GRASS logo

NAME - Compute channels and penstocks


SYNOPSIS --help [-d] elevation=name plant=name [plant_layer=string] [plant_column_plant_id=string] [plant_column_point_id=string] [plant_column_stream_id=string] [plant_column_elevup=string] [plant_column_elevdown=string] [plant_column_discharge=string] [plant_column_power=string] [ndigits=integer] [resolution=float] [contour=name] [output_point=name] output_struct=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Debug with intermediate maps
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


elevation=name [required]
Name of input elevation raster map
plant=name [required]
Name of input vector map with segments of potential plants
Or data source for direct OGR access
Name of the vector map layer of plants
Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
Default: 1
Column name with the plant id
Default: plant_id
Column name with the point id
Default: cat
Column name with the stream id
Default: stream_id
Column name with the elevation value at the intake (upstream) [m]
Default: elev_up
Column name with the elevation value at the restitution (downstream) [m]
Default: elev_down
Column name with the discharge values [m3/s]
Default: discharge
Column name with the potential power [kW]
Default: pot_power
Number of digits to use for the elevation in the contour line vector map
Default: 0
Resolution use for the contour line vector map, if 0.25 approximate 703.31 tp 703.25
Name of the contour line vector map
Name of output vector map with potential intakes and restitution
Name for output vector map
output_struct=name [required]
Name of output vector map with the structure of the plants
Name for output vector map

Table of contents

DESCRIPTION computes the derivation channel and the penstock for each potential plant and for both sides of the river.


The input maps are the elevation raster map and the one with the segments of potential plants (vector map which can be computed by or
In the section "Input column", the column names in the table of the map with potential plants have to be reported in order to read correctly the corresponding values.
The module returns a vector map with the structure for each plant on both sides of the river. The derivation channel and the penstock are distinguished and reported in the table.
In option, the module can also compute the vector map with the intake and restitution of each potential plant.

As the current potential concerns especially small hydropower (inferior to 20 MW), the structure suggested is the one for small hydropower detailed in the picture below. It is composed of an intake (A) which diverts water from the river. This water is conveyed into a derivation channel (B) with a very low slope and arrives in a forebay tank (C) which regulates the fluctuation of discharge. Finally, the penstock (D) conveys the water with the highest possible head to the turbine-alternator group (E) which produces electricity. The water is then released in the river (restitution F). We use the following vocabulary: the structure of the plant corresponds to the part with the derivation channel, the forebay tank and the penstock, whereas the segment of the plant corresponds to the part of the river (water not diverted) between the intake (A) and the restitution (F).

Structure of the plants considered in the module

The power is maximized for the highest head in the penstock so the derivation channel is computed along the same quote (the low slope is neglected here) until the point which maximizes the head along the penstock. The structure is computed for both sides of the river in order to determine which one produces the most power.


This example is based on the case-study of Gesso and Vermenagna valleys in the Natural Park of the Maritime Alps, Piedmont, Italy.

Here is the input vector map potentialplants with the segments of potential plants (in blue). The vector map with the intakes and restitution of potential plants is also visibile in red on this picture.

Input vector map potentialplants

The following command computes the derivation channel and the penstock for each potential plant and for each side of the river : elevation=elevation plant=potentialplants output_struct=structplants

The result is shown in black in the following picture which gathers the input and output maps.

Output vector map structplants in black



Picture of the plant structure taken from Micro-hydropower Systems - A Buyer's Guide, Natural Resources Canada, 2004


Pietro Zambelli (Eurac Research, Bolzano, Italy), Manual written by Julie Gros.
Last changed: $Date : 2015-07-08 14:59 GMT+1$


Available at: source code (history)

Main index | Raster index | Topics index | Keywords index | Graphical index | Full index

© 2003-2017 GRASS Development Team, GRASS GIS 7.2.3svn Reference Manual