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WATER SITUATION IN BENGALURU
Abstract and Figures
EXECUTIVE SUMMARY:
This study was undertaken to assess the quantum of water available in the region to meet the domestic demand. The study brings out that there is sufficient water available in the region, but fails to understand the inability or ineffectiveness of the local administrators to sustainably manage the water resources in the region. Sufficient water is available to meet everyone’s requirement, provided (i) water harvesting is undertaken through surface water bodies; this requires rejuvenation of lakes and reestablishment of interconnectivity; harvesting of rainwater (at decentralized levels), treatment; (ii) treatment and reuse of sewage. However, the success of sustainable water path depends on the political will, bureaucracy shedding their colonial style of functioning and more importantly citizen’s assertion for their right for equal quantity and quality of water.
Average annual rainfall in Bangalore is about 787 mm with 75% dependability and return period of 5 years. Catchment wise water yield analysis indicates about 49.5% (7.32 TMC) of water yield in the Vrishabhavathi valley (including Arkavathi and Suvarnamukhi), followed by 35.2% (5.2 TMC) in Koramangala Challaghatta valley and 15.3% (4.2 TMC) in Hebbal valley and the total annual water yield in Bengaluru is about 14.80 TMC. Domestic demand of water (at 150 lpcd) is 20.05 TMC per year (1573 MLD). This means about 73% of Bangalore’s water demand can be met by efficient harvesting of rain water. Quantification of sewage generated shows that about 16.04 TMC (1258 MLD) of sewage is generated in the city.
Sewage treatment with complete removal of nutrients and chemical contaminants can be achieved by adopting decentralized treatment plants similar to the success model (secondary treatment plant integrated with constructed wetlands and algae pond) at Jakkur lake. In addition to this, water available with efficient rainwater harvesting is about 14.8 TMC. This accounts to total of 30.85 TMC of water that is available annually would cater the demand of 20.05 TMC, provided the city administration opts for decentralized optimal water management through (i) rainwater harvesting by rejuvenating lakes - the best option to harvest rain water is through interconnected lake systems, (ii) treatment of sewage generated in households in each locality (opting the model functional since 2010 at Jakkur lake – STP (Sewage Treatment Plant) integrated with constructed wetlands and algal pond; (iii) conservation of water by avoiding the pilferages (due to faulty distribution system); (iv) ensuring water supply 24x7 and (v) ensuring all sections of the society get equal quantity and quality of water. Rejuvenating lakes in the region helps in retaining the rain water. Treating sewage and options to recycle and reuse would minimize the demand for water from outside the region.
However, this model of decentralised harvesting of water and reuse of treated sewage is not an attractive proposition for the current breed of decision makers with the colonial style of functioning/mind-set. The financial gain is much higher in the case of mega projects (such as water diversion) compared to these decentralised models. This is the sole reason for the local administrators to degrade decentralised water harvesting structures and alienating local community. The main reason for deliberate inefficient management of water resources is to maximise the net return for the ruling class themselves than the overall growth of the region with water security. The analysis illustrates that the city has at least 30 TMC (Bangalore city) of water, which is higher than the existing demand (20.08 TMC, at 150 lpcd and 2016 population), if the city adopts 5R’s (Rejuvenate, Retain, Recycle - Reuse, and Responsible citizens’ active participation with good governance).
Scope for decentralized rainwater harvesting: During 1800, the storage capacity of Bangalore was 35 TMC. In 70’s, lakes covered an area of nearly 3180 hectares and now the spatial extent of lakes cover an area of 2792 hectares. The current capacity of lakes is about 5 TMC and due to siltation, the current storage capacity of the lakes is just about 1.2 TMC, i.e., nearly 387 hectares of water bodies disappeared besides reduction in the storage capacity by 60%. Bangalore being located on the ridge, forms three watersheds – Koramangala Challagatta valley, Vrishbhavathi Valley and Hebbal Nagavara Valley. Earlier rulers of the region, created interconnected lake systems taking advantage of undulating terrain. Number of lakes in the Koramangala Challaghatta Valley is about 81, followed by the Vrishabhavathi Valley (56) and the Hebbal Nagavara Valley (46).
