Multi criiteria analysis using GIS for ground water resource evaluation in Rawasen...

Multi criiteria analysis using GIS for ground water resource evaluation in Rawasen and Pili Watershed, U.P.

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Sandeep Goyal*, R.S.Bharadwaj*, D.K.Jugran**
* Remote Sensing Applications Centre, Bhopal, M.P. 
** Indian Institute of Remote Sensing, Dehradun

Groundwater exploration is based upon terrain characteristic alongwith lithology, landuse and other parameters. These thematic information generated through remote sensing technique can be integrated in GIS for evaluation of groundwater resources. In order to achieve the objective it is essential to systematically organise the database and check out every possibility of interthematic and interclass dependencies and variability operating in nature. In the present study an attempt has been made to use Multi Criteria Evaluation technique to evaluate the interclass and intermap dependencies for ground water resource evaluation in Rawasen and Pili river watershed, which are tributaries of Ganga. The individual class weights and map scores were determined through this technique. These weights were applied in linear summation equation to obtain a unified weight map containing due weights of all input variables, which was further reclassified to arrive at groundwater potential zone map.

After air, water is indispensable for mankind. Groundwater is one of the prime sources of fresh water. Its exploration and evaluation depends on various methods and criteria, geology, geomorphology, slope etc. are the governing factors for the development of groundwater regime. The information on the above can be acquired and integrated through various techniques. In the present study an attempt has been made to use remote sensing, geographical information system (GIS) and multi-criteria analysis of decision support for evaluation of groundwater in watersheds of Rawasen and Pili rivers which are the tributaries of Ganga.

Study Area
Rawasen and Pili watershed is located in lesser Himalayas with the Ganga River as the western boundary and it lies between Haridwar and Kotdwara towns. Garhwal hills form the northern boundary and the alluvial fans of river Rawasen and Pili constitute the southern part. The watershed lies between 29° 45’ 48″ to 30° 00’ 04″ north latitudes and 78° 10’ 24″ to 78° 29’ 34″ east longitudes and cover an area of approx. 500 sq. km. Administratively the study area falls in Pauri-Garhwal and Haridwar districts of U.P. Climate of the area is sub-tropical to temperate, which is generally controlled by the altitude and slope aspects. The southern facing slopes exposed to sun are warmer than northern slopes. The average annual rainfall is 1400 mm. In winter months the temperature ranges from 1.2° C to 12 ° C. Physiographically area can be divided into two major units i.e. hilly region of lesser Himalayas and alluvial fans of Rawasen and Pili rivers.

Material Used
The material used for the purpose of the above area comprises of Survey of India toposheet on 1:250,000 and 1:50,000 scales respectively covering sheets 53 J/8, K/1 & K/5. Aerial photographs on 1:60,000 scale numbering OC/960/51-7 to 11 and no. OC/960/52-5 to 30 and satellite images IRS-1B LISS II FCC Geocoded 53 J/8, K/1 and 53 K/5 were visually interpreted. Digital data on CD-ROM, IRS-1C LISS III BIL format 4 bands, band 2,3,4,5 path 97, row 50 dated 11.2.98 was also used. Decision support system for multi-criteria analysis software DEFINITE and ILWIS GIS software version 2.1 were used for analysis purpose. Auxiliary data such as rainfall data from north division Ganga Canal, Haridwar, UP and tube-well data, hand pump data from UP Jal Nigam, Haridwar and Meerut were incorporated for meaningful analysis.

Methodology
The groundwater exploration in the study area involved thematic map generation and their integration through GIS. Geology, Landuse, Geomorphology and Lineament maps were derived from interpretation of Satellite Images and Aerial Photographs supported by selective ground truth verification. Drainage map was prepared using Survey of India toposheet on 1:50,000 scale. Slope map was obtained by creating DEM after interpolation of spot height and contour in GIS. For integration all the maps were converted into digital format in the GIS. Prior to integration of different information, individual class weights and map scores were assessed based on Satty’s Analytic Hierarchy Process. In this method a pairwise comparison matrix was prepared for each map using Satty’s nine point importance scale and this matrix was solved using Eigon Vector method. In this method the basic input is the pair wise comparison matrix “A” of order nxn constructed based on Satty’s scaling ratios.

A = [ aij ] where i,j = 1,2,3 ….n

The matrix “A” has generally the property of reciprocity and also the consistency. This is explained as

Aij = 1/aji

Mathematically the equation of matrix can be defined as

(A – Il ) x = 0
I = Identity matrix of order of n x n
l = Eigon value
x = Eigon vector

This resulted in individual class weights. The map scores were also calculated by same method. These weights were multiplied with map scores and applied to linear summation equation (proposed by Voogd 1983)

S = S wi xi
S = weighted map
wi = weight of individual class
xi = map scores

This resulted in a unified weight map containing due weights of all input variables. The weight values ranged from 1.58 to 29.072. This map was further logically classified to arrive at groundwater potential zone map.

