Download Chapter I INTRODUCTION 1.0 Introduction

Chapter I
INTRODUCTION
1.0 Introduction
Morphogenetic parameters such as climate, structure and lithology, resultant
drainage, and slope have direct bearing on the choice of natural landuse practices. It
becomes thus imperative that the physical limiting parameters must be reckoned with
while opting for landuse planning. In many developing countries, the primary landuse
determinants have been economic, social and political, whilst the physical determinants
have been ignored. It is now increasingly realised that analysis of terrain condition should
precede landuse planning . To be more precise, terrain evaluation comprises land
classification and creation of a data bank of parametric base taking into account all the
genetic factors to meet the practical requirements of any landuse planning. The reliability
of information depends on the accuracy of data on different terrain attributes, lithological
sequences, natural vegetation, geomorphic and pedologic development (Pathak, 1982).
Inversely, sustained landuse practices exert lasting impact on the landform features and
often conceal1 modulate manifestations of the dynamic processes taking place in the
earth's near surface. Landuse pattern of an area is the outcome of the interrelationship
between people living therein and its environment. Apparently static land can be highly
mobile through uses. Terrain type and environment determine the landuse pattern of an
area, whereas, landuse practices itself, can contribute to the alteration of the landscape
having long-term manifestations. Increased human activities, and consequent demand on
natural resources especially in the Kerala's context, have resulted in a plethora of changes
in landuse mosaic and morphological features, which have caused irreversible alteration
to the bio-physical foundation. Many of these alterations could lead to severe
environmental degradation and resource depletion, having serious repercussions on
State's economy. These changes have generally gone unnoticed or unrecorded. As a
result, there are little or no attempts to study thcsc issues in proper perspective capturing
all the underlying processes and future consequences. Few studies have been attempted
to highlight impact of various landuse practices on the morphogenetic processes. In a
State like Kerala, where landscape has been intensely modified to accommodate diverse
landuse types within a very limited space and time frame, it is essential to undertake a
diagnostic assessment of landuse pattern as a modifier of the geoecological processes. In
order to cany out such an in-depth study on the direct impact of geomorphological
features on the selection of landuse type, and the latter's impact on the landform, a small
river basin in Kollam district of south Kerala, namely the Ittikara river basin, has been
selected.
1.1 Conceptual background
Geomorphology is the science concemed with the study of the form of the earth.
Analysis of landforms, its evolution and change constitute the core elements of the
subject. Davisian concept (1899) of "Landform as a function of structure, process and
stage" provided the foundation for significant geomorphic enquiry attempting to study
the landform from structural, geomorphologic point of view and to understand the
erosion cycle. It has been acknowledged, that a complete understanding of the
geomorphic processes is necessary for the advancement of our understanding of
landforms, although there was little substantive investigation of processes by
geomorphologists prior to 1960 (Derbyshire et. al., 1979). The denudative processes
taking place on the earth surface is variously affected by climatic factors. Considering the
importance of climate in sculpturing the landscape, a branch of investigation of
geomorphology commonly known as "climatic geomorphology" has evolved. Process
studies, though owes its origin partly to climatic geomorphology, could evolve as a
separate approach particularly with introduction of system theory and quantitative
analysis. Chorley (1971) identified two distinct lines of investigations in physical
geography: (i) process-response systems by the study of contemporary processes, their
character as a response to external constraints and their effects and (ii) study of the
evolution of landscape and landforms concemed primarily with historical development
and chronology. These two distinct lines of investigations are oRen found to overlap and
draw from one another. Jennings (1973) identified six approaches in geomorphological
research within the realm of physical geography (Table 1.0). Process study figures either
as one of the specific lines of enquiry or as a part of climatic geomorphology, and general
systems approach.
Geomorphic research on processes has gained significant importance over time.
A major impetus came from the Geographers of Germany, France, the erstwhile Soviet
Union and East European Countries, who attempted process studies as an integrative
function of land. The works of BudeI (1977), Tricart and Cailleux (1972), Prokayev
(1962), Isanchenko (1973), Richling (1 976) among others bear testimony to the
awareness for the need for process studies in geography. Some of these studies also
attempted to understand the nature of environmental interrelationships,
TABLE I.O APPROACHES IN GEOMORPHOLOGY RESEARCH
Approach
1
Denudation chronology
Field of study
I
Elucidation of stages of evolution, study of the
Davisian trilogy of structure, process and stage.
Climatic geomorphology
Recognition of morphogenetic systems, evolving
under combination of exogenic processes, varying
particularly with climate
Morphometry
Application of quantitative techniques to define and
describe the nature of landforms and their spatial
att tern
General systems approach
1 Study of process-form relationship adopting concepts
from thermo-dynamics
Process study
of
present
processes
and
Quantification
understanding processes in physical or chemical
terms
Structural geomorphology
I Study of the influence of type and rock disposition
Source: Jennings (1973),Derbyshire et. a/. (1 979).
1
I
1
I
I
.
1
1
I
Morphogenic regions (Fig 1.O) have been identified in relation to rainfall and
temperature by Peltier (1950). This scheme of classification applicable in global scale
defines morphogenetic region as a region in which a distinctive complex of erosional,
transportational and depositional processes is responsible for landform development. The
dynamic1 system approach giving emphasis on process measurement and the relation
between process and form has been successful in identifying many features of landscape
that appear to show consistent relationship between inputs and outputs or form (Renwick,
1992). The equilibrium concept and the idea of positive feedback and thresholds
(Langbein and Leopold, 1964; Schumm, 1977, Thomes, 1983) in geomorphology
emanated from this emphasis on process studies.
MORPHOGENIC REGIONS
DOMINANANT PROCESSES
I
I
-10-
F
-d
6
-
O-
/"
c.
2
t
r:
+lo-
m
'.
t
0
2
t
Mechanical and /
Chemical weathering, I
running water /
mass movement ,/
-
,'
+20 -
Mechanical
running water
0
I
I
I
2000
1500
1000
I
500
0
Mean annual rainfall (mm)
Source: Peltier (1950).
