Ahmedabad – Gandhinagar Twin City, Gujarat
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AHMEDABAD – GANDHINAGAR TWIN CITY, GUJARAT P.R.Gupte, CGWB, Ahmedabad INTRODUCTION The city of Ahmedabad was founded in 1411 AD as a walled city on the eastern bank of the river Sabarmati, now the seventh largest metropolis in India and the largest in the state. Gandhinagar city came into existence as new capital city of Gujarat State in year 1960. Historically Ahmedabad has been one of the most important centres of trade and commerce in western India. The city was once famous as the ‘Manchester of India’ on account of its textile industry. It is also a major industrial and financial city and home of several scientific and educational institutions of national, regional and global importance. The city has a great architectural tradition reflected in many exquisite monuments, temples and modern buildings. Gandhinagar is also emerging as rapidly developing urban centre. GENERAL FEATURES Area & Administrative Divisions Ahmedabad is situated on both sides of river Sabarmati. It lies Gujarat between 22°55' & 23°08' North latitude and 72°30' & 72°42' East AhmedabadLocation -map Gandhinagar of Ahmedabad - Twin City– Gandhinagarwith surrounding Twin urban City areasalong longitudes where as new capital city, Gandhinagar is at 30 km with its urban areas north of Ahmedabad, on right bank of Sabarmati River, situated between 23°05' and 23°22' North latitude and 72°31' to 72°49' Gandhinagar City East longitude. The areas around Ahmedabad and Gandhinagar Fig -1 city are rapidly developing and became one of the largest urban Gandhinagar agglomerate known as “Greater Ahmedabad”. Out of its nearly Ahmedabad City 4200 sq km area, Ahmedabad Municipal Corporation (AMC) areas is 190.84 sq km, 1200 sq km is under Ahmedabad Urban Development Authority (AUDA), 57 sq. km is under Gandhinagar Notified Area (GNA) as Gandhinagar city and rest is of Chatral, Bopal and 9 other Municipalities and other 150 semi urban / urban villages as Urban Agglomerates (UA) falls in Dascroi taluka and Gandhinagar taluka. (Location Map - Fig -1). Demography There is rapid growth of population in the Ahmedabad Gandhinagar urban areas during last three decades (Fig. 2). The population in AMC area in 1981 was 21.5 Lakh which became 35.2 lakh in 2001, Same way the population of AUDA area also increased from 27.2 lakh in 1981 to 47.0 lakh in 2001. The population within the AMC limits appears to approach a stabilization level. The areas adjoining AMC, falling within AUDA limits have shown rapid growth. Gandhinagar is also experiencing relatively high rate of growth 40 % and population of 1.95 lakh persons as per census of 2001. Hydrometeorology Ahmedabad – Gandhinagar area has a tropical monsoon climate, which is hot and dry, except in the rainy season. Summer days are very hot with mean maximum temperature of 41.30C while, nights are pleasant with 7 mean minimum temperature of 26.30C. The mean maximum and minimum temperatures in winter are 30°C and 15.4°C respectively. The average annual rainfall of the area is 782 mm, although there is a considerable variation from year to year. It occurs generally during the months of June to September. The average relative humidity is 60% with a maximum of 80% to 90% during the rainy season. Physiography & Drainage The area as a whole, in general monotonously flat except few mildly undulating topography owing to the presence of stabilized dunal land forms. The elevation of land surface ranges from 40 to 60m AMSL with master slope towards south. The average elevation of the city area is about 48m AMSL. Isolated high grounds, with elevations more than 60m AMSL, are observed on both sides of river Sabarmati. The most important surface water body in the Ahmedabad Gandhinagar area is the river Sabarmati. The Khari river runs almost parallel to the Sabarmati towards east, beyond the city limits. One of the oldest irrigation schemes of Gujarat ‘Kharicut canal scheme’ passes through eastern part of Ahmedabad City, which also serve as ‘Storm Water Drainage’ during monsoon. The Kankaria and the Chandola are two important ponds in the Ahmedabad city area. Under ambitious ‘National Lake Conservation Plan’, AMC and AUDA have taken up project to interlink 45 surface bodies (ponds & lakes) and recharge it with storm water and surplus surface water of Narmada Canal. Soil Type The area is mostly underlain by blown sand and silt deposits of aeolian character, except localized pockets where it is fluvial. The soil is therefore either coarse sandy or fine sandy loam, with less clay content and has good to excellent drainability. The soils in the entire area are deep to very deep, with soil depths more than 100 cm. STATUS OF WATER SUPPLY AND DEMAND In decades of 1970-80, water requirement of Ahmedabad