1. River Basin Planning Tools and Models: Concepts of Simulation and Optimization Tools:

2. River Basin Planning Tools & Models: Concepts of Simulation and Optimization Tools:
Prepared by: Dr. Megersa Olumana,
School of Natural Resource and Environmental Engineering,
Institute of Technology, Haramaya University
This lecture material is a part of the course material on the module River Basin Planning and Allocation. Further details can be seen in the module’s lecture notes

3. Outline of Presentation
Concepts of Modeling
Water resource planning and Management Models
Limitation of Models
Modeling Criteria and Factors
System Analysis and Systems Concept
Optimization Models and Tools

4. 1. Modelling Concepts Notes on Modeling:
Models are physical or mathematical simplifications of natural systems. Modelling is an art and Science.
They are used in analysis and design of water resources plans and projects. Popularly used to describe equations of physical systems and techniques of finding optimal solutions;
WR systems analyst need multidisciplinary skills
Constant communication b/n model developers and users is essential. Also model users must understand the assumptions & limitations of the model.

5. 1. Modelling Concepts 1.1. Notes on Modeling:
Generally, useful models are ALIVE and constantly being modified.
Make Model simple as possible and as complex as necessary.
We don’t need complex hydrologic models which we do not understand and where the output is known to be uncertain. Instead we want simple models that are reliable. Therefore, a sound assessment of model approaches both for simple and complex models is essential for bridging the perception gap between scientists and practitioners.
Should be flexible to particular circumstances and the feed back should be known for its improvement
Decision variables should be minimized
Do not ignore the key variables, which are representative of the physical system

6. 1. 2. Limitation of Models Objectives Input Data
Not clearly defined controversial changing
E.g. environmental and water resource planning objectives overlap
Input Data
not available, independent and inaccurate
Sometimes the model is calibrated based on inadequate (inaccurate) data
Data quality (consistency, homogeniety) should be checked using certain techniques
Assumptions Made – not reasonable
Criteria of the target - May not be known
Modelling Results
Just one input to decision making
Not all required information for decision making is modelled. The precise modelling results may not be accepted for decision making

7. 1.3. Modelling Criteria and Factors
What are the criteria for evaluating modelling success?
Did the modelling have a beneficial contribution to the planning and decision making process?
Did the study result provide information on the selection & choice of alternatives?
Did the study reveal competitive alternatives which otherwise could not be considered?
Factors that determine the system to be modelled:
Objectives of the analysis
Data to be required
Time, money, computational facilities available
Modellers knowledge and skill

8. 2. Optimization Models (Operations Research)
2.1 Definition of terms
Controllable and partially controllable inputs are called decision variables
Policy: the resulting set of decisions when each decision variable is assigned a particular value
Constraints: physical, economic or any other restrictions applied to the model
Feasible policy: a policy which does not violate any constraint
Policy space: the subset consisting of all possible feasible policies
State variables: variables representing the condition of the system at any time and place

9. 2. Optimization Models (Operations Research)
2.1 Definition of terms
The performance of a given policy is evaluated based on a criteria known as objective. Objective can be either quantitative or non-quantitative
If two objectives can be measured or described in the same units or terms with the same general degree of accuracy, they are commensurate objectives; otherwise they are non-commensurate objectives
Objective function: the statement by which the consequences or outputs of the system can be determined given the policy, the initial values of the state variables and the system parameters.
Overall objective in optimization is to determine a set of values of the decision variables that satisfy the constraints and provide the optimal response to the objective function.

10. 2. Optimization Models (Operations Research)
2.2. Steps in OR
The steps in an OR involves the following distinct steps:
A. Quantifying system properties through system parameters
S1, S2, S3, …, Si, …
B. Representation of the decision values through the decision variables
X1, X2, X3, …., Xi, ….
C. Quantifying the constraints through the constraints function
Gm=gm (Xi, Si)  0 - mostly non-negativity constraints
D. Formulating the objective through the objective function
Z = z(xi, Si)
Minimization fun. Is usually used. For Maximization function, use the –ve of the function and minimize it.
E. Solution of the objective function
Z = max or min (z (Xi, Si))
with observations of the given constraints, to quantitatively obtain the values of the decision variable xi.

