Each polygon on each thematic layer was cate-

gorised according to its recharge characters as either (i)

Excellent, (ii) Very good, (iii) Good, (iv) Moderate, or (v)

Poor. This categorisation reflected thematic characteris-

tics shown on the thematic map as shown in Table 1.

Note that the relative ranking of the polygons is based

on the positive and negative consequences of their char-

No. Theme Reasoning behind categorisation I relative ranking

1 Lithology

2 Landform

3 Landuse

Hydrological soils

Drainage Density

Weathered zone thickness

Fractured zone thickness

Well yields

Water bodies/ Settlements/Forest

Lineaments

209

Compactness of the rock, weathering status, and presence of fracture & joint pattern plays an important role in demarcation of groundwater recharge zones. Areas which are characterised by rocks having less compactness and more weathered/fractured overburden material are considered to be more suitable than areas with compact and less weathered/fractured rocks.

Since the characteristics of each landform vary greatly in shape, thickness of overburden material, permeability, porosity, areal extent, and location within the basin, recharge characteristics also differ accordingly.

The present utilisation of landuse/land cover of an area provides a clue about the level of utilisation. For example, areas that fall under land with or without scrub can be rated higher, since if an area is not presently utilised it may be due to non-availability of groundwater or non-suitability of the terrain. On the other hand, areas that are already being cropped are categorised as poor since artificial recharge is not critical in those areas.

Soil characteristics invariably control penetration of surface water into an aquifer system because it is directly related to rate of infiltration, percolation and permeability. Areas that are characterised by highly permeable soils are more suitable than the areas of low permeability.

Drainage density of an area indirectly indicates its permeability and porosity due to its relationship with surface run-off. Areas with high drainage density values indicate high surface run-off, hence such areas are to be considered favourable for arresting excessive run-off.

The thickness of the weathered zone depends on the compactness of the rock, fracture/joint patterns and weathering patterns. Greater thickness indicates the possibility of better recharge, as well as suitability for groundwater localisation and movement.

The thickness of the fractured zone depends on the compactness of the rock and presence of fracture/joint patterns. Greater thickness indicates the possibility of better recharge, as well as suitability for groundwater localisation and movement.

Well yield of an area depends upon the permeability of the aquifer, in addition to the amount of groundwater available in the aquifer system. Higher well yields indicate relatively greater groundwater availability than areas with low well yields. As the demand for groundwater is greater in areas where groundwater availability is lowest, such areas are to be considered favourably for artificial recharge.

Areas categorised as surface water bodies/settlements are assigned the value ‘0’ tso that these areas can be eliminated from being identified as artificial recharge zones. Since no activity is normally permitted within a forest area, the also applies to forest areas.

Lineaments and intersections of lineaments reflect rock structures through which water can percolate and travel up to several kilometres. Depending upon the terrain, the lineament will be a zone of influence. Depending on field conditions, 300 m around the lineament was considered as the favor- able zone for artificial recharge.


acteristics relative to artificial recharge of groundwater

aquifers. For example, in a region of varying lithology,

areas characterised by rocks that have less compact and

more weathered/ fractured overburden material should

be given higher importance than areas with compact and

less weathered/fractured rocks. Similarly, areas that are

characterised by highly permeable soils are more suitable

than areas with soil of poor permeability.

After understanding their behaviour with respect to

recharge, different classes were weighted relative to

their importance in comparison to other classes in the

same thematic layer. Table 2 summarises the reasons for

the categorisation and weights assigned to different

classes of all the thematic layers. As Table 2 shows, the

maximum and minimum weights assigned to classes in

thematic layers, as well as the weight interval between

successive classes, were not kept uniform by considering

their importance and relations with respect to other

classes. For example, the maximum weight assigned for

geology for unclassified Gneisses was 30, due to charac-

teristics favourable for recharge: i.e., less compact, more

weathered and fractured overburden material. By con-

trast, Mylonite ridges and dykes were assigned a value of

5 since they comprise a narrow, linear and resistant relict

body of material. On the other hand, in the landuse

layer, a maximum weight of 70 was assigned to land cov-

ered by duricrust - flat beds of kankar and other soft

porous calcareous material - whereas a weight of 5 was

assigned to cropland that already contains adequate

water and upon which agriculture is practised regularly.

