Environmental impacts of groundwater intensification in India

Sunderrajan Krishnan Trishikhi Raychoudhary

Chaitali PurohitAnkit Patel

Definition of problem

Any disturbance from the natural regime of

groundwater flows or geochemistry caused by

intensification of groundwater use that results in

significant impact on environment and on humans

Challenges:

To define natural regime

To isolate role of GW use on the impact, eg. coastal salinity

Which issues are being studied

- Fall in water tables and rise in water tables regionally

- Highly fluctuating water table

- Quality problems emanating from exploitation eg. salinity in coastal areas, increasing mineralization of deeper aquifers, release of geogenic heavy metals associated with exploitation

- Quality problems due to use of poor quality water for irrigation

-Related surface water issues eg. tanks that recharge aquifers, being in disuse , partly due to gw use

Which issues are not considered

- Pollution from industries; pollution from agrochemicals

-Existing natural contaminants eg. Iron, Fluoride, Arsenic contamination – when existing without any disturbance

- Ecological aspects eg. impact of phreatic plants due to deepening water tables, biomagnification of contaminants through environmental media

Building blocks of study

Region based (4 regions)

IssueBased

(2 issues)

Nation-wide analysis(at district level)

Building blocks of study

Region based (4 regions)

IssueBased

(2 issues)

Nation-wide analysis(at district level)

Nation-wide analysis at district level

Objectives:

To delineate zones of GW vulnerabilty using different criterion:

a) Volumetric information: GW recharge, GW use for various purposes; Proportion GW used for irrigation

b) Depth to Groundwater Table: Median depth to water table; Median fluctuation of water table

c) Impact of well interference: well density and hydrogeology together impacting well interference

Overlap these zones to mark regions of varying vulnerablity

Nation-wide analysis at district level … cont’d

Objectives:

To demonstrate the impact of a) Variabilityb) Uncertainty

in district level figures ; therefore also on looking at GW vulnerability using these figures

This analysis will be performed for 5 districts by varying:

1. Rainfall: inter-annual variability2. Uncertainty on Hydrogeological parameter: eg specific yield

Building blocks of study

Region based (4 regions)

IssueBased

(2 issues)

Nation-wide analysis(at district level)

- Bist-Doab of Punjab: overexploitation and agro-pollution; groundwater balance and trend analysis

- North Gujarat: overexploitation, Fluoride, Salinity, urban exploitation and pollution

- Coastal West Bengal and Orissa: saline water intrusion and urban subsidence of land

- Central Tamil Nadu: Noyyal sub-basin of Cauvery: overexploitation, pollution, demand from urban areas

Studies in four regions

Studies in four regions

Bist-Doab

North Gujarat

Coastal WB, N. Orissa

Noyyal sub-basin of Cauvery

Studies in four regions

Objectives:

Detailed characterization of environmental impacts of groundwater use in the region

Extrapolation to parts of the country that are similar to this region

Eg. North Gujarat: overexploitation of aquifers; Fluoride contamination; Urban demand of groundwater from Ahmedabad area; Coastal and inland salinity of groundwater

Can be extrapolated to parts of Rajasthan

Studies in four regions

Fresh studies:

- Collecting long-term groundwater hydrographs from Bist-Doab for better hold on groundwater balance

- Collecting geochemical data in Baleshwar district, Orissa to delineate zones of differing salinity content

Building blocks of study

Region based (4 regions)

IssueBased

(2 issues)

Nation-wide analysis(at district level)

Issue 1: Coastal salinity of groundwater

Issue 1: Coastal salinity of groundwater

Compiling the conceptual picture of coastal salinity across the coast

Information on: Geomorphology, Hydrogeology, Tidal patterns, Observed salinity data

Important regions:

Gujarat (Kutch, Saurashtra, South Gujarat)Tamil Nadu (North)Central Andhra PradeshOrissa (Central to North)West Bengal

Patterns of groundwater use in urban areas:

- Major growth of urban areas is happening in 1,00,000 – 1 million population- Most of these cities are highly dependant on groundwater ; much more than million+ cities- The locus of future GW demand in urban areas will be these townsMain data: proportion dependence of urban area on GW

Issue 2: Urban groundwater exploitation

Million +1lakh – 1 Million0

100

% depOn GW

Issue 2: Urban groundwater exploitation

Aquifers in urban areas are increasingly exploitedData collection on coning in Ahmedabad city