Fig. 1.0 MORPHOGENIC REGIONS AND DOMINANT PROCESSES AS RELATED TO MEAN
ANNUAL RAINFALL AND TEMPERATURE
Morphogenetic processes fashioning the landform from earth materials can be
classified as endogenetic and exogenetic. The endogenetic processes are energy forces
acting from within the earth's crust and include crusta1 or non-isostatic warping within
the mantle, earthquake, folding, faulting, metamorphism etc. The exogenetic processes
cover weathering, and surface processes under the influence of climate. The duration,
frequency and effectiveness of geomorphic processes record wide distinguishing features
in long-time unit that are reflected on landforms. The maturity and chronological
sequence of landforms as well as the depositional pattern help reconstruction of climatic
changes. However, while analysing the sequence of fluvial or slope deposits, it may be
concluded that the deposition represents only a small fragment of time and on the
contrary much longer time intervals are reflected in a hiatus or in erosional surfaces
(Starkcl, 1977).
The present-day geornorphic processes act in smaller time frame, following the
seasons of the year, especially the annual sequence of water circulation. The tropics,
characterised by heavy seasonal rainfall and high temperature experience fluctuation in
water and sediment production and movement due to monsoonal effect. The seasonal
factor data can be used in classifying geornorphic process (Wilson, 1973). There are two
group of processes in an annual cycle- the secular and the episodic group of processes.
The secular processes are characterised by low intensity and long duration, and the
episodic processes are of very low frequency and act only during several days or even
hours in a year. Among the secular processes, it is possible to distinguish continuous
processes such as chemical denudation (solution) going on in soil throughout the year and
seasonal or periodic processes such as slope wash, cryogenic processes or transport of the
suspended load in rivers (Starkel, 1985).
Whether the process is of short-time annual duration or of long-time duration, the
modifying factors over the climatic parameters are the vegetation types or more
particularly cover types. Vegetation is considered to be an indirect impact of climate. In
a given climatic environment the plant cover modifies the morphogenetic processes, but,
in turn the latter influence the ecologic conditions (habitat) and thus have repercussions
on the vegetation (Tricart and Cailleux, 1972). The plant formation types interpose a
screen of variable importance between the agents of the weather and the lithosphere.
Depending on the density of undergrowth, vegetation plays an important role as filtering
mechanism. It has to be taken note of that it is seldom the climatic factors of precipitation
and temperature alone which determine the morphological forms. Important
morphological changes may take place through alterations in the vegetation which are
instigated by human activities rather than climatic condition (Zonneveld, 1975). Given
the complex interrelationships of geology, climate, plant, landform and soil in activating
morphogenetic processes, it is quite natural that the concept of scale has to be addressed
while considering the interaction of various morphogenetic factors. Morphogenetic
processes are greatly influenced by plant formation types on a world scale or macro scale.
On a regional scale there is an interplay of pedologic, palaeoclimatic and biogeographic
influences on the morphogenetic processes and, anthropogenic activities are the most
important universal modifier of morphogenetic processes. Further down in a local scale,
the plant species/ vegetation types are the indicators of morphogenetic processes. In
addition there is an interaction between morphogenic and pedogenic processes at the site
level. Identification of top0 sequence and its relation to soil catena forms an important
research problem in soil geography.
Spatial variability of geomorphic processes encountered on earth surface has led
to enquiries that seek identification of homogenous units. However, homogeneity itself
needs to be defined in terms of the amount of variability accommodated within such unit
(Caine, 1982) and the type and number of criteria considered. Land, as defined by
Mabbutt (1968) "is a complex of surface and near surface attributes significant to man"
and Gardiner (1976) stated that "land refers to all those physical and biological
characteristics of the land surface which affect the possibility of landuse".
Most of the land classification systems taking a broader view attempt to
encompass all environmental components, whether or not they are relevant directly or
indirectly to man's use of the land. Moss (1983) proposed a land classification scheme
by incorporating process data (Fig. 1.I). It begins with energy and moisture input and
finally provides the basis and scope for even mathematical modelling. This model
provides conceptual clarity and theoretical background for incorporating process data into
the scheme of land classification. This theoretical framework could be interlinked with
biophysical land classification proposed by Moss (1975) for Canada, Land System
approach of CSIRO, Australia and Terrain System of ITC, The Netherlands. The units
identified under different morphogenetic processes can be ordered into a hierarchy and
use of data at each level could be indicated (Table 1.1). Human induced changes are
reflected in the landuse pattern of any given area.
(1)
ENVIRON INPUI'S:
MAJOR CONTROLS
(3
INTEGRATING
LANDSCAPE
IJNITS
(2)
CONTROL
PROCESSES
(4)
(5)
LAND UNIT
COMPONENTS
(6)
BASIS AND
NATURE OF
DETERMINATION
PROCESS
RESPONSE
-
ENERGY
BIOTIC
WATER
MOISTURE
BUEGET
1
VEGETATION
AND
1
1
PEDOLOGIC
HYDROLOGIC
L
PRIMARY
PRODUCITIVITY
MATHEMATICAL
MODEL
DECAY AND
DECOMPOSITION
MATHEMATICAL
MODEL
SOIL MOISTURE
FLOW
OF NUTKI EN'I'S
1
CAI .CUI.ATIONS
SURFACE
RUN-OFF
Source: Moss (1 983).
