Groundwater Externalities of Surface Irrigation Transfers in Krishna Delta Bharat R Sharma, KVGK...

Groundwater Externalities of Surface Irrigation Transfers in Krishna Delta

Bharat R Sharma,

KVGK Rao,

Anupama Sharma,

Jean-Philippe Venot

Polavaram – Vijayawada Link

Godavari Water Disputes Tribunal (GWDT) award stipulates diversion of 2265 Mm3 (80 TMC) of Godavari waters from the Polavaram project to Krishna river above Prakasam barrage at Vijayawada.

The Right Main Canal (Polavaram – Vijayawada Link) will be 174 km long and is envisaged to provide irrigation to a CCA of about 1.40 lakh ha besides transfer of 2265 Mm3 of Godavari waters to Krishna.

National Water Development Agency (NWDA) in its analysis in 1999 had found the link as viable.

Krishna Delta

25 0 25 50 75 Kilometers

N

Mandal boundary

GeologyAlluviumShaleLimestone massiveQuartziteUndifferentiated Kamthi FormationSandstonePegmatite veinsQuartz vein/reefDoleriteKhondaliteHypersthene graniteGrey granite ,gneiss

StracturesFAULTFRACTUREJOINTLINEAMENTSHEARSTRUCTURAL TREND

LEGEND

GEOLOGICAL MAP OF KRISHNA DISTRICT A.P

Nuzvid

Chatrai

Nagayalanka

Koduru

Machilipatnam

Agiripalle

Tiruvuru

Movva

Vatsavai

G Konduru

Musunuru

Kalidindi

Gudur

Mylavaram

Jaggayyapeta

Pedana

Gampalagudem

Kaikaluru

Vissannapet

Unguturu

Nandigama

Gannavaram

Chandarlapadu

Bapulapadu

Nandivada

Mudinepalli

Kruthivennu

Mandavalli

A.Konduru

Pamarru

Reddigudem

Bantumill i

Veerullapadu

Gudivada

Kanchika Cherla

Ibrahimpatnam

Vijayawada Rural

Penuganchiprolu

VuyyuruKankipadu

Mopidevi

Gudlavalleru

Pamidimukkala

Challapalli

Thotlavalluru

Ghantasala

PedaparupudiPenamaluru

Avanigadda

Vijayawada(U)

Source: GWD, Vijayawada

Krishna Delta Irrigation System

Irrigation canals take off from Prakasam Barrage at Vijayawada

Existing command is 5.236 lakh ha. Eastern main canal’s command is 2.948 lakh

ha in Krishna and WG Districts. The Western main canal serves an ayacut of

2.284 lakh ha in Guntur and Prakasam Districts.

Climate & Topography

Krishna Delta receives an average rainfall of about 1000 to 1100 mm. Southwest monsoon contributes 63% and northeast monsoon 28% of this total respectively.

Cyclonic storms hit the coast during northeast monsoon season.

The topography of the delta is very flat with very little drainage network. In most of the area the irrigation canal network serves as drainage network also.

Low lying areas prone to submergence by the sea and middle reaches of delta prone to water stagnation

Kolleru Lake, largest fresh water lake and a declared wildlife sanctuary and spread in an area of 90,132 ha, is also part of the Delta and receives canal return flow and drainage water from the Delta in addition to run-offs of small rivulets from Eastern Ghats.

Krishna – A Closed Basin

Since the 1850s, the Krishna basin has seen an increasing mobilization of its water resources and a dramatic development of irrigation.

This has led to the progressive decline of river flows and to closure of the river basin: almost all available water is depleted with none remaining untapped.

The discharge to the ocean has dramatically declined as consumptive water uses increased from 71 to 92% of the basin net inflow between 1955/1965 and 1990/2000.

Impacted the availability and time of release of canal water to the Delta.

