Chapter 8Environment

8.1 Climatology

Climatically, the city of Bengaluru is located in the warm-humid climate zone and is considered as the most pleasant city in southern India owing to its topographical elevation. Bengaluru has a Tropical Savanna climate with distinct wet and dry seasons. Due to its high elevation, the city usually enjoys a more moderate climate throughout the year, although occasional heat waves can make summer a tad uncomfortable. There are 57 rainy days in a year on an average and that receive an average annual rainfall of 94cm. Heavy rainfall (64.5 mm in 24 hours) in Bengaluru city is mostly confined to second half of the Pre-monsoon season, Post-monsoon ${ \mathsf { s e a s o n } } ^ { 1 2 }$ during break in monsoon season and also in association with weather systems like depressions/ cyclones approaching/passing through Bengaluru. Temperature ranges from $1 2 ^ { \circ } \mathsf { C }$ to $4 0 ^ { \circ } \mathbb { C } .$ Winds are generally light; Winds are strong during South West (SW) monsoon season and predominantly are from westerly direction. Skies are heavily clouded to overcast during SW monsoon season and to lesser extent in the post-monsoon season. During the rest of the year skies are mostly clear.¹³

Bengaluru is located at latitude $1 2 ^ { \circ } 5 9 ^ { \prime } 0 ^ { \prime \prime } \mathsf { N }$ and longitude $77^{\circ} 35'0''$ . It has two topological terrains, the one at the North Bangalore taluk and other being the South Bangalore taluk. The north taluk a level plateau and lies between 839-962 m above sea level. At the middle of it along the NNE to SSW runs the ridge, and the highest point at Doddabettahalli at 962 meters elevation. The topology of Bengaluru is flat except at this ridge. There are gentle slopes and valleys on either side of this ridge, forming low lying area which constitutes water tanks in varying sizes. The river Arkavathi flows through the north western part of the city. Its tributary is River Vrishabhavathi which rises at Basavanagudi. The south Bangalore terrain has uneven and undulating landscape with hills and valleys. The South Bangalore taluk has an uneven landscape with intermingling hills and valleys. The southern and western portions of the city consist of a topology of granite and gneissic masses. The eastern portion is a plane, with rare minor undulations. The BMA specifically, has the rock type that belongs to the Charkonite Group, Saugar group and the PGC. Figure 8-7 presents the Geology and Mineral Map of BMA.

Figure 8-7: Geology and Mineral Map of BMA

Source: District Resources Map, Geological Survey of India (2000)

Physiographic Character of BUD can be defined as plateau (as it is part of Mysore plateau) and undulating terrain. Rocky upland, plateau & flat topped hills at a general elevation of about 950 above mean sea level (amsl) defines the Geomorphology of BUD. The major part is sloping towards south and south east forming pediplains interspersed with hills all along the western part. The pediplains form the majority of BUD underlain by granites and gneisses with the highest elevation of

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850 to 950 m amsl. The pediplain constitute low relief area having matured dissected rolling topography with erosional land slope covered by a layer of red loamy soil of varied thickness.

The major drainages are Cauvery and Ponniar basins. The River Cauvery flows at a distance of approximately 100 km from BUD with its tributaries of Arkavathi and Kumudavathi draining in BUD and BMA. Further, Kumudavathi, Palar and Pinakini, the tributaries of Pennar River flow in the NE part of BUD. The pediplains is dissected by streamlets flowing in southern direction. (Refer Figure 8-8)

Figure 8-8: Geomorphological Map of BMA

Source: District Resources Map, Geological Survey of India (2000)

8.2.1 Geo Technical Characteristics (Seismicity)

As per Final Report on Development of Probabilistic Seismic Hazard Map of India (PSHMI), by National Disaster Management Authority (NDMA), 2010, there are thirty two seismic zones of India (Refer Figure 8-9). Bengaluru city falls under Zone No. 29 called as Southern Craton. As per PHSMI report, Southern Craton has received 45 earthquakes and this zone has max potential of magnitude upto 6.8 Mw scale. Further, PHSMI report has carried out probabilistic analysis for 48 cities in India including Bengaluru by computing peak ground acceleration (PGA) over 500, 2500, 5000 and 10000 years. According to PHSMI report Bengaluru has relative seismic hazard at 0.02, 0.04, 0.05 and 0.06 PGA (g) respectively, which puts Bengaluru relatively the safest among the other cities.

Figure 8-9: Thirty Two Seismic Zones of India

http://www.hpsdma.nic.in/Development%20of%20Probablistic%20Seismic%20Hazard%20Map%20of%20India.pdf,

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The planning area is under the Seismic zone II making it least seismically active and low risk zone¹⁵. The geomorphological characteristics of granite and gneiss rock types along with the geotechnical characteristics of Seismic Zone II indicate that the planning area is conducive to vertical development such as high rises with adequate safety measure installed in high rise structures.

