DEPARTMENT OF CIVIL ENGINEERING
GIS & ITS APPLICATION IN WATER RESOURCES
Dept. of Civil Engineering
CONTACT NO: 8807423228
GIS & ITS APPLICATION IN WATER RESOURCES
Water requirement increases day by day for urbanization, industrialization and modern agricultural developments. Groundwater is the major readily available fresh water in the earth and hence it is being continuously tapped from the ground in order to meet the growing population , resulting in rapid decline in ground water head. Artificial recharge is one of the important techniques used to improve the ground water potential which gains lot of attention throughout the world . So an attempt has been made to improve and manage the ground water resource in a part of Tambraparani basin, South India using Remote Sensing and GIS techniques.
Definition of Remote Sensing & GIS
Remote Sensing is a Science or a technology and art of obtaining reliable information about an object, without being physical contact with the object. Various electromagnetic energy detecting sensors are currently being operated from airborne and space borne platforms to assist the inventorying, mapping and monitoring the earth resources. These sensing devices capture the data on the way, various earth surface features emit and reflect the Electro Magnetic Radiation (EMR), and provide information about the resources under investigation
A GIS is an organized collection of computer hardware, software, geographic data and personnel designed to efficiently capture ,store, update, manipulate ,analyze and display all forms of geographically referenced information.
AIM AND OBJECTIVE
- Data input from maps ,aerial photos ,satellites ,surveys and other sources regarding topography ,drainage,land use,geology, hydrogoemorphology, lineament and groundwater flow are used for map overlaying for selecting a site to construct a weir across pachiyar river (one of the tributaries of Tambraparani).
- To learn the advance techniques and methodology used in the field of remote sensing and GIS.
- To know the Groundwater fluctuation and movement.
- To demarcate the Groundwater potential zones of the study area.
STUDY AREA LOCATION
In Tamil Nadu, there are 17 major river basins have been demarcated based on the drainage system and among which Tambraparani basin is an important basin in the southern part of Tamil Nadu which is located 8°25' to 9°13'N and longitude 77°10' to 78°10'.Study area is located between latitudes 8°37'5" to 8°45' and longitudes 77°37'48" to 77°45' in the toposheet 58H/10 of 1:50000 scale, published by Survey of India in the year 1968.Tirunelveli and Palayamkottai are the major settlements in this region.
The study area experiences mostly dry climatic condition with the maximum temperature around 40°C during the month of April and May and the minimum temperature around 24°C during the month November and December. The average annual rainfall is 718mm at Tirunelveli & 688mm at palayamkottai. Among these, North East monsoon from October to December contributes 435 mm & 413mm of rainfall and the South West monsoon from June to September contributes 69mm & 71mm of rainfall recorded at the rainfall stations in Tirunelveli and Palayamkottai respectively.
Elevation contours, triangulated heights and spot heights of the terrain with respect to MSL are in the contour map. The map was prepared from toposheet 58H/10.The maximum elevation is about 145mts at the top of the structural hill situated adjacent to the Tambraparani river in the NW quadrant and the minimum elevation is about 36mts in the NE part of the study area.
IMPORTANCE OF CONTOUR MAP IN GROUND WATER MANAGEMENT
- In understanding the slope of the terrain and surface run off.
- For selecting the site to locate Dams, reservoirs, percolation ponds etc.
- To select the site for waste disposal.
- To understand the groundwater fluctuation and movement.
- For canal alignment.
Geology of any area will give the details about the lithology and the structures like folds, faults, joints etc .Granitic mica gneiss and garnetiferous gneiss are the major rock types in this area which are demarcated in the geological map.
Importance in ground water studies
- To understand the aquifer characteristics like types of aquifer, aquifer thickness, porosity, permeability etc
- To study the groundwater quality. To select the site for constructing check dams and ponds.
The drainage map of study area was prepared from toposheet 58H/10 and also the drainage patterns were three dimensionally (3D)viewed from stereopair aerial photographs under mirror stereoscope.
To understand the slope of the terrain,
- To know rainfall infiltration and runoff based on the drainage density
- More number of drainage = less infiltration and more runoff
- Less number of drainage = more infiltration and less runoff
- To understand groundwater flow direction and recharge mechanism.
- Dentritic (tree branch)type of drainage in the SE portion of the study area indicates that quantity of the rainfall infiltration is comparatively less because of less number of fractures existing in the hard rocks.
The hydraulic properties in hard rock formations mainly depend on the nature and thickness of weathered and fractured zones ,which are more pronounced near the surface .Most of the wells in the study area are partially penetrating because ,once a significant depth of water column is achieved, formers stop further deepening of wells.
Ground water always moving from the higher potentiometric level to the lower potentiometric level.this can be understood only by measuring the water level in wells with respect to some datum plane ,commonly MSL(head).The ground water was calculated for about 20 location and to be found that the general ground water flow is towards east and in the southeast portion of the study area ,the flow is towards northeast.
Geomorphological map was prepared from the IRS û IC û LISS III satellite imagery. Different geomorphological units namely flood plains, pediments, shallows pediment are marked in the map. Flood plain alluvial deposits are indicated by the presence of vegetation along the Tambraparani river which are red in colour in the satellite image.