Fig. 1.1 A MODEL TO ILLUSTRATE A METHODOLOGY FOR THE INCORPORATION OF PROCESS
DATA INTO LAND CLASSIFICATION
TABLE I.ITERRAIN SYSTEM, PROCESS DATA AND APPLICABILITY
Level of
hierarchy
Terrain
province1
eco-region
Scale
Process data
>1:250,000
Natural
vegetation1
Biomass
Terrain
pattern1
Terrain
system
1:250,000
Pedological
processes
Terrain unit/
Land unit/
Ecosection
Terrain
components1
Ecosite
1:50,000
Geomorphicl
hydrologic
processes
Natural
changes and
impacts due to
human
intervention
(anthropogenic
processes)
1:10,000
Environmental value
of data
Land surface
dynamics
(fundamental land1
biotic function
controls)
Modificationofbasic
functions by local
controls (soil
capability)
Local expression of
changes in controls by
various processes
Site specific
information processresponse
Use of data
Major regional
decisions
concerning land
management
Rankingof
potential value for
regional decisions,
geo-ecological
evaluation
Landuse planning
Soil erosion
potentiall critical
area assessment
1
Due to interlinkage of rnorphogenetic processes, the hnctional changes in humanenvironment relationship reflected through landuse pattern trigger a cascading change
from local to global levels, from specific to diffuse and from low complexity to high
complexity. Landuse change takes place at the site level or micro level, whereas, drivers
of landuse change can be either proximate cause or macro level decision or both and
similar is the case with impact of landuse change. The horizontal and vertical linkages of
landuse change, especially in the case of deforestation is given in Fig. 1.2.
Environment
Economic
Sociat
Source: Gallop in (1994); Winograd (199 7).
Fig. 1.2 VERTICAL AND HORIZONTAL LINKAGES: THE CASE OF LANDUSE
The morphogenetic processes are thus subjected to alteration as a result of landuse
change. Capturing of these changes and study of their impact on landscape form
important research agenda. Many of the landscape studies attempt to concentrate on
interaction of the ecological processes with the environment to create landscape pattem
and influence of these patterns on ecological functions (0 Neillet. al., 1995). There is a
need to develop measures of spatial pattern and to correlate pattem with ecological
processes in micro level study, particularly in today's context of societal quest for
sustainable development.
The present thesis is based on the above conceptual framework. The
morphogenetic processes have been-linked to landuse pattern and geoecological impacts
were assessed. The study framework is given in Fig. 1.3.
,
Analysis
/-+
Evaluation
Landuse
Morphogenetic
processes
+ Geology
+ Climate
+ Hydrology
Agricultural
and other use
Change
+ Landfonn
+ Soil
+ Vegetation
I
\
Environmental
evaluation
Deforestation
Soil degradation
Jr Sand and clay
mining
*
*Jr Demography
*
Occupation
Geoecological impact
+3 Landform and landuse
Q Landuse, water quality and hydrogeochemistry
+3 Landuse and demography
4
I
Load
I
I
Impact
1
Fig. I.3 STUDY FRAMEWORK
1.2 Review of literature
Study of rnorphogenetic processes had gained importance during the 2ndhalf of
the last century. Although, the necessity for the study of processes has been felt since the
development of the subject, substantive research activities related to processes could be
traced since 1950s (Chorley, Dunn and Beckinsale, 1964, 1973). As early as 1877 Gilbert
wrote about the erosion, weathering, transport, deposition and equilibrium in studying the
geology of Henry Mountain, Utah. Various approaches followed in geomorphology have
been reviewed by Chorley and Kennedy (1971), Dury (1972), Jennings (1 973), Brown
(1975) and Chorley (1978). All these reviews tried to highlight the development of the
subject and the main thrust. Development of theory of geomorphology has been
'
envisaged through a number of phases from teleological to taxonomic to functional
(Chorley, 1978). Derbyshire et. al. (1979) attempted to provide an introduction to
geomorphological processes and their operation procedure.
Process studies have progressed in four ways (Selby, 1985): These are: (i)
detailed measurements both in the field and laboratory based firmly on physical sciences,
(ii) use of statistical techniques and rigorous measurement, (iii) availability of large
volume of data and computer application and (iv) enlarged scope of work due to
availability of fund and trained manpower. Recent improvement of knowledge covering
the aspects of rate, mechanism, models and application has added impetus to geomorphic
research related to processes.
German and French geomorphologists had drawn attention in incorporating
climatic variables in geomorphic studies. The branch of climatic geomorphology has
been evolved in these processes. Budel (1977) contented that exogenous processes, in
their climatic variation, create the morphological picture of the earth, while geological
structures and tectonics merely influence and modify local landform (Selby, 1985).
Identification of morphogenetic regions associated with dominant processes and climatic
variables was attempted way back in 1950 by Peltier (1950) in a global scale. This
approach could not take note of the periodicity of geomorphic processes in relation to
climatic seasonality, role of vegetation and soil and impact of anthropogenic intervention
in modifying
the landcover. However, subsequent developments in climatic
geomorphology have tried to address the role of vegetation and soil. Climatic
geomorphology indeed must examine the interactions between all the factors influencing
the processes covering geologic structure, climate with seasonal variability, vegetation
and soil (Tricart and Cailleux, 1972). Geographers of Soviet Union and other East
European Countries have contributed significantly in furthering process studies in
geography. Works of Isachenko (1 973), Prokayev (1962), Starkel (1 976), among others,
are noteworthy.
Study of landscape evolution depends on understanding the present spatial
distribution of processes and process rate, linkage between erosional and depositional
component, comparison of spatial versus temporal change and appraisal of stratigraphic
record. The Binghamton symposia concentrated on "Space and Time in Geomorphology"
to cover these issues (Thorn et. al, 1982). Significance of the process studies, as Johnson
(19 82) pointed out is "in understanding the mechanics and control of geomorphic
processes and short-term variability and behaviour of geomorphic systems and
land forms".
Response of the processes can be captured spatially by identifying different
landform or terrain units. Since Mabbutt's (1968) and Gardiner's (1976) emphasis on
land as an end product of complex ecological interactions, there have been various
approaches proposed from time to time. Moss (1981, 1983) proposed land classification
methods by incorporating process data. The Land System approach by CSIRO, Australia
and the Terrain System approach by ITC, The Netherlands attempted to classify land
following landscape approach incorporating geomorphic processes (Meijerink, 1988,
Chattopadhyay and Mahamaya, 1995).
As process study is related to dynamic/ system approach, it is necessary to
investigate within a framework of a river basin, which collect, concentrate and coordinate
the movement of water and sediment. Gregory (1976) reviewed the drainage basin
studies since 1700 and identified seven approaches: Morphometry (spatial and topology),
Basin characteristics, Channel pattern, Channel geometry, Theory, Dynamics and Palaeo
studies. From Horton's (1945) morphometric analysis to Chorley (1962), Schumm's
(1 977) emphasis on palaeohydrology and metamorphosis of rivers and river channels, the
primary concern is to understand the process variation in water and sediment production
over time and effect of processes over landforms at present, in the past and also in the
future. Recent attention has been drawn to the applied studies.