8.2.2 Topography & Contours

As part of preparation of RMP 2031, using high resolution satellite imagery, Digital Survey Model (DSM) map and Contour map of the planning area have been generated to study the topography. Figure 8-10 presents the DSM map for BMA, which clearly depicted that the central ridge runs along North-South of BMA and the major valley is sloping towards the East and the Vrishabhavathy Valley is along the SW of BMA. Figure 8-11 presents the Contour Map of BMA. The DSM and the Contour map can be utilised while proposing and planning infrastructure such as road and drainage system and for delineation of sensitive zones such as catchment and buffer areas of natural drainage and lakes.

Figure 8-10: Topography (Digital Surface Model) of BMA

Source: Satellite Image (2012) and RMP 2031 Analysis, 2015

15 More details of the geotechnical characteristics and natural hazard is included in Part VIII-Report on Hazard & Vulnerability Survey and Assessment

Figure 8-11: Contour Map of BMA

Source: Satellite Image (2012) and RMP 2031 Analysis 2015

8.3.1 Forests

The Karnataka Forest Department (KFD) is the state department for forests in Karnataka. The total forest land in Karnataka State is 43,356.47 SqKm ¹⁶. The BUD admeasures a geographical area of 2190 SqKm¹⁷, out of which areas under forest is 122.26 SqKm Thus, only 5.5% of the BUD is under forests. The percentage of forest comes to only 2.28% of the BMA¹⁸. BMA falls under the Bangalore Urban Forest Division of the KFD which has 3 subdivisions, namely, Bangalore North Subdivision, Bangalore South Subdivision and the Lakes Subdivision.

Most of the forests in and around Bangalore now stand degraded due to biotic factors and they are classified as Dry Deciduous Scrub type (DS1). These forests are found at Govindapura, Kadugodi,

Committee 1 of KFD reports 43356.94 sq.km.

17 Annual Report 2013-2014 of Forest Department, Gok and the Reconstituted Expert Committee 1. However, the BUD admeasures a geographical area of 2174.1 sq.km. as per Plan for Bangalore Urban Forest Division 2002-03 to 2011-12; KFD. 8 Existing Land Use 2015

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Mandur, B.M. Kaval, Turaligudda, Jarakabande, Jarakabande Sandal Reserve, Marasandra, Kumbaranahalli, Madappanahalli and Doresanipalya. In most of these places, monoculture plantations of Eucalyptus and Acacia auriculiformes have been raised in the past. However, Bannerughatta National Park/ Forest has different characteristics.

Figure 8-12: Forests Areas within BMA

Source: KFD and RMP2031 Analysis, 2015

8.3.2 Eco –Sensitive Zone of Bannerghatta National Park (BNP)

Bannergahatta National Park (BNP) and Bannerghatta Reserve Forest admeasures ~260.51 sq.km. and is spread over BUD and BRD. BNP is the northern tip of this Mysore Elephant Reserve with rich faunal and floral diversity and ~15.89 sq.km. falls within the LPA of BDA and some in the LPA of BMICAPA.

To protect the wildlife, their habitat and its environment, the provisions of Wildlife Protection Act, 1972 and The Environment (Protection) Act, 1986 and the Supreme Court Decision mandates declaration of Eco-Sensitive Zones (ESZ) around the Protected Areas. The Ministry of Environment and Forest, (MoEF) GoI, in year 2007, issued Guidelines for Declaration of Eco-Sensitive Zones National Parks and Wildlife Sanctuaries. The guidelines acknowledge the fact of various existing

developments in the vicinity/ near boundaries of protected areas and has provided the flexibility to define Eco-Sensitive Zones which can extend upto 10km looking into the ground realities.

As per the draft notification issued by the MoEF & CC dated 15.06.2016 states that BNP is an area of high floral and faunal diversity and also an important watershed area through tributaries that join the Cauvery River. Thus, it becomes imperative to protect and conserve the area as an Eco-Sensitive Zone from ecological and environmental view to protect wildlife and their habitat. It states that all activities in the Forest block areas (both within and outside Municipal Areas) shall be governed by the provisions of the Forest (Conservation) Act, 1980 (69 of 1980) and all the activities in the Protected Areas (National Park) shall be governed by the provisions of the Wild life (Protection) Act, 1972 (53 of 1972). Further, buffer extant vary from 100 meter to 4.5kms around the boundary of BNP and is declared as BNP Eco- Sensitive Zone. As per the notification the zone covers 268.96 sq kms. This zone covers 77 villages, 17hamlets and is spread across BUD and BRD. However, the extent of this Eco-sensitive zone within the LPA of BDA and extent of ESZ is such that some of the survey numbers are covered in full, and others are partly falling in the buffer zone. Figure 8-13 depicts the extents and of ESZ of BNP.

