MAPPING AND CHARACTERISATION OF GROUND WATER OF GUJRAT

MAPPING AND CHARACTERISATION OF GROUND WATER OF GUJRAT








 
MAPPING AND CHARACTERISATION OF GROUND WATER OF GUJRAT

Introduction:
Gujarat state is located between 20o 01' to 24o 07' N latitudes and 68o 04' to 74o 04' E longitudes and covers an area of 195984 sq. km. This accounts for six per cent of total geographical area of the country. It is bounded by 1600 km. long Arabion sea coast in west and South –West, Pakistan in North, and Rajasthan in the North-East. Madhya Pradesh in the East and Maharashtra in the South and South -East. Out of total geographical area of 19.6 M ha, 16.9 M ha. is covered under soil units including rock outcrop. These are cultivable land making 86.4 per cent of total geographical area. Runn of Kutch covers 11 per cent and remaining 2.5 per cent area is covered by habitation water bodies mangroves and swamps (Sharma et. al., 1994).
Physiography and relief:
Depending upon elevation, slope and ruggedness of the terrain, Gujarat state has been divided into three physiographic regions, namely, Central Highlands, the western hills and the West coast. (Fig. 1)
Geology:
The important rock formation of the state is Pre-Cambrian, Archaeana and Aravalies. The Aravalies are composed of highly metamorphosed quartzite, conglomerates, slates and lime stones. Besides Jurassic sandstone is fairly wide spread in Kutch and north-eastern part of Kathiawar. The cretaceous sand stone is observed as rock outcrops in parts of wadhwan (Kathiawar) and Sabakantha. The Kathiawar peninsula is mostly covered with Eocene basaltic flows having trappean characteristics. Tertiary rocks are mainly exposed along the coastal region of Surat, Bharuch and north-east of Kathiawar and Kutch. The gypsiferous clay the Dwarka beds are located along the western coast of Kathiawar. The large alluvial tract spreading from Surat to Banaskantha is of estuarine, aeolian and marine origin which is the result of an extensive Pleistocene sedimentation.

Climate:
In terms of standard climatic types typic climates, sub humid, arid and semiarid climates spread over different regions of the state. The regions in the extreme of kutch district and western parts of Banaskanta and Mehsana in the North fringe of Saurasthra and its western parts have arid climate. Extreme South of the state has sub humid climate and the rest of the state has semi arid climate.
Gujrat receive s 127 cm rainfall in South to 50 cm in extreme North-West. The Kutch region situated in the south of Thar Desert receives annual rainfall of 36.5 cm. Kathiawar region receives 50 to 76 cm rainfall but Western and South-Western part receive less than 50 cm rainfall out of which 90% is received in SW monsoon season. The monsoon sets in the third week of June and continues for about four months. The monsoon as a whole is varying variable and unreliable in the region. The May is the hottest month of the region and the mean temperature remains 35.5 o C. The maximum temperature reaches as high as 47.8 0 C. In January mean temperature varies from 18.2 to 20.8 o C and sometimes cold wave brings down temperature to 0o C. The Kathiawar region due to vicinity of sea has low mean temperature (30.5 o C) during May. Different climatic zones, districts covered rainfall and soil types in Gujrat are given in table1.
Table 1: Agro climatic zones of Gujrat
S. No. Agro climatic zones Districts Rainfall (mm) Climate Soil
1. South Gujrat heavy rainfall Dang, Valsad 1793 Sub humid,
Semi arid dry Deep black coastal alluvium
2. South Gujrat Surat, Bharuch 974 Sub humid,
Semi arid dry Deep black coastal alluvium
3. Middle Gujrat Vadodara 735 Semi arid Medium black
4. North Gujrat Ahmedabad,Mehsana
Gandhinagar, Sabarkanta 735 Arid,
Semi arid Gray brown coastal alluvium
5. North west arid Kutch 340 Arid Gray brown Deltic alluvium
6. North Saurasthra Amreli, Bhavnagar,
Jamnagar, Rajkot,
Surendranagar 537 Semi arid Medium black calcareous
7. South Saurasthra Jamnagar 844 Dry sub humid Medium black coastal alluvium
8. Bhal & Coastal Part of Ahmedabad, Bhavnagar, Kheda 650 Semi arid dry Medium black coastal saline

Vegetation:
The wide variation in climate and topography has resulted in various type of vegetation ranging from typical desert plants in Kutch and in North western parts of the state there is deciduous forest. Major concentration of forest is observed all over the eastern border as well as in the hilly parts of Kathiawar. The plains are mostly devoid of full stocked forest cover. The major types covering over 10 percent area of the state can be grouped as tropical moist deciduous, tropical dry deciduous, typical shrubs, dry grass and pictorial and swampy forests.

