General/SetUpOfSystemPlan/hydrology/en

Creating the system plan

The spatial discretization of the catchment to be examined is the subdivision of the area in sub catchments. The river network is divided into individual nodes and the nodes connecting strands of the channel. The connected sub catchments drain into the strands of the channel. The total catchment area must be divided completely into sub catchments. Each sub catchment is associated with a strand, which is the near-surface drainage of the area. Thus, the watersheds are necessary boundaries of the sub catchments. Furthermore, it is appropriate, where possible, to select land usage definitions as part of the boundaries. This is particularly true for highly sealed areas whose rainwater sewer system has to drain to a node in the natural river system.

The spatial cross-linking of sub catchments is carried out by the connection to strands. The grid connection is achieved through the relationship made by the sub catchments to the strands. The strands the river network is represented as a structure of a branched tree. Each strand has a start and end nodes. Each end node is the top node of the subsequent strand. The flow occurs from the start node to the end node. A unique path should exist for each source node to the destination node, the termination point of the investigation area.

The time series of discharges of a sub catchment are added together at the end node of the channel section (river strand) to a total discharge. The inflows from the channel as well as the inflow of the run off component of the sub catchment flows through the channel occur as a result of the single drainage node (the end node of the river strand). At water estuaries, the runoff components of several strands are added in one node. The total outflow of an end-node represents the inflow into the following river strand.

The addition of the partial outflows has the order of the strands and must correspond to the flow path in the water network, i.e. the networking of sub catchments with the channel is carried out according to the flow processes of the near surface- runoff. However, flow processes on the topographic watershed can be simulated in KalypsoHydrology. This applies both to the aquifer and the deep aquifer. So the groundwater outflow of the groundwater storage can be defined to up to 6 other groundwater storages.

Furthermore, the outflow component of deep aquifer of a sub catchment can be added to an arbitrary node. For this purpose a virtual node can be selected which can be connected via virtual strands to the system plan. In this way, flow processes can be added up in an independent network in the model (e.g. Karst Hydrology).

With a virtual strand connection, the overall discharge of the upper node of a strand is drained to the lower node without losses. In specially marked cases, however, reductions in any form and amount can be added from a channel of any node. It is possible either a fixed portion, a constant value or a discharge distribution (main water-drainage and distribution-drain) of a channel section supplying another node (for e.g. Karst Springs). This model option is to take into account the seepage losses from the channel (for example, the deep groundwater).

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