BASEMENT Reference Manual: Description of 1D Geometry File Structure and Parameters

name - The unique name of the cross section.

distance_coord - Distance coordinate of cross section, measured from up to downstream. Note that the units of the coordinate is in [km]!

sternberg - Sternberg-factor for the reduction of volume by abrasion V = V0e**(s*Dx)

reference_height - The value of the reference height is added during input to the node elevation.

left_point_global_coords - Global coordinates of the left cross section point, which is used as the geographical reference point. If this value is provided together with the 'orientation_angle' for all cross sections, the modeled river is displayed in the region view of the graphical user interface. Further, this information is used by the cross section interpolator to estimate curvatures etc.

orientation_angle - In-plane angle of the cross section line with left point as origin. The angle is measured in a mathematical way, counter-clockwise: The angle 0 is given by the (1,0) vector.

node_coords - Coordinates of the points defining the cross section. The first coordinate is the distance to the left point, the second the absolute elevation.

interpolation_fixpoints - The interpolation fixpoints are used to create new cross sections in between existing ones. Fix points are in interpolations connected to each other. This allows to cleanly transfer slopes etc. into the interpolated cross section. The first and last nodes of the cross sections are for obvious reasons always included. Counting starts at 1.

water_flow_range - Defines which part of the cross section is considered to be flowing. Only this part will be used for solving of the momentum equation, rest of the cross section is considered to be only storage area in the continuity equation. The default is that the whole cross section area is flowing. Try to not define storage areas in the main channel, as in this case a stable behaviour is not assured, i.e. when only the non flowing part of the channel is wetted! Also the non flowing areas are not taken in accont for sediment deposition and erosion!

water_flow_slice_indexes - Same as tag 'water_flow_range', except the fact that not coordinates are supplied but slice indices.

main_channel_range - Range defining the span of the main channel. Everything left and right of the channel is treated as floodplain. If not defined, the whole cross section is assumed to belong to the main channel.

bottom_range - Range defining the span of the bottom/bedload activ zone.

main_channel_slice_indexes - Same as 'main_channel_range', except the fact that not coordinates are supplied but slice indices.

bottom_slice_indexes - Same as 'bottom_range', except the fact that not coordinates are supplied but slice indices.

active_range - This range defines the active part of the cross section and must span from the left to the right dike. If not defined, the whole cross section is assumed to be active and the elevation of the first and last point will be assumed to correspond to the dike elevation.

active_slice_indexes - Same as 'active_slice_indexes', except the fact that not coordinates are supplied but slice indices.

bed_form_factor - Factor considering the influence of bed forms on bottom shear stress (ripple factor). This factor reduces the bottom shear stress due to bedforms with a constant value. If this factor is set to 1.0 (default), there is no influence and the standard shear stress is used.

theta_critic - User defined dimensionless critical bottom shear stress (Shields paramter) for this cross section. If specified by the user (values between 0.0 and 1.0), this local theta critic is used for this cross section.However, for negative values of this local theta critical, the standard theta critical is used defined in the BEDLOAD-PARAMETER block (default behaviour)

friction_calibration_factor - Calibration factor between 0.0 and 10.0 to modify the friction value locally for this cross section.

default_friction - Default Strickler friction value which will be used for the cross section where no individual friction coefficient is defined.

friction_coefficients - Strickler Friction values which should be assigned to the 'friction_ranges' (or 'friction_slice_indices').

friction_ranges - Ranges to which the 'friction_coefficients' are applied.

friction_slice_indexes - Same as 'friction_ranges', except the fact that not coordinates but slice indices are supplied.

table_fixed_points - Some fixed points which should be included in the table calculation. Note that these values are only used if you use lookup tables for hydraulic properties (see SECTION_COMPUTATION within the command file).

table_fixed_lower_limit - This variable allows to fix the lowest water surface elevation used in the 'lookup-table' for A(z) to a different value than the lowest elevation in the cross section. This option is useful if you include a deep lake in your model containing a large water volume not participating in the dynamics of your river system.

interpolated - This is an internal tag used to indicate that the cross section is the result of an interpolation of two primary cross sections.

index - Index of the soil, as defined within the SOIL_ASSIGNMENT block in the bmc input file.

range - Range in cross section to which the soil with the corresponding 'index' should be assigned.

slice_indexes - Same as 'range', but refers to slice index rather than coordiantes.