National Programmeon

Isotope Fingerprinting of Waters of India (IWIN):Background and Roles of Participating

Agencies

S.K. GuptaNational Coordinator, IWIN

Physical Research Laboratory Ahmedabad

The ProgrammeTheme:

Fingerprinting the various water sources of India forquantifying the factors (geographical, climate etc) controlling spatial distribution during rainy season and its re-distribution within the hydrological cycle during the year.

Objectives:

1. Identifying dominant seasonal vapour sources vis-á-vis AS, BOB & continental (local and /or long distance transported).

2. Quantifying partitioning into rain and sub-partitioning into, stream flow, groundwater, evapo-transpiration and soil moisture.

3. Quantifying the extent and rates of interactions/ exchange between these components,

4. Understanding geographical and climatic controls over the entire hydrological cycle both temporally and spatially.

MotivationTo understand continental scale

hydrological cycle and Land-Ocean-Atmosphere interaction in quantitative terms.

• Why:– A challenging academic quest of probing the

Nature.– Useful in modelling air-sea-land interaction

including dynamics of monsoon.– Providing inputs to water resource

development strategies.

TOOLS– Available meteorological and river flow data give some

estimates of vapour and water fluxes across different real or hypothetical boundaries.

– To identify the vapour and water sources of particular reservoir and its temporal evolution it is necessary to trace water molecules through their hydrological cycle.

– The heavier stable isotopes (18O and 2H) in the water molecules provide such a tracer.

– Processes of selection during partitioning and fractionation effects due to rain out, phase change (condensation / evaporation / transpiration), mixing etc provide characteristic isotopic signatures to different water/ vapour masses that can be used to trace their evolution.

Points for Interpretation of Isotope Data-1

• Rainwater: Equilibrium condensation process.

• Away from coast in the direction of wind δ18O of rain →decreases due to rainout.

• Precipitation from primary oceanic sources will have d-excess ~10‰. Not affected by rainout.

• Evaporation from falling raindrops: → Isotopic enrichment and decrease in the d-excess.

• Return of vapour by transpiration: non-fractionating process → Reduction of rainout effect. No change of ‘d-excess'.

• Return of vapour by evaporation: kinetic fractionating process → Increase in the d-excess of vapour and resultant rain.

Points for Interpretation of Isotope Data-2

• Rainwater: Equilibrium condensation process.

• Away from coast in the direction of wind δ18O of rain →decreases due to rainout.

• Precipitation from primary oceanic sources will have d-excess ~10‰. Not affected by rainout.

• Evaporation from falling raindrops: → Isotopic enrichment and decrease in the d-excess.

• Return of vapour by transpiration: non-fractionating process → Reduction of rainout effect. No change of d-excess.

• Return of vapour by evaporation: kinetic fractionating process → Increase in the d-excess of vapour and resultant rain.

PRECIPITATION δ18O

Primary Oceanic Sources: West Coast -1±1‰; East Coast -5±2‰. Lower Values due to Rainout/ Altitude Effect.

Higher Values due to Evaporation.

PRECIPITATION ‘d-excess’

Primary Oceanic Sources: 8-12‰. Lower Values due to evaporation from falling raindrops. Higher Values due to continental recycling.

δ18O in Groundwater and River waters

δ18O ‰δ18Ο ‰

d-excess in Ground- and River-waters

Groundwater

Konkan Coast and Western

Ghats: δ18O ≈ -1±1‰;

d ≈ 0-5‰.Deccan Plateau

region ‘A’: δ18O ≈ -1±1‰;

d ≈ 0±5‰.NE region ‘B’: δ18O ≈ -5±2‰;

d ≈ 10±5‰.

River waters

Mimic the distribution of groundwater isotopic values indicating that lean season flow is largely derived from drainage of shallow groundwater.

South & Central India: Groundwater

Approximate geographic correlation of ‘high’ Fluoride with regions of low d-excess indicating role of aridity.

Annual Natural GW Recharge for the country is 11.5±3.6% Rain.

Indo Gangetic plains show higher values

Gujarat, Rajasthan and peninsular India show lower values

Groundwaterδ18O in

NGC region

Enriched δ18O values are seen to be associated with regions of high Fl, high EC

showing 14C ages from20 - 30 ka.