During 1970s greater emphasis was given for a more integrated approach to
environmental problems and in subsequent three decades research agenda changed at
various levels. Environmental impact assessment, sustainability and sustainable
development become part of the common usage not only in research parlance but also in
general society. Spatial heterogeneity and pattern observed in the field are recognised as
important landscape components and not averaged across the space. Site-specific
intervention of human being on the terrestrial biosphere creates a mosaic of Landuses that
tend to threaten the basic mosaic of the intact ecosystems on intact landscapes (0 Neill,
et. a[., 1995). In a review article Stuart Chapin et. al. (2000) observed that "landuse
change is projected to have the largest global impact on biodiversity by the year 2100
followed by climate change, nitrogen deposition, species introduction and changing
concentration of atmospheric COz". Studies on landuse and landuse changes are not only
gaining more and more importance but also becoming the focus of mu1ti-disciplinary
studies covering a host of issues related to drivers as well as consequence of change.
Turner (1999) proposed merger of local and regional analyses of landuse changes
because regional and local processes are highly interconnected. Butte1 and Taylor (1994)
made similar observations in their studies on environmental sociology and global
environmental change. Walker and Solecki (1999) pointed out that land conversion (local
issue) often becomes a serious environmental issue at the regional scale involving
regional ecosystems. Blakie (1989) highlighted the relation between land degradation
and landuse at the local level. He pointed out the emphasis in the classic approach on
environmental problems leading to environmental solution and on the 'ignorance' of land
users.
Several studies on landuse have been attempted in India at different levels. Most
of the works were initiated following Dudly Stamp's landuse survey of U.K. in the
beginning of 1940s. It was at the 1940 session of the Indian Science Congress held at
Madras that Prof. S.P.Chatterjee pointed out the necessity of undertaking the landuse
survey in Tndia on the lines of the landuse survey of Great Bretain. He published a report
on "Land utilization in the District of 24 Parganas, Bengal" in 1945. Dayal (1947)
prepared a thesis on agricultural geography of Bihar. He discussed the influence of soils
and climatic elements on land utilization, the pressure of population on land and the
nature of land utilization. Chattejee (1952) undertook more detailed land utilization
survey in Howrah district and 1200 landuse maps at the scale of 1:3960 covering 813
villages were prepared. Rao (1947) has emphasized the techniques of soil survey for
analysis of landuse in the Godavari region. Roy (1968) documented rural landuse pattem
in Azamgarh. Singh (1971) dealt with the optimum carrying capacity of the land in
Punjab. Deshmukh (1 975) studied rural landuse of Lonkhede. Models in land utilization
were documented by Mandal(1980). Sustainable development initiative was documented
by Singh (1996). Planning for sustainability on natural resources and bio-energy was
attempted by Maheshwari et, al. (1996). There had been a change in landuse studies in
India, from mere documentation of changes the attempt is now to investigate the cause
and consequences of landuse change. Advent of Remote Sensing and Geographic
Information System (GIs) have facilitated time-series and multi-variable analysis.
Chattopadhyay (19 85) studied deforestation in Keral a and attempted to highlight the
related issues. George and Chattopadhyay (2001) analysed the landuse in Kerala in
relation to population pressure.
Biophysical land classification for the State of Kerala was attempted by
Chattopadhyay and Mahamaya (1998) in order to design sustainable landuse pattem.
Maharnaya (1998) attempted geomorphic analysis for sustainable landuse development in
a small drainage basin of south Kerala. The thrust of the paper was to link potential
landuse with land units identified based on processes.
River basins are considered as natural integrators of the effects of many natural
and anthropogenic inputs and anthropogenic interventions. Water quality parameters are
determined and hydrogeochemical investigations of rivers, water bodies and oceans have
become important tools to evaluate the environmental degradation of catchments for
identification of sources of pollution. Major scientific concern about global river quality
dates back from the 1950's when the International Association for Scientific Hydrology
launched a world-wide programme for the first time (Durum, et. nl., 1960). This work
was one of the databases of Livingstone (1963), a master-work on river chemistry which
still constitutes the only available thesaurus at global scale. Meybeck and Helrner (1989)
did the monitoring of river quality of pristine stage to global pollution. Meybeck (1998)
studied man and river interface, its multiple impacts on the Seine river basin.
Biogeochemistry of major African rivers was documented by Martin and Probst (1991).
Further, Meybeck (2001 ) worked on global alteration of riverine geochemistry through
anthropogenic interventions.
In India, Agarwal and his team (1976) assessed water quality parameters
(physico-chemical) of the Ganges at Varanasi. Chandrasekhara Chetty (1978)
documented utility aspects of river waters affected by saline incursion in Goa.
Subramanian (1979) generated hydrogeochemical data sets for the major drainage basins
of India. Varshney (1981) worked on water pollution and management reviews, Trivedi
(1988) generated data sets on ecology and pollution of Indian rivers. Venkateswarlu and
Sarnpathkurnar (1982) made chemical and biological assessment of pollution in river
Moosi, Hyderabad. Systematic hydrogeochemical investigations have been initiated in
Kerala with the pioneering work on Killi Ar (river) (CESS Report, 1995, 1996).
Mahamaya el. al. (1996, 1997) documented results and generated data on Killi Ar (river).
Human impact on the biogeochemistry of rives has been studied by Ittekkot and
Subramanian (1999). Dekhov et. al., 1999 has documented chemical composition of
riverine suspended matter and sediments from the Indian sub-continent. Suresh (1999)
has studied impact of urbanisation on quality of groundwater regime. Status of riverine
pollution in south Kerala and its relation to physiography and landuse have been
documented by Soman, et. al. (1997,2002).
This brief general review of literature has brought out that there were several
topical studies attempted at di fferent levels but few studies tried to link rnorphogenic
processes with landuse within a larger fiame of analysis, evaluation and impact studies.