Water Development in the Krishna Basin GE KO

S

N

Long history of irrigation development and decreasing discharge to the ocean

Warnings of Closure – Enhanced by recognition of Environmental Water Requirements

0

20

40

60

80

100

120

1901 1911 1921 1931 1941 1951 1961 1971 1981 1991 2001

Dis

char

ge

to t

he

oce

an a

nd

Gro

ss S

tora

ge

cap

acit

y (k

m3)

0

100

200

300

400

500

600

700

800R

ain

fall

(km

3)

Rainfall Cumulative Gross Storage Capacity

Uncontrolled discharge at Vijayawada Rainfall long term (100 years) average

Rainfall long term (30 years) average

• Before 1965: Average at 57 Km3/yr

• After 1965Decrease by about 0.8 Km3/yr

• In 2000: 11 Km3/yr

• Between 2001 and 2004

0.75 Km3/yr

Decreasing discharge into the Krishna delta canals

Until 2000: 6.15 Km3/yr

2001-2004: 4.8 Km3/yr

0

200

400

600

800

1000

1200

1400

1996-97 1997-98 1998-99 1999-2000 2000-2001 2001-2002 2002-2003 2003-2004

Year

TM

C

Utilisation

Dicharge to the river

Water Utilization - Krishna Delta 1996-97 to 2003-04

Source: I&CAD Department, Vijayawada

Monthly Water Utilization in 1996 -97 and 2003-04

0

5

10

15

20

25

30

35

TMC

1996-97 2003-04


Water Release Dates to Krishna Delta from 1996-2005

05

1015202530354045505560657075808590

1996 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005Year

Da

te

Date

1st Jun

1st July

1st Aug

1st Sep


Agriculture and Irrigation

Agriculture and fisheries are the main farm land based activities in the delta. About 58% of the delta land is under agriculture .

About 33,000 ha area has been developed for shrimp farming. Another 74409 ha has been taken up freshwater fish production in Krishna District

Mangrove forest area occupies about 18,000 ha. Most of the wasteland, which is saline, and mangrove area have been

converted to aquaculture. Main crop in monsoon season in Delta is rice occupies about 4,21,189 ha. In rabi rice is covered 1,15,764 ha in tail end. Sugarcane is grown in 15,596 ha. Black gram and green gram are grown in residual moisture after harvest

of Khariff rice in 2,43,991 ha. About 6% of the area in tail end Mandals has been left fallow in rabi

season may be due to high soil salinity and insufficient water supply.

Irrigated Area

0

100000

200000

300000

400000

500000

600000

700000

800000

Khariff Rabi Total

Ha

1974 1979 1984 1989

1994 1999 2003

Irrigation Potential

Kharif - 5.23 Lakh Ha; Rabi - 1.20 Lakh HaTotal - 6.43 Lakh Ha


Average Yields of Paddy in Krishna Delta

0

1000

2000

3000

4000

5000

6000

1996 1997 1998 1999 2000 2001 2002 2003 2004

Year

Kg

/Ha

Yeilds


Mandalwise paddy yield in 2003

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Mandal

T / H

a

Kharif 2003 Average 1996-2004


Mandalwise Kharif and Rabi Crop yields in Krishna Delta

01

23

45

67

Kankipadu Uyyuru Koduru NagailankaMandal

T/h

a

Kharif Average Yield

Rabi Average Yield

RiceRice

Rice Rice

Rice Rice

B.G B.G

Source: Farm Survey

Yield black gram vs date of sowing

Date of sowing

10-20 November

20-30 November

1-10 December

10-20 December

20-30 December

Yield, q/ha 12.5 – 13.75

11.25 – 12.50

10.0 – 11.25

8.75 – 10.0 7.5 – 8.75

Source: APWAM Project, ANGRAU, Bapatla

Area under black gram & Green gram 2,44, 000 ha

Average Net Returns in Krishna Delta

05000

1000015000200002500030000350004000045000

Kharif Paddy Rabi Paddy Rabi Blackgram Sugarcane

Crop

Rs

/ha

Source: Farm Survey

Reduction in Rice Production in tail end area due to reduced canal supplies.