Pediment is nothing but, the occurrence of bed rock at or near the surface. It is further grouped as shallow pediments and deep pediments.
· Shallow pediments
· Deep pediments
In the case of shallow pediments, the thickness of the topsoil is quite less and in deep pediments the thickness of overburden top soil, weathered and fractured zones are more. Hence deep pediments are the better places for ground water exploration.
A knowledge of land use and land cover is important for many planning and management activities concerned with the surface of the earth. Panchromatic medium scale aerial photographs were used in olden days for land cover studies. More recently small scale aerial photographs and satellite images have been utilized for land use mapping of large areas.
The term land cover relates to the type of features present on the surface. Corn fields, lakes, trees and high ways are all examples of land cover types. The term land use relates to the human activity or economic function associated with a specific piece of land. United States Geological survey has classified the land use pattern into 9 groups as
· Urban or built up land Agricultural land
· Range land
· Forest land
· Wet land
· Barren land
· Perennial snow or ice
Land use map of the study area was prepared from IRS û IC û satellite imagery. The map gives the details about the classification of agricultural and barren lands. Agricultural lands has been categorized as
· Command areas
· Ayacut areas
· Nonayacut areas
· Land irrigated using river ands canal water is said to be command land.
· Ayacut lands are associated with lakes and other water bodies.
· The areas irrigated by bore wells and dug wells are called as nonayacut areas.
· Barren land is the land of limited ability to support life. In general dry salt flats, beaches, bare rock exposures, mines and quarries are said to be barren lands.
GROUND WATER POTENTIAL ZONATION
Recent days Remote Sensing and GIS techniques are widely used as an important tool to go for ground water targeting. Flood plains, palaeo channels, alluvial fans & cones, bajadas, lineament intersections in hard rock terrain are some of the important areas of ground water occurrences.
Eventhough the lineament intersections are marked as moderate to high ground water potential zones in the ground water potential zone map of the study area, the detail geophysical investigations to be carried out to conform the occurrence of ground water.
OVERLAYING OF THEMATIC MAP
The information in the form of hard copy maps and tables or as computer files that can be merged with other layers of information in a Geographical Information System (GIS) and then the output is presented to users who apply it to their decision-making process.GIS is one of the powerful tool to handle and analyze the spatial data.
Ground water potential zonation map was brought out after overlaying all the thematic maps namely topography, drainage, geology, hydrogeomorphology, land use and lineament by assigning proper weightage for these themes using GIS. Flood plain alluvial deposits all along the rive Tambraparani are coming under high ground water potential zones" and most of the lineament intersections are falling under the category of " moderate to high ground water potential zones.
SATELLITE DATA ANALYSIS AND INTERPRETATION
Various thematic maps namely lineament map, geomorpological map, land use map and ground water potential zonation map were prepared from the geocoded IRS satellite imageries. Size, shape, scale, shadow, pattern, tone, texture, location and association are the important interpretation keys used for identifying different features.
IRS û ID û LISS III, Jan 1998 and IRS- IC û LISS III, April 1999 satellite imageries were used for our interpretation. Here IRS indicates the name of the platform/satellite û Indian Remote sensing Satellite and LISS indicates the name of the sensor.
Lineaments are the linear features of geological origin. Lineaments can be traced using aerial photographs and satellite imageries. It is defined as a mappable single or composite linear feature of a surface whose parts are aligned in a rectilinear or slightly curvilinear pattern and which differs distinctly from the pattern of adjacent features and presumably reflects the sub surface phenomenon.
The lineaments of the study are were marked using the geocoded IRS û ID û LISS III Jan 1998 satellite image based on the alignment of vegetation, alignment of tanks, straight river course and the linear tonal variation. Generally lineaments are resulted by faulting and fracturing. They represent areas and Zones of increasing porosity and permeability in hard rock areas. Such Zones may have significance in the accumulation and movement of ground water.
SIGNIFICANCE OF LINEAMENTS IN GROUND WATER STUDIES
- Weaker Zones of high rainfall infiltration in hard rock areas.
- Most of the lineaments holding ground water resulting in vegetation along them on the surface.
- Useful locations for the construction of water weirs and recharge ponds.
- Controlling the accumulation and movement of ground water.
INSTRUMENTS USED FOR INTERPRETATION
· Digital Planimeter
· Global Positioning System
· Mirror stereoscope
· Computers & Softwares-ARC/INFO, MAP/INFO etc
· Various thematic maps namely base map, contour map, drainage map, lineament map, land use map, geomorphology map, ground water potential zone map have been prepared from the toposheet and geocoded satellite imageries. Importance of these maps pertaining to groundwater studies were elaborately discussed in this paper.
· No necessity of constructing new ponds because numerous tanks are already existing in the study area, which can be maintained to improve the quantity and quality of ground water by desilting and clearing the bushes.
Well inventory survey was carried out and various details were collected from 16 wells in different locations of the study area .Ground water level variation with respect to topography was also established.
- Remote Sensing & GIS by Anju Reddy
2. Basic Remote Sensing & GIS by Anand
3. Raghunath.H.M (1996),"Ground Water",2nd Edition,New Age International Publishers ,New Delhi.
4. Lillesand.M.and Kiefer.W., (1994), " Remote Sensing and Image Interpretation", 3 rd Education, John Wilexy & Sons, New york