Columns | DATE | TEMP | TOTPP | RAIN | ETA | UCD (max. 5 columns) |
---|---|---|---|---|---|---|
Units | yyyy-mm-dd | °C | mm | mm | mm | user choice |
Values | eg. 2021-12-24 | -90 to 60 | 0 to 1800 | 0 to 1800 | 0 to 100 | user choice |
STARTING VALUES | |||
---|---|---|---|
NAME | LONG NAME | DEFINITION | VALUES |
SNWTinit | Initial snow layer thickness (cm) | Thickness of the snow layer on the first day of the analysis. This is converted into mm for subsequent calculations using 1/CFSmc | ≥ 0 |
SNWMinit | Initial snowmelt (mm) | Amount of snow melted on the first day of the analysis | ≥ 0 |
COEFFICIENTS | |||
---|---|---|---|
NAME | LONG NAME | DEFINITION | VALUES |
THRrs | Air temperature threshold for rain to be accumulated as snow (° C) | Precipitation falling as rain is treated as snow when air temperature is below this threshold. This results in the respective rain amount to be added to the snow layer instead of infiltrating and/or becoming surface runoff | -20 to 10 |
THRsm | Air temperature threshold for initiating snowmelt (° C) | Precipitation falling as snow is treated as rain when air temperature is above this threshold. In addition, melting of the snow occurs on days with air temperature above this threshold | -20 to 10 |
CFTsm | Correction factor - snowmelt due to air temperature (mm) | The amount of snow that is melted for each degree of air temperature above THRsm. | ≥ 0 |
CFRsm | Correction factor - snowmelt due to rain (mm) | The amount of snow that is melted for each mm of rain that is not accumulated in the snow layer | ≥ 0 |
CFSmc | Correction factor - snow as mm water to cm snow | Factor for converting calculated snow layer thickness from mm water (as calculated by the model) to cm of snow | ≥ 0 |
CFets | Correction factor - portion of evapotranspiration occurring in the soil | Factor for estimating the portion of actual evapotranspiration (ET) occuring in the soil. The remainder of ET is considered to occur before water enters the soil (e.g., canopy interception; water ponding at the soil surface, etc.). Due to the model calculations routines and routing of water through various components of the model depending on various model coefficients and calculated soil water content, the final ratio between ET above soil and ET in the soil will be different than the value set via CFets. | 0 to 1 |
STARTING VALUES | |||
---|---|---|---|
NAME | LONG NAME | DEFINITION | VALUES |
SWCinit | Soil water content (SWC) (% of PORe) | SWC, as percentage of PORe on the first day of the analysis. SWCinit cannot be higher than the effective porosity of the layer (PORe) | 1 to 100 |
SRinit | Surface runoff (mm) | Amount of surface runoff on the first day of the analysis | ≥ 0 |
NGinit | Net SWC gain (mm) | Net gain in SWC on the first day of the analysis | ≥ 0 |
NLinit | Net SWC loss (mm) | Net loss in SWC on the first day of the analysis | ≥ 0 |
LAYER PROPERTIES | |||
---|---|---|---|
NAME | LONG NAME | DEFINITION | VALUES |
THKN | Layer or root zone thickness (mm) | The thickness of the modelled layer. The layer can be the root zone, a soil horizon or the entire soil profile | ≥ 0 |
PORe | Layer effective porosity (%) | Effective porosity of the layer. This is used for defining the maximum soil water content (SWC) | 1 to 100 |
INFILTRATION COEFFICIENTS | |||
---|---|---|---|
NAME | LONG NAME | DEFINITION | VALUES |
THRinfLH | SWC threshold for switching between low and high infiltration rate (% of PORe) | Infiltration rate is high when soil water content (SWC) is below this threshold and low when SWC is above this threshold | 0 to 1 |
INFlr | Infiltration rate at low SWC (mm/hr) | Infiltration rate when SWC is lower than THRinfLH (i.e., high infiltration rate) | ≥ 0 |
INFhr | Infiltration rate at high SWC (mm/hr) | Infiltration rate when SWC is higher than THRinfLH (i.e., low infiltration rate) | ≥ 0 |
DRAINAGE COEFFICIENTS | |||
---|---|---|---|
NAME | LONG NAME | DEFINITION | VALUES |
THRdraHL | SWC threshold for switching drainage from high to low rate (% of PORe) | Drainage rate is high when soil water content (SWC) is above this threshold and low when SWC is below this threshold | 1 to 100 |
DRAlr | Drainage rate at low SWC (mm/hr) | Drainage rate when SWC is lower than THRdraHL (i.e., low drainage rate) | ≥ 0 |
DRAhr | Drainage rate at high SWC (mm/hr) | Drainage rate when SWC is higher than THRdraHL (i.e., high drainage rate) | ≥ 0 |
THRswstd | SWC threshold for stopping drainage (% of PORe) | Drainage stops when the SWC is below this threshold. This corresponds to dry soil conditions when drainage is expected to cease | 1 to 100 |
THRtstd | Air temperature threshold for stopping drainage (° C) | Drainage stops when the air temperature is below this threshold. This is considered to be a reasonable proxy for simulating frozen soil conditions. THRtstd is generally lower than the actual soil temperature | -20 to 10 |
