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start:hype_model_description:processes_above_ground

Processes above ground

Temperature and precipitation

HYPE has many possibilities to adjust the precipitation and temperature given in the Pobs.txt and Tobs.txt files. Adjustment is done because the supplied data can be of different reference height or (known to be) wrong in some areas, or because data vary over the subbasin but the input is given as one value, and or to compensate for non modelled processes.

Temperature adjustments

Subbasin air temperatures (T_i) in the input file are normally assumed to be for the subbasin’s average elevation (elev). The same adjustments are made for maximum and minimum temperatures if available.

(1) If data with other reference height is used it is possible to adjust for that. The subbasin temperature can be adjusted depending on subbasin elevation with general parameter tcelevadd (° / 100m). This adjustment assumes observations are located at sea level.

(2) Alternatively it can be adjusted based on the difference between subbasin elevation and temperature observation elevation by general parameter tcobselev (° / 100m). The temperature observation elevation (elev_obs) then need to be supplied to the model.

(3) It can be adjusted based on month with the monthly dependent parameter monthlapse (° / 100m)). These three subbasin elevation adjustments should not be used together. Subbasin temperature can be adjusted equally over all subbasins within a region with the parameter region dependent parameter tempcorr.

T_gc = T_i + tempcorr - tcelevadd * elev/100 - tcobselev * (elev - elev_obs)/100 - monthlapse*elev/100

The temperature can also be adjusted for each class depending on their deviation from the subbasin average elevation ({Delta}h). The class-dependent temperature (T) is calculated using the parameter tcalt. The temperature lapse rate often has a value of 0.6 (° / 100m).

T = T_gc - tcalt*{{Delta} h}/100

Precipitation adjustments

Subbasin input precipitation (P_i) can be adjusted equally over all subbasins with the general parameter pcaddg or for some subbasins with the parameter region dependent parameter preccorr. Additionally it is possible to adjust precipitation for undercatch with different parameters (pcurain,pcusnow) depending on if the precipitation falls as snow or rain.

Subbasin precipitation (P_gc) is for subbasin average elevation (elev), but can be adjusted for elevation variations within the subbasin. The precipitation of a class (P) is adjusted for classes where the class average elevation is greater than a threshold (general model parameter pcelevth). The adjustment is determined by a general parameter (pcelevadd) that is the correction per 100m. The class elevation adjustment can alternatively be determined from the basin standard deviation of elevation (elev_std) and a parameter pcelevstd. The class height adjustment is limited by a general parameter pcelevmax. The precipitation of a class can additionally be adjusted with land-use dependent parameter pcluse, e.g. for interception evaporation.

P_gc=P_i*(1+pcaddg)*(1+preccorr)*(1+(pcurain*(1-snfrac)+pcusnow*snfrac))

pc_{height}=delim{lbrace}{ 
matrix{2}{2}{
    0 {elev+{Delta}h<pcelevth}
    {MIN({{elev+{Delta}h-pcelevth}/{100}}*pcelevadd+{{elev_std}/{100}}*pcelevstd,pcelevmax)}  else
   }}{}

P=P_gc*(1+pc_{height} )*(1-pcluse)

Where {Delta}h is a class's elevation deviation from the subbasin average elevation and snfrac is the average fraction of precipitation that falls as snow calculated from subbasin temperature (T_i) and temperature thresholds (see equation below), or from input.

Rainfall and snowfall separation

The rain/snow fraction of precipitation is calculated based on temperature or given as an input time series. Different temperatures can be used in the equation, i.e. basin average or class temperature. When the air temperature (T) is around the threshold temperature for mixed precipitation (land-use dependent parameter ttmp plus general parameter ttpd) both rain and snow. The interval for mixed precipitation is given by the parameter ttpi. For temperature below threshold minus ttpi, the precipitation is assumed to be in solid form only and is added to the snowpack. If the air temperature is greater than the threshold temperature plus ttpi, the precipitation is assumed to be solely in liquid form. For intermediate temperatures, the precipitation is assumed to be a mixture of liquid and solid forms i.e. as both rain and snow. The proportion (a_rain) of precipitation that falls as rain depends linearly on the temperature.

a_{rain}=delim{lbrace}{ 
matrix{3}{2}{
    0 {T<ttmp+ttpd-ttpi}
    1 {T>ttmp+ttpd+ttpi}
    {{(T-(ttmp+ttpd-ttpi))}/{(2*ttpi)}}  else
   }}{}

