1. Energy Balance and Heat Storage
of Small Shallow Water Bodies
in Semi-arid Areas
Ali Abbasi
Department of Water Management
Delft University of Technology
28-11-2016
Promotor: Prof. Nick van de Giesen

2. Research Question
 There are some small lakes in Africa…
 There are no sufficient measurements …
 We have no money to carry out extra measurement …
 We need to know:
Evaporation
Circulation
Wind effects
Temperature Profiles
Heat exchanges
Velocity
TurbulenceCost-effective
Generalizable Easy-to-run etc.

3. Why Small & Shallow Lakes(1/2)?
 the only permanent open water bodies in (semi-)arid
regions;
 provide water to improve the food security, stimulate
the agricultural economy, livestock farming, fishing,
stock watering, brick making, etc.;
 contribute to local development (direct & indirect
economic activities);
 to slow down rural migration;

4. Why Small & Shallow Lakes(2/2)?
 improving farmers collaboration in rural communities;
 they are a priority for national governments and local
authorities;
 operationally efficient with high flexibility in (semi-)arid
regions with scattered rural population;
 the requirement for few parties to come together to
operate them (local community management);
 closeness to the point of use

5. Why Small & Shallow Lakes (Disadvantages)
 some possible threats to the sustainability of SSL:
siltation, the spread of water borne diseases,
deterioration of water quality;
 their dispersion can be considered as an obstacle to
access markets and ensuring farmers’ position in value
chains;
 These small shallow lakes are scattered in large
numbers, and hence monitoring them could be difficult
and costly on a regional scale.
 due to lack of maintenance, sub-optimal crop
management, and poor product marketing the
agronomic and economic performance of small
reservoirs are far from perfect;
 limited information on small reservoirs and the
inadequate in-situ measurements;

6. Introduction: Research Components
ABL: Atmospheric Boundary Layer;
SSLF: Small Shallow Lake Framework;
CFDEvap: CFD Evaporation Model;
WS:Water Surface;
SSL: Small Shallow Lake

7. Challenges …
Making Decisions!
 0-D/1-D/2-D/3-D Models?
 Open-Source & Free or Commercial Tools;
 Cost-effective; and Generalizable;
 Verification & Validation;
 Scales (e.g. ABL and SSL)
 Numerical Approaches (FVM/FEM/…);
 Computational Resources (HPC, HPC-Cloud, etc.);
 etc.

8. Region of Study
Upper East Region of Ghana

9. Region of Study
 +160 SSL in UER-Ghana;
 +2000 SSL in Upper Volta Basin;

10. Region of Study
 Population: 1 million
 Population density: 96.5 inhabitant/km2
 Poverty incidents: 88%
 Annual rainfall (average): 1100 mm
 90% of rainfall occurs as thunderstorms;
 Rainy season: late May … mid-October
 Dry season: November … early May
 Annual reference evaporation 2000 mm;

11. Lake Binaba
 Surface area : 31 ha
 Max. & ave. depth : 4.0 & 1.1 m
 Capacity : 1.2 million m3
 Irrigation scheme: 26 ha

12. Measurements

13. Evaporation Estimation

14. Mass Transfer Method
 Atmospheric Stability Conditions;
 Using over land measurements;
 Footprint (FP) Analysis;
 Heat Flux data Filtering;
 Daily averaged evaporation: 2.5 mm/day;

15. Mass Transfer Method

16. CFDEvap
 CFD: Computational Fluid dynamics;
 CFDEvap: Computational Fluid dynamics for
Evaporation estimation;

17. CFDEvap

18. CFDEvap
 min. 2.75 mm/day
 ave. 4.30 mm/day
 max. 5.90 mm/day
 Spatial distribution of heat fluxes
 evaporation

19. SSLF
 SSLF: Shallow Small Lake Framework
ABL Conditions Circulation Temperature
Heat storageEvaporation

20. SSLF
 Turbulent Flow
 Time-dependent & complex BC
 Data-scarcity
 Bathymetry (geometry)
Credit: http://aed.see.uwa.edu.au/research/models/GLM/overview.html

21. SSLF

22. SSLF
Credit: http://aed.see.uwa.edu.au/research/models/GLM/overview.html

23. ABL-WS
ABL: Atmospheric Boundary Layer
WS: Water Surface
 Interaction
between

24. ABL-WS

25. Measurement or Simulation?!
All models are fake.
But some can be useful.
Make a decision on: Accuracy or Utility?

26. Tools/Software
Free of charge &
Open Source Software
Commercial Software

27. Tools/Software
Commercial Software The Easy Road?!
Free/OS Software The Hard Road?!
The easy road often becomes hard, and the hard road often becomes easy
(Robert Kiyosaki)

28. Tools/Software
“Taking the Exit for the Hard Road”

29. Parallel Computing
• Parallel Simulation
• Decomposing, Reconstructing, etc.
• The optimized Number of CPUs

30. Parallel Computing
A graphical representation of Amdahl's law. The speed-up of a program from parallelization
is limited by how much of the program can be parallelized. For example, if 90% of the
program can be parallelized, the theoretical maximum speed-up using parallel computing
would be 10x no matter how many processors are used.

31. Computational Resources
PC (6 CPUs, 24GB Memory)
HPC03(Remote Sensing
Department) as a GUEST!
HPC-Cloud SURFsara

32. Conclusion
Both setting-up a model and raising a baby
will have errors. Don’t try to eliminate their
errors! Find a way for living with them!
Before starting to solve the problems, there
are no difficulties. When you try to find the
solution, everything seems difficult.

33. Summary
You have one hour free time to rest and
think about your dreams while I am
struggling to satisfy the committee
members;
After the defense, you are kindly invited to
the reception in the same building;

34. Thank You