Presentation held at the General Assembly 2019 of the European Geosciences Union (EGU) is held at the Austria Center Vienna (ACV) in Vienna, Austria, from 7–12 April 2019

1. How water storage for
energy and food production
affects the Zambezi River’s water quality.
EGU Vienna, 8/4/2019
Picture: Simon Spratley, ATEC3D
Elisa Calamita, Martin Schmid, Bernhard Wehrli

2. A Decision-Analytic Framework to explore the water-
energy-food NExus in complex and transboundary water
resources systems of fast growing developing countries
[https://dafne.ethz.ch/]
Introduction
2

3. 3
[United Nations, 2017; Poff & Schmidt, 2016; Wilcox and Asbjornsen, 2018; Moran et al., 2018; Best, 2019]
population
time40% of world’s population
Low latitudes…
~3700 dams proposed

4. [Winton, Calamita, Wehrli (2019)]
4
How are dams changing water quality at low latitudes?

5. 5
Water supply Food security
Economic value
Tourist attraction
Water
quality
• ecological functioning
• biodiversity
• fish communities
T
DO
[Caissie 2006; Arvola et al, 2010; Danladi Bello et al., 2017]

6. [The World Bank, 2010; esa.un.org; SADC 2012]
• Transboundary
• Population
• Water-energy-food security
Zambezi River Basin
only 23 % of its
hydropower potential
is being exploited

7. 7
Lake Kariba
• world largest artificial lake by volume
• volume = 150 km3
• hydropower reservoir (1958)
• max depth = 97 m
• monomictic lake
• 4 sub-basins
[https://thetruesize.com]

8. Spatial heterogeneity
8
inflow
outflow
[Calamita et al. Under review]

9. Lake Kariba – basin IV
9
inflow
Unified database
• Vertical profiles of water temperature
and dissolved oxygen
• Coverage of 23 years
outflow
[Calamita et al. Under review]

10. Frequency maps
10
[Calamita et al. Under review]

11. T , O2 , N , P …
11
water intake Zambia water intake Zimbabwe
Lake Kariba – basin IV: a transboundary problem…
459 m a.s.l. 460 m a.s.l.
447 m a.s.l.
457 m a.s.l.
spilling gates

12. Zambia
Zimbabwe 1
Zimbabwe 2
Spilling gates
12
[Hipsey et al., 2014]
Lake modelling

13. 13
weighted average
with discharge
measurements
model
Zambia
Zimbabwe 1
Zimbabwe 2
Spilling gates

14. 14
Scenarios analysis
Max hydropower
Min irrigation deficit
Min delta deficit
Trade-off
Baseline
• Multi-objective optimization
• Simultaneous operation policies
• Scenarios 1986-2005
In collaboration with:
• Federica Bertoni
• Andrea Castelletti
Optimization targets:

15. Summary
 Stratification dynamics of Lake Kariba lead to alterations of
the thermal and oxygen regime of the Zambezi River.
 Transboundary operation policies directly affect the
downstream water quality.
 Workflow to assess the impact of dam operation on
downstream water quality.
Outlook: downstream travelling of thermal (oxygen-) signals…
elisa.calamita@usys.ethz.ch
Thank you!