Presentation by Marnix van der Vat (Deltares, Netherlands) at the Hydrology Suite User Days (Day 1) - Hydrology Suite introduction and River Basin Management software (RIBASIM), during the Delft Software Days - Edition 2023 (DSD-INT 2023). Tuesday, 28 November 2023, Delft.

1. Marnix van der Vat
Integrated modelling to
support Strategic Basin
Planning for the Ganga River
Basin in India

2. What are the issues?
Problems related to:
• water availability
• water quality
• ecological degradation
Due to:
• over-abstraction of surface and groundwater
• the presence of various hydraulic infrastructure
• discharge of untreated sewage water
• other point and non-point source pollution
2
Strategic
Basin
Planning
Ganga
River
Basin

3. Objective of the study
1. Strengthen capacity with respect to strategic basin
planning;
2. Development set of scenarios and strategies for the
Ganga basin;
3. Build a strong and accessible knowledge base;
4. Establish a multi-stakeholder engagement process to
support strategic basin planning.
2015-2018
Strategic
Basin
Planning
Ganga
River
Basin
3
Title: Analytical Work and Technical Assistance to
support Strategic Basin Planning for Ganga
River Basin in India
Financed by: South Asia Water Initiative (a multi-donor
trust fund managed by the World Bank)
Consortium: Deltares, AECOM and Future Water
Van der Vat et al., 2019. Participatory Modelling of
Surface and Groundwater to Support Strategic
Planning in the Ganga Basin in India. MDPI Water
2019, 11, 2443; doi:10.3390/w11122443

4. Some figures about Ganga River in India
• Most densely populated river basin in the world
• 860.000 km2, covering 4 countries and 11 states in
India
• Home to more than 500 million inhabitants with a
disproportional high share of India’s poor
• One of the largest irrigation systems in the world,
contributes to >50% of national water use
• Approximately 50-50% surface and groundwater
Strategic
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5. Strategic
Basin
Planning
Ganga
River
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• Result of a multi-stakeholder process
Colaborative or participatory modelling
Basco-Carrera, L., Warren, A., van Beek, E., Jonoski, A., & Giardino, A. (2017). Collaborative
modelling or participatory modelling? A framework for water resources management.
Environmental Modelling & Software, 91, 95–110. https://doi.org/10.1016/j.envsoft.2017.01.014

6. Stakeholder Engagement & Collaborative Modeling
All 11 states in the basin have been consulted
with engaging and collaborative modeling
workshops
Strategic
Basin
Planning
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River
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7. Causes, impacts and inter-relations analyzed
INTERVENTIONS
INDICATORS
Strategic
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8. Why an integrated model?
Interaction between many processes
• Rainfall-runoff
• Groundwater
• Water use
− Domestic
− Industrial
− Irrigation
• Water quality (emissions & flows)
• Ecology
• Ecosystem services
• No flooding and sedimentation
Strategic
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River
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9. Strategic
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Ganga river basin integrated model approach

10. Brief introduction to the models
SPHY: mountain hydrology
wflow: distributed hydrological model for rainfall-runoff
RIBASIM:
• Describes management and use of water
• Schematization of links and nodes
Strategic
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11. Brief introduction to the models
iMOD/MODFLOW
• Detailed groundwater model
• Applied in alluvial plain
• Groundwater recharge is obtained from
wflow for the non-irrigated areas and
• from RIBASIM for the irrigated areas
• river water levels are used for the
calculation of the flux between the river
and the groundwater
Strategic
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12. Brief introduction to the models
iMOD/MODFLOW
• Detailed groundwater model
• Applied in alluvial plain
• Groundwater recharge is obtained from
wflow for the non-irrigated areas and
• from RIBASIM for the irrigated areas
• river water levels are used for the
calculation of the flux between the river
and the groundwater
Strategic
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13. Brief introduction to the models
D-Water Quality
• Calculates concentration of pollutants (BOD, F/T-
COLI) as function of space and time
Strategic
Basin
Planning
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River
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14. Brief introduction to the models
Environmental flow:
Indicator scores for:
• Hydrological alteration
• Habitat suitability
• Socio-economic services
Assessment based on comparison with a simulated
pristine situation
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15. Brief introduction to the models
Dashboard:
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16. Some results – flow at Varanasi
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Van der Vat et al., 2019. Participatory Modelling of Surface and Groundwater to
Support Strategic Planning in the Ganga Basin in India. MDPI Water 2019, 11, 2443;
doi:10.3390/w11122443
Model run period 1980 – 2014
Calibration period 1995 – 2009
Validation period 1985 – 1994
Time step SPHY and wflow: daily
RIBASIM, D-Water Quality and MODFLOW: monthly

17. Some results – environmental flow analysis at Varanasi
Strategic
Basin
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Figure 9-2: Variation in monthly discharge for 1980-2014 in eco-zone G6 from Allahabad to Chhapra. Left: pristine scenario, right: present scenario.
Bons, C.A. (Ed.), 2018. Ganga River Basin Planning Assessment Report. Main volume and Appendices. Deltares with AECOM and FutureWater for
the World Bank and the Government of India, Report 1220123-002-ZWS-0003.

18. Strategic
Basin
Planning
Ganga
River
Basin
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Scenarios:
• 3 climate change scenarios
• 2 socio economic scenarios including increases in
demands for domestic, industrial, and agricultural uses
Strategies:
• Do nothing
• Improved infrastructure
• Inter-Basin Transfer Links
• New or improved WWTP
• Increased irrigation efficiency with 20%
• Conjunctive use: groundwater abstraction capacity
reduced in over-extracted areas
Scenario and strategy assessment

19. Strategic
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River
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Scenario assessment

20. Strategic
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Scenario assessment
• Significant degradation from pristine condition
• Significant additional degradation in coming
decades in water availability, water quality
and ecological status under the 2040 scenario
• Mainly caused by socio-economic
development, not climate change

21. Strategic
Basin
Planning
Ganga
River
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Strategy assessment
• Water availability is insufficient to meet
the projected future demands
• No single intervention can address the
multiple pressures
• All currently consider interventions
combined not enough to address the
future and even the current pressures
• Trade-offs are required between
sectors
• Non-technical interventions, like
changing cropping patters and
reducing water demand, are required

22. 22
Training
• On-the-job training of
partner staff
• Training of counterparts
at the end of the project
➔ Hard to train staff in such
a complex model with many
interactions, if not involved
in the development

23. Strategic
Basin
Planning
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River
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Lessons learnt
• Complex system requires complex integrated model
instrument to assess the impact of scenarios & strategies
• Socio-economic costs and benefits to be added to the
decision information
• Offline integration of models facilitated by scripts is
cumbersome and error prone (like dealing with precipitation
in both RIBASIM and wflow)
• Difficult to keep input for different models consistent. Was
done using scripts, but automated model construction from a
database is preferable
• Integrated model leads to integration between sectors, not
only in the model
• It is hard to transfer such a complex model, if counterpart is
not involved actively from the beginning

24. Strategic
Basin
Planning
Ganga
River
Basin
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References

25. Contact
www.deltares.nl
info@deltares.nl
@deltares
@deltares
linkedin.com/company/deltares
facebook.com/deltaresNL