urban area was totally met through series of deep tube wells spread in entire city areas. During decades of 1980-90, (fig.3) to supplement groundwater resources, surface water supply from Dharoi reservoirs was planned with construction of riverbed intake wells. With increasing agriculture demand in upstream reach of Sabarmati river and also due to diminishing base flow in Sabarmati river, project could not be succeeded to lessen stress on groundwater resources. Table -1 a - Present Water Supply & Projected Demand – As per water supply data of AMC, before Ahmedabad Urban Area 1986, out of total 400 mld water supplied, Projection Year 1991 2001 contribution from groundwater resources 2011 2021 2023 was 350 mld (88 %). With implementation Population in lakh 33.00 44.27 53.99 79.58 101.44 of various surface water sources projects Water Requirements at present, out of total 760 mld water 528 706 863 1273 1623 in mld @ 160 LPCD supply, only 30 mld (4 %) is from ground water resources (AUDA 2008). The water demand is increasing with rise in Table – 1 b - Present Water Supply & Projected Demand – population. AMC has projected that by Gandhinagar Urban Area Projection year 2031 projected population of Year 1999 2001 1,01,44,000 persons would require around 2025 1623 MLD from present 760 MLD in AMC Population in lakh 1.90 2.00 4.25 area. Same way, water requirement of Water Requirements in mld @ 250 Gandhinagar Urban area is mainly meeting LPCD 45 50 120 through surface water resources as in 1999 & @ 270 in 2001 & 2025 groundwater levels are rapidly declining and deep water has high TDS, making it unsuitable for drinking uses. Preset and projected water demand of Ahmedabad – Gandhinagar urban area is given in Table 1a & 1b. 8 WATER PROFILE State has created huge surface water potential in Narmada Canal Networks, large part of urban areas, mainly in Urban Agglomerate (UA), outside Ahmedabad Municipal and Gandhinagar Capital city area which are equally urbanised and have high demand of water resources, depends on local groundwater sources. At present, most of the groundwater development is mainly through private tube wells. It is observed that UA is rapidly developing & with rising population its demand on groundwater resources is increasing tremendously and still there is large gap between supply and demand. Although, there is huge potential of surface water resources, lack of piped supply network in all developing urban areas is creating tremendous pressure on existing groundwater resources. The rapid developments during last four decades in Ahmedabad urban areas have created tremendous stress on its natural environs. Increasing Fig -4 groundwater draft to cater the domestic and industrial requirements has rendered most of the unconfined aquifer zone dry. At places, groundwater is brackish at shallow depth. With increasing urbanization process, groundwater pollution also rendered some of the shallow aquifer unsuitable for domestic need. All such development resulted in exploitation of deep confined aquifers, which in turn has led to sharp decline in piezometric level below 60 to 80 m at places. Projected overall water demand and availability through ground water resources, for Ahmedabad Urban Area, (Fig - 4) indicate that there is urgent need to conserve recharge groundwater resources for sustainable development. GROUNDWATER SCENARIO Geologically, the Ahmedabad -Gandhinagar urban area forms a part of the Cambay Basin. The thickness of multilayered Quaternary alluvium system in Ahmedabad – Gandhinagar urban area is around 300 to 600m, which is underlain by Tertiary sediments. The unconsolidated Quaternary formation consists mainly of alternate layers of sand, silt gravels and intermixed kankars etc granular materials and yellow to gray colored sticky clay (Table 2). Table -2 – Geological sequence of Cambay Basin Age Lithology Thickness Quaternary Maximum 700 m ; (Holocene – Alluvium 400 - 600 m around A`bad –G`Nagar Pleistocene) Tertiary Maximum 900 m. Sandstone and Shale (Miocene) 200-300 m near margin of the basin - - - -- - - - - - - - - - - -- - -- - -Unconformity - - - - - - -- - -- - - - - - - - - - - - Sandstones, shale and (Oligocene) Maximum 160 m limestone Shale and siltstone with About 100 m thick in the centre and thinning (Eocene) sandstone and limestone towards east and west margin intercalation Mesozoic Deccan Trap (Cretaceous) -- - - - - - - - - - - -- - -- - -Unconformity - - - - - - -- - -- - - - - - - - - - - - Bagh Beds Geomorphologically they represent two types of landforms, i.e. fluvial and aeolian of Quaternary period. The fluvial landforms consist terrace deposit, abandoned channels, cut-off meanders and swampy lands while 9 aeolian landform consist dunes, inter dunes and sandy flats etc, of geological past in Quaternary period. Accordingly,