Results & Discussions
The main factors responsible for groundwater resource development are geology, geomorphology, landuse/landcover, slope, lineaments etc. Geologically the area is characterised by distinct rock types showing structural and stratigraphic controls. These rocks are quartzites, phyllites and schists of Garhwal and Tal group, red shales of Subathus, sandstone and shales of Siwaliks and Recent Alluviums. Alluviums, middle and Upper Siwalik sandstone and Garhwal quartzites are supporting good groundwater regime (Fig. 1). Geomorphology is one of the main controlling factor of groundwater. Genetically the landforms of the study area were divided in three parts i.e. Fluvial origin, Denudational origin and Structural origin (Fig. 2). The landforms such as flood plain, alluvial fan, fan terrace are supporting good groundwater condition. The landuse refers to the main activities and human intervention and are carried on land. Two level of classification was done in area by visual interpretation of satellite data of two seasons i.e. April and November (Fig. 3). The maximum area was occupied by dense forest followed by agricultural land.

Slope map is generated from the contours and spot heights taken from the SOI toposheet consist of five classes from gentle to very steep slope (Fig. 4). Gentle, moderately gentle and moderate slopes are supporting favourable conditions.

The drainage system of an area gives important clues of the subsurface conditions, which helps in deciphering groundwater conditions of that area. The common drainage patterns observed in the study area are parallel to sub-parallel and dendritic. Parallel to sub-parallel pattern is dominant in siwalik group of rocks, whereas in garhwal group of rocks mainly dendritic to sub-dendritic pattern is found (Fig. 5). Water divide zones were delineated with the help of drainage map because they are the zones where no percolation of water takes place and are not suitable for groundwater storage (Fig. 6).

Lineament plays vital role in the development of groundwater regime. Lineaments were mapped from aerial photographs and satellite images. IRS LISS III-B AND 3 digital data is also used to delineate the lineaments by applying – 5 x 5 predefined directional filter. Which has enhanced the edge and helped in updating the lineament map. These lineaments were classified in four classes i.e. major, minor, fault and thrust depending upon their nature and extent. Fault and thrust were not considered in the study because of non-availability of any ground data to assess their behaviour. Major and minor lineaments were considered in study and buffer zones of 75m and 150m for major and 50 m and 100 m for minor lineaments are taken for study (Fig. 7).

Criteria Weights and Map Scores
To determine the relative importance or weights of each individual class with another in each thematic map six importance matrices were prepared by pairwise comparison on Satty’s importance scale. These matrices have the property of consistency known as consistency ratios (CR). Satty indicates that the matrices with CR ratings greater than 0.1 should be re-evaluated. This way it helps to analyse the matrix to determine the inconsistency in defining the interrelationships. The above method was applied to the six matrices to evaluate the individual class weights. These weights were normalised by multiplying with 100 to avoid complexities of computation. The importance matrices and their weights are as follows:

GEOLOGY MAP

  ALLU LGMM LTAL UTAL LSIVA MSIVA USIVA SUB WEIGHT
ALLU 1.00 7.00 7.00 7.00 7.00 6.00 5.00 7 0.460
LGMM 1/7 1.00 3.00 3.00 2.00 1.00 1.30 2 0.093
LTAL 1/7 1/3 1.00 1.00 1/2 1/3 1/3 1/2 0.038
UTAL 1/7 1/3 1.00 1.00 1/2 1/3 1/3 1/2 0.038
LSIVA 1/7 1/2 2.00 2.00 1.00 1/20 1/3 2 0.064
MSIVA 1/7 1.00 3.00 3.00 2.00 1.00 1.00 3 0.112
USIVA 1/7 3.00 3.00 3.00 3.00 1.00 1.00 2 0.144
SUB 1/7 1/2 2.00 2.00 1/2 1/3 1/3 1 0.052

CR = 0.034
ALLU = Alluviums
LGMM = Garhwal Quartizite and Phyllite
LTAL = Lower Tal Quartizite and Phyllite
UTAL = Upper Tal Quartizite
LSIVA = Lower Siwalik sandstone
MSIVA = Middle Siwalik Sandstone
USIVA = Upper Siwalik sandstone
SUB = Subathu shale
SLOPE MAP

  GENTLE MOD. GENTLE MODE RATE STEEP VERY STEEP WEIGHT
GENTLE 1.00 1.00 3.00 5.00 7.00 0.377
MOD. GENTLE 1.00 1.00 3.00 4.00 5.00 0.341
MODERATE 1/3 1/3 1.00 2.00 4.00 0.146
STEEP 1/5 1/4 1/2 1.00 3.00 0.090
VERY STEEP 1/7 1/5 1/4 1/3 2.00 0.046