Land use analysis in Bangalore City shows 1005% increase in urban (built-up) area between 1973 and 2016 i.e., from 8.0% (in 1973) to 77% (in 2016). Land use prediction using Agent Based Model showed that built up area would increase to 93.3% by 2020, and the landscape is almost at the verge of saturation.
In order to enhance the water retaining capability in the catchment, it is essential to rejuvenate lakes and undertake large scale watershed programme (soil and water conservation). Lakes are the optimal means of rainwater harvesting at community level. This entails
(i) Reestablishing interconnectivity among lakes (requires removal of all encroachments without any consideration, as the water security of a region is vital than the vested interests, who have unauthorisedly occupied without respecting future generation’s food and water security). This would also reduce the frequency of floods and consequent damage to life and property,
(ii) removal of all encroachments of lakes and lake bed, and maintaining buffer region with the good riparian vegetation cover (without any artifacts),
(iii) rejuvenation and regular maintenance of water bodies. This involves de-silting of lakes to (a) enhance the storage capacity to retain rainwater, (b) increase the recharge potential – will improve groundwater table, (c) ensure recharging without any contamination,
(iv) allowing only treated sewage (removal of chemical and biological contaminants) through adoption of integrated wetlands ecosystem (Jakkur lake model),
(v) creation of wetlands with native vegetation and regular harvesting of macrophytes; food and fodder, which supports local people’s livelihood, and
(vi) maintaining at least 33% green cover with native vegetation (grass, trees, shrubs) in the catchment and planting riparian vegetation in the buffer region. This would help infiltration of water and retain this water.
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... Many of these ancient lakes are still in place. However, intensive urbanization, entailing typical "megacity problems" such as high demands for land and poor urban planning [15], caused 79% of waterbodies to vanish within 40 years and 90% of those remaining to suffer from sprawling construction and continuous inflow of sewage [9,16]. Degradation was caused in part by a shift of urban lake management from local communities towards a multiplicity of uncoordinated authorities [8,16]. ...
... Although Bengaluru's water demand rose at exorbitant rates, its multitude of water bodies have not been integrated in a water supply and water reuse system [18]. However, private borewells have been drilled down to 400 m and a 100 km long trench was built to extract the contested water resources of the Cauvery-Arkavathy river system to fulfill the water demands of the city [9,16]. If misused as urban dumpsters, vulnerable urban water commons become part of the public health problems due to severe surface and ground-water contamination [15]. ...
... Aquatic macrophytes can be mayor indicators of water quality [32], fulfill many critical ecological services of wetlands [33], sequester organic loads and nutrients, and stabilize sediments and shorelines [34]. Ramachandra et al. [9] reported that 25 of Bengaluru's 105 remaining lakes are already fully covered by macrophytes. This often happens through quickly propagating exotic invasive species indicating lake degradation [35]. ...
Rapid urbanization processes and indiscriminate disposal of urban wastewaters are major causes for anthropogenic lake-sediment deposition and eutrophication. However, information about the spatial and temporal variation of macrophyte and phytoplankton distribution as indicators for water contamination is limited. To gain insights into the dynamics, we analyzed lake-cover changes of Bellandur and Varthur Lake in the S-Indian megacity of Bengaluru for the post-rainy seasons of the years 2002–2019. Supervised maximum likelihood classifications were conducted on 62 freely available, true-color satellite images in order to distinguish between macrophytes, algae, and free water surface. The image-derived results were verified by supervised classification and manual mapping of two simultaneously recorded multispectral satellite images (Sentinel-2 and WorldView-2). Seasonal interrelations between macrophytes and algae distribution were similar for both lakes. The increase in macrophyte cover during post-rainy season negatively correlated with algal abundance. Macrophyte expansion progressively suppressed algae development at both lakes, reflective of increasing eutrophication caused by on-going wastewater input. Seasonal variation in precipitation, wind direction, and temperature seemed to trigger intra-annual shifts of macrophytes and algae while similar macrophyte spread intensities during the post-monsoon season indicated independence of nutrient loads in the lake water.
... The Chalukyas (6 th to 12 th century) are remembered for constructing various water harvesting structures like lakes, tanks and canals. A 'golden age' of implementation of high level of scientific and technical expertise during 937 A.D. to 1336 A.D. was witnessed in South India (Ramachandra et al., 2016). The technique of cascading tanks for controlling floods as well as use of water for irrigation was advanced. ...