Alternatively snowfall fraction (sffrac) may be read from input file and a_rain calculated as:

a_{rain}=1-sffrac

The amount of rainfall and snowfall is calculated from the corrected precipitation (P).

rainfall=P*a_{rain} snowfall=P*(1-a_{rain} )

Snowfall distribution

The optional snowfall distribution models redistribute the snowfall of a catchment among the classes within a subbasin or between subbasins depending on wind. The model uses Winstral coefficients. For each subbasin and class and wind direction a Winstral coefficient (WSF) is given as input data to the model. Wind direction is calculated from forcingdata of westerly (U) and southerly (V) wind. The wind direction is translated to the closest quadrant or octant, and the Winstral coefficient of that direction is used.

The Winstral coefficient is, with some scaling parameters, used to calculate the relative snowfall for each class this time step. There are two models; one that use a linear function (Gustafsson et al, 2015) and one that is log-linear (Clemenzi et al., 2023):

relative_snowfall = 1. + WSFscale * WSFwind * WSFluse * (WSF + WSFbias)

relative_snowfall = 10 ^ (WSFscale * WSFwind * WSFluse * (WSF + WSFbias))

WSFscale and WSFbias are general parameter, WSFwind is a scaling factor depending on wind speed (wind), WSFluse is a scaling parameter depending on land-use. The wind speed scaling factor reduced the snow fall redistribution for low wind speeds. It depends on one general parameter, sndrwscale, and the windspeed, and is calculated as:

WSFwind = 1 - exp( - {({sndrwscale*wind})^2} )

The relative snowfall is limited to the interval [1 - sfdmax, 1 + sfdmax] for the linear model and [0,sfdmax] for the log-linear. sfdmax is a general parameter. The relative snowfall is normalized within each subbasin so that the subbasin mean snowfall is preserved. The snowfall distribution is applied only if snow is falling for a fraction of the subbasin area that is larger than a limit (limit).

For the option of distributing snowfall also between subbasins, two versions are currently implemented. One option may distribute snowfall to the nearest downwind subbasin, while the other option distribute snowfall to all subbasins within a distance range. Both variants use the log-linear Winstral coefficients. They are used to calculate the relative snowfall for each class in all the subbasins separately. For the first version, the distribution of the snowfall of the upwind subbasin between the upwind and downwind subbasins is then calculated based on windspeed (wind) and distance (d). The two subbasins share the sharefrac of snowfall, and the rest goes to the upwind subbasin only. For the other version, the distribution of the snowfall is calculated for the subbasin within a range depending on windspeed, and with a reducing weight (weight) depending on distance (d).

sharefrac = exp(-2*(d/{sndrscale*wind})^2)

weigth = exp(-2*(d/{sndrscale*wind})^2)

The sndrscale parameter is a general length scale parameter (m per m/s). The distance is calculated for the subbasins X/Y coordinates. Subbasins with weight less than 0.1 is cut off.

References

Gustafsson et al., 2015

Ilaria Clemenzi, David Gustafsson, Wolf-Dietrich Marchand, Björn Norell, Jie Zhang, Rickard Pettersson, Veijo Allan Pohjola, 2023. Impact of snow distribution modelling for runoff predictions. Hydrology Research 1 May 2023; 54 (5): 633–647. https://doi.org/10.2166/nh.2023.043

Section Symbol Parameter/Data File
Temperature adjustmentsT_i Tobs.txt
elevelev_meanGeoData.txt
{Delta}hdhslc_nn
elev_obstobselevForcKey.txt
tcelevadd, tcobselev, monthlapse, tempcorr, tcaltpar.txt
Precipitation adjustmentsP_i Pobs.txt
pcaddg, preccorr, pcurain, pcusnow, pcelevth, pcelevadd, pcelevstd, pcelevmax, pclusepar.txt
{Delta}hdhslc_nnGeoData.txt
elev_stdelev_std
snfraccalculated based on T_i or from SFobs.txt
Rainfall and snowfall calculations ttmp, ttpd, ttpipar.txt
sffrac SFobs.txt
Snowfall distributionU, V UWobs.txt, VWobs.txt
windcalculated from U, V
WSFwsf_nn_d GeoData.txt
dcalculated from xcoord, ycoord
WSFscale,WSFluse,WSFbias,sfdmax par.txt
limit sfdlim
sndrscale sndrlscale
Modules (file) Procedures
modelmodule (model_hype.f90) model
soil_processes (soil_proc.f90) calculate_snow
infiltration
atmospheric_processes (atm_proc.f90) calculate_class_atmospheric_forcing
calculate_rain_snow_from_precipitation
calculate_subbasin_temperature
calculate_subbasin_precipitation
set_atmospheric_parameters_corrections
calculate_winddirspeed
calculate_snowfall_distribution