Soils:
On the basis of soil Taxonomy classification Gujrat soils have been classified into 5 orders, 11 sub orders, 20 great groups and 45 sub groups by NBSS & LUP (Sharma et al. , 1994 ). The extent and per cent coverage of soils under different orders of total geographical area of state is depicted in Fig.2. Amongst the different orders, Inceptisol covers 50.8 per cent of the total area. This is followed by Entisols, Aridisols, Vertisols and Alfisols covering 13.8, 10.6, 8.9, and 0.6 per cent of total area, respectively and rock outcrops covers 1.8 per cent. The estimated total area of Gujrat affected by coastal salinity is approximately 7.14 lac ha. (Bhumbla, 1977). This is 50 per cent of the reported salt affected area of 12 lac ha. (Yadav et. al., 1983). The area under salt affected soils increased up to 16.9 lac ha (Minhas et. al., 1998). These soils are distributed in districts of Kutch in North Gujrat, Ahmedabad and Kheda in middle Gujrat and Surendranagar, Rajkot, Bhavnagar, Jamnagar and Junagarh in Saurashtra and Valsad, Surat and Bharuch district in South Gujrat.
The state has around 26.9 percent area under irrigation, 78.4 percent of which is irrigated by wells, 20.2 per cent by canals and 1.4 percent by other sources, mainly tanks. Way back in 1951-52 about 5.5 % of gross cropped area was irrigated. Land use pattern in gujrat is given in Table2.
 
Table 2: Land use Pattern in Gujrat

Type of land use Percent area
1. Net sown area 38.5
2.Double cropped area 13.5
3. Total cropped area 52.0
4. Cultivable waste land 10.3
5.Area under forest 10.0
6. Non agricultural use 5.8
7.Current and cultivable fallow 16.5
8.permanent pasture and grazing land 4.6
9.Misc. 0.8
10. Total geographical area 196 Lac ha.

Of the total geographical area, 9.5 Mha is cropped area, while the cultivable waste and current cultivable fallow, permanent pasture and forest accounts for 1.98, 0.26, 0.84 and 1.88 Mha, respectively.
Among major crops, food grains occupy 35 percent of GCA followed by oil seeds (25%), and cotton (13%). Other important crops grown are sugarcane (1.5%), tobacco (1.1%) and spices (1.4%).
Ground water:
In Gujarat, 80 per cent of total irrigated area is covered by ground waters. Fourteen districts of the state fall in arid and semi arid zones. Kutch and Jamnagar districts fall in the arid zone. Kutch receives the lowest rainfall in the state, only 322 mm in the year. Five districts namely, Amreli, Banaskantha, Junagarh, Mehsana and Surendranagar fall in the arid cum semi arid zone. The remaining seven districts namely, Ahmedabad, Bhavnagar, Bharuch, Kheda , Panchamahal, Rajkot and Subarkantha have semi-arid climate.Thus northern, central and south- west parts of Gujarat state may be classified as arid and semi-arid regions.
An immense accumulation of volcanic rocks, principally basaltic lavas, known as the Deccan Trap is most important and extensive geographical formation which exists in the state. At a few places, particularly in Panchamahal and Bharuch district a few granites and gneisses are occasionally met with. The major portion of the land is, however, covered with old and recent alluvium. The saline tracts of Gujrat are lying in the rocky terrains of Kutch and Saurashtra, which are in turn covered by the sub recent deposits of the Gulf of Bombay and Gulf of Kutch. These saline tracts are situated in the vicinity of the Kutch desert (70o 72' E, 22 o 24' N) and the Bhal Kantha - Ahmedabad districts (71o 5’, 72 o 5' E, 21 o 22.5' N).
Trivedi et al.(1962) examined 452 ground water samples collected from the semi-arid tract of northern Gujrat. About 34 per cent water had EC<0.75 dSm-1 and 16 per cent waters showed EC between 0.75 and 2 dSm-1. The remaining 50 per cent waters exhibited EC greater than 2 dSm-1, and these waters were classified as "doubtful to unsuitable" for irrigation.
A systemic examination of 8,982 ground water samples from almost all the districts of Gujrat showed that 75 per cent of the water had EC less than 2 dSm-1. Another group of 607 water sample collected from eight districts, namely, Ahemedabad, Baroda, Bharuch, Banaskantha, Katra, Kutch, Mehsana and Saberkantha, revealed that 78 per cent waters had EC less than 2 dSm-1 . In the Kutch district which is the driest in the state, only 50 per cent waters had EC less than 2 dSm-1. Analysis of 62 water samples from Bhal area comprising part of Bhavnagar, Ahmedabad and Katra districts showed that 75 per cent waters were in low EC range but 3 per cent waters had EC >15 dSm-1 out of these two bore water samples exhibited EC of 40 and 140 dSm-1 (Table-3)
Table 3: Percent distribution of ground waters of Gujarat in EC classes

