Model Concept
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In order to model a river basin, the water management system must be converted into a mathematically usable representation. The storage management simulation requires the mathematically usable representation of a water management system. Thereby reality has to be abstracted, divided into hydrological or hydraulic processes, and then be put into algorithms. The result of the abstraction are different system elements. The most important properties of a system element are listed below. thumb|300px|General abstract representation of a system element.
- A system element integrates related transport and storage processes to a calculation unit.
- A system element has properties in the form of characteristics and parameters.
Characteristics are clearly definable features of system elements. Parameters are also characteristics of system elements, but they are subject to calibration and verification. - System elements have according to their type corresponding methods, which describe the behaviour of an element. Loads acting on the element trigger system reactions and states using the methods.
- Under the same loads as well as the same parameters and parameters, the methods always provide the same system reactions and states.
thumb|500px|Comparison of real water management structure with a system logic
If the System Elements are now arranged in such a way that they reproduce the flow relationships existing in reality, the real water management structure is prepared for a mathematical simulation. This process, also known as structural analysis, determines the geographical relationships and interactions. The result of a structural analysis is the system logic. The interaction between several elements takes place via the load and the element outlet, whereby the load corresponds in most cases to an inflow and the outlet to an outflow. The outlet of one element corresponds to the load of the next element below. Almost any water management system structures can be simulated by different arrangements of the elements.
System elements are thus the hydrological building blocks of the river basin model. If these are linked together according to their flow relationships, the system logic and, as a visual representation of it, the system plan is created.
The more detailed the spatial and temporal discretization is operated, the more information can be gained about the system itself. However, the highest possible resolution of a system is not always of unrestricted advantage, because a closer examination requires more characteristic values and parameters, some of which are hardly available in sufficient quality and are therefore difficult to estimate. Thus, there is a corresponding degree of abstraction for each task, which is subject to change due to increasing requirements and better available input data. The collection of characteristics and parameters can be combined under the term system data analysis. The collection of the control relationships and their implementation for the simulation is the content of the operational analysis. From it a kind of second system logic arises, which does not contain flow relations but the logical connections of the state variables to derive the output decisions. It can be called control logic.