Isotopes in Groundwater

δD= 7.6*δ18O - 2.9R2 = 0.9

-90

-70

-50

-30

-10

10-10 -8 -6 -4 -2 0 2

δ D (‰

)

-40

-30

-20

-10

0

10-10 -8 -6 -4 -2 0 2

d-ex

cess

(‰)

Groundwater

-90

-70

-50

-30

-10

10

-10 -8 -6 -4 -2 0 2δ18O (‰)

δ D (‰

)Groundwater

-40

-30

-20

-10

0

10

-10 -8 -6 -4 -2 0 2δ18O (‰)

d-ex

cess

(‰)

North Gujarat

Average values (amount weighted in case of precipitation)

(a) (b)

(c) (d)

Precipitation

Precipitation

Precipitation: Avg. (δ18O = -4.3 ± 2.1‰; δD = -33 ± 16‰; d = 1.2 ± 4.8 ‰)LMWL slope (7.6 ± 0.6) - (2.9 ± 2.2‰). Significant evaporation from falling raindrops.

Groundwater: Avg. (δ18O = -2.8±0.8‰; δD = -25 ± 4‰; d = -2.7 ± 5.6‰). Significant evaporation before recharge.

Stratification maintained by inflow to hypolimnion of cold and depleted groundwater recharged from higher elevations. (i) Hypolimnion inflow peaks in winter (Nov to Jan); Epilimnion inflow peaks around Oct. (ii) The average flushing time of the Lake is 1.63 years.

NAINITAL LAKE

Jan-Feb.

?

Delaygue et al, 2001.

δ18O – Salinity Northern Indian Ocean

Isotopic depletion due to fresh water influx in northern BOB.

No data available during the period of SW monsoon when fresh water floats over saline water.

Seasonal variation in isotopic composition of BOB vapour ?

Movement of Strom Tracks

Beginning July, depressions and storms originating in northern BOB moving north-westerly cause heavy rain in northern India. Frequency is highest in August and September.

Depleted Vapour Sources forEast Coast During SW Monsoon

• Heavy (~3m) rainfall over BOB• Heavy discharge (~1500km3) of Himalayan rivers.• Crossing over fraction from AS

Assuming East Coast precipitation δ18O = -5±2‰ with no contribution from the BOB, Applying Rayleigh equation:

δ = δ0 + ε ln f or δ18Ov(f) ≈ δ018Ov + ε18Ol-v . ln f

with δ0 = -1.4 ± 1.1‰ (Bombay Rain); δ018Ov = -10.7 ± 1.1 ‰

and δ = -5 ± 2‰ (EC GW); δ18Ov(f) = -14.3 ± 2 ‰

and ε = 9.3‰ at 25°Cf = 0.68 ± 0.16 as an estimate of the maximum AS cross over fraction.

The cross over fraction may be smaller because of contribution from BOB, δ18O of which may be >-5±2‰.

1 Indus2a Ganga2 (b+c) B’putra + Meghna3 Godavari4 Krishna5 Cauvery6 Pennar7 EF: Mahanadi to

Pennar8 EF: Pennar to

K’kumari9 Mahanadi10 Brahmani-Baitarni11 Subernarekha12 Sabarmati13 Mahi14 WF: Kachchh, S’tra

and Luni15 Narmada16 Tapi17 WF: Tapi to Tadri18 WF: Tadri to K’kumari19 Inland drainage in

Rajasthan20 Minor rivers draining

into Bangladesh and Myanmar

Major Drainage Basins

Enough surplus monsoon runoff, in excess of utilisable surface water, is not available to fully utilise the subsurface storage potential of aquifers in most basins in the country shown in brown.

India: Water budget for 2050 (km3/yr)

Possible measures to meet the deficit

Year1998

(1)

Year2050

Reqmnt.

(2) (3)

Deficitover1998

(4) = (5)=

EUSW+

GW in

exc. of

1998 (6)

Model RecyclableWaste Water

(7) (8)

Model Irrigation Return Flow

(9) (10)

Mod. Art.GW

Rech.

(11)

Pop.Mod.

L H L(2-1)

H(3-1)

SW 290GW 202

L H L H H

630 1180 1450 550 820 443 128 144 33 79 125 1421

Total Avail.

= 1+6+8

+10+11

(12)

Imminent Hydrological Change• Whichever way water demand is met, large scale

modification of the hydrological cycle in the country is eminent– By engineered structures and controlled stream flows.– By changing residence time of water in the aquifers: larger

abstractions; artificial groundwater recharge; seepage of irrigation water; soil-aquifer-treatment of waste water.