Potential evaporation

Potential evaporation is calculated for each class based on land use and atmopheric variables. The potential evaporation is then used to calculate the current actual evapotranspiration from each land class (see Soil water - Evaporation. A river with an area (i.e. is a class), flooded floodplains and lakes are assumed to evaporate at the potential rate, when the air temperature is above the threshold temperature (ttmp). Evaporation is limited by the water body's volume.

Potential evaporation (epot in mm) is calculated based on the temperature if it is not read in from file (repo in Xobs.txt). Alternative PET models exist, and is described below. When the air temperature (T) is greater than the threshold temperature ttmp evaporation is assumed to occur. Snow melting, snow density and evaporation use the same threshold temperature. The basic potential evapotranspiration (epot_base) depends on the land use dependent rate parameter cevp.

cseason = 1 + cevpam*sin(2*pi*(dayno-cevpph)/365)

epot_{base} = (cevp * cseason) * (T-ttmp)

A seasonal factor cseason adjusts the potential evaporation rate (cevp) e.g. making it higher in the spring when the air is often dry, and lower in autumn when the air is often more humid than in spring. The factor is sinusoidal with two parameters cevpam and cevpph. It is not used if cevpam is zero. A cevpph around 45 days give a maximum correction in mid May (dayno=45+91=136). The minimum correction will then be a half year later in September (dayno=136+182). For an earlier maximum, reduce cevpph.

The basic potential evapotranspiration may be adjusted with a regional correction factor (cevpcorr) equally over the year depending on parameter region.

epot = epot_{base} * (1 + cevpcorr)

Alternative potential evaporation models

HYPE give the option to exchange the default potential evaporation model for another model. Only the basic potential evaporation (epot_base) differs between models. Models 0-2 only use air temperature forcing. Models 3-5 want shortwave radiation and minimum and maximum daily air temperature, although if lacking approximations are made (see section Input to alternative potential evaporation models below). In addition, model 5 wants relative humidity and wind speed if available. Note, regardless of potential evaporation model, the actual evaporation is limited to temperatures above parameter ttmp.

Model 0 (default)

As described above; evapotranspiration depends on the rate parameter cevp and air temperature (T) above a threshold ttmp. If the variable repo is given in Xobs.txt those values are used.

epot_{base} = (cevp * cseason) * (T-ttmp)

Model 1

Model 1 is the same as model 0, but it will not be using repo from input data, even if it is present.

Model 2 - Modified Jensen-Haise/McGuiness

The modified Jensen-Haise/McGuiness model follow Oudin et al. (2005). The potential evaporation depends on extraterrestrial radiation (radext), latent heat of vaporization (lambda) and temperature (T). Two general parameters (jhtadd and jhtscale) are used and one land use dependent (crop coefficient kc2 or kc).

epot_{base} = {kc/jhtscale} * MAX(0,{radext/lambda}*(T+jhtadd))

Model 3 - Modified Hargreaves-Samani

The Hargreaves-Samani evaporation is modified to limit the “turbidity-factor”. The potential evaporation depends on extraterrestrial radiation (radext), latent heat of vaporization (lambda), temperature (T) and turbidity (turbidity). One general parameter (krs) is used and one land use dependent (crop coefficient kc3 or kc).

epot_{base} = MAX(0,kc*0.0023 * {radext/lambda}*{turbidity/krs}*(T+17.8))

Model 4 - Priestly-Taylor

The Priestly-Taylor potential evaporation depends on net downward radiation (netrad), slope of saturated vapour pressure curve (dsatvap), latent heat of vaporization (lambda) and a psychrometric constant (gamma). One general parameter (alfapt) are used and one land use dependent (crop coefficient kc4 or kc).