Subsidence problems (Kolkata) because of overexploitation

The situation in various other cities: Chennai, Delhi, …

Structure of reportChapter 1: Summary

Chapter 2: A national picture

2.1 National level statistics and District level analysis2.2 A theoretical description of each specific impact and regions experiencing them

Chapter 3: Analysis of four regions

3.1 Groundwater exploitation in Bist-Doab, Punjab3.2 Exploitation, contamination and urban demands in North Gujarat3.3. Salinity, Arsenic, Land subsidence and exploitation in Coastal West Bengal and North

Orissa3.4 Exploitation, pollution and urban demands for groundwater in Noyyal sub-basin of

Cauvery in Tamil Nadu

Chapter 4: Coastal salinity of groundwater in India

Chapter 5: Groundwater exploitation in urban areas of India

Chapter 6: An ecological look at groundwater exploitation

Timeline

March: presentation in Anand on work till then

- Preliminary analysis of nationwide district level data

- Initial data collection from all 4 regions

- A synthesis of coastal salinity

- Presentation of collected data in urban groundwater study

July: final report

3860

32.4

7786

2132

33.3

8742

3359

46.2

9407

4754

63.6

10120

5379

67.6

10501

6743

900

2000

4000

6000

8000

10000

12000

Abstruction structures

(000)

Mar'51

Mar'80

Mar'85

Mar'90

Mar'92

Mar'97

Dug wellsPvt. TWPub. TW

Growth of Abstraction Structures

(’000)

Cumulative Irrigation Potential Created from

Ground Water (Mha)

6.5

2227.82

35.6238.89

50.31

0

10

20

30

40

50

60

irrigation potential (MHa)

Mar'51

Mar'80

Mar'85

Mar'90

Mar'92

Mar'97

Distribution of Fluoride in Ground Water

Objectives1. Define coastal saline area of 500ppm 2. A plan view specifying different concentration saline area• Very high saline area (salinity: more than7500mg/l) • High saline area (salinity: 4000mg/l-7500mg/l)• Moderate saline area (salinity: 1500mg/l-4000mg/l) • Low saline area (salinity: 500mg/l-1500mg/l)3. Construction of a pictorial view of vertical cross-section of Aquifer

system of Indian coast4. Pictorial vertical cross-sectional of saltwater intrusion

mechanism of specified area. 5. Agricultural and Aquaculture activity of Indian coast6. Preventive or Remedial measure taken in different part of Indian

coast

Specific Objectives Geomorphology Coastal area specification and Geography, river basin and other

natural surface details of the area Aquifer system coastal hydro-geology Salinity related study Surface soil-salinity condition Seasonal variation of saltwater and groundwater profile in a

specific focused area Special variation of salinity over years (movement of salinity

profile of fixed concentration over time) Groundwater table depletion over time in that area. ( to compare

saltwater intrusion with groundwater depletion)

Methodology

1. Data Collection

• Govt. Organization: CGWB, GSI, CSSRI, State Water and Irrigation Department (SWID)

• Non-Govt. Organization and Universities: Universities (BEC,Howrah etc) and NGOs

• Literature Review: Published papers and Books

2. Linking, analyzing and processing of data

3. Preparation of Report

Demographic studyMaximum growth in urban population is occurring in 1,00000 to 1 million population citiesCensus population, 1971, 81, 91, 2001 & trend of 2011, 21, 31..cities of > 1 millions : 34 citiesClass I >100,000-1 millionClass II = 50-100,000Class III = 20-50,000Class IV = 10-20,000Total = 4378 cities> 1 millions = 35 citiesMethodology: Review of demographic studies done by UNDP, Kundu et al., Census projectionsIndividual studies done by others will be collected (literature review) for 35 cities.Total water useProportion of SW & GW in total water useTo take @ 20 cities from these 35

Patterns of present and future groundwater in urban areas

For rest, 400 cities will be classified into broad category, class I 100,000 to 1 million and class II, III & IV as 10,000-100,000. We would consider Class I for our study

Cities in different regions will be identified based on several factors (i.e. cities above hard rock strata/ with alluvium strata, river bank, coastal, hill stations, rainfall, GW quality)Probable Source of data for, total water use: Through, irrigation data - statewise (as many as possible), SW supply to the townsCGWB district water data & estimating GW useSewerage disposal of towns & estimation of total water useSamples from various classifications - Tree, leaves @ 30 townsCheck histograms of population -True Vs Sample, for both cities/townsExpected out put: Weighted Indicators with final GW use pattern, Ex. CART analysis (ref: Sunder)