Figure 8-13: Extents of Eco-Sensitive zone of Bannerghatta National Park in BMA

Source: Draft notification MoEF & CC dated 15.06.2016 and RMP 2031

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8.3.3 Historical Trees

KBB has initiated a program to identify certain trees in various districts which are unique, historical and have high significance. The same will be considered for declaring as Heritage Trees. KBB has recommended the following trees within BUD to be declared as Heritage trees under section 63 (2) (i) of the Biological Diversity Act 2002. Table 8-2 presents trees declared as heritage trees by the board.

Source: Annual Report 2012-13, Karnataka Biodiversity Board

8.3.4 Historical gardens in BMA

Lalbagh botanical gardens and Cubbon Park mark the two major lung spaces of the city. The central and south Bengaluru were structured around these large gardens.

Lal Bagh: Established in 1776 by Hyder Ali and further developed by his son Tippu Sultan, it was initially meant to be a private garden designed in the Moghul style. In terms of area, Lal bagh spreads across 97 Ha. It holds rare plants added by Tippu Sultan in the 18th century from Turkey, Mauratius, Persia and Afghanistan. Some trees over 100 years old still exist. Some of the exotic species introduced from different parts of the world include largest specimen of Kopak tree also called Ceiba pentandra, it is a tropical tree of the order Malvales and the family Malvaceae , native to Mexico, Central America and the Caribbean, northern South America, and to tropical west Africa. Cupressses or Cypress native to scattered localities in mainly warm temperate regions in the Northern Hemisphere, including western North America, Central America, northwest Africa, the Middle East, the Himalayas, southern China and northern Vietnam. It has rare tropical and sub tropic plants like the gymnosperms or early trees which are a group of seed-bearing plants that includes conifers, cycads, Ginkgo and Gnetales. In addition, a number of ornamental and economic plant species both of exotic and indigenous origin can be found in Lalbagh. Take a walk around the lake and you may come across herons, egrets, kingfishers, coppersmiths and even pelicans if you are lucky. These are only some of the close to 50 types of birds which are regular visitors here. Other birds in the city include Common Iora. Yellow-wattled Lapwing,B lack Kite, Ashy Prinia, Large-billed Crow, Green Bee Eater,Rose-ringed Parakeet, Different types of bulbul, Black Ibis, Spotted Dove, White-throated Kingfisher, Pied Bushchat, Black Drongo, Oriental Magpie Robin, Common Hoopoe, Greater Coucal, Red-wattled Lapwing, Plum-headed Parakeet, Asian Koel and Ashy Woodswallow. Also Lal Bagh is the most visited tourist destination in 2014 as per GoK Tourism department statistics.

Cubbon Park: The Cubbon Park has a history of over 100 years. It was established in the year 1870 by Sri John Meade, the then acting Commissioner of Mysore. The vast landscape of the park was conceived by Major General Richard Sankey, the then Chief Engineer of the State. As a mark of honour to Sri John Meade, the park was initially named as "Meade’s Park" and subsequently it was called the Cubbon Park. Since the inception of the park, it was developed and improved by adding new structures and features. In the year 1927, the park was officially renamed as "Sri Chamarajendra Park" to celebrate the Silver Jubilee of Sri Krishnaraja Wodeyar’s rule in Mysore State. Cubbon Park is under the control of the Department of Horticulture. The Deputy Director of Horticulture (Cubbon Park) is responsible for the administration and maintenance of the park. The park has about 68 genera and 96 species with a total of around 6000 plants / trees growing in its locale. The Gulmohar trees and massive clumps of bamboo add a distinct identity to this large lung space.

8.3.5 Conservation Zones along Arkavathi River and Thippagondanahalli Reservoir

Arkavathi River flows from the north west of the BMA to converge at the Thippagonadanahalli (T.G.Halli) Reservoir at the western side of the BMA. As per G.O. No. FEE 215 ENV 2000 dated 18.11.2003, Bangalore. Under Section 18 (I b) of the Prevention and Control of Pollution Act, 1974 and 1981, the GoK declared the catchment area of Thippagondanahalli (T.G. Halli) as a "regulated zone". This means the industries that have come up in the catchment area will not be allowed to let their waste flow into the reservoir. Future development in the catchment area is restricted. BMA falls under the regulation area of Zones 1, 3 and 4. The regulations of Conservations zones along Arakavathi are given in Table 8-3.

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8.4.1 Natural Drainage System

Watershed: Watershed is a geo-hydrological unit of all land and water within the confines of drainage divide which contributes runoff to a common point. It is a land area that captures rainfall and conveys the overland flow and runoff to an outlet in the main flow channel.