– Increasing vapour content of atmosphere: from ~500 km3/yr to 1,450 km3/yr ⇒ ~1mm/day during the dry season.

– Increased emission of CO2 and energy consumption.– Will superimpose Global Change and will be faster and

bigger than any similar change in past.

• A detailed understanding of interactions between components of the hydrological cycle is vital.

Trend in water balance for Control and GHG climate scenarios

Trends in Waterbalance Components (Control and GHG Climate Scenarios)

0

200

400

600

800

1000

1200

1400

1600

1800

Cauvery Brahmani Godavari Krishna Luni Mahanadi Mahi Narmada Pennar Tapi Ganga Sabarmati

Valu

e (m

m)

Rain (Control) Rain (GHG) Runoff (Control) Runoff (GHG) AET (Control) AET (GHG)

From: Gosain, A.K. (I.I.T. Delhi)

What New will be Learned ?– How fast is the dispersion of ‘oceanic vapour front’

ahead of the ‘rain front’ before the rainy seasons?– What are the seasonal sources of water vapours in

different regions of the country?– How much of rain is contributed by evapo-

transpiration over land areas?– What is the relative proportion of plant transpiration

and direct evaporation in the land derived vapour?– How much water is contributed by groundwater

drainage to different streams and other surface water bodies in different seasons and vice-versa.

– Does the water draining into the sea contribute to vapour influx in a large scale hydrological cycle during the later part of the rainy season?

– Do AS and BOB contribute to the atmospheric vapour during the dry season?

BKG Summary -1• A National programme with multi-institutional participation is

being launched to study temporal and spatial (seasonal and geographical) distribution of stable isotopes (18O and 2H) in the four components of the hydrological cycle over India.

• Atmospheric Vapour: Primary source and fastest changing component, directly interacts/ exchanges with other components, exhibits highest variability. Isotopic signatures modify through mixing of vapour masses, evaporation, condensation, exchange with rain drops, surface water bodies, soil and groundwater.

• Rain Water: Carries the signature of parent vapours, primary source for surface and groundwater, important for agriculture economy.

• Surface water: Runoff fraction of rainfall in streams, lakes, ponds and other reservoirs – selection effect. Interacts /exchanges with atmospheric vapours through evaporation; with groundwater by slow drainage and recharging over timescale of hours to season.

• Groundwater: Ground percolating component of the rainwater. Interacts with atmosphere through evaporation from soil moisture, plant transpiration; with surface water through recharge and drainage.

• Bay of Bengal Surface water (in satellite project): One of the Primary sources of vapour to North India during SW monsoon and to southern peninsular India during NE monsoon. Can have a large scale regional hydrological cycle involving Himalayan rivers and evaporation from the northern Bay of Bengal during SW monsoon.

BKG Summary -2

THE GOALS:• Identifying dominant seasonal vapour sources.• Partitioning into rain and its sub-partitioning.• Identifying geographical and climate controls both temporally

and spatially.

WHY:• Understanding Continental scale hydrological cycle and Land-

Ocean-Atmosphere interaction.• The programme takes advantage of the expertise, experience

and analytical capabilities existing and/or in the process of being established.

• The success critically depends on sample collection and its storage ensuring no isotopic modification from collection to measurement.

• Institutional Partners are: IMD/ CWC/ CPCB/ CGWB, CRIDA, IIT-KGP, BARC, NIH, NRL, NIO, Anna Univ and PRL.

BKG Summary -3

Role of Participating Agencies – AUPI: Dr. Hema Achyuthan

AU will be responsible for collection and analyses (Salinity) of surface water samples from the BOB. AU will also setup and operate a station for daily collection of precipitation and atmospheric vapour at Chennai. It will also setup stations at Visakhapattnam, Kolkata and Port Blair for monthly rainfall and atmospheric vapour sample collection.

Role of Participating Agencies – BARCPI: Dr. S.V. Navada

• BARC has an established Stable Isotope Ratio Mass Spectrometer Laboratory. Some part of the analytical capability of this laboratory is expected to be available to IWIN.

• BARC will also setup and operate a station for daily collection of precipitation and atmospheric vapour at Mumbai.

• BARC along with NIH will also be analysing tritium in selected samples that will be available as part of this National Programme.

• CGWB operates a programme of groundwater quality and water level monitoring during pre- and post-monsoon period.