Also, due care was taken while assigning a weight to

each class by considering its local conditions and not

merely judging its importance on recharge characteristics

alone. For example, flood plain in the landform layer has

a shallow water-table, it was assigned a weight of 10

even though this unit is characterised by porous and per-

meable alluvial material. In the landuse layer, land with

out scrub and land with scrub were given weights of 60

and 40, respectively. The land without scrub comprises

gently undulating terrain without any vegetation cover

whatsoever, so it can be used for productive agricultural

activity. As the land covered with scrub can be used for

agriculture only after major reclamation activities, land

without scrub was rated higher. Similarly, areas with the

highest well yields were rated as lowest because of low ground water requirement in such areas. Areas covered

by forest were not considered for artificial recharge

zonation because activities are not normally permitted

within forest areas.

Integration of thematic layers

After categorisation, all the thematic layers were inte-

grated with one another by a GIS technique that uses the

weighted aggregation method. In this method the total


weights of the integrated polygons that were ultimately

formed were derived as a sum or product of the weights

that had been assigned to the different layers according

to their suitability [ESRI, 1988, 19891. The sequence fol-

lowed to create the final integrated layers was:

Thematic/integrated layer Resultant layer

Lithology (Al) + Landform (AZ) = Ul

Ul + Landuse (A3) = u2

u2 + Hydrological Soil (A4) = u3

u3 + Drainage Density (A5) u4

u4 + Weathered zone thickness (A6) 1 U5

u5 + Fractured zone thickness (A7) = U6

U6 + Well yield (A8) = u7

u7 * Water bodies/settlement/

Forest (A9) = U8

U8 + Lineament buffer (AIO) = u9

In the first step, lithology (Al) and Landform (AZ) layers

were integrated with one another and Ul (the resultant

output) was obtained. The Ul layer was then integrated

with the Landuse layer (A3) and the resultant layer, U2,

was obtained. This process was repeated until U6 was

integrated with the well yield layer (A8). The resultant

layer, U7, was multiplied with the polygons of surface

water body/settlements/forest - which had been

assigned 0 value to prevent them being considered as

artificial recharge zones - to give U8. Finally, polygons

made around lineaments were integrated with the U8

layer to produce the final integrated layer (U9).

Theoretically this final layer should have a maximum

value of 495 and a minimum value of 140, but in the

analysis we present in this paper a maximum weight of

440 and a minimum of 140 were obtained, due to exist-

ing polygon combinations.

The polygons of the final integrated layer were classed as

either excellent, good, fairly good, fair and not suitable,

based on the weight ranges obtained from logical condi-

tions that had been established. The way in which the

upper and the lower limits of the weights were derived

for demarcation of artificial recharge zones is given in

Table 3.

The areas which were categorised excellent for artificial

recharge were delineated by grouping polygons that had

weights between 375 and 440 in the final integrated

layer. The theoretical upper limit is 505, if all the layers

considered are categorised excellent. In the analysis pre-

sented in this paper a maximum weight of 440 was

obtained due to the varying combination of polygons.

The good category artificial recharge zones involved

polygons that had weights from 370 to 300. The upper

weight limit was derived by adding layers categorised

good in landform and hydrological soil layers and cate-

gorised very good in all other layers.