CFeidr | Surface runoff to drainage correction factor - excess infiltration | Forces a portion of water from excess infiltration to be re-routed to drainage instead of surface runoff. Non-zero values for CFeidr do not impact SWC. CFeidr initial value should be set to zero, and should be adjusted only if model calibration using other coefficients does not produce satisfactory results. | 0 to 1 |
CFosdr | Surface runoff to drainage correction factor - oversaturation | Forces a portion of water from oversaturation (i.e., when SWC > PORe) to be re-routed to drainage instead of surface runoff. Non-zero values for CFosdr do not impact SWC. CFosdr initial value should be set to zero, and should be adjusted only if model calibration using other coefficients does not produce satisfactory results. | 0 to 1 |
OTHER COEFFICIENTS | |||
---|---|---|---|
NAME | LONG NAME | DEFINITION | VALUES |
CFets | Correction factor - portion of evapotranspiration occurring in the soil | Factor for estimating the portion of actual evapotranspiration (ET) that occurs in the soil. The remainder of ET is considered to occur before water enters the soil (e.g., canopy interception; water ponding at the soil surface, etc.). Due to the model calculations routines and routing of water through various components of the model depending on various model coefficients and calculated soil water content, the final ratio between ET above soil and ET in the soil will be different than the value set via CFets. | 0 to 1 |
THRets | SWC threshold for stopping soil evapotranspiration (% of PORe) | Forces evapotranspiration to stop when SWC is below this value. | 1 to 100 |
THRlw | Threshold for low SWC state (% of PORe) | Threshold for considering the soil to be in a low SWC state. This is used only for counting the number of days when the soil is in this SWC state and can be used for example for estimating the number of days that require irrigation or number of days with water deficit. | 1 to 100 |
THRhw | Threshold for high SWC state (% of PORe) | Threshold for considering the soil to be in a high SWC state. This is used only for counting the number of days when the soil is in this SWC state and can be used for example for estimating the number of days with excess water present in the soil. | 1 to 100 |
NAME | LONG NAME | DEFINITION |
DATE | Day (yyyy-mm-dd) | Date for analyzed data |
TEMP | Temperature (° C) | Mean air temperature (input data) |
TOTPP | Total precipitation (mm) | Total precipitation amount (input data) |
RAIN | Rain (mm) | Rain amount (input data) |
SNOF | Snowfall (mm) | Snowfall amount (difference between TOTPP and RAIN) |
RAINS | Rain added to the snow layer (mm) | Amount of rain that is converted to snow (dependent on THRrs) |
RAINNS | Rain not added to the snow layer (mm) | Amount of rain that is preserved as rain (dependent on THRrs) |
SNOA | Snowfall added to the snow layer (mm) | Amount of snowfall that is added to the snow layer (dependent on THRsm) |
SNOM | Snowfall not added to the snow layer (mm) | Amount of snowfall that is converted to rain |
RSSL | Rain and snowfall contributing to snow layer (mm) | Amount of water from rain and snowfall that is converted to snow and accumulates to the snow layer before temperature and precipitation corrections for the snow layer are applied |
RSI | Rain and snowfall contributing to infiltration (mm) | Amount of water from rain and snowfall that is preserved in liquid form and contributes to water available for infiltration |
SNMT | Potential snowmelt due to temperature (mm) | The amount of snowmelt is dependent on the air temperature. SNMT is calculated using the degree-day concept and is dependent on THRsm and CFTsm. SNMT is used in calculation of SNTFmm and thus, water rerouted to SNMT does not accumulate in the snow layer. |
SNMR | Potential snowmelt due to rain (mm) | Rain that is not converted to snow can produce snowmelt. SNMR represents the amount of snowmelt associated with rain. SNMR is calculated as the product of rainfall amount and CFRsm. SNMR is used in calculation of SNTFmm and thus, water rerouted to SNMR does not accumulate in the snow layer. |
SNTFmm | Snow layer thickness (mm) | Snow layer thickness (expressed as mm) after temperature and precipitation corrections. SNTF represents the final values of snow layer thickness and is a key output parameter |
SNG | Net snow gain to the snowpack (mm) | Net addition of water to the snow layer. SNG represents the net additions to the snowpack and is available only when the snowpack increases between two consecutive days. |
SNMF | Net snowmelt from the snowpack (mm) | Net loss of water from the snow layer. SNMF represents water originating from the snow layer that becomes available for infiltration and/or surface runoff and is available only when the snowpack decreases between consecutive days. The assumption is that all the snow that melts become available for infiltration and/or surface runoff instead of being stored in the snow layer. |