epot_{base} = MAX(0,kc*alfapt * {dsatvap*netrad/lambda*(dsatvap+gamma)})

Model 5 - FAO Penman-Monteith

The FAO Penman-Monteith potential evaporation depends on net downward radiation (netrad), slope of saturated vapour pressure curve (dsatvap), saturated and actual vapour pressure (satvap and actvap), temperature (T), wind speed (wind) and a psychrometric constant (gamma). One land use dependent parameter (crop coefficient kc5 or kc) is used.

epot_{base} = MAX(0,kc*{0.408 * dsatvap*netrad + gamma*{{900}/{T+273}}*wind*(satvap-actvap)}/{dsatvap+gamma*(1+0.34*wind)})

Input to alternative potential evaporation models

Summary of alternative input to PET models, and link to file reference.

Model Parameters (par.txt) Static data (GeoData.txt) Forcing data (files)
0 cevp, ttmp Xobs:repo, Tobs
1 cevp, ttmp Tobs
2: modified Jensen-Haise/McGuiness jhtadd, jhtscale, kc latitude Tobs
3: modified Hargreaves-Samani kc, krs elevation, latitude SWobs, Tobs
3: modified Hargreaves-Samani kc, krs elevation, latitude, cloudiness Tobs
3: modified Hargreaves-Samani kc, krs elevation, latitude TMINobs, TMAXobs, Tobs
4: Priestly-Taylor alb, alfapt, kc elevation, latitude RHobs, SWobs, TMINobs, TMAXobs, Tobs
4: Priestly-Taylor alb, alfapt, kc, krs elevation, latitude SWobs, TMINobs, TMAXobs, Tobs
4: Priestly-Taylor alb, alfapt, kc, krs elevation, latitude TMINobs, TMAXobs, Tobs
4: Priestly-Taylor alb, alfapt, kc, krs elevation, latitude, cloudiness Tobs
5: FAO Penman-Monteith alb, kc, roughness, zphd, zwind, zwish elevation, latitude RHobs, SWobs, TMINobs, TMAXobs, Tobs, Uobs
5: FAO Penman-Monteith alb, kc, mwind elevation, latitude RHobs, SWobs, TMINobs, TMAXobs, Tobs
5: FAO Penman-Monteith alb, kc, krs, roughness, zphd, zwind, zwish elevation, latitude SWobs, TMINobs, TMAXobs, Tobs, Uobs
5: FAO Penman-Monteith alb, kc, krs, mwind elevation, latitude SWobs, TMINobs, TMAXobs, Tobs
5: FAO Penman-Monteith alb, kc, krs, roughness, zphd, zwind, zwish elevation, latitude TMINobs, TMAXobs, Tobs, Uobs
5: FAO Penman-Monteith alb, kc, krs, mwind elevation, latitude TMINobs, TMAXobs, Tobs
5: FAO Penman-Monteith alb, kc, krs, mwind elevation, latitude, cloudiness Tobs

Actual vapour pressure

Actual vapour pressure (actvap) is calculated following FAO recommended procedure and function/data priority. Depending on availability of minimum, mean and maximum relative humidity (rh) and minimum, mean and maximum air temperature (T_min, T, T_max) equations with different combinations of saturated vapour pressure (calculated from temperature) times relative humidity is used. For example:

actvap = {satvap(T_max)*rh_min+satvap(T_min)*rh_max}/2

actvap = satvap(T_min)*rh_max

actvap = satvap(T)*rh_mean

actvap = satvap(T_min)*1

In case not enough data is available, minimum temperature is calculated from turbidity and a general parameter (krs) and the last equation of those above is used.

T_min = T - 0.5*(turbidity/krs)^2

Eventually actual vapour pressure is limited by the calculated saturated vapour pressure.

Air pressure

Air pressure (pa) is calculated as a function of elevation for the class (elev).

pa = 101.3*({293-0.0065*elev}/{293})^5.26

Shortwave radiation

Shortwave radiation (swrad) is supplied as input forcing time series or otherwise calculated from extraterrestrial radiation.

swrad=radext*turbidity

Extraterrestrial radiation

Extraterrestrial solar radiation (radext) is estimated from day of year and latitude. The equations used comes from FAO. The day of the year are used to estimate distance to the sun and declination. The sunset hour angle are calculated from latitude, but with special care for high latitudes (polar night and midnight sun). These variables together with latitude and the solar constant eventually give the current extraterrestrial radiation for each subbasin.