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Groundwater resources development in hard rock terrain JAG . Volume 2 - Issue 3/4 - 2000

TABLE 2: Reasoning behind categorisation of and weights assigned to different features affect artificial recharge site selection

No. Theme Class Reasoning behind categorisation Category Weight

1 Lithology Unclassified Gneisses

Charnockite

Mylonite ridge

Dyke

2 Landform Duricrust

Denudation hill

Residual hill

Valley fill

Pediplain

Pediment

Pediment insulberg Complex

Linear Ridge

Flood Plain permeable

3 Landuse Land covered under duricrust

Land without scrub

Land with The area covered under this category is characterized by gently undulating. scrub terrain and is covered with scrub. It could be used for agricultural activity

This rock unit is characterised by less compact rock with more weathered/ fractured overburden material than Charnockite; it is therefore considered to be relatively better than Charnockite. This observation corroborates with data on the thickness of the weathered/fractured overburden material collected in the field through borehole logs, geophysical vertical electrical sounding measurements and open well/road cuttings.

Compact and having less weathered/fractured overburden material than unclassified gneisses, it also has less joints/fracture patterns. Hence it is rated relatively lower than Unclassified Gneisses.

Linear ridge of resistant body, which acts as a run-off zone. Because of its linear relict nature, this unit is categorised poor.

Linear ridge of resistant body that acts as a run-off zone. Because of its linear relict nature and its narrower spatial extent, this unit is categorised poor.

This unit is characterised by flat lying beds of kankar and other calcareous material under a thin soil cover. These materials are soft and porous with high rate of percolation and infiltration. In places they are exposed as barren crust. Hence this unit has been categorised excellent when compared to any other landforms.

They are an exfoliated, elongated feature with a fractured &jointed rocky area still affected by the process of denudation. These hills are concentrated around catchment regions and a number of streams originate from and criss-cross the hilly region of the sub-basin. This unit is rated as good. If a recharge structure is located within this unit it will benefit not only the area immediately surrounding the structure it but also down stream areas of the basin.

This unit is characterised by the hills, which are relatively less in spatial extent and occur as isolated land masses left over due to differential weathering.Within the study area this unit is concentrated mainly in the catchment area.lf a recharge structure is located with in this unit it will benefit not only the area immediately surrounding the structure but also the down stream areas of the basin. This unit is rated relatively lower than Denudational hill due to its spatial extent

As this unit is characterised by unconsolidated sediments of both colluvial and alluvial material, it is considered to be a good recharge area.

These are gently undulating landscape broken by isolated residual uplands and covered with varying thickness of overburden material that itself covered by soil. Generally they are characterised by high porosity and permeability, suggesting high infiltration rates. As this unit is characterised by gently undulating surfaces and lesser drainage networks, only specific artificial recharge structures can be constructed. Hence this unit is considered after Duricrust. Denudational hill, and Residual hill.

A rock-floored surface of low relief, generally without a weathered mantle. Normally this surface has low permeability.

A number of small isolated island-like hills that stands out in prominence in a dome form because of their resistance to weathering within the extensive pediment zone. Only a pediment zone within this entire unit is suitable for artificial recharge, hence it is categorised lower than pediment alone.

Linear ridge of resistant material; it acts as a run-off zone. Because of its linear relict nature, this unit is categorised poor.

Though this unit is characterized by alluvial material that is highly and porous, it is deliberately characterised as poor because this unit has experienced shallow water-tables.

This unit is characterised by the flat lying beds of kankar and other calcareous material under thin cover of soil. These materials are soft and porous with high rates of percolation and infiltration. In spots they are exposed as barren crust. Hence this unit has been rated as excellent when compared to any other landforms.

This area is characterized by gently undulating terrain that is not covered with any vegetation, be it either crops or scrub. It could however be used for productive agricultural activity. Hence this unit is considered very good (better than Land with scrub).

Very Good

Good

Poor

Poor

Excellent

Good

Good

Good

Good

Moderate

Moderate

Poor

Poor

Excellent

Very Good

Good

30

20

5

5

70

60

55

55

50

30

25

10

10

70

60

40

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Groundwater resources development in hard rock terrain JAG l Volume 2 - issue 3/4 - 2000

TABLE 2: Continued

No. Theme Class Reasoning behind categorisation Category Weight

Fallow land Though it was in the past put to agriculture earlier, it is currently fallow. This unit is categorised as moderate due to plain topography and existing agricultural activity.

