DWBmodelUN (version 1.0.0)

DWBCalculator: DWB model function

Description

The function performs the distributed DWB hydrological model calculations in the defined domain and time period. It is a model based on the postulates of Budyko, which stated that not only does the actual evapotranspiration depend on potential evapotranspiration, but it is also constrained by water availability (Budyko, 1974). The monthly Dynamic Water Balance is underpinned in the demand and supply limits demonstrated by funFU, postulate that is applied to three variables in order to acquire the values of the fluxes and state variables on a monthly time step. The named variables affected by funFU are: the available storage capacity (X), the evapotranspiration opportunity (Y) and the actual evapotranspiration (ET). The model is controlled by four parameters: retention efficiency (\(\alpha-1\)), evapotranspiration efficiency (\(\alpha-2\)), soil water storage capacity (S_max), and a recession parameter in the groundwater storage that controls the baseflow (d).

Usage

DWBCalculator(
  p_v,
  pet_v,
  g_v,
  s_v,
  alpha1_v,
  alpha2_v,
  smax_v,
  d_v,
  calibration = FALSE
)

Arguments

p_v

matrix comprised by the precipitation records, that has as rows the number of cells that will be simulated and as columns the number of time steps to be simulated.

pet_v

matrix comprised by the potential evapotranspiration records, that has as rows the number of cells that will be simulated and as columns the number of time steps to be simulated.

g_v

vector comprised of the initial values of the groundwater storage, it must have as many values as cells defined to simulate.

s_v

vector comprised of the initial values of the soil water storage, it must have as many values as cells defined to simulate.

alpha1_v

vector comprised of the values of the retention efficiency that must be between 0 and 1, it must have as many values as cells defined to simulate.

alpha2_v

vector comprised of the values of the evapotranspiration efficiency that must be between 0 and 1, it must have as many values as cells defined to simulate.

smax_v

vector comprised of the values of the soil water storage capacity that must be above 0, it must have as many values as cells defined to simulate.

d_v

vector comprised of the values of the recession constant that must be between 0 and 1, it must have as many values as cells defined to simulate.

calibration

boolean variable which sets the printing of the waitbar that indicates the progress of the calculation of the time series results. The default value is FALSE, indicating that just one run of the model is going to be performed and there is no other waitbar such as the one used by a calibration algorithm.

Value

a list comprised by the time series of the hydrological fluxes calculated by the model. The time series have the same length as the forcings that were employed to run the model. The fluxes are:

• q_total a numeric matrix of the total runoff - units (mm/month).

• aet a numeric matrix of actual evapotranspiration - units (mm/month).

• r a numeric matrix of groundwater recharge - units (mm/month).

• qd a numeric matrix of surface runoff - units (mm/month).

• qb a numeric matrix of baseflow - units (mm/month).

• s a numeric matrix of soil water storage - units (mm).

• g a numeric matrix of groundwater storage - units (mm).

Details

DWBCalculator only performs one simulation of the distributed hydrological model. The decision to perform other kinds of procedure, such as calibration or assimilation, is entirely on modelers' requirements and necessities. A complementary function is available in the package to calibrate the model using the (dds) algorithm, which has proved to be effective in calibrating models with several GRUs.

To start the model one should set the model features using the readSetup function, load the precipitation and evapotranspiration forcings with the upForcing function, build the GRU and parameter maps with the buildGRUmaps function, compare the coordinates of the uploaded datasets with the Coord_comparison (i.e. the forcings and GRU cells), set the initial conditions of the soil moisture and the groundwater storage, and run the model with DWBCalculator function.

References

Budyko. (1974). "Climate and life". New York: Academic Press, INC.

Zhang, L., Potter, N., Hickel, K., Zhang, Y., & Shao, Q. (2008). "Water balance modeling over variable time scales based on the Budyko framework <U+2013> Model development and testing". Journal of Hydrology, 360(1-4), 117<U+2013>131.

Examples

# NOT RUN {
# Load P and PET databases
data(P_sogamoso, PET_sogamoso)
 
# Verify that the coordinates of the databases match
Coord_comparison(P_sogamoso, PET_sogamoso)
# Load geographic info of GRU and parameters per cell
data(GRU, param)
# Construction of parameter maps from values by GRU
GRU.maps <- buildGRUmaps(GRU, param)
alpha1_v <- GRU.maps$alpha1
alpha2_v <- GRU.maps$alpha2
smax_v <- GRU.maps$smax
d_v <- GRU.maps$d

# Establish the initial modeling conditions
init <- init_state(GRU.maps$smaxR)
g_v <- init$In_ground
s_v <- init$In_storage
rm(init)

# Load general characteristics of modeling
setup_data <- readSetup(Read = TRUE)
Dates <- seq(as.Date( gsub('[^0-9.]','',colnames(P_sogamoso)[3]), 
format = "%Y.%m.%d"), 
             as.Date(gsub('[^0-9.]','',tail(colnames(P_sogamoso),1)) , 
             format = "%Y.%m.%d"), by = "month")
Start.sim <- which(Dates == setup_data[8,1]); End.sim <- which(Dates == setup_data[10,1])
# Sim.Period: the 1st two columns of the P and PET are the coordinates of the cells
Sim.Period <- c(Start.sim:End.sim)+2  

# Run DWB model
DWB.sogamoso <- DWBCalculator(P_sogamoso[ ,Sim.Period], 
                    PET_sogamoso[ ,Sim.Period],
                    g_v, s_v, alpha1_v, alpha2_v, smax_v, d_v)
                    
# }