• Samples (~1,000) from Shallow unconfined aquifers, representing most active GW phase will be provided along with water level and quality data.

• Subsequently, samples from aquifers with palaeo-groundwater and those from special ‘problem areas’ will be provided.

Role of Participating Agencies – CGWBCoordinator: Dr. Uma Kapoor

Bangladesh

Myanmar

• CPCB maintains a network of stations where flow discharges are routinely measured and water samples collected for water quality monitoring.

• Fortnightly / monthly samples from selected stations along with data of water flow and standard water quality parameters will be provided.

Role of Participating Agencies – CPCBCoordinator: Dr. R.C. Trivedi

Role of Participating Agencies – CRIDACoordinator: Dr. G.G.S.N. Rao

• CRIDA maintains a network of agro-meteorology centres at 25 agricultural Universities in the country.

• Fortnightly/monthly rainwater and atmospheric condensed vapour collection from these stations.

• In addition half yearly samples of groundwater are also requested from the nearest hand pump/ dug well /bore well.

Role of Participating Agencies – CWCCoordinator: Er. R.K. Khanna

• CWC Maintains a network of stations where flow discharges are routinely measured and water samples collected for water quality monitoring.

• Fortnightly /monthly samples from selected stations along with data of water flow and standard water quality parameters will be provided.

Role of Participating Agencies – IIT-KGPCoordinator: Dr. A. Sarkar

• IIT-KGP is has set up a new SIRM Laboratory.

• Significant part of the analytical capability this facility will be made available for IWIN samples.

• IIT-KGP will also setup and operate a station for daily collection of precipitation and atmospheric vapour at Kharagpur.

Role of Participating Agencies – IMDCoordinator: Dr. B. Mukhopadhyay

• IMD will identify stations (from those shown) where it will be possible to setup fortnightly / monthly rainwater and atmospheric condensed vapour collection systems.

• Supplemental data, namely, precipitation, temperature, relative humidity, pan-evaporation, wind velocities from the selected stations will be provided.

Role of Participating Agencies – NGRICoordinator: Dr. P. Nagabhushanam

NGRI will primarily be responsible for analyses of samples from the southern region. NGRI will also setup and operate a station for daily collection of precipitation and atmospheric vapour at Hyderabad.

Role of Participating Agencies – NIHCoordinator: Dr. Bhishm Kumar

• NIH has established its own network of precipitation monitoring stations and has established a SIRM Laboratory.

• NIH will also setup and operate stations for daily collection of precipitation and atmospheric vapour at Roorkee and Sagar (NIH Regional Centre).

• NIH along with BARC will also be analysing tritium in selected samples that will be available as part of IWIN.

• NIO will collect and analyse surface water samples from the Arabian Sea.

• NIO will also setup a Vaisala Radiosonde system at Goa and make periodic measurements of atmospheric parameters.

• Modelling of atmospheric process using ECMWF and the isotope data will also be largely handled by NIO.

• NIO will also setup and operate a station for daily collection of precipitation and atmospheric vapour at Goa.

Role of Participating Agencies – NIOCoordinator: Dr. P.M. Muraleedharan

• NRL has an existing SIRM Laboratory that is to be upgraded.

• Some part of the analytical capability of this laboratory will be available to IWIN.

• NRL will also setup and operate a station for daily collection of precipitation and atmospheric vapour at Delhi.

Role of Participating Agencies – NRLCoordinator: Dr. P.S. Datta

• A fully dedicated new SIRM Laboratory will be setup at PRL. • PRL will also setup and operate a station for daily collection of

precipitation and atmospheric vapour at Ahmedabad.• Radiosonde measurements will be made at Ahmedabad during

rainy season. • PRL will be the Principal Coordinating Institution for IWIN and

will jointly operate the same with NIH, IIT-KGP, BARC and NRL in every respect including construction and maintenance of IWIN website, data organisation, management and dissemination, arranging training and orientation workshops, inter-laboratory calibration programmes etc.

Role of Participating Agencies – PRLCoordinator: Dr. S.K. Gupta

• All partners will be closely involved in interpretation of results.

• Results will be published after due deliberations in coordination meetings and clearance from respective agencies.

• A very sincere and conscious effort will be made by the Partners of IWIN to encourage newer applications of Isotope Techniques to their respective fields of activity, in particular to catchment hydrology, meteorology, pollution studies, ecology and agricultural studies.

Role of Participating Agencies –Common to all

Thanks…