ETA | Evapotranspiration (ET) (mm) | Actual evapotranspiration (input data) |
ETasi | Above soil ET (mm) before correction for dry soil (mm) | Portion of evapotranspiration that occurs above soil. The assumption is that a portion of evapotranspiration occurs in the soil and the reminder occurs above the soil via processes such as canopy interception and/or water ponding at the soil surface. The magnitude of Etasi is controlled by CFets. ETasi can occur only on days when precipitation occurs or snowpack is present, and hence, ETasi is smaller than the value set via CFets. This is an intermediate result that is adjusted via subsequent calculations |
ETfsas | ET from soil transferred to ET above soil when soil is dry (mm) | Evapotranspiration from soil ceases under dry soil conditions (controlled by THRets). THRets allows for transferring ET from soil to ET above ground ET (ETAs) if evaporative demand is still present (ETA) when the soil is dry. The full calculations for ETfsas are performed in the SOIL WATER module. If the SOIL WATER module has not been run, ETfsas is assumed to be zero. Generally, ETfsas is small and hence this limitation is not expected to impact calculations significantly. ETfsas values are adjusted once the SOIL WATER module calculations are performed. ETfsas is the amount transferred from soil ET to above soil ET. |
ETasf | Above soil ET after rerouting ET from dry soil (mm) | Portion of evapotranspiration that occurs above soil. The assumption is that a portion of evapotranspiration occurs in the soil and the reminder occurs above the soil via processes such as canopy interception and/or water ponding at the soil surface. The magnitude of Etasf (and ETasi) is controlled by CFets. This is the final result representing the portion of evapotranspiration that occurs above soil and includes corrections for dry soil conditions (ETfsas) |
WATisrf | Water available for infiltration or surface runoff after ET correction (mm) | The water amount that is available for either infiltration or surface runoff after all corrections, including impact of evapotranspiration. WATisrf is a key parameter calculated in the SNOW module and is the starting point for the calculations conducted in the WATER BALANCE module |
SNTFcm | Snow layer thickness (cm) | Snow layer thickness (expressed as cm) after temperature and precipitation corrections. SNTFcm is obtained by converting SNTFmm to cm of snow by using CFSmc. SNTFcm represents the final values of snow layer thickness and is a key output parameter. |
UCD | User-provided calibration data | If provided, UCD data allows for pairing of SNOSWAB output with data from other sources during the calibration of the model |
NAME | LONG NAME | DEFINITION |
DATE | Day (yyyy-mm-dd) | Date for analyzed data |
TEMP | Temperature (° C) | Mean air temperature (input data) |
TOTPP | Total precipitation (mm) | Total precipitation amount (input data) |
RAIN | Rain (mm) | Rain amount (input data) |
SNOF | Snowfall (mm) | Snowfall amount (difference between TOTPP and RAIN) |
WATisrf | >Water available for infiltration or surface runoff after ET correction (mm) | The water amount that is available for either infiltration or surface runoff after all corrections, including impact of evapotranspiration. WATisrf is a key parameter calculated in the SNOW module and is the starting point for the calculations conducted in the WATER BALANCE module |
INFact | Actual infiltration (mm) | Actual infiltration as constrained by WATisrf and INFcap. WATisrf that is in excess of INFcap is re-routed to surface runoff. INFact incorporates all adjustments relative to the infiltration process and is considered a key output parameter |
DRAcap | Drainage capacity (mm) | Maximum allowed daily drainage. DRAcap is based on either DRAlr (low infiltration rate) or DRAhr (high infiltration rate) as triggered by THRdraLH |
DRAfre | Drainage with frozen soil conditions (mm) | DRAcap corrected for frozen soil conditions as triggered by THRtstd. Drainage stops when soil temperature is lower than THRtstd |
DRAfin | Drainage with dry soil correction (mm) | DRAfre corrected for dry soil conditions as triggered by THRswstd. Drainage stops when SWC is lower than THRtstd. DRAfin represents the drainage before surface runoff correction (if any) is applied. |
DRAbinf | Drainage boost from excess infiltration (mm) | Excess water is transferred to surface runoff when WATisrf > INFcap. For these cases, drainage can be set to receive a portion of the water directly from surface runoff, as triggered by CFeidr. |
DRAoss | Drainage boost from oversaturated soil (mm) | When soil becomes oversaturated, excess water is transferred to surface runoff. For these cases, drainage can be set to receive a portion of the water directly from surface runoff, as triggered by CFosdr. Use of non-zero CFosdr forces the model to bypass SWC calculation. Hence, CFosdr starting values should be zero, and should be adjusted only if model calibration using other coefficients is not satisfactory |
