2.3.1 Boundary Definition File

The boundary definition file contains a list of parameters that control the operation of the makeBoundary program. The parameters are defined in the file as a sequence of “key-value” pairs. The key is the name of the variable. Each key has an associated value. Each value is either a boolean (“True” or “False”) signifier, an integer or floating point number, or a list of integers or floating point numbers. Keys and values are defined on the same line, separated by a colon.

The keys are defined as follows:

type

boundary type (1=imposed height, 2=wall, 3=Neumann, 4=periodic, 5=imposed discharge). For cases 1 and 5, the height and imposed discharge are both specified for each cell along the boundary. For sub-critical inflow the type value (1 or 5) determines which of the specified values are used. For super-critical inflow both values are used. For super-critical outflow neither value is used.

plotting

enable plotting (True or False). The program can display plots of hydraulic radius, conveyance and discharge versus water level for each active panel. To cycle through the plots press the ‘q’ key.

printing

enable printing (True or False). The program can write output files containing data for the rating curve for each active panel. Rating curves express the relation between water level and discharge.

slope

local gradient. This is the value normal to the boundary, derived from survey data or from running the slope.py program.

target_flow

imposed discharge (/m³/s). This is the total flow crossing the boundary.

markers

panel marker co-ordinates (/m). This is a comma-separated list of distances. The distances indicate the measurement from the left-hand edge of the domain to the internal marker points. Markers at the corner points are automatically generated to complete the list.

panel

fill order. The fill order is a comma-separated list of panel indices. The list specifies the manner in which the wetted area changes as the flow increases.

ztol

channel overtopping tolerance (/m). For the main channel, the overtopping tolerance sets the difference between the minimum ground elevation at the channel banks and the maximum water level. When the flow is sufficiently high for the water level to reach this level the next panel, specified by the fill order, is activated. This panel can then fill to the same maximum water level. The panels are filled in sequence until one panel is part-filled so that the total flow across the boundary matches the target flow.

n_co

Manning’s ‘n’ coefficients. This is a comma-separated list, ordered by panel index. Each panel is allocated a coefficient representing the roughness value for that section of the boundary.

numH

number of height intervals. The relation between water level and discharge is calculated at the specified number of points, for each active panel.

Comment lines are allowed in the boundary definition file. Lines that start with the ‘#’ character are treated as comments.