Rocky area

Crop land

Settlement

A rock-cut surface without any weathered over burden material, generally impervious other than for joints & fractures. Hence it is rated as poor.

Already cropped, which signifies the availability of water. The demand for artificial recharge is not critical, hence, it is categorised poor.

Areas under settlement are assigned a value of 0 to exclude them from artificial recharge zonation.

Water body Areas covered by water are assigned values of 0 to exclude them from artificial recharge zonation.

Forest Since no activity is normally permitted within this area, it is categorised poor.

4 Hydrological Type 4 Yellowish-red to dark reddish-brown; shallow to moderately deep; coarse to fine loamy; non-calcareous; well drained with rapid to moderately rapid permeability. As this area is covered by coarse to fine loamy and rapidly permeable soil, it is categorised excellent and is given the highest weights.

Dark-brown; moderately deep; well drained with moderately high permeability; inter-bedded with calcium carbonate.

Dark yellowish-brown to reddish-brown; fine loamy; excessively drained externally, and moderately low permeability.

Red to reddish-brown; moderately deep; non-calcareous; fine loamy; well drained with moderately high permeability.

Dark-grey to very dark-grey; very deep; clayey; calcareous; cracks; moderate to low permeability. Moderate 20

Red; moderately deep; calcareous; well drained; moderately low permeability.

soils

5 Drainage Density

6 Weathered zone thickness

7 Fractured zone thickness

Type 5

Type 7

Type 2

Type 1

Type 3

Type 6

Type 8

Me 9

Type 10

Category 5

Category 4

Category 3

Category 2

Category 1

Category 4

Category 3

Category 2

Category 1

Category 4

only after major reclamation. Hence this unit is rated lower than land without scrub.

Dark-brown to dark reddish-brown; very deep; fine loamy; moderately well drained; moderate to moderately-low permeability.

Brown to dark reddish-brown; moderately deep to deep; fine loamy; slightly calcareous; intermixed with the clayey soils.

Mixed soils; low to moderate permeability.

Soils within the forest area. Since activity is not generally permitted in forest areas, they are categorised poor.

Sub-basins that have drainage density values greater than 2.20 km/km-z (highest value in the basin) are categorised excellent and are given the highest weight due to the high run-off.

Sub-basins that have drainage density values between 1.85 - 2.20 km/km-z (second highest value in the basin) are categorised very good.

Sub-basins that have drainage density values between 1.75 - 1.85 km/km-z (third highest value in the basin) are categorised good.

Sub-basins that have drainage density values between 1.50 - 1.75 km/km-z (second lowest value in the basin) are categorised moderate.

Sub-basins that have drainage density values less 1.50 km/km-z lowest value in the basin) are categorised poor.

The areas that have highest values of more than 40 m thick weathered overburden material are categorised excellent and are given the highest weight due to the possibility of better recharge conditions, as well as having greater occurrence of groundwater.

Areas having a weathered mantle greater than 25 m thick but less than 40 m are categorised very good.

Areas having a weathered mantle greater than 15 m but less than 25 m thick (second lowest value in the basin) are categorised good.

Areas having the least thick amount of weathered overburden material, i.e., less than 15 m, are categorised moderate.

Areas having the highest values of greater than 50 m thick fractured zone are categorised excellent and are given the highest weight due to the possibility of better recharge, as well as greater occurrence of ground water

212

Moderate O15

Poor 10

Poor 5

Poor 0

Poor 0

Poor

Excellent

0

45

Very good 40

Good 30

Good 25

Moderate 20

Moderate 15

Poor 10

Poor 10

Poor

Poor

10

10

Excellent 50

Very good 40

Good 35

Moderate 25

Poor 10

Excellent 60

Very good 50

Good 40

Moderate 30

Excellent 60

Groundwater resources development in hard rock terrain JAG l Volume 2 - Issue 314 - 2000

TABLE 2: Continued

No. Theme Class Reasoning behind categorization Category Weight

Category 3

Category 2

Category I

8 Well yields Category I

Category 2

Category 3

9 Water Water bodies/ bodies/ Settlements/ Settlements/ Forest Forest Other land

cover

IO Lineament Lineament buffer zone

and greater groundwater movement.

