NOMBRE

USO

DESCRIPTION

r.watershed puede ejecutarse de modo interactivo o desde la linea de comandos. Si se ejecuta de modo interactivo..

r.watershed

The user can run the program non-interactively, by specifying input map names on the command line. Parameter names may be specified by their full names, or by any initial string that distinguish them from other parameter names. In 's case, the first two letters of each name sufficiently distinguishes parameter names. For example, the two expressions below are equivalent inputs to :

el=elev.map th=100 st=stream.map ba=basin.map

elevation=elev.map threshold=100 stream=stream.map basin=basin.map

OPTIONS

-m

Without this flag set, the entire analysis is run in memory maintained by the operating system. This can be limiting, but is relatively fast. Setting the flag causes the program to manage memory on disk which allows larger maps to be processes but is considerably slower.

-4

Permite solamente flujos de agua horizontales y verticales. Allow only horizontal and vertical flow of water. Stream and slope lengths are approximately the same as outputs from default surface flow (allows horizontal, vertical, and diagonal flow of water). This flag will also make the drainage basins look more homogeneous.

elevation

Input map: Modelo Digital de Terreno a partir del que se realiza la modelización hidrológica

depression

Input map: Mapa de depresiones reales en el terreno que son suficientemente grandes como para almacenar escorrentía en un episodio de precipitación. Cualquier valor distinto de cero indica una depresión.

flow

Input map: Indica la cantidad de flujo superficial generada por cada pixel. Sis e omite se asume un valor de 1.

disturbed.land

Mapa raster en el que en cada pixel se indica el tanto por ciento de terreno alterado (construcciones cultivos, etc.) que contiene. Se utiliza en algunos cálculos de la  RUSLE.

blocking

Input map: Terreno que bloquearía el flujo superficial. Cualquier valor diferente de cero indica un bloqueo en el terreno.

threshold

Tamaño mínimo de una cuenca para que aparezca individualizada en el mapa de cuencas.

max.slope.length

Input value indicating the maximum length of overland surface flow in meters. If overland flow travels greater than the maximum length, the program assumes the maximum length (it assumes that landscape characteristics not discernible in the digital elevation model exist that maximize the slope length). This input is used for the RUSLE calculations and is a sensitive parameter.

accumulation

Output map: Cada celda contiene el agua acumulada que drena (expresada como la suma de los valores registrados en el flow map). Los números negativos indican celdas cuyas cuencas vertientes se extienden más allá de los límites de la región activa.

drainage

Output map: Direcciones de drenaje. Multiplicando los valores que aparecen en este mapa por 45 se obtiene la dirección en grados que seguirá por término medio el flujo superficial. Valores de -1 indican que el epixel está en el fondo de una depresión. Otros valores negativos diferentes de uno indican que el pixel esta en los límtes de la región activa.

basin

Output map: Una única etiqueta (número entero positivo) para cada cuenca vertiente. Los valores de 0 indican que el pixel no forma parte de una cuenca completa en la región activa.

stream

Output map: Segmentos fluviales cuyos valores corresponden con los valores registrados en las cuencas.

half.basin

Output map: Se da un único valor a cada media cuencaeach half-basin is given a unique value. Watershed basins are divided into left and right sides. The right-hand side cell of the watershed basin (looking upstream) are given even values corresponding to the watershed basin values. The left-hand side cells of the watershed basin are given odd values which are one less than the value of the watershed basin.

visual

Output map: useful for visual display of results. Surface runoff accumulation with the values modified to provide for easy display. All negative accumulation values are changed to zero. All positive values above the basin threshold are given the value of the basin threshold.

length.slope

Output map: slope length and steepness (LS) factor. Contains the LS factor for the Revised Universal Soil Loss Equation. Equations taken from Revised Universal Soil Loss Equation for Western Rangelands (see SEE ALSO section). Since the LS factor is a small number, it is multiplied by 100 for the GRASS output map.

slope.steepness

Output map: slope steepness (S) factor for RUSLE. Contains the revised S factor for the Universal Soil Loss Equation. Equations taken from article enTITLEd Revised Slope Steepness Factor for the Universal Soil Loss Equation (see SEE ALSO section). Since the S factor is a small number (usually less than one), it is multiplied by 100 for the GRASS output map layer.

NOTAS

seg uses the A\uT\d least-cost search algorithm to determine the flow of water over the landscape (see SEE ALSO section). The algorithm produces results similar to those obtained when running r.cost and r.drain on every cell on the map.

En diversas situaciones, los datros de elevación
In many situations, the elevation data will be too finely detailed for the amount of time or memory available. Running will require use of a coarser resolution. To make the results more closely resemble the finer terrain data, create a map layer containing the lowest elevation values at the coarser resolution. This is done by: 1) Setting the current geographic region equal to the elevation map layer, and 2) Using the neighborhood command to find the lowest value for an area equal in size to the desired resolution. For example, if the resolution of the elevation data is 30 meters and the resolution of the geographic region for will be 90 meters: use the minimum function for a 3 by 3 neighborhood. After going to the resolution at which will be run, will be taking values from the neighborhood output map layer that represents the minimum elevation within the region of the coarser cell.

El tamaño mínimo de las áreas de drenaje es sólo relevante para aquellas cuencas que no tienen otras cuencas drenando hacia ellas (cuencas exteriores). Una cuenca interior puede ser de cualquier tamaño.

Los valores 0 serán considerados como valores de elevación reales. Las áreas sin elevaciones reales deben ser eliminadas del análisis mediante una máscara

VER

Length slope and steepness (length.slope) factor equations were taken from Revised Universal Soil Loss Equation for Western Rangelands, presented at the U.S.A./Mexico Symposium of Strategies for Classification and Management of Native Vegetation for Food Production In Arid Zones (Tucson, AZ, 12-16 Oct 1987), by M. A. Weltz, K. G. Renard, and J. R. Simanton.

El factor de pendiente (slope.steepness) contiene the revised slope steepness factor for the Universal Soil Loss Equation. Equations were taken from article enTITLEd Revised Slope Steepness Factor for the Universal Soil Loss Equation, in Transactions of the ASAE (Vol 30(5), Sept-Oct 1987), by McCool et al.

Referencia: "Using the AT Search Algorithm to Develop Hydrologic Models from Digital Elevation Data," International Geographic Information System Symposium, Baltimore MD, 1989
http://geography.hunter.cuny.edu/~chuck/IGIS/paper.html

r.cost, r.drain, r.flow, r.flowmd, r.mask, r.topidx, r.water.outlet

AUTOR