DRAact | Actual drainage (mm) | Actual drainage. DRAact incorporates all adjustments relative to the drainage processes and is considered a key output parameter |
ETisi | Soil ET (mm) before correction for dry soil | Portion of evapotranspiration that occurs in the soil. The assumption is that a portion of evapotranspiration occurs in the soil and the reminder occurs above the soil via processes such as canopy interception and/or water ponding at the soil surface. The magnitude of ETisi is controlled by CFets. This is an intermediate result that is adjusted via subsequent calculations |
ETcds | Soil ET corrected for dry soil (mm) | Evapotranspiration from soil ceases under dry soil conditions (controlled by THRets). ETcds is a key output parameter and is equal to ETisi when the soil is not under dry conditions and zero on the days with dry soil conditions |
ETfsas | ET from soil transferred to ET above soil when soil is dry (mm) | Evapotranspiration from soil ceases under dry soil conditions (controlled by THRets). THRets allows for transferring ET from soil to ET above ground ET (ETAs) if evaporative demand is still present (ETA) when the soil is dry. ETfsas is the amount transferred from soil ET to above soil ET |
SWCint | Soil water content (mm) - intermediate | SWC (soil water content) after integrating infiltration, drainage and evapotranspiration processes. This is an intermediate result as SWC is adjusted via subsequent calculations |
SWCfinmm | Soil water content - corrected for saturated soil (mm) | SWC (soil water content) after SWCint is corrected for saturated soil conditions as set by PORe. SWCfinmm incorporates all adjustments relative to the SWC and is a key output parameter |
SWCfin | Soil water content - corrected for saturated soil (%) | SWC (soil water content) after SWCint is corrected for saturated soil conditions as set by PORe. SWCfin incorporates all adjustments relative to the SWC and is a key output parameter |
SReinf | Surface runoff due to excess infiltration (mm) | Surface runoff due to excess water available for infiltration. Excess water is transferred to surface runoff when WATisrf > INFcap. |
SReinfDB | Surface runoff due to excess infiltration after drainage correction (mm) | Surface runoff due to excess water available for infiltration (WATisrf > INFcap) after a portion (controlled by CFeidr) has been re-routed to drainage (DRAbinf) |
SResas | Surface runoff due to saturated soil (mm) | Surface runoff due to soil oversaturation (SWC > PORe). When soil becomes oversaturated, excess water is transferred to surface runoff |
SResasDB | Surface runoff due to saturated soil after drainage correction (mm) | Surface runoff due to soil oversaturation (SWC > PORe) after a portion (controlled by CFosdr) has been re-routed to drainage (DRAoss) |
SRTint | Total surface runoff before drainage correction (mm) | Total surface runoff, including all adjustments except for drainage correction (DRAbinf and DRAoss). This is an intermediate result that is adjusted via subsequent calculations |
SRTact | Total surface runoff after drainage correction (mm) | SRTact is SRTint after drainage correction (DRAbinf and DRAoss). SRTact incorporates all adjustments relative to the surface runoff processes and is considered a key output parameter |
SWCgain | Net SWC gain (mm) | Soil layer gains water when SWCfinmm on day i+1 is higher than on day i. SWCgain similar to SWCloss over the long-term indicates that the soil water storage is in equilibrium |
SWCloss | Net SWC loss (mm) | Soil layer losses water when SWCfinmm on day i+1 is lower than on day i. SWCloss similar to SWCgain over the long-term indicates that the soil water storage is in equilibrium |
SWClow | Days with low soil water content | Count for days in low SWC state (triggered by THRlw). This is used only for counting the number of days when the soil is in this SWC state and can be used for example for estimating the number of days that require irrigation or number of days with water deficit |
SWChigh | Days with high soil water content | Count for days in high SWC state (triggered by THRlw). This is used only for counting the number of days when the soil is in this SWC state and can be used for example for estimating the number of days with excess water present in the soil |
UCD | User-provided calibration data | If provided, UCD data allows for pairing of SNOSWAB output with data from other sources during the calibration of the model (e.g., soil water content, groundwater recharge, stream baseflow, surface runoff, etc.). |
Columns | DATE | TEMP | TOTPP | RAIN | ETA | UCD (max. 5 columns) |
---|---|---|---|---|---|---|
Units | yyyy-mm-dd | °C | mm | mm | mm | user choice |
Values | eg. 2021-12-24 | -90 to 60 | 0 to 1800 | 0 to 1800 | 0 to 100 | user choice |