Areas having a fractured zone thickness of greater than 35 m but less than Very good 50 m are categorised very good.

50

Areas having a fractured zone thickness of greater than 10 m but less than Good 35 m (second lowest value in the basin) are categorised good.

Areas having the least fractured zone thickness, ie, less than IO m, Moderate are categorised moderate.

40

30

Areas having lowest well yield i.e. less than 45 litres per minute is categorised as excellent and given highest weight considering higher requirement.

Excellent 60

Areas having well yields greater than 45 litres per minute but less than Very good 67.5 litres per minute are categorised as very good.

Areas having highest well yield i.e. greater than 67.5 litres per minute are Good categorised as very good.

Areas of surface water bodies and settlements are assigned 0 values to - exclude them from artificial recharge zonation when using the multiplying option.

Areas covered under land cover features other than surface water bodies - and settlements are assigned value of I, so that these areas can retain the same integrated value obtained so far.

Based on field information, the zone of influence of lineaments is Excellent considered to extend up to 150 m from the lineament. Hence a buffer zone of 300 m (150 m on either side of the lineaments) was created; these zones are rated excellent.

50

40

0

I

50

TABLE 3: Grouping of weighting criteria for deriving artificial recharge zones

Thematic layers Total Category1 Al A2 A3 A4 A5 A6 A7 A8 A9 weights Weight limit

30 70 70 45 50 60 60 60 50 E E E E E E E E E

30 60 60 30 40 50 50 50 - VG G VG G VG VG VG VG

20 55 40 25 35 40 40 40 - G G G G G G G G

20 30 I5 20 25 30 30 40 -

G M M M M M M G

5 IO 5 IO 10 30 30 40 - P P P P P M M G

495 E

370

295

210

140

Excellent

(Upper)

Good

(Upper)

Fairly good

(Upper)

Fairly

(Upper)

Fairly (Lower)

No. Category Weight limits Upper Lower

1 Excellent 495 375

2 Good 370 300

3 Fairly good 295 215

4 Fair 210 140

5 Not suitable 0

The polygons categorised fairly good were obtained by in lithology and well yields with those categorised mod-

grouping polygons having weights from 295 to 215. The crate in all other layers. The lower limit of 140 was upper limit of the weight was derived by combining all obtained by adding all least-values in all layers. layers categorised good.

The areas under surface water body, settlement and for- Fair artificial recharge zones were delineated by grouping est were categorised not suitable. The forest area was polygons that had weights from 210 to 140. The upper specifically categorised not suitable because no activities

value was derived by combining layers categorised good are normally permitted within forested areas.

213


By utilising the model discussed above, a map showing

the artificial recharge zones of the study area was pre-

pared (Figure 13). The preliminary artificial recharge

zone map prepared through remote sensing and GIS

techniques was verified in the field for correctness: the

artificial zones demarcated were in agreement with

conditions in the field. By superimposing the drainage

network map over the artificial recharge zone map and

also considering the terrain conditions, the exact type

of artificial recharge structure suitable for replenishing

groundwater in the study area was identified. The

results of our study should help decision-makers set in

motion the steps required to replenish groundwater

aquifer systems.

LDmND KALLAR BASIN EXCELLENT B B*SIN BO”YDeiRI E DOOD m ARTIFICIAL RECHAROE ZONE

FIGURE 13 Map of artificial recharge zones in the study area prepared using remote sensing and GIS techniques

CONCLUSIONS

In order to demarcate artificial recharge zones, different

thematic maps were prepared using either remote sens-

ing techniques or data collected through conventional

field methods. These included maps of lithology, linea-

ments, landforms and landuse from remotely sensed

data; and maps of drainage density, weathered thickness

zone, fractured thickness zone, hydrological soils and

well yield from data collected by conventional survey

methods. By integrating the different thematic layers

using a G&based model developed specifically for this

purpose, an artificial recharge zones map of the study

area was prepared. The drainage network map was

superimposed over the artificial recharge zones map and,

taking into consideration terrain conditions, suitable sites

for construction of artificial recharge structures were

identified. Our study demonstrates the capabilities of

remotely sensed data and GIS techniques for selection of

sites for artificial recharge, especially in hard rock terrain.

