mixr {transfR}

Transfer of net rainfall to ungauged catchments

Description

Combine the net rainfall of gauged catchments to simulate the net rainfall of an ungauged catchment.

Usage

mixr(
  obs,
  sim,
  mdist,
  distance = "rghosh",
  gres = 5,
  weightO = 0.8,
  weightC = 0.2,
  parallel = FALSE,
  cores = NULL,
  power = 1,
  ndonors = 5,
  donors = NULL,
  maxdist = 50000,
  flexible_donor = TRUE,
  cv = FALSE,
  save_donor = FALSE,
  verbose = TRUE
)

Arguments

obs

"transfR" object of the gauged catchments

sim

"transfR" object of the ungauged catchments

mdist

the distance matrix between gauged and ungauged catchments as computed by the function hdist

distance

the method to use for computing distance matrix if mdist is not provided. Possible values are "ghosh", "rghosh", "points", "centroids", "combined" as available in the function hdist

gres

resolution of spatial discretisation (number of points by km²) for Ghosh distance (see the function hdist)

weightO

weight given to the distance between outlets if distance is "combined" (see the function hdist)

weightC

weight given to the distance between centroids if distance is "combined" (see the function hdist)

parallel

logical indicating if the computation should be parallelised

cores

the number of cores to use for parallel execution if parallel is TRUE. If not specified, the number of cores is set to the value of parallel::detectCores()

power

exponent applied in the inverse distance weighting strategy as defined by the function weightr

ndonors

maximum number of catchments to be used to simulate discharge of an ungauged catchment as defined by the function weightr

donors

vector of catchments id from which donors are selected. If empty, the ndonors closest catchments are used

maxdist

maximum distance between a gauged and an ungauged catchment to allow the net rainfall to be transfered. This threshold is applied on the mdist distance matrix. If no units is provided, maxdist is assumed to be in [m].

flexible_donor

boolean indicating if the donor catchments can change during the simulation period according to the availability of discharge observations. See weightr for more details

cv

boolean indicating if cross validation evaluation should be done. If true, it will estimate the net rainfall of every gauged catchments (obs) as if they were ungauged (leave-one-out evaluation)

save_donor

boolean indicating if the net rainfall of each of the ndonors catchments should be stored in the sim object for further analysis. If true, it is adding three new space-time attributes in the sim object called "RnDonor", "Idonor" and "Wdonor" describing the net rainfall, the id and the weight of the donor catchments respectively

verbose

boolean indicating if information messages should be written to the console

Details

This function is a wrapper function for hdist and weightr to directly estimate the net rainfall on a set of ungauged catchments (sim) from a set of gauged catchments (obs). It returns the simulated net rainfall as a new space-time attribute in the sim object called "RnSim". The simulated net rainfall of a given ungauged catchment i is a weighted average of the net rainfalls of ndonors gauged catchments j:

R_n^i =\Sigma_{j=1}^{ndonors} R_n^j \cdot \lambda_j

where \lambda_j are defined by an inverse distance weighting function (see weightr).

Value

The sim object incremented by the new computed attributes.

See Also

hdist, weightr

Examples

data(Oudon)
object <- as_transfr(st = Oudon$obs, hl = Oudon$hl)
object <- velocity(object)
object <- uh(object)
object <- lagtime(object)
object <- rapriori(object)
object <- inversion(object, parallel = TRUE, cores = 2)
mdist  <- hdist(x = object, y = object, method = "rghosh")
object <- mixr(obs = object, mdist = mdist, parallel = TRUE, cores=2,
cv = TRUE, flexible_donor = TRUE, save_donor = FALSE)
object <- convolution(object, save_donor = FALSE)
plot(object, i = 1, attribute = c("Qobs", "Qsim"))