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

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

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

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.

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

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

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

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

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.

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.

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

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

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

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.

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.

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).

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

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.

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).

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.

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.

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.

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.

Optimization Tools/Softwares Decision Support Systems (DSS)

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

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.

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. 

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

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)

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).

THANK YOU! Questions & Discussion Welcome