Karst water resources evaluations have been increasingly implemented in recent
years as the demand for water has been increased. Information on karst water
resources characteristics provides threshold values for different water based
activities. Approximately 11% of Iran territories is covered by carbonate rocks
(Afrasiabian, 1998) and within the Lar catchments, 33%
of the area is occupied by exposed karstified carbonate rocks, in which sinkholes,
caves and karstic springs occur locally.
Characterization of the natural and regional extend of lineaments developed
on the hard formations and their relationship to water resource discharge points
is important for the evaluation of ground water resources. Tectonic elements
such as faults, joints, folds and bedding patterns play an important role in
the karstification and lineaments derived from remotely sensed data, might have
high correlation with vertical or near vertical zones of fractures concentration
which may act as conduits for transport and storage of ground water (Lattham
and Parizek, 1964; Parizek, 1976; Krishnamurthy
et al., 2000).
In the last two decades remote sensing and GIS have been widely used for preparation
of different types of thematic layers and integration of them for different
purposes. Application of remote sensing and GIS in ground water resources management
and using structural element and lineament for investigating water resource
have been practiced by Krishnamurthy and Srinivas (1995),
Solomon and Ghebreab (2008), Sener
et al. (2005) and Pirasteh et al. (2006).
Krishnamurthy and Srinivas (1995) discussed the role
of geological and geomorphological factors in ground water exploration. Sener
(2005) and Kim et al. (2004)
investigated ground water potential zone through the analysis of lineament and
Pirasteh et al. (2006) distinguished groundwater
potential zones in karst area using geospatial techniques.
This research was carried out in an area of approximately 740 km2
within Lar river catchment, about 85 km North East of Tehran, capital
city of Iran.
The propose of this research was to investigate the spatial correlation
of hydro geomorphologic features identified as lineament and fracture
traces located in a karst geological catchments of the studied area as
they might be possibly related to the subsurface ground water parameters.
MATERIALS AND METHODS
The research was conducted within the Lar catchment located in upstream
of Lar dam, southern part of Alborz Mountains and 85 km far from Tehran city,
Iran, from May to December 2007. The study area, about 750 km2, located
in the coordinates of between 35, 48 to 36, 04 N and 51.32 to 52.04 E and at
the elevations of 2400-5670 m above sea level, as a part of Lar river catchment,
has been shown in Fig. 1. Lar river flows from north west
to south west and has 6 main tributaries. The area covers the middle sector
of the Alborz Mountains. The Alborz Mountains are a continuation of the Alpine
Type Mountains, which are a complex asymmetric belt of folded and faulted rocks
(Stoklin, 1974). The area is mainly underlain by limestone,
volcanic beds and lake deposits. The limestone units consist of medium bedded
limestone of upper Jurassic age (Lar formation) and a massive fine grained limestone
of Early Cretaceous age (Tiz-koh formation) and marly limestone of Middle Jurassic
(Dalichai formation). The volcanic rocks include mainly trachy- andesitses,
formed by the activities of Damavand Mountain which is of Early Pleistocene
age and also Tuff of Miocene age (Karaj formation). The lake deposits consist
of two units informally named as lower and upper deposits (Stoklin,
|| Location map of the study area
|| Karst potential map
This research was accomplished using ILWIS 3.1 (Integrated Land and Water
Information System), PCI EASI/PACE 8.2 and Microsoft Excel software at
Soil Conservation and Watershed Management Research Institute of Iran
(SCWMRI). Land Sat TM 2002 satellite images and 1/50000 scaled topographical
maps, geological maps and black and white 1/20000 aerial photos used in
this research were supplied from Geological Survey of Iran and Iran Remote
Sensing center. The research had five stages; i.e., data collection, satellite
image processing, thematic layer creation, building a database and spatial
Different thematic layers were prepared and classified to several
classes to investigate spatial relationship between geo-structural and
hydro geomorphic data. After categorization, all the thematic layers were
integrated with one another by GIS technique using the cross, distance
and buffer operation.
Karst Potential Layer
The concept of karst potential was used to provide an indication of
where karst might occur and what level of karst development might be anticipated.
This was carried out by analyzing geology maps, images and aerial photos
Criteria used to evaluate karst potential within a particular polygon
created by the researcher are likelihood that karst forms on soluble bed
-rock (e.g., massive and thickly bedded limestone, dolomite)` the proportion
of soluble bed -rock based on lithology, unit thickness and strati-graphic
information and position. There are, of course other important factors
that control karst potential (e.g., secondary porosity, mineralogical
composition, etc.), but that type of information was not available at
this scale of mapping and data collection.
Topo Springs Layer
The topographic map shows a large number of ground water discharge
points such as springs and seeps observed at the time of the topographical
survey. They have been classified in the form of discharges with short
duration. Data of the fieldwork have been added to what was termed as
topo-spring layer (Fig. 3).
||Topo spring map
|| Tectonics elements layer
Topography, Elevation and Slop Layer
Topographic data is a vital element in determining the water table.
The topographic map was digitized on a 1/50000 scale base map and after
generating a Digital Elevation Model (DEM), topographic elevation and
slope maps were extracted from the DEM.