... The construction of tanks progressed remarkably during this period. However, in the late 18 th century during the British Raj, the tank system degraded and the systems of natural resources management was centralized (Ramachandra et al., 2016). More than 12 anicuts were constructed across the river Tungabhadra in Bellary district which was the major source of water in Vijayanagara (Shivakumar and Cheluvaraju, 2016). ...
Since the early times Indians have used various ingenious methods to conserve and use water for various purposes like domestic, irrigation, hydropower, navigation and recreation. This chapter traces the history and evolution of water management since the earliest times in India and briefly covers the history from the Indus Valley (Harappa) Civilisation till recent times. Evolution of water conservation systems under the rule of Chola’s, Mughal’s, and other empires are also discussed. Steps taken for water resources development (WRD) in the colonial era (under British Raj) and how the advancements were made till the present times are briefly mentioned along with future challenges for water management in India.
The expansion of water resources infrastructure and water service provisioning in the last few decades have been a response to three major drivers: (a) demographic change, (b) growing standards of living and (c) expansion of irrigated agriculture (Gleick, Water Int 25:127–138, 2000). With growing urbanisation, Urban Water Supply (UWS) has been challenged for meeting the water needs of people. Therefore, managing UWS has required estimation of population projections and urban growth, per capita water demand and finding solutions to bridge the gap between demand and supply of water. This chapter attempts to understand the drinking water situation in urban and rural areas of India and presents urban water supply system using secondary data sources using census reports and data from relevant water utilities.
Poor maintenance of stormwater drains, encroachment of rainfed tanks are some of the major reasons cited for recent floods in Indian cities. Hence the priority for stormwater management has shifted from centralized to decentralized systems through new concepts like low impact development and green infrastructure. The present study is an attempt in this direction where a building which experienced water stagnation issues during a heavy rainfall was taken into account and maps of topographic and hydrologic parameters were prepared. With that, low-lying areas surrounding the building were identified, which were then used by the estates department for designing a suitable stormwater management plan. Hydrological analysis was also carried out to find the peak runoffs of extreme rainfalls in order to check the effectiveness of the recharging structure. The study would be useful in places where the water stagnation is a potential problem and thus demand a decentralized stormwater management system.
Pervading urbanisation creates uncertainty in prospects of agriculture across the rural–urban interface, which may affect capital formation for productive farm capital assets. To assess the capital investment behaviour of households north of Bengaluru and to identify factors influencing it, the present study used primary data at 2016–17 prices. Capital formation per hectare decreased from urban to peri-urban and rural areas (₹1.20 million, 0.67 million and 0.40 million, respectively). Investment on irrigation structure was highest throughout and formed half of the total farm investment in the rural area, owing to the dependence of agriculture on ground water. Another significant share of total capital was invested on labour saving farm machinery (18% in urban and peri-urban areas). Investment on livestock increased with urban influence and became a major livelihood source. The Cobb–Douglas type of production function revealed that land holding size significantly influenced the non-land capital stock throughout. The land sale status was non-significant in urban and peri-urban areas, whereas it was significant in the rural area, where most of the capital assets were generated out of land sale proceeds. The study concludes that urban influence increased investment on farm capital assets to cope with uncertainties in agriculture, namely acute labour shortage, increasing competition for water and increasing demand for livestock products.
