How-to: dimensions module

For simple water bodies, the dimensions module provides classes to easily calculate the h and a (height and surface area) parameters for the MorphometryBlock class, i.e., the morphometry block. These are:

• InvertedTruncatedPyramid for pyramidal water bodies with a square/rectangular base
• InvertedTruncatedCone for circular water bodies.

After initialisation, various getter methods can be called to return lists of the heights (get_heights()), surface areas (get_surface_areas()), and volumes (get_volumes()).

Initialising dimensions classes

InvertedTruncatedPyramid

InvertedTruncatedPyramid is initialised with the waterbody's surface length, surface width, depth, and slide slope. The base length and base width are calculated by the class. In addition, num_vals must be set to control the length of the lists returned by the various getter methods. This should be equal to the bsn_vals parameter from the morphometry block. Consider the example below of a waterbody that is 40 m long, 40 m wide, 6 m deep, and has a side slope of 1/3:

from glmpy import dimensions

wb = dimensions.InvertedTruncatedPyramid(
    height=6,
    surface_length=40,
    surface_width=40,
    num_vals=7,
    side_slope=1/3
)

InvertedTruncatedCone

InvertedTruncatedCone is initialised with the waterbody's surface radius, height, and side slope. Like InvertedTruncatedPyramid, num_vals must be set to control the length of the lists returned by the various getter methods. Consider the example below of a waterbody with a surface radius of 15 m, slide slope of 1/3, and is 3 m deep:

from glmpy import dimensions

wb = dimensions.InvertedTruncatedCone(
    surface_radius=15,
    height=3,
    side_slope=1/3,
    num_vals=3
)

Get heights with get_heights()

The list of waterbody height values required for the morphometry block's h parameter can be returned by calling get_heights(). Heights are returned in order from the bottom of the waterbody to the top.

from glmpy import dimensions

wb = dimensions.InvertedTruncatedPyramid(
    height=6,
    surface_length=40,
    surface_width=40,
    num_vals=7,
    side_slope=1/3
)

print(wb.get_heights())

[-6.0, -5.0, -4.0, -3.0, -2.0, -1.0, 0.0]

from glmpy import dimensions

wb = dimensions.InvertedTruncatedCone(
    surface_radius=15,
    height=3,
    side_slope=1/3,
    num_vals=3
)

print(wb.get_heights())

[-3.0, -1.5, 0.0]

Get surface areas with get_surface_areas()

The list of waterbody surface areas required for the morphometry block's a parameter can be returned by calling get_surface_areas(). Each element of the surface area list corresponds with the heights returned by get_heights().

from glmpy import dimensions

wb = dimensions.InvertedTruncatedPyramid(
    height=6,
    surface_length=40,
    surface_width=40,
    num_vals=7,
    side_slope=1/3
)

print(wb.get_surface_areas())

[16.0, 100.0, 256.0, 484.0, 784.0, 1156.0, 1600.0]

from glmpy import dimensions

wb = dimensions.InvertedTruncatedCone(
    surface_radius=15,
    height=3,
    side_slope=1/3,
    num_vals=3
)

print(wb.get_surface_areas())

[0.0, 328.6891313818321, 1102.6990214100174]

Get volumes with get_volumes()

A list of waterbody volumes can be returned using get_volumes(). Each element of the list corresponds with the heights returned by get_volumes().

from glmpy import dimensions

wb = dimensions.InvertedTruncatedPyramid(
    height=6,
    surface_length=40,
    surface_width=40,
    num_vals=7,
    side_slope=1/3
)

print(wb.get_volumes())

[0.0, 52.0, 224.0, 588.0, 1216.0, 2180.0, 3552.0]

from glmpy import dimensions

wb = dimensions.InvertedTruncatedCone(
    surface_radius=15,
    height=3,
    side_slope=1/3,
    num_vals=3
)

print(wb.get_volumes())

[0.0, 328.6891313818321, 1102.6990214100174]

Adjusting surface elevation

Heights returned by get_heights() can be adjusted for elevation by setting the surface_elevation parameter during class initialisation:

from glmpy import dimensions

wb = dimensions.InvertedTruncatedPyramid(
    height=6,
    surface_length=40,
    surface_width=40,
    side_slope=1/3,
    num_vals=7,
    surface_elevation=100 # <- Surface elevation of 100 m
)

print(wb.get_heights())

[94.0, 95.0, 96.0, 97.0, 98.0, 99.0, 100.0]