11. 2. Optimization Models (Operations Research)
2.3. Solution for optimization Problems
For the solution of the optimization problems, there are variety of solution methods:
Analytical/Numerical differentiation
Linear Programming (LP)-The non-linear problems are lineralized using certain techniques
Dynamic Programming (DP) - Recursion (forward/backward) techniques
Non-Linear Programming (NLP),
Integer Programming (IP)
Goal Programming
… are the main tools of optimization.
The appropriate solution procedure mainly depends on the type of the objective and constraint functions. It also depends on the available facilities for data processing

12. 3. WR Modelling & Planning Tools
Optimization & simulation modeling are not mutually exclusive. In many studies, they are used as complementary to support decision making.
In a review of literature, the most comprehensive generic IWRM models/tools are:
WEAP
RIBASIM
MODSIM
MIKE Family: MIKE-SHE, MIKE-BASIN
HEC Family: HEC-ResSim, HEC-HMS
WBalMo
WaterWare or RiverWare
Oasis
SWAT

13. 4. Optimization Tools/Softwares
Decision Support Systems (DSS)
E.g. Nile Basin DSS; Delft DSS
Other Optimization Softwares:
Solvex
Simplex
LINDO/LINGO
MPL
GAMS
MINOS
Win QSB

14. Generic IWRM Models Water Evaluation And Planning (WEAP) Model
developed by the Stockholm Environment Institute's Boston Center at the Tellus Institute.
is one of most generic IWRM model. Although WEAP meets the criteria for generic, comprehensive, integrated, and accessible, it does not provide management optimization other than for balancing water supply reservoir storage contents.
user-friendly and open source software tool that takes an integrated approach to water resources planning.
Includes scarce WR allocation issues by balancing the demand- and supply-side values for water resources planning & policy analysis.

15. Generic IWRM Models Soil and Water Assessment Tool (SWAT) Model
is a river basin or watershed scale model developed by Dr. Jeff Arnold for the USDA Agricultural Research Service (ARS).
is a basin-scale, continuous-time model that operates on a daily time step and is designed to predict the impact of management on water, sediment, and agricultural chemical yields in ungauged watersheds. The model is physically based, computationally efficient, and capable of continuous simulation over long time periods (Arnold et al., 2009; Neitsch et al., 2005).
has gained international acceptance as a robust interdisciplinary watershed modeling. SWAT is currently applied worldwide and considered as a versatile model that can be used to integrate multiple environmental processes.
Major model components include weather, hydrology, soil temperature and properties, plant growth, nutrients, pesticides, bacteria and pathogens, and land management.

16. Generic IWRM Models Soil and Water Assessment Tool (SWAT) Model
Application in Ethiopia:
Has applications to Ethiopian situations at relatively larger watersheds (Dilnesaw, 2006; Ashenafi, 2009; Biniam, 2009; Eyob, 2010; Setegn, 2010).
Their study result indicated that the model is capable of simulating hydrological processes with reasonable accuracy and can be applied to large ungauged watershed. SWAT model can be a potential monitoring tool for watersheds in mountainous catchments of the tropical regions (Birhanu et al., 2007).

17. Generic IWRM Models Soil and Water Assessment Tool (SWAT) Model
In SWAT, a watershed is divided into multiple sub-basins, which are then further subdivided into hydrologic response units (HRUs) that consist of homogeneous land use, management, and soil characteristics. The HRUs represent percentages of the sub-basin area and are not identified spatially within a SWAT simulation. Alternatively, a watershed can be subdivided into only sub-basins that are characterized by dominant land use, soil type, and management (Gassman et al., 2007).
The Simulation of the hydrology of a watershed is separated into two divisions (read Neitsch et al., 2005):
land phase of the hydrological cycle
routing phase of the hydrologic cycle

18. Generic IWRM Models RIver BAsin SIMulation (RIBASIM) Model
provides an effective tool to support the process of planning and resource analysis since 1985.
is a WINDOWS-based software package and includes a range of DELFT Decision Support Systems Tools.
is a generic model package for simulating the behaviour of river basins under various hydrological conditions. The model package is a comprehensive and flexible tool which links the hydrological water inputs at various locations with the specific water-users in the basin.
enables the user to evaluate a variety of measures related to infrastructure, operational & demand management and to see the results in terms of water quantity, water quality & flow composition.
can also generate flow patterns which provide a basis for detailed water quality & sedimentation analyses in river reaches & reservoirs.

19. RIver BAsin SIMulation (RIBASIM) Model
Generic IWRM Models
RIver BAsin SIMulation (RIBASIM) Model
RIBASIM schematization of the Nile river basin upstream from the High Aswan Dam (Burundi, Congo,
Egypt, Eritrea, Ethiopia, Kenya, Sudan, Tanzania and Uganda).