Since the present approach was based on logical condi-

tions and reasoning, the same approach can be used

elsewhere with appropriate modifications, especially in

hard rock terrain, where the occurrence of groundwater

is more restricted and complex in nature.


ACKNOWLEDGEMENTS

We are grateful to Dr M.G. Chandrasekhar in his previ-

ous capacity of Scientific Secretary, ISRO Hq, Bangalore,

and Professor S.M. Ramasamy, School of Earth Science,

Tiruchirapalli, for their encouragement to carry out this

study. We are also thankful to officials of the Public

Works Department, Tamil Nadu, for providing ground-

water yield and bore hole data, and to officials of the Soil

and Land use Organisation, Coimbatore, Tamil Nadu, for

providing us with a soil map of the study area.

REFERENCES

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Baldev, S., A. Bhattacharya & V.S. Hedge, 1991. IRS-IA applicatron for ground water targeting. Journal of Current Science 61(3&4): 172-179.

Basappa Reddy, M. & R.L. Gaikwad, 1985. Use of remote sensing techniques for targetting ground water in fractured crystalline rocks: two case studies from Karnataka. Proceedings, Sixth Asian Conference on Remote Sensing, Hyderabad, 21-26 November 1985, pp. 322-327. (Japan : Asian Association on Remote Sensing)

Chaturvedi, R.S., D.C. Bhattacharya, P. Kamal, J. Krishnamurthy & N. Sunder Raman, 1983. Integrating remote sensing technrques in ground water exploration - a typical case study from Bundelkhand region in Uttar Pradesh. Proceedings, National Symposium on Remote Sensing in Development and Management of Water Resources, Ahmedabad, 25-27, October 1983, pp 267-276, edited by Baldev sahai, R.S Chaturvedi, H.S.lyer, (Dehradun : Indian Society of Photo-Interpretation and Remote Sensing)

Chi, K.H. & B.J. Lee, 1994. Extracting potential ground water area using remotely sensed data and GIS techniques. Proceedings, Regional Seminar on Integrated Applications of Remote Sensing and GIS for Land and Water Resources Management ESCAP. Bangkok, pp. 64-69.

ESRI (Environmental System Research Instrtute), 1988. User Guide ARC/INFO: The Geographic Information System software. ESRI, Redlands, CA.

ESRI (Environmental System Research Institute), 1989. ARC/INFO training course class material, Volume 1. ESRI, Redlands, CA.

Gustafsson, P., 1993. High resolution satellite data and GIS as a tool for assessment of ground water potential of a semi-arid area. IXth Thematic Conference on Geologic Remote Sensing, Pasadena, CA, 8-11 February 1993, Vol 1, pp 609619.

Jeyaram, A., 1997. Water Resources Assessment and Management in Uma-Kalhar Watershed, Chandrapur District, Using Remote Sensing and a Geographic Information System. PhD thesis (unpublished), Nagpur University, India.

Krishnamurthy, J., 1993. Geological and hydrogeologrcal studies of parts of Karnataka between latrtudes 13” N and 14” N using remote sensing techniques. PhD thesis (unpublished). Bangalore University, India, I-21 5.

Krishnamurthy, J. & G. Srinivas, 1995. Role of geological and geo- morphological factors in ground water exploration: a study using IRS LISS data. International Journal of Remote Sensing 16(14): 2595-2618.

Krishnamurthy, J., P. Manavalan & V. Saivasan, 1992. Application of digital enhancement techniques for ground water exploration in a hard rock terrain. International Journal of Remote Sensing 13 (15): 2925-2942.