CR = 0.026

GEOMORPHOLOGY MAP

  FP UAF LAF HILL DS UFT LFT weight
FP 1.00 2.00 1.00 8.00 7.00 4.00 3.00 0.297
UAF 1/2 1.00 1.00 8.00 7.00 3.00 2.00 0.204
LAF 1.00 1.00 1.00 8.00 7.00 4.00 3.00 0.251
HILL 1/8 1/8 1/8 1.00 1/31 1/6 1/7 0.021
DS 1/7 1/7 1/7 3.00 1.00 1/5 1/6 0.032
UFT 1/4 1/3 1/4 6.00 5.00 1.00 1/2 0.087
LFT 1/3 1/2 1/3 7.00 6.00 2.00 1.00 0.125

CR = 0.044
FP = Flood Plain
UAF = Upper Alluvial Fan
LAF = Lower Alluvial Fan
HILL = All types of hill
DS = Denudational/Dissected slope
UFT = Upper Fan Terrace
LFT = Lower Fan Terrace

LANDUSE MAP

  AGRI DF DF1 GL BL OF SC WEIGHT
AGRI 1.00 3.00 5.00 1.00 2.00 5.00 5.00 0.299
DF 1/31 1.00 2.00 1/31 1/20 2.00 2.00 0.106
DF1 1/50 1/20 1.00 1/31 1/20 1.00 1.00 0.065
GL 1.00 3.00 3.00 1.00 3.00 3.00 3.00 0.263
BL 1/20 2.00 2.00 1/31 1.00 2.00 2.00 0.137
OF 1/50 1/20 1.00 1/31 1/20 1.00 1.00 0.065
SC 1/50 1/20 1.00 1/31 1/20 1.00 1.00 0.065

CR = 0.015
AGRI = Agricultural Land GL = Grass Land
DF = Dense forest BL = Barren land
DF1 = Degraded forest SC = Scrub Land
OF = Open Forest

LINEAMENT BUFFER MAP

  MAJOR (75m) MAJOR 1 (150m) MINOR (50m) MINOR 1 (100m) WEIGHT
MAJOR (75m) 1.00 2.00 3.00 5.00 0.486
MAJOR 1 (150m) 1/2 1.00 1.00 5.00 0.227
MINOR (50m) 1/3 1.00 1.00 3.00 0.207
MINOR 1 (100m) 1/5 1/3 1/3 1.00 0.080

CR = 0.011

WATER DIVIDE ZONE MAP

  WATER DIVIDE ZONE NO WATER DIVIDE ZONE WEIGHT
WATER DIVIDE ZONE 1.00 1/9 0.1
NO WATER DIVIDE ZONE 9.00 1.00 0.9

CR = 0.032

Same process was also applied to define the map scores. The matrix and weight is as follows :

ALL THEMATIC LAYERS

  GEOM GEOL LIN LUSE SLOPE WDface =Arial size=2 WEIGHT
GEOM 1.00 5.00 5.00 8.00 5.00 9.00 0.486
GEOL 1/50 1.00 3.0 3.00 2.00 9.00 0.188
LIN 1/50 1/31 1.00 5.00 3.00 9.00 0.156
LUSE 1/80 1/31 1.50 1.00 1.00 9.00 0.069
SLOPE 1/50 1/20 1/31 1.00 1.00 9.00 0.082
WD 1/90 1/90 1/90 1/90 1/90 1.00 0.019

CR = 0.092
GEOM = Geomorphology map
GEOL = Geology map
LIN = Lineament buffer map
LUSE = Land use map
SLOPE = Slope map
WD = Water divide zone map

All individual class weights were multiplied with map scores and kept in linear summation equation to result in a unified weight map. This map was classified to get five potential zones from excellent to poor (Fig. 8).

Acknowledgement
This study has been carried out under partial fulfilment of 10 month’s PG Diploma in Remote Sensing at IIRS Dehradun. Authors are thankful to Dr. S.N. Divedi, Director General, MPCST, Dr. S. Khan, Incharge, RSAC, Dr. P.S. Roy, Dean IIRS for providing the opportunity to carryout the study and their support time to time.

Thanks are also due to Shri S.P. Agarwal, Scientist ‘SD’, WRD, IIRS, Dehradun, and Dr. Alok Dubey, Reader, Geography Deptt, Allahabad University, Dr. R.K. Singh, Sr. Scientist and Shri Alok Choudhary and Shri P. Kawishwar, scientists, RSAC for their great support during the study.

References

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