SNo Mandal Kharif RiceArea Ha 2001

Khariff 2001Rice Yields

Kg/ ha

Total Rice yield in Khariff 2001

Tons

Kharif RiceArea Ha 2003

Khariff 2003Rice Yields

Kg/ ha

Total Riceyield in

Khariff 2003Tons

1 2 3 4 5 6 7 8

1 Machlipatnam 7740 3659 28,322 7458.8 1556 11,606

2 Guduru 10111 5116 51,729 9730.4 2049 19,938

3 Pedana 10554 4574 48,272 10432.4 1922 20,051

4 Bantumilli 7057 3654 25,786 6860 2022 13,871

5 Kruthivennu 3366 4814 16,204 3401.6 2000 6,803

6 Movva 11681 4886 57,074 11747.2 2222 26,102

7 Challapalli 5017 5813 29,163 4932.8 3501 17,270

8 Ghantasala 7922 4776 37,837 8021.2 3057 24,521

9 Avanigadda 3048 5653 17,228 2987.6 2079 6,211

10 Nagayalanka 6385 4543 29,006 6146.4 994 6,110

11 Koduru 6041 5085 30,720 6020 1220 7,344

12 Mopidevi 5211 5835 30,407 4983.2 1763 8,785

Total/average 84,133 4,867 401,748 82,722 2,032 168,612

Loss of production : 58% which is about Rs 153 Crores in Kharif Season

Groundwater Net Irrigated Area (Ha) in the Eastern Delta

Division 1998-99 2004-05

Machilipatnam 0 1228

Gudivada 0 31

Vijayawada (Part) 47 3679

Nuzvid (Part) 56 992

Total 103 5930

Source : Chief Planning Officer, Krishna, Machilipatnam.

Groundwater Quality


Groundwater Development Status


Depth of tubewell & pump capacity in different Mandals

Sno Mandal Average Depth, m Range, m AveragePumpsetCapacity

, HP

Range, HP

1 Kankipadu 99.2 27 - 300 7 5 - 15

2 Uyyuru 91.1 30 - 270 6.1 5 - 15

3 Koduru 13.7 12 - 20 6.4 5 - 15

4 Nagailanka - - - -

Source: Farm Survey

Impact on groundwater

The impact of canal supplies on groundwater is very rapid. The comparison of electrical conductance of shallow aquifers in 2003 with

those of 1976 show that the saline water -fresh water interface has moved inland in the eastern delta and certain fresh water zones within regional saline areas are no more present. Similar land-ward movement of the saline water - fresh water interface is observed in the western delta also.

The boundary between fresh and saline water lies in the upper aquifers all of which are unconfined at some place or the other. Hence, any change in water level is likely to disturb this interface and up-coning of saline water can occur wherever hydraulic continuity with sea exists; and that is likely to leave a permanent imprint on groundwater quality in the area.

There is a need to understand the effects of poor flows in Krishna River and the canal network in terms of water quality and ecology of the river system

Threats to the Krishna Delta EnvironmentGroundwater Salinization

Canal and river flows are central for groundwater recharge

GoAP. (2003). Freshwater-saline water interrelationhip in the multi-aquifer system of the Krishna delta. R&D project Abridged version. Groundwater department, GoAP: Hyderabad.

Threats to the Krishna Delta Environment GE KO

S

N

Groundwater Salinization

Inland migration of Saline/Freshwater interface: some ag wells tap saline water

Post Monsoon 1976 Post Monsoon 2002

GoAP. (2007). Presentation on the nature of coastal alluvial aquifer in the Krishna delta. Presentation held by the Department of Groundwater at International Water Management Institute Workshop on Groundwater Externalities. September, 5th of 2006, Hyderabad.

Water Contamination: Urban, Industrial and Aquaculture Effluents

Soil Salinity

About 25,000 ha is suffering from soil salinity and alkalinity.

Most of the effected area is located in the coastal zone. Their formation is in marine environment and salts impregnate in soils and groundwater.

Their use for agriculture depends on availability of adequate fresh water to flush out the salts, which is done by repeated flooding and drainage, and to grow rice crop with a continuous submergence to keep the rootzone free from salts.

4.8

3.89

2.9

2.3

4.3

5.5 5.55

6.57

0

1

2

3

4

5

6

7

1998-99 1999-00 2000-01 2001-02

Pre-drainage Post-drainage

Salinity(dS/m)

Yield(t/ha)

Uppugunduru Pilot AreaRice Crop Yields in Relation to Salinity

Source : AP Water Management Project, Bapatla

Yield of black gram vs soil salinity

Soil Salinity, ECe, dS/m

>1.0 1.0 – 2.0 2.0 – 3.0 3.0 – 4.0 4.0 – 5.0 >5.0

Yield Q/ha 13.75 12.0 7.25 3.5 2.5 0.0

Source: APWAM Project, ANGRAU, Bapatla

Cost of coping measures for soil salinity

Sno SS Coping Measures Average Cost Rs/ Ha

Range Rs/Ha

1 Scrapping of Salts 1000 1000

2 Gypsum application 1545 400 - 3000

3 FYM 815 500 - 1000

4 Additional Expenditure due to SS 2366 1500 - 3000

Rice crop in saline area requires about 25 % more water for flushing of salts.Source: Farm Survey