Environmental/Ecological flow refers to the minimum flow of water to be maintained in a water body (river, lake, etc.) to sustain ecosystem services. Understanding environmental flow is important to ensure the local ecological and social (people, agriculture and horticulture, etc.) needs in a sustained and balanced way, while designing large scale projects (such as hydroelectric , river diversion, etc.). Western Ghats are the mountain ranges extending from southern tip of India (Tamil Nadu-Kanyakumari) to Gujarat. These mountain ranges are rich in biodiversity with diverse and endemic flora and fauna, and is birth place to numerous perennial rivers namely Netravathi, Sita, Sharavathi, Aghanashini, Krishna, Cauvery, etc. Western Ghats is often referred as water tower of peninsular India, due to the water and food security provided by the ecosystem through array of services. The region is also one among 35 global biodiversity hotspots. However, deforestation due to large scale land cover changes has affected the water sustenance in the region evident from the quantity and duration of water availability during post monsoon period. Forests in the Western Ghats along with the soil characteristics and precipitation plays a major role in storing water in sub-surface (vadoze and groundwater) zones during monsoon, and releases to the streams during post monsoon periods catering to the needs of the dependent biota including humans. Some of these undisturbed/ unaltered natural flow conditions in rivers and streams have proved their worth with the presence of rich and diverse species and array of ecosystem services, which also has helped in sustaining the livelihood of dependent populations. The undisturbed flow conditions guarantees the natural flow as well as minimum flow in streams to sustain the ecosystem services, which helps in meeting the social and ecological needs. Growing demand to cater the demands of burgeoning human population coupled with accelerated pace of deforestation due to unplanned and senseless developmental projects in the ecologically fragile regions have led the water scarcity even in regions receiving high amount of rainfall. In the current communication an attempt is made to understand the linkages between the hydrological dynamics across varied landscape with the anthropogenic and ecological water needs. If the available water resource meets the societal and environmental demands across seasons, the catchment is said to achieve the minimum flow requirements. The federal government has plans to divert the water from rivers in Western Ghats region to the dry arid regions in Karnataka. In this regard, environmental flow assessment of Yettinaholé river in Central Western Ghats is carried out to understand the feasibility of river diversion through the assessment of hydrologic regime with the analysis of land use dynamics (using remote sensing data), meteorological data (rainfall, temperature, etc. from IMD, Pune), hydrological data (from gauged streams) apart from field investigations in the catchment. The catchments receive annual rainfall of 3000-5000 mm (Department of Statistics, Government of Karnataka). Land use analyses reveal that Major portion of the catchment is covered with evergreen forest (45.08%) followed by agriculture plantations (29.05%) and grass lands (24.06%). Water yield in the catchment computed for each of sub-catchments based on the current land use and other related hydrological parameters using empirical method. The total runoff yield from the catchments is estimated to be 9.55 TMC. About 5.84 TMC is required for domestic purposes including agriculture, horticulture and livestock rearing. The quantum of water required to sustain fish life in the streams is about 2 TMC, computed based on hydrological discharge monitoring and fish diversity in streams during 18 months (covering all seasons) in select streams in Western Ghats. Considering the available water is sufficient only to meet the anthropogenic and ecological needs in the region, the sustainable option to meet the water requirements in dry arid regions would be through (i) decentralized water harvesting (through tanks, ponds, lakes, etc.), (ii) rejuvenation or restoration of existing lakes/ponds, (iii) reuse of waste water, (iv) recharging groundwater resources, (v) planting native species of grasses and tree species in the catchment (to enhance percolation of water in the catchment), (vi) implementation of soil and water conservation through micro-watershed approaches. Implementation of these location specific approaches in arid regions would cost much less compared to the river diversion projects, which if implemented would help the section of the society involved in decision making, construction and implementation of the project.
Our goal is to compare and quantify diversity of epiphyllous bryophyte communities in East Africa and in the neighbouring Indian Ocean islands. Alpha- and beta-diversities and diversity ordering were used. We have also used nonmetric multidimensional scaling to compare their species composition. Separation of the samples is caused both by geographical factors and degradation. Vulnerable, degradation tolerant and degradation marker species were recognised by indicator species analyses. The average number of species of the most diverse communities is 8-9 species per leaf. In a degraded habitat it may decrease until 3-4 species, probably due to the worsening conditions for reproduction with decreasing number of juvenile specimens. The number of species per habitats, based on 15-15 releves, varies from 25 to 14. While the average number of species per leaves is correlated with degradation, the total number of species in the habitat does not correlate. because the increased beta-diversity may balance the loss of species of the individual leaves. We have also demonstrated that the result primarily depends on the scale of the study, and the method used to quantify the diversity.
