In inrae/airGRiwrm: 'airGR' Integrated Water Resource Management

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.width = 6,
  fig.asp = 0.68,
  out.width = "70%",
  fig.align = "center"
)

library(airGRiwrm)

An Ungauged station is a virtual hydrometric station where no observed flows are available for calibration.

Why modeling Ungauged station in a semi-distributed model?

Ungauged nodes in a semi-distributed model can be used to reach two different goals:

• increase spatial resolution of the rain fall to improve streamflow simulation [@lobligeoisWhenDoesHigher2014].
• simulate streamflows in location of interest for management purpose

This vignette introduces the implementation in airGRiwrm of the method developed by @lobligeoisMieuxConnaitreDistribution2014 for calibrating Ungauged nodes in a semi-distributed model.

Presentation of the study case

Using the study case of the vignette #1 and #2, we consider this time that nodes 54001 and 54029 are Ungauged. We simulate the streamflow at these locations by sharing hydrological parameters of the gauged node 54032.

plot.mermaid("
graph LR
id95[54095]
id01[54001]
id29[54029]

id95 -->| 42 km| id01

subgraph Shared parameters from node 54032
id01 -->| 45 km| 54032
id29 -->| 32 km| 54032
end

54032 -->| 15 km| 54057
54002 -->| 43 km| 54057

classDef UpUng fill:#eef
classDef UpGau fill:#aaf
classDef IntUng fill:#efe
classDef IntGau fill:#afa
classDef DirInj fill:#faa

class id29 UpUng
class 54057,54032 IntGau
class id01 IntUng
class id95,54002 UpGau
")

Hydrological parameters at the ungauged nodes will be the same as the one at the gauged node 54032 except for the unit hydrograph parameter which depend on the area of the sub-basin. @lobligeoisMieuxConnaitreDistribution2014 provides the following conversion formula for this parameter:

$$ x_{4i} = \left( \dfrac{S_i}{S_{BV}} \right) ^ {0.3} X_4 $$ With $X_4$ the unit hydrograph parameter for the entire basin at 54032 which as an area of $S_{BV}$; $S_i$ the area and $x_{4i}$ the parameter for the sub-basin $i$.

Using Ungauged stations in the airGRiwrm model

Ungauged stations are specified by using the model "Ungauged" in the model column provided in the CreateGRiwrm function:

data(Severn)
nodes <- Severn$BasinsInfo[, c("gauge_id", "downstream_id", "distance_downstream", "area")]
nodes$model <- "RunModel_GR4J"
nodes$model[nodes$gauge_id %in% c("54029", "54001")] <- "Ungauged"
griwrmV05 <- CreateGRiwrm(
  nodes,
  list(id = "gauge_id", down = "downstream_id", length = "distance_downstream")
)
griwrmV05

It should be noted that the GRiwrm object includes a column which automatically define the first gauged station at downstream for each Ungauged node. It is also possible to manually define the donor node of an Ungauged node, which may be upstream or in a parallel sub-basin. Type ?CreateGRiwrm for more details.

On the following network scheme, the Ungauged nodes are clearer than gauged ones with the same color (blue for upstream nodes and green for intermediate and downstream nodes)

plot(griwrmV05)

Generation of the GRiwrmInputsModel object

The formatting of the input data is described in the vignette "V01_Structure_SD_model". The following code chunk resumes this formatting procedure:

BasinsObs <- Severn$BasinsObs
DatesR <- BasinsObs[[1]]$DatesR
PrecipTot <- cbind(sapply(BasinsObs, function(x) {x$precipitation}))
PotEvapTot <- cbind(sapply(BasinsObs, function(x) {x$peti}))
Precip <- ConvertMeteoSD(griwrmV05, PrecipTot)
PotEvap <- ConvertMeteoSD(griwrmV05, PotEvapTot)

Then, the GRiwrmInputsModel object can be generated taking into account the new GRiwrm object:

IM_U <- CreateInputsModel(griwrmV05, DatesR, Precip, PotEvap)

Calibration of the model integrating ungauged nodes

Calibration options is detailed in vignette "V02_Calibration_SD_model". We also apply a parameter regularization here but only where an upstream simulated catchment is available.

The following code chunk resumes this procedure:

IndPeriod_Run <- seq(
  which(DatesR == (DatesR[1] + 365*24*60*60)), # Set aside warm-up period
  length(DatesR) # Until the end of the time series
)
IndPeriod_WarmUp = seq(1,IndPeriod_Run[1]-1)
RunOptions <- CreateRunOptions(IM_U,
                               IndPeriod_WarmUp = IndPeriod_WarmUp,
                               IndPeriod_Run = IndPeriod_Run)
Qobs <- cbind(sapply(BasinsObs, function(x) {x$discharge_spec}))
InputsCrit <- CreateInputsCrit(IM_U,
                               FUN_CRIT = ErrorCrit_KGE2,
                               RunOptions = RunOptions, Obs = Qobs[IndPeriod_Run,],
                               AprioriIds = c("54057" = "54032", "54032" = "54095"),
                               transfo = "sqrt", k = 0.15
)
CalibOptions <- CreateCalibOptions(IM_U)

The airGR calibration process is applied on each hydrological node of the GRiwrm network from upstream nodes to downstream nodes but this time the calibration of the sub-basin 54032 invokes a semi-distributed model composed of the nodes 54029, 54001 and 54032 sharing the same parameters.

OC_U <- suppressWarnings(
  Calibration(IM_U, RunOptions, InputsCrit, CalibOptions))

Hydrological parameters for sub-basins

Run the model with the optimized model parameters

The hydrological model uses parameters inherited from the calibration of the gauged sub-basin 54032 for the Ungauged nodes 54001 and 54029:

ParamV05 <- sapply(griwrmV05$id, function(x) {OC_U[[x]]$Param})
dfParam <- do.call(
  rbind,
  lapply(ParamV05, function(x)
    if (length(x)==4) {return(c(NA, x))} else return(x))
)
colnames(dfParam) <- c("velocity", paste0("X", 1:4))
knitr::kable(round(dfParam, 3))

We can run the model with these calibrated parameters:

OutputsModels <- RunModel(
  IM_U,
  RunOptions = RunOptions,
  Param = ParamV05
)

and plot the comparison of the modeled and the observed flows including the so-called Ungauged stations :

plot(OutputsModels, Qobs = Qobs[IndPeriod_Run,], which = c("Regime", "CumFreq"))

References

inrae/airGRiwrm documentation built on Sept. 27, 2024, 6:08 p.m.