Module OptiEco, economic optimum allocation of water







OptiEco is a program (or model) generic, to optimize the assignment of raw water in Water Resources Systems (WRS), based in of economic efficiency or market approach.

This program is useful and recommended to analyze basins with shortage of water resources in that it isn't possible that all the uses have all the water that they want.  The model assigns the water to the uses in competition, considering the willing to pay of each use and the operation costs and maintenance of the infrastructures. In the total period of time to optimize, is assumes the existence of an ideal market that distributes the water between the uses and users. This model is deterministic, with monthly time step, and it assumes the perfect knowledge of the future (the hydrological contributions and the economic functions of the elements).

1 -  First one must carry out the conceptual scheme of the basin to model (Figure 1). This scheme is built adding one to one the elements (contributions, reservoirs, uses, conductions, aquifer, etc.) and introducing its characteristics, using for it the Decision Support System H2O.

This scheme is a simplified representation of the basin or Water Resources Systems (WRS) to study, that must preserve the most important relationships among the elements of the system.

The model complexity and its capacity of representing the reality must are balanced: an excessively simple model will give results very far from the reality, without allowing to reproduce the complexity of the problem; while an excessively detailed model will be more complex of using,  will required more time of calculation and bigger quantity of data to run it.

scheme of Water Resources System

Figure 1: scheme of one simple basin.

scheme of WRS and economic functions associated at the uses

Figure 2: scheme of WRS and y fe of the uses.


2 -  In second place one must obtain the economic functions (fe) of the elements that have associates costs or benefits.  These fe contains information about the use cost, or of the willing to pay of the elements. This unitary cost/profit will vary in function of the assigned or circulating volume.

In the case of the uses, the fe is (in principle) coincident with the demand curve of water. In the Figure 2 you can see another scheme, with the fe (or demand curve in this case) of the two existent uses in this system.

The obtaining of the fe is a relatively complex task, many times artistic task, that it requires the realization of local economic studies and the summary of data that in few places are obtained in a systematic way.


3 -  Later, is possible to run the OptiEco model. The economics functions (fe) of all the elements they are used jointly to maximize a function objective (FO) no-linear that represents the net profit of the whole system (Equation 1):




 - nT: quantity of periods (months) to optimize.

 - nElem: quantity of elements of the system with fe.

The contribution of each element to the FO is the area under the fe from zero until the supply value x' (Figure 3). The group of values x' (assigned flows) of all the elements of the WRS are the incognito of the optimization problem.

fe and profit for one element

Figure 3: fe and contribution to the FO for one element.


4 -  Concluded the execution of the program, the output files text with the optimum values of the variables and the marginal indicators associated to the restrictions can be seen (and chart) with the DSS H2O or import with Excel or another similar program.

A particularly useful indicator is the marginal value of the water in the different points of the basin. This value is the opportunity cost of the resource (water) in that place, or cost of shortage of the water, and it indicates the minimum willing to pay of the users to reduce that shortage.


For more details about the OptiEco module:

- "Sistema Soporte de Decisión para evaluación y optimización económica de Sistemas de Recursos Hídricos"; Collazos, G.; Tesis Doctoral, Universidad Politécnica de Valencia; septiembre de 2004. ISBN: 0-542-13628-7.

- "Manual del usuario de OptiEco, módulo de optimización económica del SSD H2O (V 1.0)"; Collazos, G.; setiembre de 2006.


Upgrade April 2007.