Latent heat of vaporization

Latent heat of vaporization (lambda) is a function of temperature (T).

lambda = 2.501-0.002361*T

Net downward radiation

The net downward radiation (netrad) is used explicitly for PET model 4 and 5 (Priestly-Taylor and FAO Penman-Monteith). The net radiation is calculated following FAO recommended procedure. It is calculated as net shortwave radiation minus net longwave radiation. Net shortwave radiation (net_short) is calculated from the shortwave radiation (swrad) and the land use dependent albedo parameter (alb). Net longwave radiation (net_long) is calculated using temperature (T_min, T_max, T), actual vapour pressure (actvap) and relative shortwave radiation (relsh) if those are available, otherwise it is set to zero. The relative shortwave radiation is shortwave radiation in relation to clear sky shortwave radiation.

net_short = swrad*(1-alb)

net_long = 4.903*10^9*{{(T_max+273.15)^4+(T_min+273.15)^4}/2}*(0.34-0.14*actvap^0.5)*(1.35*relsh-0.35)

relsh = turbidity/clearturb

Psychrometric constant

The psychrometric constant (gamma) is a function of air pressure (pa) and latent heat of vaporization (lambda) following FAO.

gamma = 0.001013*pa/{0.622*lambda}

Saturated vapour pressure

Saturated vapour pressure (satvap, kPa) is calculated from temperature (temp) following FAO. If daily minimum and maximum air temperature is available satvap is set to the average of the saturated vapour pressure calculated for each of those two temperatures, otherwise it is calculated from daily average air temperature.

satvap=0.6108*{EXP({17.27*temp}/{temp+237.3})}

Slope of saturated vapour pressure curve

The slope of saturated vapour pressure temperature function (dsatvap) is used explicitly for PET model 4 and 5 (Priestly-Taylor and FAO Penman-Monteith). The slope is calculated from daily mean air temperature (T).

dsatvap=4098*0.6108*{EXP({17.27*T}/{T+237.3})}*{{1}/{(T+237.3)^2}}

Turbidity

The turbidity factor is used explicitly for the PET model 3 - modified Hargreaves-Samani. If shortwave radiation (swrad) has been given as forcing data time serie, the turbidity factor is calculated as

turbidity = swrad/radext

but limited by a minimum turbidity value (0.25) and an estimated clearsky turbidity. The clearsky turbidity (clearturb) is estimated by the Ångström formula (FAO):

clearturb = 0.75+elev*0.00002

where elev is subbasin elevation in meter above sea level. If no shortwave radiaton time series are given, but montly cloudiness climatology is provided (cloudiness), the turbidity is calculated as

turbidity = (clearturb - 0.25)*(1-cloudiness) + 0.25

If no cloudiness are given either, but time series of daily minimum and maximum temperature are, the turbidity is calculated as in the “ordinary” Hargreaves-Samani turbidity function:

turbidity = krs*SQRT(T_max - T_min)

but still limited by the minimum turbidity value and the calculated clearsky turbidity.

Wind speed

Wind speed is used in PET model 5 - FAO Penman-Monteith. Wind speed (wind) may be given as a constant general parameter (mwind) or as a forcing data time series. The time serie wind is given for each subbasin (U_i). It is possible to adjust the time serie wind speed to different height than observations. If the general parameters zwind, zwish, roughness, and zpdh is set, wind speed is adjusted with the transformation factor windtrans.

wind=U_i*windtrans

windtrans = {ln(zwind-zpdh)-ln(roughness)}/{ln(zwish-zpdh)-ln(roughness)}

Section Symbol Parameter/Data File
Evaporation cevp, ttmp, cevpam, cevpph, cevpcorr, epotdist, lp, ttrig, tredA, tredB par.txt
wp calculated from wcwp, wcwp1, wcwp2, wcwp3 and soillayerdepth
fc calculated from wcfc, wcfc1, wcfc2, wcfc3 and soillayerdepth
soillayerdepth GeoClass.txt
Alternative potential evaporation models epot Xobs.txt
jhtadd, jhtscale, kc, kc2, kc3, kc4, kc5, krs, alfapt par.txt
Input to alternative potential evaporation models alb, mwind, zwind, zwish, roughness, zpdh par.txt
U_i Uobs.txt
swrad calculated or from SWobs.txt
elev elev_mean GeoData.txt
latitude, cloudiness
Modules (file) Procedures
soil_processes (soil_proc.f90) initiate_soil_water
calculate_potential_evaporation
calculate_actual_soil_evapotranspiration
surfacewater_processes (sw_proc.f90) calculate_river_evaporation
calculate_actual_lake_evaporation