20. Generic IWRM Models RIver BAsin SIMulation (RIBASIM) Model
Important Features of RIBASIM
supports a default and user-defined source analysis giving insight in the water’s origin and residence time at any location of the basin and at any time within the simulation period
has a fully graphical user interface for designing the river basin network but also for crop cultivation planning.
water is allocated on a "first come-first served" basis along the natural flow direction. That means it is based on the Prior Appropriation Water Right Doctrine.
This allocation can be amended by rules which, for example, allocate priority to particular users, or which result in an allocation proportional to demand.

21. Generic IWRM Models MIKE BASIN is developed by DHI in Denmark.
it addresses water allocation, conjunctive use, reservoir operation, or water quality issues.
it couples ArcGIS with hydrologic modeling to provide basin-scale solutions.
its philosophy is to keep modeling simple and intuitive, yet provide in-depth insight for planning and management. The emphasis is on both simulation and visualization in both space and time, making it appropriate for building understanding and consensus.

22. Generic IWRM Models MIKE BASIN water availability analysis,
Typical areas of application:
water availability analysis,
conjunctive use of surface- and ground-water,
planning infrastructure,
assessing irrigation potential and reservoir performance,
estimating water supply capacity,
determining waste water treatment requirements.
has also been used to analyze multisectoral demands (domestic, industry, agriculture, hydropower, navigation, recreation, ecological) and find equitable trade-offs among them.

23. Optimization Tools/Softwares
Decision Support System (DSS)
Multi-sector planning to allocate scarce resources at the river basin level is increasingly needed in the water sector, as water users and governmental agencies become more aware of the trade-offs occurring b/n quantity, quality, routing, timing, costs & reliability.
DSS accounts all the management options and simultaneously considering the positive, negative, direct, and indirect effects of each option in the net benefit calculation.
The primary objective of DSS is to contribute to better policy and decision making for resource management at the basin scale.

24. Optimization Tools/Softwares
Decision Support Systems (DSS)

25. Optimization Tools/Softwares
LINDO API 7.0
Key Benefits of the LINDO API:
Fast, Easy Application Development
Powerful Solvers
New Stochastic Programming Features
Comprehensive Set of Routines
Convenient Interface to MATLAB
Extensive Documentation and Help
Analyze Infeasible and Unbounded Models
Model Size Flexibility

26. Optimization Tools/Softwares
GAMS (General Algebraic Modeling System)
GAMS is specifically designed for modeling linear, nonlinear and mixed integer optimization problems. The system is especially useful with large, complex problems.
System Features
It lets the user concentrate on modeling. By eliminating the need to think about purely technical machine-specific problems such as address calculations, storage assignments, subroutine linkage, and input-output and flow control, GAMS increases the time available for conceptualizing and running the model, and analyzing the results. GAMS structures good modeling habits itself by requiring concise and exact specification of entities and relationships.

27. Optimization Tools/Softwares
GAMS
System Features
flexible and powerful.
GAMS language is formally similar to commonly used programming languages. It is therefore familiar to anyone with programming experience. .
Models are fully portable from one computer platform to another when GAMS is loaded to each platform. GAMS facilitates sensitivity analysis.
Models can be developed and documented simultaneously because GAMS allows the user to include explanatory text as part of the definition of any symbol or equation. GAMS is being enhanced and expanded on a continuing basis. 

28. Optimization Tools/Softwares
CASE STUDY
Optimization of Water Resource Use in the Awash Basin
Use of any optimization tool for water regulation and allocation in Awash Basin among different sectors.
The basin was selected because:
its significant contribution for the development of the country.
There are a number of irrigation schemes with different scale and distributed along the course of the river
There are also hydropower development in the basin

29. REFERENCES RIBASIM, River Basin Planning and Management
Optimization Modelling: A Practical Approach. Sarker & Newton (2008)
Optimization Applications in Water Resources Systems Engineering
The Use Of River Basin Modeling As A Tool To Assess Conflict And Potential Cooperation
Water Resources Management: Economic Valuation And Participatory Multi-criteria Optimization. Fedra et al. (2007).
Simulation-based Optimization. Deng (2007)

30. REFERENCES
Modelling tools for river basin management: How reliable are predictions for water quality? Rode (2009).
Mathematical Tools for Irrigation Water Management: An Overview. Mujumdar (2002)
Integrated Watershed Management Modeling: Generic Optimization Model Applied to the Ipswich River Basin. Zoltay et al. (2010).
A Water Resources Planning Tool for the Jordan River Basin. Hoff et al. (2011).

31. THANK YOU!
Questions & Discussion Welcome