T2 Model Examples

A retention basin is used to catch the runoff and precipitation and therefore to avoid flooding events. That is why we need to know the discharge volume of the flood event to know how much the retention basin needs to catch.

The discharge rate will change over time during this event (unsteady flow) and the total volume is needed to be calculated with, not only the peak discharge.

For comparison: for dimensioning a sewer system, the peak flow is needed to be known. In order to prevent flooding since there is no storage and the peak water flow is relevant.

Process Model (e.g. Rainfall-runoff models):

• based on wisdom and try to understand the relationship between two known states

• Simulates a process / event by understanding whats is happening inbetween input and output

• If boundary conditions / parameters change, the model can beadjusted by updating the necessary parameters —> more flexible

Empirical models:

• based on measured information (experiments, emprirical data, evidences)

• Input and output are known, processes inbetween are unknown similar to Black Box Model —> trying finding a transfer function between input & output

• if conditions / parameters change, it is necessary to create a new transfer function otherwise the model can be imprecise or incorrect —> not very flexible

RR-Model:

• Most basic model to simulate the process of runoff generation and runoff concentration

• Rainfall-runoff models are single event models, that means what happens before or after is not relevant —> smaller time-scale

• Example: flood risk management

Water-Balance model:

• Depicts the movement of water in the water cycle between atmosphere, groundwater, soil … by including processes like percolation, evaporation, retention, precipitation and runoff —> it is not good enough to just know the input, but we need to take all processes that happen in that area into account

• describes the in- & outflow of water in a system —> input & output need to be simulated

• larger time-scale: timespan at least 1 year

• example for use: monitoring of the human impact on the water quality (groundwater pollution); water supply systems (yield / duration of possible use of wells, reservoirs etc.)

RR,WBM,WQM Simulation of processes of runoff, their storage and the exchange of water volumes in the individual compartments of the water cycle

HM

• Modelling of flow conditions

• Complex numerical mode/mathematic model of fluid flow systems and it is used to analyze hydraulic behavior

•Need input data from the other models

• Descriptive models are used in situations where a crisp representation of the process/object/system/status in numbers is not possible – instead it can be described with fuzzy, linguistic terms.

• connections between the Influencing factors are known

• Example: during a flood event it is often difficult to state the exact water level. In this case, we would say for example “the water level is high.”

• Furthermore, rule-based models (if…, then…) are typical descriptive models, since they try to depict fuzzy situations. For example: “if a flood event destroys many homes, then the people will be sad.” You see, it is not clearly stated how sad the people will be, because it is very difficult to describe it in words – the required data for mathematical equations or parameters is missing.

1. Data collection of Real World Data

2. Model design with Data, Knowledge, Problem definition, Target and Assumptions

3. Model development & Model application

4. Validation with Simulations and Results

Documentation of all steps

• Lack of or limitied availability of reliable data

• High demporal effort for the development and validation

• Difficult balance between high quality model and spatial / temporal aggregation

• Lack of transparency of the process modeling

Water Management Models – main application of water management models

—> Simulation of processes of runoff, their storage and the exchange of water volumes in the individual compartments of the water cycle

1. Rainfall-Runoff models

• single event model, what happens before and after isn‘t relevant

2. Water balance models

• not good enough to just know the input, but we need to take all processes that happen in that area into account; input & output need to be simulated; timespan: min. 1 year

3. Groundwater models

• very specific

4. Management models

• very specific; to solve a certain task, focusing on one single management issue

5. Water quality models

• very specific, not only quantity, but also quality

—> by skipping from one level to the next one: increasing complexity

• used to simulate the flow regime and to describe the process of runoff generation and runoff concentration

• Usually the following phases are represented in such a model:

1. Runoff generation

2. Runoff concentration

3. Flood routing

4. Storage

Groundwater models usually simulate both the flow and the mass transport processes in the saturated soil zone

Possible application areas are:

• Analysis and forecast of groundwater conditions under changing conditions of use in the catchment area

• Evaluation of the impact of anthropogenic interventions on groundwater management

• Groundwater monitoring / protection

• Groundwater remediation issues

• Groundwater management

—>E.g. groundwater models in lignite mining planning (Garzweiler)  quantify the impact of draining measures, determine necessary measures to protect the wetlands, forecast the future groundwater conditions