evaluating the impacts of rainwater harvesting (rwh) in...

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INTERNATIONAL ASSOCIATION OF HYDROGEOLOGISTS Australian National Chapter

NSW Branch

2009 Seminar Series

This presentation is made available by IAH NSW in the interests of promoting discussion, critique and exchange of knowledge.

The content, products, methods, equipment, findings or recommendations of these presentations are not endorsed by IAH NSW or by UNSW who has offered to host the presentations on their website www.connectedwaters.unsw.edu.au

Claire Glendenning Claire Glendenning Supervisor: Dr Willem Supervisor: Dr Willem VervoortVervoort

Evaluating the impacts of Evaluating the impacts of RRainWWater HHarvesting (arvesting (RWHRWH) ) in the in the ArvariArvari River, IndiaRiver, India

Faculty of Agriculture, Food and Natural Resources The University of Sydney

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Groundwater in India• World’s largest user

• ~ 80% rural domestic use ~ 45% for irrigation

• <1 million tubewells (1960)to 20 million (2000)

• Common resource = Decline

• Management option: RRainwwater HHarvesting (RWHRWH)?

• collect/store RUNOFF for DIRECT USE or RECHARGE

What is RRainwwater HHarvesting?

Catchment

Storage

September 06 December 06

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• > 1000 years in India

• Monsoon: 100 hr rainfall (80 days)/yrRWHRWH=more time for recharge

• past neglect, now large reinvestment

• Impacts?

RWHRWH in India

Quantified field studies of RWHRWH• Recharge = 3 – 8 % P: WTF

(Badiger et al. 2002)

• Local impact on groundwater levels: 1 structure (Neumann et al. 2004, 2005)

• Limiting capacity to induce recharge WTF / water balance in 812 ha (Sharda et al. 2006)

• Hydrological catchment impacts not known(Calder et al. 2006, Kumar et al. 2006)

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Case study of Case study of RWH RWH impacts in the impacts in the

Arvari River CatchmentArvari River Catchment

How to evaluate RWHRWH impacts?

1. Field-scale impacts of RWH

2. Catchment-scale impacts of RWH

a. Build a conceptual water balance model

b. Run scenarios to investigate RWH impacts

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Case Study Location

458km2 (45,800 ha)

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7

8

28 Anicuts28 Anicuts

84 84 BandhsBandhs

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127 127 JohadsJohads

88 Medbandhi88 Medbandhi

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Monitoring Monitoring NetworkNetwork

Daily measurements in monsoon 2007 and 2008

Monitoring Monitoring NetworkNetwork

29 dug wellsdug wells which tap unconfined/shallow

aquifer

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Monitoring Monitoring NetworkNetwork

SankaraSankara

BerujiBeruji

Monitoring Monitoring NetworkNetwork

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Monitoring Monitoring NetworkNetwork

Monitoring Monitoring NetworkNetwork

Rain Gauges

13

499 mm 494 mm

361 mm

751 mm

449 mm

897 mm

Variability of Rainfall (P)

Potential Recharge (Rep) estimates

.ep s tR A h ET O= − ∆ − −

bep avR ah=

non-rainy days

rainy days(Sharda et al. 2006)

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Rep estimates (m3/day)

+270

+270

201

260

2008

240

273

138

169

2007

Days Storage

23

19

27

55

2008

15

12

20

45

2007

Rep mm/day % P -> Rep

6

6

8

14

2007

8Lalpura Johad

8Jhiri Johad

10Beruji Bandh

22Sankara Bandh

2008RWH

Structure

Cumulative sum Rep and Cumulative sum Rainfall relationship

= RWH limited capacity to induce more recharge

LalpuraR2=0.81

BerujiR2=0.88

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Dep

th (

m)

Well Response

Bhaonta: well heights asl (m)

Bhaonta: relative well heights

Water Table Fluctuation MethodRecharge Estimation Re . hSy

t∆

=∆

2007 2008

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Comparison of recharge estimates

River flow

Recharge from Anicuts on River

42Nitata

25Kaled

44Hamirpur

Average Re mm/day

Anicut

Jul-2

007

Oct

-200

7

Jan-

2007

Apr-

2008

Jul-2

008

Oct

-200

8

Date

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Field-Scale Characteristics• High inter/intra-annual P variability

• RWH - 12-55 mm/day ~ 170-260 storage days- Dependent on P, but limiting capacity- Difference btw Johad / Bandh- ~ 7% P -> Rep

• Wells and Groundwater- No baseflow, high lateral flow - Annual fluctuation

AcknowledgementsAcknowledgements

•• Faculty of Agriculture, Faculty of Agriculture, UniUni of Sydneyof Sydney

•• TBS; TBS; KhanyialaljiKhanyialalji, , GopaljiGopalji

•• MurariMurari Lal Lal GujjarGujjar

•• ArvariArvari River Community River Community

•• Willem Willem VervoortVervoort