Energy Balance and Heat Storage of Small Shallow Water Bodies

in Semi-arid Areas

Ali Abbasi

Department of Water ManagementDelft University of Technology

28-11-2016

Promotor: Prof. Nick van de Giesen

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:

EvaporationCirculationWind effects

Temperature ProfilesHeat exchangesVelocityTurbulenceCost-effective

Generalizable Easy-to-run etc.

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;

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

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;

Introduction: Research Components

ABL: Atmospheric Boundary Layer; SSLF: Small Shallow Lake Framework;

CFDEvap: CFD Evaporation Model; WS:Water Surface; SSL: Small Shallow Lake

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.

Region of Study

Upper East Region of Ghana

Region of Study

+160 SSL in UER-Ghana; +2000 SSL in Upper Volta Basin;

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;

Lake Binaba

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

Measurements

Evaporation Estimation

Mass Transfer Method

Atmospheric Stability Conditions; Using over land measurements; Footprint (FP) Analysis;

Heat Flux data Filtering;

Daily averaged evaporation: 2.5 mm/day;

Mass Transfer Method

CFDEvap

CFD: Computational Fluid dynamics; CFDEvap: Computational Fluid dynamics for

Evaporation estimation;

CFDEvap

CFDEvap min. 2.75 mm/day ave. 4.30 mm/day max. 5.90 mm/day

Spatial distribution of heat fluxes

evaporation

SSLF SSLF: Shallow Small Lake Framework

ABL Conditions

Circulation

Temperature

Heat storage

Evaporation

SSLF Turbulent Flow Time-dependent & complex

BC Data-scarcity Bathymetry

(geometry)

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

SSLF

SSLF

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

ABL-WSABL: Atmospheric Boundary LayerWS: Water Surface

Interaction between

ABL-WS

Measurement or Simulation?!

All models are fake.But some can be useful.

Make a decision on: Accuracy or Utility?

Tools/Software

Free of charge & Open Source Software

Commercial Software

Tools/SoftwareCommercial 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)

Tools/Software

“Taking the Exit for the Hard Road”

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

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.

Computational Resources

PC (6 CPUs, 24GB Memory)

HPC03(Remote Sensing Department) as a GUEST!

HPC-Cloud SURFsara

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.

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;

Thank You