EC (dSm-1) All districts (8982)1 Eight districts of North Gujarat2 (607) 2 Kutch3
(286) Bhal area4
(62)
<1 38 10 18 22
1-2 37 68 33 50
2-4 18 14 24 17
4-6 8 4 12 6
6-8 3 5 -
8-10 2 2
10.15 2 -
>15 3 3
Figures in parenthesis are No. of water samples tested Source:1. Shah and Bhupat (1972) 2. Talati (1972) 3. Bhargava et al. ( 1977) 4. Nedeco (1968)
The average values of EC , range of EC and per cent distribution of ground waters to different classes of EC of 13 districts , all falling either in arid or semi-arid zone of Gujrat are shown in Table 4. Interestingly the waters of highest salinity are noticed in Kutch district (Table 3). Next to this district the ground waters in the districts of Ahemedabad, Banaskantha, Bhavnagar, Broach, Junagarh, Mensana and Surendranagar, exhibit higher salinity as compared to the remaining 6 districts.
Table 4 : Percent distribution of ground waters of Gujarat in EC classes
Districts No. of samples Average EC (dSm-1)
<0.25 0.25-0.75 0.75-2.25 2.25-5.0 >5
Ahmednagar 75 2.8 27 15 11 18 28
Amzeli- Bhavnagar 20 1.2 15 23 8 31 23
Banaskanta 10 2.1 33 11 33 11 12
Broach 75 2.7 45 15 12 8 19
Junagarh 25 0.8 41 45 - 9 5
Jamnagar 20 2.3 29 33 25 6 6
Katra 60 3.1 29 17 15 19 20
Mehsana 80 2.2 43 13 18 17 9
Panchmahal 25 0.9 84 8 - - 8
Rajkot 35 0.9 66 19 16 - -
Sabarkanta 25 0.9 80 12 4 4 -
Surendranagar 36 1.8 34 25 3 9 28
Source: Shah and Mankad (1969)
Per cent wise distribution of the ground waters from eight districts of Gujrat in different EC classes with respect to RSC and average value of RSC and SAR are presented in Table -5. A perusal of data showed that about 40 per cent waters were free of residual sodium carbonate. Out of 60 per cent waters which contained RSC, 45 per cent were in EC range of 1 to 2 dSm-1. Average values of RSC and SAR increased with increase in EC. Average values of SAR of waters, which contained RSC, were relatively higher than those waters, which were free of RSC. Ground water quality map has been presented in Figure -3 .

Table 5: Percent distribution of ground waters of North Gujarat in RSC (meL-1) and average value of RSC and SAR