1.3 Objectives
The study on Ittikara river basin has been undertaken with the following precise
objectives:
a. In-depth analysis of the morphogenetic processes operative in the Ittikara basin
including elucidation of the role of geology and structure on landforms,
morphometric analysis of surface drainage, landform analysis covering slope form
and profile analysis, and finally identification of morphogenetic regions,
b. Detailed analysis of the landuse pattem and its changing trend over the years,
c. Assessment of human resources and importance of demographic parameters in
altering physical processes,
d. Evaluation of major environmental issues, especially problems of deforestation, soil
degradation, sand and clay mining as contributors to changes in riverine ecology, and
analysis of hydrogeochemistry and environmental biogeochemistry as indicators of
water quality and onland changes,
e. Impact assessment of morphogenetic processes on landuse pattem and
1 'ce
versa,
impact analysis of landuse pattern on water quality, interrelation of landuse pattern
and demography, and
f. Application of Geographic Information System (GIs) for understanding the
geoecological impact.
1.4 Study area
The Ittikara drainage basin occupies the southern sector of Kollam and a small
portion of Thiruvananthapuram districts and it extends from 8" 44 10 N to 9' 0 50
latitudes and 76" 37 E to 77' 2 20 E longitudesl'he river Ittikara originates from the
low hills of Karakumu (250 metre above Mean Sea Level) adjacent to Madathara in the
foothill region of the Westcm Ghats and flows through the Yeroor Reserved Forest area
in a straight north-westerly course where streams of various orders are formed and join
the main river (Fig. 1-4). After flowing over the midland terrain river Tttikara debouches
N
LOCATION MAP
IlTlKARA DRAINAGE BASIN
-
5-
D
I
INDEX
Roed
cr--H
------- k b l d bwndary
Fig. 1.4
I
Railway
I
W
-
Stream
I
I
into the Paravur Kayal north of Paravur in the south-western portion of Kollam district
(Fig. 1.5). The river Ittikara is a west-flowing stream. The river has a length of 56 km out
of which 16 km stretch is considered for navigation in the downstream section.
Catchment area of the basin is 650 km2. The length of :he coastline forming the western
boundary of the study area is 9.50 lan.The basin comes under the realm of tropical drywet climate. Ittikara basin encompasses 7 blocks covering 32 panchayats and one
municipality (Fig. 1.6).
Before discussing characteristics of the study area surface and groundwater
conditions are discussed here briefly in order to provide the background information. The
total surface water potential in the Ittikara basin has been computed to be 446 MCM
(CGWB, 1987). Monthly discharge varies from 1972 to 1992 (Appendix I). Around
7.1% of the annual rainfall drains out as base flow in the basin, however, it records
spatial variation depending on terrain type, soil, landuse and management practices. Base
flow contribution derived from data obtained fiom Ayur gauging station for the period of
1972 to 1992 is determined to be 14.5% of the annual run-off. The annual percentages of
base flow varied between 2.7% and 19.9% of the annual run-off. With the available
limited data, water table contour map has been prepared for Ittikara basin (Fig. 1.7). It
was based on water-level measurements in the wells for the pre-monsoon, 1994.
Contours could not be drawn in the upland portion of the basin due to non-availability of
data. Water table of the basin is controlled by its physiography, geological formations,
extent of weathering of rocks, rainfall and vegetation cover. Water table contour pattern
tends to follow the contours of the overlying ground surface, although in a more subdued
form. Water table contour map shows that the general flow o f groundwater is towards
west.
Geologic and geomorphic setting and structural features of the area under normal
conditions of precipitation control the occurrence and movement of groundwater.
Continuity, thickness and aquifer characteristics of the strata determine the groundwater
storage potential (CESS Report, 2001). In order to assess the groundwater potential of the
Ittikara basin hydrogeology map was prepared (Fig. 1.8). Along with lithologic features,
DRA l NAGE
ITTIKARA BASIN
I
Fig. 1 . 5
I
I
ADMINISTRATIVE MAP
ITTIKARA DRAINAGE BASIN
1 -0
I
2
h
Legend
O D i s l r i c l Boundary
Block Bol~ndary
Panohayat Boundary
Road
Rnl lway
WATER TABLE CONTOUR
ITlKARA DRAINAGE BASIN
D
-10-
Contour (m) (above MSL)
NA
Dala not available
5Kms
Sourn: year 1994. R-onn
HYDROGEOLOGY
IlTlKARA DRAINAGE BASIN
0
urkm.~
Lateli.
m
Gama - blots.
Khondallte
Fig.1.8
Ple~~t~cene
gneiss
h
INTRUSIVES
AGE
Recant
5
#
-
SIhb and d ~ p
d]olnI
--._
. .
M~owne
-+ C
Archasan
t
---.
+
Area suhble for grnund
water dmloprnenl wilh a
thick zone of latent0 Imlley fill
Major fault zone
Araa s u W c Lor groundmter
~ a b w w l b
p
o
~
Alarmn
Ummant
Gatrce CGWB 1087
structural and terrain details were also considered for evaluating the water resource
potential. Areal spread of lithological units show that hard crystalline rocks comprising
khondalites, garnet-biotite gneisses and the intrusives occupy about 45% of the study
area. Groundwater potential in this zone is relatively low. Towards west, rolling terrain
with laterite formation has better groundwater potential. Coastal sedimentary beds show
good groundwater prospect.
The Ittikara basin displays unique physical diversity ranging from wide coastal
plain and low-lying lands in the west to dissected midland and highlands of the Western
Ghats in the east. The major landuse category in the basin is settlement with mixed tree
crops. Recent landuse survey reveals that a considerable portion of the area under mixed
tree crops and forest are converted into rubber and plantation crops. The water resource
of the basin is assessed as 429 ~ r n The
~ .wetlands of the basin, according to the PWD
(1974) estimate require 343 ~ r n of
) water for imgating three paddy crops and 50% of
gardenlands need 123 ~
r ofn water.
