This file sets the river routing options. It contains two namelists called JULES_RIVERS and JULES_OVERBANK.
Note
The river routing code in JULES is still in development. Users should ensure that results are as expected, and provide feedback where deficiencies are identified.
Type: | logical |
---|---|
Default: | F |
Switch for enabling river routing.
Type: | character |
---|---|
Default: | rfm |
Switch to select the river routing algorithm to use for river routing.
Type: | integer |
---|---|
Permitted: | > 0 |
Default: | -32768 |
The number of model timesteps per routing timestep.
For example, rivers_timestep = 5 means that runoff will be accumulated for 5 model timesteps before being routed on the 5th timestep.
Warning
The river routing parameter values can be highly dependent on model resolution, so care is required by the user to ensure that appropriate values are selected, tested and adjusted as required.
Suggested values for global and high-resolution runs are listed below, however these should be treated as a starting point.
Values for some typical configurations are included in the jules_riversparm module.
RFM parameters - used if rivers_type = rfm
Type: | real |
---|---|
Default: | 0.2 |
Suggested: | 0.2 (global), 0.4 (high-resolution) |
The land wave speed (m s-1). See Bell et al. (2007).
Type: | real |
---|---|
Default: | 0.62 |
Suggested: | 0.62 (global), 0.5 (high-resolution) |
The river wave speed (m s-1). See Bell et al. (2007).
Type: | real |
---|---|
Permitted: | <= cland |
Default: | 0.1 |
Suggested: | 0.1 (global), 0.05 (high-resolution) |
The subsurface land wave speed (m s-1). See Bell et al. (2007).
Type: | real |
---|---|
Permitted: | <= criver |
Default: | 0.15 |
Suggested: | 0.15 (global), 0.05 (high-resolution) |
The subsurface river wave speed (m s-1). See Bell et al. (2007).
Type: | real |
---|---|
Permitted: | 0-1 |
Default: | 0.0 |
The (resolution dependent) land return flow fraction. See Bell et al. (2007).
Type: | real |
---|---|
Permitted: | 0-1 |
Default: | 0.005 |
Suggested: | 0.005 (global), 0.005 (high-resolution) |
The (resolution dependent) river return flow fraction. See Bell et al. (2007).
Type: | integer |
---|---|
Default: | 1 |
Suggested: | 1 (global), ~10 (high-resolution) |
The threshold drainage area (specified in number of cells) draining to a gridbox, above which the gridbox is considered to be a river point. This is resolution dependent.
Remaining points are treated as land (drainage area = 0) or sea (drainage area < 0). See Bell et al. (2007).
Type: | real |
---|---|
Default: | 1.0 |
It is highly recommended that this is set to 1.0 (i.e. no runoff adjustment).
TRIP parameters - used if rivers_type = trip
Type: | real |
---|---|
Default: | 0.4 |
The effective river velocity (m s-1). See Oki et al. (1999).
Type: | real |
---|---|
Default: | 1.4 |
The ratio of the actual to calculated river lengths in a river routing gridbox. See Oki et al. (1999).
Type: | logical |
---|---|
Default: | F |
Switch for enabling river overbank inundation. Only used if l_rivers is TRUE. Default setting is FALSE.
See also
References:
- Bell, V.A. et al. (2007) Development of a high resolution grid-based river flow model for use with regional climate model output. Hydrology and Earth System Sciences. 11 532-549
- Dadson, S.J. and Bell, V.A. (2010) Comparison of Grid-2-Grid and TRIP runoff routing schemes. Centre for Ecology & Hydrology Internal Report http://nora.nerc.ac.uk/10890/1/dadson_etal_2010_g2gtrip.pdf
- Dadson S.J. et al. (2011) Evaluation of a grid-based river flow model configured for use in a regional climate model. Journal of Hydrology. 411 238-250
- Falloon, P.D. et al (2007) New global river routing scheme in the Unified Model. Hadley Centre Technical Note 72, available from the Met Office Library.
- Jones R., Dadson, S. and Bell, V.A. (2007) Report on European grid-based river-flow modelling for application to Regional Climate Models. Met Office Hadley Centre deliverable report.
- Oki, T., et al (1999) Assessment of annual runoff from land surface models using Total Runoff Integrating Pathways (TRIP). Journal of the Meteorological Society of Japan. 77 235-255
Warning
The overbank inundation parameter values can be highly dependent on model resolution, so care is required by the user to ensure that appropriate values are selected, tested and adjusted as required.
Suggested values for global and high-resolution runs are listed below, however these should be treated as a starting point only.
Type: | logical |
---|---|
Default: | F |
Switch for enabling use of a hypsometric integral calculation.
River width allometry (used if l_riv_hypsometry is false or use_rosgen is true)
Allometry is: (WIDTH in m) = riv_a * ( (SURFACE RIVER INFLOW in m3 s-1) ** riv_b) (Leopold & Maddock 1953:eqn1)
River depth allometry (used if l_riv_hypsometry is true or use_rosgen is true)
Allometry is: (DEPTH in m) = riv_c * ( (SURFACE RIVER INFLOW in m3 s-1) ** riv_f) (Leopold & Maddock 1953:eqn2)
Rosgen stream classification parameters describing river channel morphology (Rosgen 1994)
Type: | logical |
---|---|
Default: | F |
Switch for applying the Rosgen entrenchment ratio approach
Bankfull flow allometry (used if use_rosgen is true)
Allometry is: (BANKFULL DISCHARGE RATE in m3 s-1) = coef_b * ( (CONTRIBUTING AREA in km2) ** exp_c ) (see e.g. Andreadis et al. 2013)
Type: | real |
---|---|
Default: | 0.08 |
Coefficient in the allometry for bankfull flow
Type: | real |
---|---|
Default: | 0.95 |
Exponent in the allometry for bankfull flow
See also
References:
- Andreadis KM, Schumann GJ & Pavelsky T (2013). A simple global river bankfull width and depth database. Water Resources Research 49:7164-7168
- Leopold LB & Maddock T (1953). The Hydraulic Geometry of Stream Channels and Some Physiographic Implications. United States Geological Survey Professional Papers 252:1-57
- Rosgen DL (1994). A classification of natural rivers. Catena 22:169-199.