Urban Groundwater Scenario. M. S. Mohan Kumar. Department of Civil Engineering Indian Institute of Science Bangalore

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1 Urban Groundwater Scenario M. S. Mohan Kumar Department of Civil Engineering Indian Institute of Science Bangalore

2 Global Water Scarcity Increased global water stress

3 Groundwater Groundwater is the largest accessible and often still untapped freshwater reservoir on earth. Global groundwater resources are assessed to be around 10.5 million km³. (Source: BGR & UNESCO)

4 Groundwater Groundwater depletion remapped in three-dimensional topography to show 'mountains of groundwater depletion' especially in the United States, Mexico, Saudi Arabia, Pakistan, India and China.

5 Per Capita Water Availability (Cubic Meter Per Year) Water Demand (Billion Cubic Metre) Present Demand 813 Total Anticipated Demand In In

6 Demand and Supply Gap

7 Demands of various Sectors Major portion from Groundwater (In percentage) Sector Irrigation Domestic Industries Power others Evaporation losses 6 6 7

8 Groundwater Groundwater is the major source of drinking water in both urban and rural India. Besides, it is an important source of water for the agricultural and the industrial sector. 85% of rural population obtain water mainly from wells where the source is shallow or deep aquifers (groundwater). The total annual replenishable ground water resource in India is about 433 BCM. 16 percent of total potential used for drinking, industrial and other purposes, the remaining available for irrigation. Its availability depends on the rainfall and recharge conditions.

9 Total Annual Ground Water Recharge: 433 BCM Balanced Dynamic Ground Water: 168 BCM Annual ground Water Draft: 231 BCM Major source of ground water recharge: Rainfall (67%)

10 Withdrawals of Surface and Groundwater Exploitation of ground water has reached such a state that natural recharge is not sufficient. Pollution of groundwater resources has become a major problem today. The pollution of air, water, and land has an effect on the pollution and contamination of groundwater. A major portion of ground Water in India is used for irrigation.

11 Groundwater Status Global and Indian Context Global trends in groundwater irrigation India: around 27Mha Source IWMI Top 20 groundwater irrigating countries

12 Urban Groundwater Generally used for domestic and industrial use. Natural groundwater recharge is less due to impermeable surfaces. Groundwater pollution is high compared to rural groundwater Rural Groundwater Generally used for agricultural uses. Natural recharge is more compared to urban areas. Pollution is less due to lack of industries polluting surface water etc.

13 Urban Groundwater Uses: Residential Commercial Industrial Recharge: Rainfall recharge Leakages from drinking water pipelines Leaking sewers Surface water (contaminated)

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17 Urban Groundwater Issues Reduction in water level Inadequate recharge Water Quantity Issues: Climate change and Urbanization Water table rise will cause water logging in lowlying areas. Recharge from sewers Water Quality Issues Natural contaminants like arsenic, fluoride, iron etc. Agricultural pollution Industrial pollution

18 Groundwater Quantity Issues CATEGORISATION OF BLOCKS/MANDALS/TALUKAS As on March 2004 (CGWB) Water level Fluctuation January 2007 vs Decadal Mean ( )

19 Groundwater Quality Issues Most of the contaminants are due to anthropogenic activities, while a few are due to natural geologic deposits of salts 14 states in India have fluoride levels above 1.5 ppm High levels of arsenic (above 50 ppb) found in 6 districts in West Bengal Excessive withdrawal of water from coastal aquifers especially in Kutch & Saurashtra in Gujarat, Chennai in Tamil Nadu and Calicut in Kerala has led to saltwater intrusion

20 Groundwater Quality Issues Arsenic affected areas in West Bengal Fluoride affected areas in India

21 Groundwater Scenario in Bangalore Groundwater plays an important role in the total water supply of the city. 40% of the population of Bangalore is dependent on groundwater. Number of borewells in the city is ranging from 200,000 to 400,000. Overexploitation and poor management have contributed to groundwater depletion and quality problems.

22 Piped and Groundwater Supply: Bangalore Zone Surface Water (MLD) Groundwater (MLD) Central North West East South South East Total BWSSB Zonewise Piped Water Supply and Groundwater Consumption

23 Ground Water Scenario in Bangalore Source: CGWB, 2011

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25 Groundwater pumping Groundwater Pumping Total Pumping = 4.26 MLD/Km 2 Population Density : Persons/Km 2 BWSSB Water Supply : MLD/Km 2 Well Density= Number/Km 2 House Borewell Public Borewell 29

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27 Bangalore: GW Pumping and Recharge Annual Rainfall in Bangalore: 900mm; of which 10% is recharge (0.07 km 3 /yr) Piped water supply to Bangalore is about: 910 MLD out of which 45% is UFW. And of this UFW, 50% recharges the ground water (0.07 km 3 /yr) Wastewater: Considering 50% of wastewater recharges the ground water, (0.07 km 3 /yr) total ground water recharge is 0.21 km 3 /yr. Groundwater - Assuming 50% of the borewells are dry, and the remaining borewells yielding about 1.5lit/sec, with a pumping of 2 hours duration per day, groundwater pumping is 0.59 km 3 /yr. Pumping=2.8 times Recharge

28 Ground Water Scenario in Bangalore: Water Quality Source: CGWB, 2011

29 Status of groundwater quality in Bangalore: Conducted by the Department of Mines and Geology, Government of Karnataka The study collected 918 samples from 735 locations across an area of 400 square kilometers of the city. In 370 locations (50.34%), the groundwater was found not suitable for domestic purposes as per the ISO 10500:1991 standard. 278 samples showed higher than permissible nitrate contamination, as high as 747 mg/l (permissible limit of 50 mg/l). Bacteriological contamination was tested separately at 100 locations that were deemed high-risk, and contamination was found in 74 of the 100 samples.