~ At present, no major irrigation scheme is in
operation. However, the Kallada Irrigation Project is supposed to imgate an area of 152
km2 of the basin. Irrigation facilities are provided by a few lift and minor imgation
schemes at present. Detailed investigations are being carried out for the Ittikara River
Valley scheme for examining the scope for irrigating the lands to the right bank of the
Ittikara river which are not covered by the Kallada Project and those to the right bank of
the Varnanapuram river. In addition to these, there lies the scope for construction of a
number of subsidiary storage across the river in its upper reaches.
Eravipuram panchayat of Mukhathala block recorded the highest population
density of 5533 personsflanL whereas Kulathupuzha panchayat of Anchal block had a
population density of 78 persons/krn2 according to 1991 census. The basin area has well
connected road networks. According to the Department of Economics and Statistics,
1996, the National Highway has 25 km, coverage within two panchayats and 66 km of
State Highway falls within seven blocks encompassing the study area (Appendix 2).
Other than these, Main District Roads (MDR) owned by FWD, Kerala and panchayat
roads are also well maintained.
1.5 Methodology and data source
In order to pursue the study proposed here, qualitative and quantitative analyses
of a large number of parameters covering biophysical, landuse, and demographic
characteristics are envisaged. The methodology will address the issues related to
morphogenesis and interrelated aspects like terrain pattern,
geoecology and
environmental evaluation. An effort has been made to establish causal relationship among
apparently independent factors. Methodology adopted included primary data collection,
field mapping, map analysis in laboratory with the help of topographic sheets of
1:250,000and 1:50,000 scales, secondary data collection from various departments and
computer application in data assimilation and display. Analyses of physical factors and
landuse mapping on macro scale as well as in micro scale have been taken up. Analysis
and mapping have been done for the Ittikara basin as a whole and for its three important
sub-basins, eg. Palliman Ar., Kulanji Thodu (stream) and Man Ar which are situated on
three different physiographic units. Geographic Information System (GIs) are a useful
and perhaps necessary tool for incorporating environmental indicators into the
development process. As the data really represents actual-ground condition and can be
transformed and manipulated interactively in a GIs, they can serve as a test bed for
understanding the environmental processes or for analysing the results or trends or for
anticipating the possible results of planning decision (Burrough, 1986).
The geological map has been prepared by assimilating data from existing
geological maps. The lineament map was prepared by deciphering data from IRS image
in 1:50,000 scale.
Morp hometric analyses or quantitative geomorphology of drainage basins and
channel networks were taken up to understand river geometry. This section treats
quantitative landform analysis as it applies to normally developed watersheds in which
running water and associated mass gravity movements, acting over long period of time,
are the chief agents in developing surface geometry. Emphasis is upon the geometry
itself, rather than upon the dynamic processes of erosion and transportation which shape
the forms (Strahler, 1964). Linear aspects of the channel system, areal aspects of drainage
basin and relief aspect of drainage basin have been attempted in order to appraise the
channel morphometry and to understand the denudational processes operative in various
parts of the basin.
In evaluating terrain, the classification system must begin with the "main origin",
the dominant process currently operative. Under each of these dominant processes or
specific origin a number of sub-units have been identified which has formed the base of
morphogenetic regions. Geomorphological mapping has been done based on
identification of terrain units by landscape approach propagated by International Institute
for Aerospace Survey and Earth Sciences (ITC), the Netherlands (Verstappen and Van
Zuidam, 1968) and as adopted for Kerala by Chattopadhyay and Mahamaya (1995). It
was based on experience in the use of the then known geomorphologic systems and
legends used for map-making of various parts of the world. The ITC methods were
modified and developed further and it became a true mapping system with distinct
characteristics. Three main approaches can be recognized which have been considered in
designing such a system; these are:
1.
the genetic approach
2.
the landscape approach
3.
the parametric approach
In the genetic approach, much attention is given to geologic aspects and
geomorphologic processes, with little attention to landforms. The landscape approach can
be further modified if it is based on landform, lithology and genesis. The landform
characterises the landscape quite well. They are recognized with ease both in the field as
well as from image and can easily be grouped into systems or sub-divided into
components. Another advantage of this approach is that the units can be grouped into
higher order or can be sub-divided into lower order depending upon the number of
variables considered. The parametric approach refers to the terrain classification on the
basis of selected attributes like slope, altitude etc. It provides a quantitative fiamework
for an otherwise qualitative or descriptive map.
Table 1.2 modified and adopted from Babiker (1 977) provides a comparative
statement of important characteristics of different approaches:
TABLE I.2 TERRAIN CLASSIFICATION APPROACHES
I Genetic approach I Landscape approach I Parametric approach I
I Characteristics
Reconnaissance
survey
Possible
Possible
Difficult
Semi-detailed
Not Applicable
Possible
Possible
Unit dimension
Large Units
Medium to small size
Small
Boundary
Vague
Clear
Vague
Homogeneity of units
Not possible
Possible
Field identification of
units
Possible in terms of
single parameter
Difficult
Easy
Limited, mainly
academic
Planning Oriented
Short
Short
survey
Time
duration
for
Difficult
Limited
Long
survey
Although, there are differences among these approaches, it is important to
consider them as complimentary. A combined approach provides significant results
particularly where the purpose is application oriented. It is possible to consider genetic
data, landform attributes and specific parametric data for the units depending upon the
need or planning requirement. It is possible to establish hierarchical classification system
for terrain analysis by involving more and more parameters at different levels. The
classification process begins with geomorphologic origin followed by specific origin,
lithology, morphometry (relief, valley density, slope form) and finally incorporating
soillcatena information, sequence can be established. Table 1.3 is compiled to show the
hierarchical classification system followed in various countr~eslinstitutions. It is evident
from this Table 1.3 that there is a similarity of thought about the occurrence of
identifiable units of landscape, which can be arranged into a hierarchical order.