Tectonics Elements Layer
This layer was prepared from tectonic elements shown on the geologic
map and compiled by adding some elements which were extracted by visual
stereoscopic analysis of 1/20000 scale, black and white aerial photographs
(Fig. 4). The lineaments resulting from visual interpretation
of enhanced images were in a separate layer although the same features
Drainage pattern is one of the most important indicators of hydro
geological features and the pattern, texture and density are function
of underlying lithology. Drainage map was prepared from the topographical
map with 1/50000 scale.
|| Lineament layer
|| Rose diagram for the lineaments showing major trends
of lineaments occurring in the study area
Identification of Lineaments on Land Sat TM Image
The Land Sat Imagery was acquired on 18.7.2002, which was suitable
because vegetation was developed after the spring period and in July it
could be assumed that vegetation cover possibly responded to the soil
moisture in fractures.
For lineament extraction, different techniques have been used, suggested by
Suzen and Toprak (1998) and Moore
and Waltz (1983) and also automatic lineament extraction by PCI EASI/PACE
soft ware was experimented. The most effective method was found to be image
enhancement by different filter operations and visual extraction of lineaments,
checking and removal of questionable lineament and integration of the lineament
extracted from different filter operations in one layer. In addition, the images
were integrated with digital elevation model in order to better evaluate the
relationships between tonal linear features and topography. The land sat images
were also compared with geological map and black and white 1:20000 aerial photos
to provide additional information on lineament. Optimum bands used for lineament
extraction were the summation of band 4, 5, 7 (Fig. 5). Lineaments
were detected and summarized in a Rose diagram (Fig. 6).
RESULTS AND DISCUSSION
Ground water studies on hard formations often require extraction of data
from images and remote sensing and GIS providing support in groundwater
studies. Due to insufficient data, maps of Lineament and structural elements
are important tools that may reveal points of groundwater recharge and
discharge, flow and development. In particular, groundwater occurrence
in hard formations are mainly controlled by the lineaments corresponding
to fractures, joints and faults. Furthermore, the distribution of lineament
is closely related to groundwater discharge points and their concentration.
Most ground water resource exploration and evaluation projects consider
relationship between lineament and tectonic elements with well data as
a tool, on the contrary, this study uses relationship between springs
data and lineament to narrow down the study targets. The overall results
demonstrate that relationship between lineament, structural elements and
groundwater discharge points presented in this study can be used for future
groundwater exploration to narrow down exploration targets. In this study,
to investigate further relationship between lineament and groundwater
occurrence, all data layers were integrated in GIS environment and results
were discussed as follow:
The relationship between the percentage of springs and the distance from
the main tectonic elements and lineaments. Figure 7
and 8 showed a tendency for springs to occur at short
distance from tectonic elements and lineament and it can be concluded
that they were conduits of water and signify their role in conveying water.
||Relationship between percentages of springs and distance
from tectonic elements
|| Relationship between percentages of springs and distances
away from lineaments
||Relationship between tectonic elements length and number
of springs in sub catchments of study area
|| Relationship between tectonic elements and drainage
From the good correlation between number of springs and tectonic elements`
length and also the concentration of springs close to the lineament and
tectonic element, it was concluded that fractures indicate zones of enhanced
porosity and conductivity thus they can have a positive influence on the
ground water occurrence and they act as transmission routes in the limestone
Tectonics elements generally correspond to fracture zone and location
of springs is a function of fracture zones then it can be expected that
there is a good relationship between tectonics elements and number of
springs. Figure 9 and 10 showed that
this was the case in the Lar catchment.
In geologically active region, drainage is a function of tectonic and
generally high drainage is expected in regions of high faults and fold.
Figure 11 showed a good correlation between tectonics
elements and drainage lengths.
A concentration of springs was found in the lower slope classes. The
same was true for the relationship between elevation classes and percentage
The relationship between number of springs in karstic area and distance
from limestone contact, Fig. 12 shows a tendency for
springs to occur at short distance from limestone contact. This can be
the result of ground water escaping from the karstic area through the
shear zone near the contact of competent and in competent rocks.
|| Relationship between drainage length and number of
||Relationship between number of springs within karstic
area and distance away from limestone contact
A rose diagram generated for lineaments Fig. 6, extracted
from the satellite image, suggests that the dominant lineaments orientation
is between 140-170 degrees and that it can be related to the main structural
direction. The second lineaments trend lied between 140-110 N-W, shows
cross folding or shear zones. The third class of lineaments was orthogonal
to the first directions and was consistent with the counterclockwise rotation
of compressive stress.
In karst potential map generated based on previously described criteria,
a continuous body of karst units bounded by non-karstic terrains was distinguished.
There was also a small discontinuity in North West, north and south of
the study area.
From the dominant trends of lineament extracted from satellite image
and the tectonics elements` map and the location of discontinuity, it
is likely that underground passage ways and exchange of groundwater occurs
between adjacent catchments and sub catchments within Lar catchment. This
is also confirmed by the presence of large and active sinkholes in the
study area and known under ground water losses to the reservoir.
The research was supported by Soil Conservation and Watershed Management
Research Institute of Islamic Republic of Iran. This support is gratefully