The major drainages in the BUD are the Cauvery and the South Pennar basins¹⁹. BMA by its N-S ridge is drained by rivers Arkavathy on the west and South Pennar or South Pinakani River to the east. Arkavathy River is a mountain river originating from Nandi hills which is further north of the BMA boundary and is a tributary of Cauvery River. Arkavathy joins Cauvery River at 34 kms south of Kanakpura outside the boundary of BMA. Additionally, Kumudavathy and Vrishabhavathy rivers are tributaries to the Arkavathy. The two catchments of Arkavathy and Pennar rivers (Figure 8-14) are further divided to four main watersheds in BMA which form separate and distinct drainage zones.

The Arkavathy River in the Arkavathy catchment is a tributary to the Cauvery River and flows in N-S direction. Its drainage pattern is trellis to sub-dendritic and it has high drainage density mainly due to a higher density of first order streams with lesser lengths and is dotted with number of mounds, hills and possesses only small sized tanks to the south west. The Arkavathy catchment is divided into two watersheds, namely,

• the Kumadavathy or upper Arkavathy watershed along the north west of BMA and the

• the Lower Arkavathy watershed along the south west of BMA

The two main tributary systems are flowing from North east to South east direction and the other from east to west and confluence each other at Mysore road. The eastern area of BMA comes under the Upper Pennar watershed and South Pennar watershed. The Figure 8-15 presents the four watersheds in BMA. The lower Arkavathy watershed comprises of the Vrishavabhavathi valley. The Vrishabahavathy River originates at the Bull temple and flows further from the south of BMA where it joins the Cauvery River.

19 The South Pennar river of Ponnaiyar basin takes its birth from Nandi hills and flows towards south.

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Figure 8-14: Two Catchments in BMA

Figure 8-15: Four Major Watersheds in BMA

Source: Karnataka State Remote Sensing Application Centre, GoK, 2015

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Lakes & Valley System: In the eastern part of BMA is the Upper Pennar watershed and South Pennar watershed, there are two major drainages, namely one is from Yelahanka flowing south easterly and the other from Sarakki area. These two watersheds constitutes the Hebbal valley to the north is characterized by first and second order stream, and the Bellandur valley to the south east where the streams passes on to third order. The Bellandur valley system further has the Challaghatta sub valley and Koramangala sub valley. The rainfall in BMA due to its N-S ridge gets divided and flows down to the east or west over the valleys of gentle slopes of Vrishbhavathy, Hebbal and Koramangala & Chalaghatta.

Five minor valleys, the Kathriguppa and Tavarekere to the south, the Arkavathi and Kethamaranahally to the northwest and Marathhally to the east, lie outside the tributary area of the major valleys and they drain independently to the fringe areas. The configurations of valleys in well graded side slopes of their tributary areas have provided Bangalore with a natural system of drainage without resource to pumping. Both sewage and storm water flows by gravity beyond the city. It is noteworthy that each of the valley systems, comprise of system of lake series that are essentially formed by interlinking / cascading lakes or tanks to one another through natural streams/ drains. Figure 8-16 presents the valley system and their respective lake series in BMA. The valley systems and their respective lake series are as following:

a) Hebbal Valley: Yellamappachetty Lake Series and Madvara lake series

b) Koramangala and Challaghatta Valley: Varthur Lake Series, Puttanahalli lake series, Hulimavu Series

c) Vrishbhavathi Valley: Byramangala lake Series

Figure 8-16: Lake Series in the Valleys of BMA

Source: KLCDA

Thippagondanahalli Reservoir: Another important physical feature relevant to the context of natural drainage in BMA is the Thippagondanahalli Reservoir²⁰ (TGR) is located at the confluence of the Arkavathy River and Kumudavathi River, 35 km westwards, outside the BMA boundary. This manmade reservoir built in 1933 has a catchment of 1453 sq.km and covers parts of Doddaballapur, Nelamangala, Devanahalli, Magadi and Bangalore Taluks. The water body used to act as a source of drinking water for western part of Bangalore supplying up to 117MLD, but at present the source has been abandoned due to much decreased inflow to the TGR.

8.4.2 Natural Drainage Classification

The application of buffers as prescribed by National Green Tribunal is dependent on the classification of streams/ natural drainage, namely – Primary Stream, Secondary Stream and Tertiary Stream. RMP 2031 using the DEM and GIS based software has classified the natural drainage system in consultation with KSNMDC for BMA. Figure 8-17 presents the Drainage Classification for BMA.

Figure 8-17: Drainage Classification

20 Thippagondanahalli Reservoir is also known as T.G.Halli Dam and Chamaraja Sagar.

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The natural drainage so classified was translated to ground situation using Base Map prepared for RMP 2031. The buffers, as prescribed by National Green Tribunal, have been applied to streams/ drainage accordingly for preparation of Proposed Land Use Map.