Increasing water withdrawals from many rivers of the world is leading to severe degradation in river ecosystems. Water is allocated for environmental needs so that a river can perform its natural functions. Environmental flows (EF) try to strike a balance between the use of water of a river for economic development, societal needs and delivering ecosystem services. This article describes a framework to assess environmental flows for a hydropower project in India in a situation where limited hydrological and very limited ecosystem data are available. It recommends that in such a situation, an acceptable EF regime can be arrived at by analysing hydrological data, supplemented by whatever ecosystem data are available and creating various scenarios of EFs. Benefits and impacts of different EF scenarios can then form the basis to determine an appropriate EF regime. Application of the framework is demonstrated in a case study in India. Adaptive management, where feedbacks are used to update and improve the decisions is helpful in such situations.
Unplanned anthropogenic activities have contributed to the shrinkage of wetlands as well as degrading their quality. is necessitates watershed-based planning such as inventorying, mapping and regular monitoring with cost-eeective and reliable assessment protocols. Diatoms have been used across continents as bioindicators for reeecting the physical, chemical and biological integrity of their habitats. e current study attempts to understand the role of environmental factors in the formation of the diatom community structure in the shallow wetlands of Peninsular India. Diatoms from diierent habitats and water chemical variables were assessed for 43 wetlands of Bangalore, a profoundly urbanized region of Peninsular India. A total of 181 diatom taxa from 45 genera highlights the rich biodiversity of the region. Wetlands located in the densely populated urban regions are dominated by a proliic growth of eutrophic indicator species such as Gomphonema parvulum Kütz., Nitzschia palea (Kütz.) W.Sm., N. umbonata (Ehrenb.) Lange-Bert., Diadesmis confervacea Kütz., Cyclotella meneghiniana Kütz. and C. atomus Hust. Wetlands located at the outskirts of the city characterize oligo-mesotrophic conditions where Achnanthidium sp. dominates. De-trended canonical correspondence analysis showed a strong innuence of eutrophication and organic/inor-ganic pollution on diatom assemblages but a relatively weak innuence of conductivity. TWINSPAN shows grouping of wetlands based on species composition and suggests that Achnanthidium sp. and Cyclotella meneghiniana are initial indicator taxa for oligo-mesotrophic and eutrophic conditions respectively. results indicate that the environmental factors consistently act as limiting variables in structuring diatom assemblages at a regional scale in urban ecosystems. e study provided insights into the ecological importance of endemic diatoms found in diierent environments. diatom-based biomonitoring can become a viable surrogate for physical and chemical parameters of water quality. Also, region-speciic dia-tom indices will enable the easy and eecient investigations of wetlands.
Urbanization involves the transformation of traditional agrarian economy to urban economies dominated by industries and other commercial activities. Our study focuses on the urbanization process in Bhopal (India), a prominent Tier I city, during the last four decades and the visualisation of future growth in 2018 and 2022 with an understanding of urban morphology dynamics through spatial analysis of time-series (of 1977-2014) remote sensing data with spatial metrics, density gradients and Markov - Cellular automata.
Zone-wise urban density gradients recorded between 1977 and 2014 aided in understanding the urban morphology with intense urbanization at core regions and sprawl at outskirts in NW and SE regions. Our study shows an increaseof built up ranges by 162% (from 1977 to 1992), by 111% (from 1992 to 2000), by 150% (from 2000 to 2010) and by 49% (from 2010 to2014). CA-Markov based urban growth modelling indicates urban changes of 50% (2018) and 121% (2022), while agent based modelling (ABM) indicates urban changes of 57% (2018) and 243% (2022) with increasing urban population as compared to 2014. ABM simulations captured reality more effectively and provided the flexibility to vary quantities and characteristics based on proximity of various amenities generating probability surface influenced by various agents, indicating urban development. Simulation of urban growth based on ABM can help planning infrastructure and basic amenities and support the sustainable management of natural resources
The tools of geographic information system (GIS) which can be used in a variety of ways to address the local problems of rapid urbanization have been discussed. With the availability of high spatial resolution data of IRS-1C many new ways of looking at urban utilities and environment have been illustrated. The new GIS models which can be adopted on an operational basis by developing and linking data bases in spatial and non-spatial form down to cadastral level have been explored. Day-to-day problems of the urban dwellings, i.e., traffic and transportation, greenery, solid waste disposal, pollution, location of new layout for urban growth, road alignments, etc., have been given a new look under the GIS environment with possibilities arising from the high resolution colour images of IRS-1C satellite.
