Transcript Document

Environmental impacts of
groundwater intensification in India
Sunderrajan Krishnan
Trishikhi Raychoudhary
Chaitali Purohit
Ankit 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)
Issue
Based
(2 issues)
Nation-wide analysis
(at district level)
Building blocks of study
Region based (4 regions)
Issue
Based
(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) Variability
b) 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 variability
2. Uncertainty on Hydrogeological parameter: eg specific yield
Building blocks of study
Region based (4 regions)
Issue
Based
(2 issues)
Nation-wide analysis
(at district level)
Studies in four regions
- Bist-Doab of Punjab: overexploitation and agropollution; 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
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)
Issue
Based
(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 Pradesh
Orissa (Central to North)
West Bengal
Issue 2: Urban groundwater exploitation
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
towns
Main data: proportion dependence of urban area on GW
100
% dep
On GW
0
1lakh – 1 Million
Million +
Issue 2: Urban groundwater exploitation
Aquifers in urban areas are increasingly
exploited
Data collection on coning in Ahmedabad city
Subsidence problems (Kolkata) because of
overexploitation
The situation in various other cities: Chennai,
Delhi, …
Structure of report
Chapter 1: Summary
Chapter 2: A national picture
2.1 National level statistics and District level analysis
2.2 A theoretical description of each specific impact and regions experiencing them
Chapter 3: Analysis of four regions
3.1 Groundwater exploitation in Bist-Doab, Punjab
3.2 Exploitation, contamination and urban demands in North Gujarat
3.3. Salinity, Arsenic, Land subsidence and exploitation in Coastal West Bengal and North
Orissa
3.4 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
Growth of Abstraction
Structures
(’000)
12000
10000
8000
Abstruction
structures 6000
(000)
4000 3860
2000
0
7786
8742
9407
10120 10501
6743
4754
5379
3359
2132
90
33.3 46.2 63.6 67.6
32.4
Mar Mar Mar Mar Mar Mar
'51
'80
'85
'90
'92
'97
Dug wells
Pvt. TW
Pub. TW
Cumulative Irrigation Potential Created from
Ground Water (Mha)
60
50.31
50
40
35.62
irrigation
potential 30
(MHa)
20
10
38.89
27.82
22
6.5
0
Mar Mar Mar Mar Mar Mar
'51
'80
'85
'90
'92
'97
Distribution of
Fluoride in
Ground Water
Objectives
1.
2.
•
•
•
•
3.
4.
5.
6.
Define coastal saline area of 500ppm
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)
Construction of a pictorial view of vertical cross-section of Aquifer
system of Indian coast
Pictorial vertical cross-sectional of saltwater intrusion
mechanism of specified area.
Agricultural and Aquaculture activity of Indian coast
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
Patterns of present and future groundwater in urban areas
Demographic study
Maximum growth in urban population is occurring in 1,00000 to 1 million population cities
Census population, 1971, 81, 91, 2001 & trend of 2011, 21, 31..
cities of > 1 millions : 34 cities
Class I >100,000-1 million
Class II = 50-100,000
Class III = 20-50,000
Class IV = 10-20,000
Total
= 4378 cities
> 1 millions
= 35 cities
Methodology:
Review of demographic studies done by UNDP, Kundu et al., Census projections
Individual studies done by others will be collected (literature review) for 35 cities.
Total water use
Proportion of SW & GW in total water use
To take @ 20 cities from these 35
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
towns
CGWB district water data & estimating GW use
Sewerage disposal of towns & estimation of total water use
Samples from various classifications - Tree, leaves @ 30 towns
Check histograms of population -True Vs Sample, for both cities/towns
Expected out put:
Weighted Indicators with final GW use pattern, Ex. CART analysis (ref:
Sunder)