ResEvapAlgorithm
Exec Class: decodes.cwms.algo.ResEvapAlgo
The “ResEvap” algorithm aggregates and calculates the evaporation of water from a reservoir over the period of a day. By default, if the following parameter values are not provided they will be retrieved from the CWMS DataBase.
Longitude
Latitude
TimeZone
Coming Soon - Secchi Depth
Coming soon - Max Temperature Depth
Important Notes:
Make sure to set your aggregateTimeOffset to your timezoneOffset in the form “8 hours”
Always set your aggregateTimeZone to “ETC/GMT”
When setting Zero_elevation property, check the rating table to find the exact and correct Zero_elevation.
This algorithm Requires that a rating table exist within your CWMS data base for the area of your reservoir with rating id test to “FTPK.Elev;Area.Linear.Step”.
This algorithm Requires that a set of Water Temperature profiles exist with the WtpTsid format of “FTPK-Lower-D000,0m.Temp-Water.Inst.1Day.0.Rev-NWO-Evap-test”.
Thermal diffusivity coefficient is a unitless scaling factor applied to the computed thermal diffusivity. Lower values will reduce temperature transfer between layers. Adjust this value down if deeper water layers warm too quickly or up if they are warming too slowly. The default value is 1.2 with a recommended range of 0.5-2.0.
The following tables detail the Inputs, Outputs, and Properties for the ResEvap algorithm.
Inputs
Role Name |
Description |
Units |
|---|---|---|
windSpeed |
Wind speed at reservoir |
m/s |
airTemp |
Air temperature at reservoir |
°C |
relativeHumidity |
Relative humidity |
% |
atmPress |
Atmospheric pressure |
mbar |
percentLowCloud |
Low cloud cover |
% |
elevLowCloud |
High of low cloud cover |
m |
percentMidCloud |
Mid cloud cover |
% |
elevMidCloud |
High of mid cloud cover |
m |
percentHighCloud |
High cloud cover |
% |
elevHighCloud |
High of high cloud cover |
m |
elev |
Elevation of water level at reservoir |
m |
Outputs
Role Name |
Description |
Units |
|---|---|---|
hourlySurfaceTemp |
Hourly surface temperature |
°C |
hourlyEvapDepth |
Depth of hourly evaporation |
mm |
dailyEvapDepth |
Depth of daily evaporation |
mm |
dailyEvapAsFlow |
Daily evaporation as flow |
cms |
hourlyFluxOut |
Hourly flux out |
W/m² |
hourlyFluxIn |
Hourly flux in |
W/m² |
hourlySolar |
Hourly solar radiation |
W/m² |
hourlyLatent |
Hourly latent heat flux |
W/m² |
hourlySensible |
Hourly sensible heat flux |
W/m² |
Properties
Role Name |
Description |
Example |
|---|---|---|
wtpTsId |
Base String for Water Temp Profiles |
FTPK-Lower-D000,0m.Temp-Water.Inst.1Day.0.Rev-NWO-Evap-test |
reservoirId |
Location ID of reservoir |
SPK |
secchi |
Average secchi depth of reservoir (ft) |
|
zeroElevation |
Streamed elevation of reservoir (ft) |
|
latitude |
Latitude of reservoir |
|
longitude |
Longitude of reservoir |
|
timezone |
Time zone at reservoir location |
D%03d,%dm |
windShear |
Wind shear equation to be used in computation |
Donelan (default) or Fischer |
thermalDifCoe |
Thermal diffusivity scaling coefficient. |
1.2 (default) |
rating |
Rating Curve specification for Elevation-Area curve |
FTPK.Elev;Area.Linear.Step |
Note
See ResEvap Documentation to better understand how the algorithm behaves.