References

Richard G. Allen, Luis S. Pereira, Dirk Raes & Martin Smith, 1998. Crop Evapotranspiration – Guidelines for Computing Crop Water Requirements. FAO Irrigation and drainage paper 56. Rome, Italy: Food and Agriculture Organization of the United Nations. ISBN 92-5-104219-5

Oudin, L., F. Hervieu, C. Michel, C. Perrin, V. Andreassian, F. Anctil and C. Loumagne 2005. Which potential evapotranspiration input for a lumped rainfall–runoff model?: Part 2—Towards a simple and efficient potential evapotranspiration model for rainfall–runoff modelling, Journal of Hydrology 303(1-4):290-306.

Atmospheric deposition

Atmospheric deposition can be added to the model as load or as concentration of precipitation.

Wet deposition

Atmospheric deposition in the form of wet deposition of IN and SP is added as a concentration of rainfall. You can specify a time series of the concentration in precipitation in Xobs.txt (implemented for IN, SP, and T1). Otherwise wet deposition (as a concentration) is specified in AtmdepData.txt for each subbasin.

If parameter (aloadconst) is set, the wet deposition load in considered constant and not dependent on precipitation corrections. Thus the concentration of precipitation is changed to keep the load constant, when precipitation correction is applied.

Atmospheric deposition to the soil

Dry deposition is specified in AtmdepData.txt for each subbasin. It can be specified for different vegetation types or land uses.

Dry deposition of nitrogen and phosphorus is added to the snow or, if there is no snow, directly to the ground. Phosphorus deposition is added to PartP-pool in the upper soil layer and nitrogen deposits to the IN dissolved in soil water if the parameter ponatm is not set. A new concentration of IN in the soil water is then calculated. The parameter ponatm indicates that some of the nitrogen deposition will be added to organic nitrogen pool (fastN) instead of to the IN pool.

For both nitrogen and phosphorus wet deposition is added through the concentration of precipitation (as described above). Precipitation may fall as snow and be added to the snow pack or if it is rain added to the potential infiltration. Depending on the fate of the infiltration, the wet atmospheric deposition will mix with the recieving water (e.g. surface runoff, soil layer water, macropore flow).

Atmospheric deposition to rivers and lakes

Deposition is specified in AtmdepData.txt for each subbasin, as load and/or as concentration for wet deposition. It can be specified for different vegetation types or land uses, and thus water surfaces may have a different deposition than land surfaces. In addition monthly deposition can be specified.

For both nitrogen and phosphorus wet deposition is added through the concentration of precipitation (as described above), while for dry deposition an amount of the nutrient is added to the river (if it has a class-area) or lake water.

Section Parameter/Data File
Wet depositioncpT1, cpIN, cpSPXobs.txt
XX_WD, XX_WD_Ln, XX_WD_Vn (XX is substance, n is index of landuse or vegetation type)AtmdepData.txt
aloadconstpar.txt
Atmospheric deposition to the soilXX_DD, XX_DD_Ln, XX_DD_Vn, XX_DD_Mn_Vn (XX is substance, n is index of landuse, vegetation type, or month)AtmdepData.txt
ponatmpar.txt
Atmospheric deposition to rivers and lakesXX_DD, XX_DD_Ln, XX_DD_Vn, XX_DD_Mn_Vn (XX is substance, n is index of landuse, vegetation type, or month)AtmdepData.txt
Modules (file) Procedures
npc_soil_processes (npc_soil_proc.f90)add_dry_deposition_to_landclass
atmdep_in_loss
atmospheric_processes (atm_proc.f90)set_class_precipitation_concentration_and_load
set_T2_concentration_in_precipitation_on_water
npc_surfacewater_processes (npc_sw_proc.f90)add_deposition_to_river_as_load
add_deposition_to_lake_as_load
start/hype_model_description/processes_above_ground.txt · Last modified: 2024/02/21 08:54 by cpers