EC (dSm-1) % Samples Average Average SAR
With out RSC With RSC RSC SAR With out RSC With RSC
<1 5.9 4.3 0.7 1.8 1.4 2.4
1-2 21.9 45.6 2.6 4.2 3.1 4.8
2.4 5.6 9.4 3.2 9.1 7.6 12.0
4-6 3.3 0.5 3.8 14.2 12.9 22.6
>6 1.3 1.8 8.3 30.5 23.4 35.7
Source: Talati (1972)
SAR of the ground water of Kutch district varied from 0.3 to 66.7 , out of which 79 , 14 , 4 and 4 per cent waters had SAR less than 10 ,10-20, 20-30 and >30, respectively. EC varied from 0.1 to 83 dSm-1 and SAR of the ground waters of Bhal tract ranged from 2 to 57 (Nedeco. 1968). According to Shah et el. (1962 a :1962 b), ground water collected from Bhal tract exhibited EC between 0.7 and 67.0 dSm-1 , SAR between 4.5 and 72 and RSC varied from 0.0 to 15.6 meL-1.
In 231 samples of ground waters which did not contain RSC, calcium dominated amongst cations in waters with EC less than 1 dSm-1 and sodium in higher salinity waters. In higher salinity waters having EC between 1 and 4 dSm-1 calcium was the second dominant cation but in waters with salinity greater than 4 dSm-1 magnesium became the second cation. Interestingly, in 376 waters which contained RSC, sodium was the first cation in all waters; calcium was second cation in waters with EC less than 2 dSm-1 and magnesium in higher salinity waters. Mg/Ca ratio was higher in RSC waters as compared to RSC free waters. With respect to anions, RSC free waters were Cl-CO3 type up to EC of 4 dSm-1 and Cl -SO4 type in higher EC waters. Carbonates + bicarbonates dominate up to EC 2 dSm-1 and then chlorides tended to dominate (Table-6)
In Gujrat state the main geo-chemical types of ground waters, conform to Na-Mg/Ca cation type and Cl-SO4 Cl-HCO3 or HCO3-Cl anion type.
Table 6: Mean chemical composition of ground water of Gujrat
EC (dSm-1) class No. of samples PH EC (dSm-1) Ionic compositio(meL-1) SAR RSC
(meL-1)
Na Mg Ca Cl SO4 CO3 HCO3
Samples without RSC(237)
<1 36 7.8 0.65 2.3 2.0 3.5 3.2 0.8 3.6 0.4 1.4 0
1-2 133 7.6 1.3 6.2 3.5 4.9 6.1 1.8 5.4 0.6 3.1 0
2.4 34 8.3 2.8 19.2 5.3 7.0 18.0 5.4 6.8 0.6 7.6 0
4-6 20 7.3 4.5 35.2 9.5 7.1 37.9 7.6 4.6 1.5 12.9 0
>6 8 7.9 9.6 74.3 15.2 7.9 74.5 12.3 4.4 4.8 23.4 0
Samples with RSC(376)
<1 28 8.0 0.7 3.3 1.9 2.2 1.6 0.7 2.7 1.6 2.4 0.7
1-2 277 7.7 1.5 9.5 2.4 2.8 5.4 1.5 4.8 3.2 4.8 2.6
2.4 57 7.9 2.7 21.2 3.7 3.2 14.8 3.0 5.1 4.9 12.0 3.2
4-6 3 8.2 4.9 38.2 7.2 1.9 26.4 7.7 3.2 9.6 22.6 3.8
>6 11 8.4 7.6 74.7 5.8 2.9 57.0 9.1 3.0 13.8 35.7 8.3
Source: Talati (1969)


Zone wise under ground water:
Ground water potential and utilizable ground water for irrigation in different districts is estimated as below as on 1984
Particulars Quantity MCM/ Yr Total
Un confined Semi confined & confined aquifers
Potential ground water 20377 2175 22552
Utilizable for irrigation 17320 1849 19169
Source: (Anonymous, 1989)
Annual available ground water recharge in the state is about 12 lac ha. M. Out of which 4.0 ha.m is in Saurastra but the net draft is only 7.0 ha.m amounting to about 58.0 % utilizable. Though in all zones the percent utilization is far below the potential recharge, yet in north Gujrat it is more than 90 % which is mainly due to the over exploitation (195% ) in Mehasana district (Raman,1996).
The ground water resources position as on 1.4.98 s given below (India-, 2003))
The ground water resources 20376.7 Mcm
Utilizable ground water for irrigation 17319.9Mcm
Utilized for irrigation 8532.7 Mcm
Ground water balance 8787.2 Mcm
Stage of ground water development 49.3 %

1. South Gujarat heavy rainfall zone:
As per state underground water board’s report (1986) about 1500 MCM/Yr recoverable recharge is available in the zone. But unfortunately the annual net draft is only 177 MCM working out only around 12 per cent. This is considerable low as compared to state utilization of 30.8 per cent. There are about 15000 wells in the zone and almost all of them are open dug wells. The irrigation through wells contributes to 43% of the net area irrigated (81278 HA.) The underground water quality in the zone is generally good.The analysis of about 2640 samples showed a pH 7.0 to 9.4 with an average of 7.82. The mean pH value are comparatively high in Valsad (8.0) and Pardi (8.5) talukas.. The salinity of water ranged from 0.26 dSm-1 ( Valvada) to 24 dSm-1 ( Navsari) with a mean of 1.02 dSm-1., while in the rest of talukas only 10% water is saline. In Navsari and Gandevi talukas 50 and 37% of water is poor respectively. This may be one of the reasons for under utilization of ground water in Navsari taluka.
2. South Gujrat zone:
The potential of under ground water resources utilization is 51665 MCM/ Yr of which the net draft is only 184 MCM/ Yr. Per cent utilization of under ground water in Surat district is 10.6 whereas it is 12.0% in Bharuch district. The quality of the eastern part of the zone is very good. But in the western portion and in the north-western portion of the zone the quality is medium to poor. There are about 220 tub wells and 13700 dug wells in the zone. The waters from Amod, Jambusar, Vagra and some parts of Bharuch talukas indicated the predominance of Mg.