TABLE 1.3 HIERARCHICAL CLASSIFICATION SYSTEM
Level
I
II
Scale
CSlRO
Australia
Bio-physical
(Canada)
I:250,000
Terrain
Province/
Complex
land
system
Eco areal
Eco region
Land
Terrain
pattern/
Land
Eco zone
Ecodistrict
1:250,000
Oxford
MEXE
Physio
graphic
ITC
(Netherlands)
Germany
Soviet
Union
Physiographic province
Terrain
Province
Macrochore
Landscape
mestnest
Land
System
Main
physiographic unit
Terrain
system
(pattern)
Mesochore
Urochische
Eco section
Land
facet
Detailed
physio
graphic unit
Terrain
Unit
Microchore
Urochischa
Ecosite
Land
element
Physio
graphic
element
Terrain
component
Eco-tope
complex
Facies
region
system
III
I : 50,000
Terrain
unitlland
unit
IV
1 :I
0,000
Terrain
componentlsite
-
The terrain classif cation scheme adopted for Ittikara basin is landscape approach
based on a scale of 1:50,000 and incorporates data related to all aspects of morphologic
processes, rnorphometry, soil and landuse. This scheme partly draws from the ITC
system of geornorphologic mapping. The classification scheme adopted here follows the
principle of hierarchy theory (Haigh, 1987). A 4-order classification system has been
built-up (Fig. 1.9). Each order is so defined that the units are mutually exclusive with a
specific generic concepts and a lower order unit represents a sub-order of the immediate
higher order unit. The higher order units (1'' and 2" order) have been identified using the
. terrain units have been
existing body of knowledge. The 3" order categories, i . ~ the
demarcated from the landsat data products, whereas the 4th order categories were
identified from PAN image analysis and through field mapping.
'
ATTRIBUTE
LEVEL
SAMPLE TYPE
Terrain province
level-1
Western Ghats1
Upland
1
I
Climate
1
~rocess-1
r
Physiography
Lithology
I
I
Terrain system
level-ll
Structure
Accretionall
Erosional units
Erosional state -
i
Landform
Morphograp hy
--
h
Terrain component
Floodplain1
level-Ill
Beach
-
Geoforrn
I
Terrain component
level-IV
Valley floor1
Levee
Fig. 1.9 THE SCHEME OF TERRAIN CLASSIFICATION
Mapping has been done in 1 :50,000 scale by using topographical maps and in
1:25,000 scale extracting data from PAN image (IRS IC, 1999) for selected sub-basins.
Slope maps of selected three sub-basins of Ittikara Ar have been prepared by
dividing the area in 0.25 km2 grid and computing the average slope for each grid by
taking into account the lowest and the highest altitude and distance between these two
points within the concerned grid (Chattopadhyay and Mahamaya, 1995).
The importance of hydrology in the assessment, development, utilisation and
management of the water resources of 'any region is being increasingly realised at all
levels (Raghunath, 1985). Rainfall data analyses have been done with the available data.
The river is being gauged at Ayur and Ittikara. However, the available discharge data are
not suficient for any correlation study. Hydrogeological map has been prepared along
with the water table contour map. Well depths were monitored for this purpose with
supplementary data obtained from the Central Ground Water Board.
Landuse bears a close correspondence with the terrain characteristics, especially
in the tropical countries, where agriculture is much akin to the natural ecosystem
(Mahamaya and Sakunthala, 1987). The study envisages to characterize landuse units in
relation to land system units and in turn to assess the land potential for better
management. Landuse map for the Ittikara basin has been prepared in 1:50,000 scale
using topographical maps and IRS image. Three sub-basins of Ittikara river covering 48 %
of the basinal area have been taken up for detailed analysis. Data have been extracted
from PAN image (IRS IC, 1999). The principle of visual interpretation of satellite image
is followed. As a first step image characteristics are translated into land management
attributes. The translation process (transfer function) is guided by local knowledge (eg.
soil, geologic or landuse maps; reports or agricultural statistics), which can be gathered
during fieldwork or through background studies. In the next step polygons are drawn
around features (fields, land units, homogeneous areas with natural vegetation, settlement
etc.) and a label referenced to tables is assigned to each polygon characterizing it by
attributes (the legend). Image characteristics can be pattern, texture; colours or tones on
the image; or the changing colour during a growing season (Bronsveld et. al., 1994).
These were subjected to detailed field verifications. Time-series landuse maps were
prepared to detect changes oveL the years. Accurate up-to-date information is of critical
importance for land management. Data on changing conditions are needed continually to
detect problems, plan activities and predict and monitor results of activities.
Agriculture is the prime occupation of the people of this basin. Crop statistics for
the period of 1996 for Kollam and Thiruvananthapuram districts were collected from the
State Planning Board, Government of Kerala, Thiruvananthapuram. Crop combination
method proposed by Weaver (1954) has been used to indicate dominance of crop
practices at panchayat level. The details of the method are given in Appendix 3.
Analyses of demographic parameters were based primarily on 1991 census data.
Decadal growth of population, and population density have been calculated for each
panchayat. Occupational structure of the populace has been dealt with.
The chapter on environmental evaluation is based mainly on primary data and
observations. Secondary data were also used to supplement the findings. Extent and
depletion of forest coverage have been marked from satellite image of 1999. Estimate on
sand and clay mining were based on primary data. Hydrogeochemical analysis and study
on environmental biogeochemistry were conducted through primary s w e y . 17 sampling
stations were selected based on a combination of physiography, drainage and landuse
parameters. Water samples were collected and they were analysed for physico-chemical
and microbiological parameters in the Chemical laboratory of the Centre for Earth
Science Studies. Biogeochemical samples were analysed at the Institute of
Biogeochemistry and Marine Chemistry, University of Hamburg and at the Center for
Tropical Marine Ecology (ZMT), Bremen, Germany.
