T.V. Ramachandra*, Bharath H. Aithal, Gouri Kulkarni, Vinay S

Energy & Wetlands Research Group, Centre for Ecological Sciences [CES],
Indian Institute of Science, Bangalore, Karnataka, 560 012, India,
Web URL: http://ces.iisc.ernet.in/energy; http://ces.iisc.ernet.in/foss,
*Corresponding author:cestvr@ces.iisc.ernet.in


Bengaluru / Greater-Bangalore / Bruhat Bengaluru / Bangalore (geographically located at the south eastern part of Karnataka state  at 77°37’19.54’’  E  and  12°59’09.76’’  N encompassing an area of 741 km2)  is  the  principal  administrative,  cultural, commercial,  industrial,  and  knowledge  capital  of  the  state (Figure1).

Figure 1: Study area Greater Bangalore / Bengaluru / Bruhat Bengaluru / Bangalore

Bengaluru is the  principal  administrative,  cultural, commercial,  industrial,  and  knowledge  capital  of  the  state  of  Karnataka. The present name Bengaluru has its origin to ‘benga’, the local term for Pterocarpus marsupium, a species of dry and moist deciduous tree, and ooru, meaning town (Ramachandra and Mujumdar, 2006; Sudha and Ravindranath, 2000).  The city is now subdivided 8 zones with 198 wards under the jurisdiction of BBMP. Bangalore is the 5th largest metropolis in India (Ramachandra et al, 2012a; Sudhira et al., 2007). Population of Bangalore urban (BBMP limits) has increased by 48%, from 5.84 millon in 2001(Census, 2001) to 8.64 million (Census, 2011) in 2011.The population density in the region has increased from 7881 persons/km2 (2001) to 11664 persons/km2 (2011).

The topography of the region is undulating, the altitude varies from about 740 m to over 960 m above mean sea  in the region is main cause for formation of large number of drainages and storage tanks. These water bodies and open green spaces are responsible for moderating local climate. Temperature varies from 22 oC to 38 oC during summer and 14 oC to 27 oC in winter. Bangalore receives an annual average rainfall of about 800 mm.  
Bengaluru (Bangalore) was known as ‘Garden city of India’ due to its lush green cover with diverse fauna and two nationally recognized institutions and defense establishment’s green campuses, botanical gardens - Cubbon Park and Lalbagh, etc. Currently Bangalore is second fastest and fifth largest metropolis in India and has experienced unprecedented expansion of urban area 69 km2 in 1949 to 741 km2 in 2010 (Ramachandra and Kumar, 2010; Ramachandra et al., 2012b). Bangalore city population has increased enormously from 6,537,124 (in 2001) to 9,588,910 (in 2011), accounting to decadal growth of 46.68%. Population density has increased from as 10,732 (in 2001) to 13,392 (in 2011) persons per sq. km (Ramachandra et al., 2012c).  The vegetation of Bangalore was classified as dry deciduous forest-type (Champion and Seth, 1968) under the Terminalia-Anogeissus latifolia-Tectona series (Puri et al., 1983). The city enjoys the salubrious climate throughout the year.
In the early 17th century, Bangalore comprised natural thorny forests (Kamath 1990). Green vegetation within the Bangalore city was initiated by Hyder Ali, a ruler of Mysore city. He also established Lalbagh with an area cover of 100 hectares as his private garden, which is now a public garden. Subsequently in 1831, British further established greening the city with the creation of Cubbon Park (Issar 1998, Iyer et al., 2012). Bangalore city was once identified as ‘Garden city’ due to the afforestation initiatives of erstwhile visionary decision makers.
During the British tenure, park culture was introduced, which was a new perspective to the use of social spaces. The park culture got integrated slowly among Indians, through the elite and educated.  For instance, Malleshwaram is one of the oldest area in the city. It has readily adopted the park culture and also retained Indian traditional practices. Residents started to grow vegetables and fruits in their home gardens and also planted trees along the roads. Some streets in Malleshwaram derived their names from the trees that were grown along the entire stretch like “Sampige” (Michelia champaka) and “Margosa” (Azadirachta indica) roads.
Bangalore began to evolve into a city of small–scale industries from 1965 onwards. Globalisation and consequent opening of Indian markets gave impetus to IT (Information Technology) and BT (Bio technology) sectors and now the city is recognized as IT hub. Bangalore also houses numerous leading commercial and educational institutions, industries like textile, aviation, space, etc. The immediate consequence of this growth also created pressure on infrastructure and basic amenities like water supply, energy, public transportation, land etc. Large plots and colonial bungalows with home gardens gave way to multi-storied apartment blocks with just small patches of lawn. In terms of natural flora, Bangalore city had 979 species in 542 genera, 133 families (Ramaswamy and Razi, 1973). Due to the rapid unplanned urbanization and urban sprawl, the spatial extent of Bangalore increased from 69 sq.km (1949) to 741 sq. km (2010). Now Bangalore is the fifth largest metropolis in  India  with  a  population of  about 8.4  million (census, 2011). 
Urban ecosystems are the consequence of the intrinsic nature of humans as social beings to live together (Ramachandra et al., 2012a; Ramachandra and Kumar, 2009). The process of urbanisation is contributed by the adoption of concentrated growth model with infrastructure initiatives, consequent population growth and migration. Urbanisation and urban sprawl have posed serious challenges to the decision makers in the city planning and management process involving plethora of issues like infrastructure development, traffic congestion, and basic amenities (electricity, water, and sanitation), etc. (Kulkarni and Ramachandra, 2006).  Unplanned urbanisation during the post globalisation era has drastically altered the landscape with the disappearance of green cover and water bodies, leading to alterations in the drainage characteristics of natural catchments, or drainage areas, which has enhanced the rate of surface runoff. Drainage systems are unable to cope with the increased volume of water, and are often blocked due to indiscriminate disposal of solid wastes. Encroachment of wetlands, floodplains, etc. obstructs flood-ways causing loss of natural flood storage.  Apart from these, major implications of urbanisation are:

        • Loss of wetlands and green spaces:  Urbanisation has telling influences on the natural resources such as decline in green spaces (vegetation) including wetlands and / or depleting groundwater table. 925% increase in paved surfaces (built-up, roads, etc.) with the decline of 78% vegetation and 79% water bodies is noticed during the four decades (1973-2014). Quantification of number of trees in the region using remote sensing data with field census reveal 1.5 million trees and human population is 9.5 million, indicating one tree for seven persons in the city.
        • Floods: Conversion of wetlands to residential layouts has compounded the problem by removing the interconnectivities in an undulating terrain. Encroachment of natural drains, alteration of topography involving the construction of high-rise buildings, removal of vegetative cover, reclamation of wetlands are the prime reasons for frequent flooding even during normal rainfall post 2000.
        • Decline in groundwater table: Studies reveal the removal of wetlands has led to the decline in water table. Water table has declined to 300 m from 28 m over a period of 20 years after the reclamation of lake with its catchment for commercial activities. In addition, in an intensely urbanized area such as Whitefield, etc. groundwater table has now dropped to 400 to 500 m.
        • Heat island: Surface and atmospheric temperatures are increased by anthropogenic heat discharge due to energy consumption, increased land surface coverage by artificial materials having high heat capacities and conductivities, and the associated decreases in vegetation and water pervious surfaces, which reduce surface temperature through evapotranspiration.
        • Increased carbon footprint: Due to the adoption of inappropriate building architecture, the consumption of electricity has increased in certain corporation wards drastically. The building design conducive to tropical climate would have reduced the dependence on electricity. Higher energy consumption, enhanced pollution levels due to the increase of private vehicles, traffic bottlenecks have contributed to carbon emissions significantly. Apart from these, mismanagement of solid and liquid wastes has aggravated the situation.

Bangalore’s urban vegetation  comprises of  trees are Alstonia scholaris, Artocarpus heterophyllus  (Jack fruit), Azadirachta indica (Neem), Bombax cieba (Red silk cotton), Butea monosperma, Ficus bengalensis (Alada mara), F. religiosa (Ashwatha),  Gmelina arborea, Kigelia pinnata (Sausage tree), Lagerstroemia speciosa (Pride of India), Mangifera indica  (Mango),  Madhuca longifolia (Mehwa or Ippe), Melia composite (Malabar Neem), Michelia champaca, Neolamarkia kadamba (Kadamba), Pongamia pinnata (Honge), Pterocarpus marsupium (Honne), Syzigium cumini (Jaamun), Saraca indica (Seeta Asok), Swetenia sp (Mahogani), Terminalia arjuna (Arjuna),  T. bellerica (Tare), Tabebuia spectabilis etc. Some of the gracious exotic trees found as avenue trees are: Delonix regia (Gulmhur), Enterolobium saman (Rain tree), Parkia biglandulosa (Badminton ball tree), Peltophorum pterocarpum (Coppar pod), Spathodea companulata (African tulip tree), Tabebuia spectabilis, Polythia longifolia etc. Trees have various important roles to play in the ecosystem. In recent years, the increase in vehicular traffic has also increased the Carbon dioxide, Nitrogen, Sulphur dioxide and suspended particulate matter in the environment. Air pollution and reduction in the green vegetation induced the urban heat island effect which results in variation in microclimate.
Bangalore is also known for their lakes which are paradise for ecology. In 1962 Bangalore had 265 water bodies due to the rapid urbanization the water bodies decreased to 98 in 2010. As the city grew over the space and time, inner areas got more crowded and congested (Ramachandra et al., 2012a). Road network has increased and also being widened by axing the numerous road trees. Many lakes and tanks were encroached and converted to residential layouts, multi-storey buildings, playgrounds, bus stands etc. and some lakes were used for dumping of municipal solid waste or building debris (Sudhira et al., 2007; Ramachandra et al., 2012).
Bangalore is located on a ridge with natural water courses along the three directions of the Vrishabhavaty, Koramangala-Challaghatta (K&C) and Hebbal-Nagavara valley systems. The drainage allows the flows to Cauvery through its tributaries Arkavathi (East flowing), Pinakini/Pennar (East Flowing) and Shimsha (West Flowing).