3. Middle Gujarat zone:
Area irrigated by wells constitutes 65.8% of total irrigated area (4.18 Lac ha.). There are about 710 tube-well and 58309 wells in different area of Middle Gujarat zone. The waters of this region have low to very high salinity and medium to very high sodium hazard. As per Indian standards (1972) for light to medium textured soils of this region 4 to 6 dSm-1 EC be considered as the upper limit. The waters of the eastern part do not cause much problems. But, the problems of salinity and sodicity tend to increase in western part of the zone.
4. North Gujarat Zone:
Ground water is the major source of irrigation in North Gujarat. Area irrigated by wells and tube-wells constitutes 89.5% of the total irrigated area of the zone (6.68 lac ha). There are 6185 tube-wells and 150576 dug wells in different tallukas of North Gujrat. Waters of the this region have high to very high salinity and low to very high sodium hazards. As per Indian standards (1972) for light to medium textured soils of this region 4 to 6 dSm-1 EC be considered as the upper limit, but EC of most of the waters is below this limit. Most of the waters are under the C3 category of salinity, which can be used, with fewer problems in the light textured soil of the zone. The total net ground water available for exploitation in the zone is 864 MCM / year whereas, the net draft is 1476 MCM/year.
5. North West Zone:
This is one of the zones having severe ground water quality problems. Majority of the waters are exhibiting high salinity and medium to very high sodicity problems. As per USSL standards waters of the region have very high salinity and medium to very high sodium hazards. The net ground water available for exploitation in the zone is 377 MCM/year whereas the net draft is 136.5 MCM/year. There are 1232 tube wells and 68514 dug wells. Most of the irrigated area (1.57 lac ha.) is fed by tube wells.
6. North Saurashtra zone:
Except in few patches the quality of ground waters can be rated as usable. The salinity of most of the waters ranged from C1 to C3 and sodicity from S1 to S3. Though in sandy soil tract some waters having marginally higher RSC have been reported. , yet the good drainability nature of the soils of the region, may pose lesser problems. On the basis of EC and SAR values most of the waters are safe to use. Ground water is the major source of irrigation 4.51 lac ha. followed by canal irrigation (40974 ha.)
7. South Saurashtra:
The well irrigated area of the zone is 1.01 Lac ha. out of total irrigated area of 2.10 Lac ha.. This represents 79.5% of the total irrigated area. EC of water varied from 0.42 to 13.0 dSm-1 .Higher salt content creats serious problems and requires special management. On the basis of SAR Maliya (Halina) , Porbander and Rajula talukas had higher SAR values than the critical limit ( SAR>18), the RSC is also high in some well waters. In the inland areas the ground water quality is normal but the coastal area which constitutes bulk of the zone suffers from sever water quality problems mainly due to ingress of the sea water.
8. Bahl and coastal area:
Groud water is the major source of irrigation .Area irrigated by wells and tube wells constitutes about 52.2 and 48.0 % of total irrigated area. EC of under ground water ranged from 0.40 dSm-1 at Arnej in Dhokala taluka to 70.8 dSm-1 at Dholera in Dhanduka taluka of Ahemdabad district. The chloride ranged from 264 mgL-1 in Vallabppur to 8640 mgL-1 in Bhavanagar. Along seacoast the tidal effect of sea is also deteriorating the under ground water quality. Majority of ground waters are either saline or sodic in nature.

Fluoride:
Raghava Rao (1974) reviewed the available information and categorized the areas in four groups showing the concentrations of fluoride in the range of 0-1.5, 1.5-4.0, 4.0-8.0 and > 8.0 mg L-1 (Table 7).

Table 7: Fluoride concentration (mgL-1) in ground water of different district of Gujrat
Range of fluoride in ground water
0-1.5 1.5-4.0 4.0-8.0 > 8.0
- Mehasana, Surendranagar, Ahmadabad, Banaskanta, Bhavnagar, Jamngar and Rajkot South-eastern and western parts of Mehasana district, South part of Kutch district, western part of Jannagar district Naliya in Kutch district
Source: Rao (1974)
Nitrate:
Handa (1987) reported that more than 50 % of the well waters having more than 50 mgL-1 Nitrate in Mehsana district and coastal area of Saurastra.

Site pH EC (dSm-1) NO3 (mgL-1)
Deesa 8.50 0.86 125
Bhatson-1 7.65 6.87 166
Bhatson-2 7.40 6.39 206
Unawa-1 8.10 5.85 248
Unawa-2 7.30 5.56 262
Viramgam 8.00 4.72 108
Rasana 7.55 2.98 141
Kamliwara 7.50 2.95 100
Patan 7.85 3.92 196
Kalij 8.25 1.08 410
Jadka-1 7.35 2.00 144
Jadka-2 7.65 1.73 126
Handa (1987)

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