30 Groundwater in Coastal towns Over exploitation of coastal aquifers results in environmental impacts including seawater intrusion and land subsidence. Rivers are the major contributors of pollution of the coast and coastal aquifers. A case study of Warakali aquifer in Kerala (Thiruvananthapuram) showed high amounts of salts and fluoride. A rise in sea-level will affect ground-water flow in coastal aquifers

31 Mulbagal experience: Groundwater based water supply To develop a sustainable water management plan towards the future needs of Mulbagal Town, Kolar district, Karnataka. To efficiently manage the groundwater resources. To achieve these groundwater studies have been taken up, which envisage to assess the behavior of the groundwater system through monitoring of groundwater levels & its use. Models are being developed that would be used as diagnostic tools for current and future assessments. Emphasis is also on development of generic models applicable for urban groundwater management goals with the optimal data collection. Population , Borewells-105, Water supply 4 MLD

32 System Details 1. The Mulbagal town (~ 6 Km 2 ) is in the Kolar district of Karnataka and is on the highway between Bangalore and Chennai.The population of the town is ~80,000. The demand for water is 4.0 mld. 2. The current water supply is ~3.0 mld. The water needs are mainly met from groundwater sources. Municipality has (75%) wells, which are pumped. In addition there are private wells (25%) as well. 3. The municipality has a total of 105 bore wells. There are Five pumping stations, which are located outside the town and each station has a cluster of bore wells that are pumped to distribute water to the town. A total of 51 bore wells (~50%) are there in these five pumping stations. 32

33 Investigations 1. During July 2008-August 2009, monthly groundwater table mapping and its dynamics during the monsoon & non-monsoon season have been obtained through extensive monitoring. This was performed by a novel approach in which the existing wells are used as observation wells. Since there is no observation well network of any government agency in the town, the first step was to create a data base specific to the scale of the town. 2. The data base of monitoring comprises of: Municipal wells = 98; Private wells = 37; Agricultural wells = The yields of wells (~ 140 wells) are obtained by extensive data collection. The yields vary from 1 L/s to 3 L/s (average ~ 2 L/s with a cov of 60%). 33

34 Groundwater Studies 1. A simple methodology is developed that uses groundwater level fluctuations during monsoon and non-monosoon in various zones with different controls to estimate (i) rainfall recharge, (ii) recharge from indirect sources, (iii) subsurface drainage. 2. The recharge amount estimated in the town is much higher than outside town region due to the other sources of recharge. The relatively lower quality of water in the town indicates the impacts of other indirect recharge sources. 3. The recharge in the town occurs both from direct rainfall recharge as well as indirect sources of leakages. 34

35 Policy Issues 1. At present there is no operating approach for assessing the groundwater balance components at the scale of a town or city. This needs to be jump started since several towns depend for a large fraction on groundwater. 2. Such a practice would lead to sustainable development in the future considering the large investments (to the tune of few crores towards bore wells drilling, pumping machinery and ancillary systems) made by municipalities and private users. 3. The studies being performed at Mulbagal town would bring out (a) how to protect the catchment areas of pumping zones and their sustainability, and (b) how to efficiently manage the groundwater within the town combining it with water and waste water treatment options. 35

36 Mulbagal town limits & setting 36

37 GW Monitoring Network with Wards 37

38 Way Forward: Ground Water Management Demarcation and assessment of artesian aquifers Mapping of flood plain aquifers Mapping of important aquifer system Management of coastal aquifer Conjunctive use of surface and ground water in irrigation Remote sensing studies for ground water studies Water balance studies at city scale for groundwater usage. Ground water resource assessment in: Over-exploited area, Naturally contaminated area Water scarce areas

39 National Project on Aquifer Management (NAQUIM) The importance of groundwater for national development has deemed it necessary to be more specific; more general groundwater management has become aquifer management to answer the specific queries on availability and sustainability. CGWB has taken up National Project on Aquifer Management in XII & XIII Plan period to formulate sustainable aquifer management plan.

40 National Project on Aquifer Management (NAQUIM): Flow chart

41 Ground Water Regime Monitoring Total number of ground water monitoring wells are located all over the country. Ground water samples are collected from these observation wells once a year during the month of April/ May to obtain background information of ground water quality changes on regional scale. This data is used for assessment of ground water resources and changes in the ground water regime. Karnataka : 1507 monitoring wells.

42 Ground Water Resources Assessment Ground Water Resources of the country have been assessed and being updated periodically by CGWB. There are two types of resources viz: Annually Rechargeable Dynamic Ground Water Resource: This resource is computed jointly by CGWB and State Ground Water Departments Static Ground Water Resource: This occurs below the dynamic resource and it has been evaluated on the basis of explorartory drilling. Till now the static resource has been assessed to the depth of 450m in soft rock and 100m in hard rock

43 Artificial Recharge of Ground Water A demonstrative scheme on Rain Water Harvesting and Artificial Recharge to Ground Water has been taken up at following areas: Lingala, Pulivendula Vemula and Vemalli blocks in Kadapa district, Andhra Pradesh Gangavalli block in Salem district, Tamil Nadu Mallur Block in Kolar district, Karnataka Bel watershed, Amla & Multai Blocks in Betul District, Madhya Pradesh. Upper reaches of Choti kali Sindh river in parts of Sonkatch & Bagli blocks in Dewas district, Madhya Pradesh. Combination of Percolation Tanks, Watershed Structures, Recharge wells, Roof Top Rain Water Harvesting are adopted for artificial recharge of ground water.

44 Acknowledgements Anjana G R Usha Manohar Sheetal Kumar K R

45 Thank you..