Geoecological impact assessment aims at identifying the consequences for the
biogeophysical environment and for man's health and welfare of implementing particular
activities (Michele et. nl., 1995). Geographic Information System (GIs) is a useful and
perhaps necessary tool for incorporating environmental indicators into the developmental
process. The integration of economic, social and environmental indicators in a spatial
framework allow for more powerful and realistic analyses than those offered by
conventional non-spatial methods (Wingrad and Eade, 1997). GIs based overlay analysis
and modelling are extremely useful for aiding our understanding of environmental
systems and helping in management decision making. Integration of data on landform,
landuse and water quality was possible through application of GIs. Thematic maps on
landform, landuse, relief, drainage, drainage density, population density along with their
attributes were integrated using PC ARC/INFO and PC TIN softwares. 3-D modelling
was accomplished from the 20 m-interval contour map of the study area (part). This is a
representation of a surface derived from irregularly spaced sample points and break line
features. Each sample point has an X, Y coordinate and a surface of Z value. These points
are connected by edges to form a set of non-overlapping triangles that can be used to
model the surface (PC ARCtINFO, 1995). Thus digital terrain model (DTM) for a subbasin has been created by regular array of Z value, referenced to a common datum which
represents terrain relief. Overlay analysis is also done to ascertain the interconnectivity.
Spatial and seasonal variations of DO, BOD and FC are shown through G I s analysis. The
sampling stations along the main and tributary streams were digitized. DO values for
different sampling seasons were marked by attributing class interval and linear influence
of the sampling stations as emerged from the analytical results (CESS Report, 1996).
Product moment correlation coefficient has been worked out based on the indices value
calculated for each panchayat in order to understand the spatial association and
intercorrelations among population, landuse and gross cropped area of panchayats.
1.6 Hypothesis
Following hypotheses related to objectives for the study on Ittikara river basin
have been cited. An attempt has been taken to establish the hypotheses regarding
morphogenesis and landuse and vice versa, in the following chapters. The hypotheses are
as follows:
* Terrain condition is a determinant of landuse pattern
Landuse pattem is primarily governed by the terrain condition. The physiography-soilmatrix exerts pronounced influence on landuse pattern as is explicit in the State of
Kerala. It is intended to test this observation under this hypothesis.
* Landuse/landcover alterations impact landscape type
Landscape types are modified by landusel landcover changes. When wetlands are
diverted to garden lands and to accommodate settlement, the local slope condition,
surface run-off and infiltration rate etc are modified. This hypothesis attempts to
highlight this issue.
* Spatial variations in landuse pattern influences water quality
Drainage discharges, both quality and quantities are influenced by rainfall, terrain type,
soil, geology and landuselland cover. Given a uniform rainfall pattern soil, ten-ain and
geologic condition, it is the landusel landcover that affects the drainage discharge pattern.
It is necessary to study the spatial variability of landuse and water quality parameters to
capture this impact. This hypothesis is designed to test this interrelationship.
* Landuse and landscape alterations affect biogeochemical cycling.
Alterations of landuse and landscape, although occur locally, have long- range impact on
biogeochemical cycles as they affect the water system through which the cycles are
linked. This hypothesis will posit the study in a larger fi-ame.
1.7 Expected contribution of the thesis
This thesis is expected to contribute in understanding the overall environmental
condition of the basin especifically in the realm of the following five issues: 1)
deciphering the responses of natural systems to environmental changes; especially in the
realm of landusel landcover changes and their responses on the landscape as well in the
aquatic system, 2) integration of environmental parameters into landuse planning and
management, 3) geoecological impact assessment of activities that can affect land-water
systems through RS-GIs application, 4) definition and listing of indicators that can be
used to assess different impacts, and 5) design of remedial actions.
Geomorphologic indicators, measured successively over time, are expected to
describe trends in the conditions of phenomena, systems, resources or assets.
Goemorphologic indices can help in assessing the impact of human activities, for
example on sediment transport and erosion processes, and the degree to which these
processes interfere with human activities (Rix,1995). Reconsideration of earth science
education was proposed by Fabbri and Cendrero (1995) in view of research contribution
in problem identification and problem solving.
In this context the present thesis will have a long-term contribution. As the
framework of this thesis is multi-disciplinary, it is expected to enrich the roots of Earth
Science education.
,
1.8 Arrangement/ Organisation of the thesis
The integrated structure of the many different components in the complex array of
morphogenetic analysis and its impact on landuse pattem as well as geoecological
assessment make it difficult to compartmentalize the material. A division of these
materials into seven large parts, however, provides a logical and convenient form for
analysis.
Chapter I- Introduction: This chapter provides a synopsis for the thesis and sets the stage
for the types of problems and for the considerations that are necessary for their solution.
This chapter introduces the topic in Kerala's context, its purpose and broad aim and its
linkage to larger issue. Literature review, methodology of the work and hypotheses have
been dealt in separate sub-chapters.
Chapter 11- Analysis of Morphogenetic Processes: This chapter deals mainly with the
analyses of morphogenetic processes highlighting on morphometric analysis of river
Ittikara, slope profile, landform and identification of morphogenetic regions and it is
discussed under appropriate separate sub-headings.
Chapter III- Londuse: Analysis of landuse pattern is of ovemding importance in the
context of physical and environmental resource assessment and it is dealt in separate subheadings. Landuse pattern of the total basin as well as of three sub-basins- Palliman Ar,
Kulanji Thodu and Man Ar have been discussed in detail. Time-series landuse mapping
of these sub-basins occupy an important part within this chapter. Cropping pattem along
with crop combination within the basin area have been dealt with.
Chapter IV- Demography: Demographic pattern of the basin area emphasizing on
population density distribution and decadal growth has been discussed in this Chapter IV.
Description of occupational structure of the working population is provided under various
headings.
Chapter V- Environmental Evaluation: This chapter deals with deforestation, soil
degradation, hydrogeochernistry, environmental biogeochemistry, groundwater quality
and sand and clay mining. A sample survey on critical area analysis is also included.
Chapter VI- Geoecological Impact Assessment: This chapter puts forward geoecological
impact assessment derived from parametric analyses and deductions of hypotheses
discussed in proceeding chapters. Impact of landuse changes on water quality as well as
on population density and impact of landform on setting landuse pattern have been
discussed under separate sub-headings.
Chapter VII- Conclusion: The concluding chapter advances the major findings of the
study after analytically evaluating adoption of methodology and data source. Limitations
felt on the methodology and data source have also been recorded. Finally, the study
concludes by suggesting remedial measures for improving the situation faced by
environmental as well as by anthropogenic dimensions.