Projections using the 2D ModelNIH Study

To study the response of fresh-saline water interface to – delayed canal supplies, and – increased gw draft during a typical deficient

rainfall period. – Deficient rainfall year: 2002-03– (actual average rainfall in Krishna District was

573.8 mm against a normal value of 1033.0 mm)– Extended deficient period: four years

Variation in water table and GW salt concentration in Avanigadda

Fall in water table (m) Rise in gw salt concentration (g/l)

Variation in water table and GW salt concentration in Mopidevi

Fall in water table (m) Rise in gw salt concentration (g/l)

Variation in water table and GW salt concentration in a freshwater zone in Koduru

Fall in water table (m)

Rise in gw salt concentration (g/l)

Findings

Freshwater in shallow aquifer zone is vulnerable to contamination from saltwater in lower aquifer zone because of susceptibility of saltwater front to vertical hydraulic gradients that get accentuated due to large gw drafts.

Changes in salinity levels during a typical deficient rainfall period - Mandals located towards the coastline like Mopidevi, Avanigadda, Koduru and Nagayalanka exhibit an increase in gw salinity when the canal water supply is reduced and gw draft is more during extended periods of deficient rainfall.

Since the salinity in the delta varies both areally and with depth, the rise in salt concentration in wells (e.g. Mopidevi) is not uniform for similar decline in the water table.

Findings

In case of intermediate aquifer in which the salinity levels are higher, the rise in salinity due to reduction in net recharge is not appreciable during the short simulation time period of four years.

Saltwater front is slow to respond to variations in the water table elevation.

It would take longer time before the effects become significant at the regional-scale.

Adverse Impacts of Low River/Canal Flows

Agriculture Reduction in rice production in tail end Mandals

more than 50% and 25% in middle reaches - About Rs 500 crores

Rabi rice crop not taken in 1.20 lakh ha – About Rs.150 crores

Reduction in black gram production in 2,44,000 ha by about 5 q/ha – About Rs. 150 crores

Loss of indirect benefits & social costs could be very significant

Long term effects may be more severe.

Land Use Krishna Delta

6.32%

10.62%

19.85%

0.99%

2.34%

1.89%

57.99%

Forests

Wastelands

Non agriculture uses

Tree crops

Current Fallows

Other Fallow Lands

Net area sown

Threats to the Krishna Delta EnvironmentAquaculture and Ecosystem Degradation

• Development of brackish and fresh water aquaculture in the coastal area and Kolleru lake region since the 1970s

• Increasing pollution due to heavy loaded pollutants from aquaculture ponds

• Declining Areas of Mangroves

• Drying up of the Kolleru Ramsar area (encroached by ponds)

Impacts of the Polavaram-Vijayawada Link

• Allocation of 1,236 Mm3/yr to stabilize Krishna Delta agriculture

Need for understanding how this may affect groundwater dynamics and slow down groundwater salinization- At best return to pre 2000 period.

Gowing, J.W.; Tuong, T.P.; Hoanh, C.T. (2006). Land and Water Management in Coastal Zones: dealing with Agriculture-Aquaculture-Fishery Conflicts In. Tuong, T.P.; Hoanh, C.T.; Gowing, J.W.; Hardy, B..(eds) (2006) Environment and livelihoods in tropical coastal zones: managing agriculture-fishery-aquaculture conflicts. CABI, Oxford.Smakhtin, V.; Anputhas, M. (2007). An assessment of environmental flow requirements of Indian river basins. International Water Management Institute: Research report No. 107. Colombo, Sri Lanka: International Water Management Institute.

In comparison Smakhtin and Anputhas (2007) evaluates at 6.5 to 14.2 km3/yr the volume needed to keep the Krishna basin in its current moderately modified

environmental Status

Supply of water and/or Environmental Water Allocation are needed but will not, alone, stop environmental degradation. Need for Integrated Coastal Management and Farm operation regulation (Gowing et al. 2006)

• 607 Mm3/yr for “environmental flows”?

• No Direct impact on the Kolleru lake (canals may impede secondary stream flows in the Ramsar protected area)

Total Transfer: 2,265 Mm3/yr - A Partial response?

Will the Godavari diversions off-set the adverse conditions?

Can we expect: More stable flows to Delta? Early releases to Delta? Godavari diversions: a substitute or

supplemental? Environmental flow?

Thank You

Groundwater Externalities of Surface Irrigation Transfers in Krishna Delta Bharat R Sharma, KVGK...

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