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Krishnamurthy, J., N. Venkatesa Kumar, V. Jayaraman & M. Manivel, 1996. An approach to demarcate ground water potential zones through remote sensing and geographic information systems. International Journal of Remote Sensing 17( 10): 1867-l 884.

Manavalan, P., J. Krishnamurthy, B. Manikiam, S. Adiga, K. Radhakrishnan & M.G. Chandrasekhar, 1993. Watershed analysis response using digital data integration techniques. Advanced Space Research 13, No.5, (5) 177 - (5) 180.

Murthy, K.S.R., 2000. Ground water potential in a semi-arid region of Andhra Pradesh - a geographical information system approach. International Journal of Remote Sensing 21(g): 1867- 1884.

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RESUME

Pour demontrer les capacites de la t&detection et des techniques de SystPme d’lnformation Geographique (SIG) pour le developpement des ressources d’eau souterraine dans des terrains de roche dure, specialement pour la demarcation de sites appropries pour la recharge artificielle d’eau souterraine, une etude a ete faite dans le bassin Kallar, qui est situ& en partie dans les districts de Salem et Tiruchirapalli, Tamil Nadu, lnde. Des cartes thematiques definissant la lithologie, les lineaments, les formes de terrain, I’occupation du sol, la densite de drainage, I’epaisseur de zone humide, I’epaisseur de zone fracturee, les sols hydrologiques et le rendement des sources ont ete pre- parees a partir de donnees acquises par le satellite indien de teledetection (IRS) - IC et par des methodes conventionnelles. Toutes les couches thematiques ont et@ integrees en utilisant un modele SIG developpe specialement dans ce but, permettant de creer une carte montrant les zones de recharge artificielle. Le type exact de structure de recharge artificielle, ex. barrage de controle, “nallabund”, mise en place de caniveaux, etang de percolation, appropries pour alimenter I’eau souterraine a ete identifie en superposant une carte de reseau de drainage sur une carte de zones de recharge artificielle. La demarcation de zones artificielles basee sur un SIG developpe dans cette etude a ete basee sur des conditions logiques et le raisonnement, de sorte que les m@mes techniques (avec des modifications appro- prices) pourraient @tre adoptees ailleurs, specialement dans un terrain a roche dure, oti I’occurrence d’eau souterraine est limi- tee et sujette a une plus grande complexite.

RESUMEN

Se realize un estudio en la cuenca de Kallar localizada en partes de 10s distritos Salem y Tiruchirapalli, en Tamil Nadu, India, para demostrar la capacidad de las tecnicas de teledeteccion y de 10s sistemas de informacidn geogrdfica (SIG) para el desarrollo de 10s recursos de aguas subterraneas en terrenos de rotas duras, especificamente para la delineation de sitios aptos para la recarga artificial de acuiferos subterraneos. Se elaboraron mapas tematicos referidos a litologia, lineamientos, formas de terreno, uso de las tierras, densidad de drenaje, espesor de la zona de meteorizacion, espesor de la zona fracturada, suelos hidrologi- cos, y rendimiento de pozos, a partir de datos suministrados por el Indian Remote Sensing Satellite (IRS)-IC y por metodos con- vencionales. Se integraron todas las capas tematicas en un modelo basado en SIG y desarrollado especificamente para este proposito, el cual permitio elaborar un mapa mostrando las zonas de recarga artificial a ser generadas. El tipo precise de estructura requerido para la recarga artificial, por ejemplo dique de retention, nallabund (dique), tapon de cdrcava y laguna de percolation, apropiado para reabastecer las aguas subterraneas, se identific6 mediante superposition de un mapa de la red de drenaje sobre un mapa de las zonas de recarga artificial. La deli- neaci6n de las zonas de recarga artificial en SIG se bas6 en con- diciones y razonamiento Iogicos, de tal manera que las mismas tecnicas (con modificaciones apropiadas) podrian ser adoptadas en otras areas, especialmente en terrenos de rotas duras donde la ocurrencia de aguas subterraneas es limitada y sujeta a patro- nes complejos.

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