lambda {hydromad} | R Documentation |
Lambda unit hydrograph. Transfer function with two exponential components and variable partitioning.
lambda.sim(U, delay = 0, tau_s = 0, tau_q = 0, lambda = 0, v_s = 1, loss = 0, Xs_0 = 0, Xq_0 = 0, return_components = FALSE, na.action = na.pass, epsilon = hydromad.getOption("sim.epsilon"))
U |
input time series. |
delay |
lag (dead time) between input and response, in time steps. |
tau_s, tau_q |
time constants for the exponential components. |
lambda |
variable partitioning parameter, see Details. |
v_s |
maximum fractional volume for the slower exponential component. |
loss |
a constant loss (or gain) term subtracted from the slow
( |
Xs_0, Xq_0 |
initial values of the exponential components. |
return_components |
whether to return all component time series. |
na.action |
function to remove missing values,
e.g. |
epsilon |
values smaller than this will be set to zero. |
The lambda unit hydrograph model is a variant of the
second-order expuh
model, i.e. two exponentially
receding stores in parallel. The lambda form allows the
partitioning of flow between quick and slow components to depend on
the magnitude of effective rainfall. In this model, runoff from large
rainfall events tends to be quick flow, and runoff from small events
tends to be slow flow.
v_s[t] = v_{s,0} U[t] ^ λ
v_q[t] = 1 - v_s[t]
where U is the input (effective rainfall); v_{s,0} is the
maximum fractional volume of the slow flow component, and is given by
the v_s
argument.
The λ parameter (lambda
argument) must be between 0
and -1; the case lambda = 0
corresponds to the basic
expuh
model.
the model output as a ts
object,
with the same dimensions and time window as the input U
.
If return_components = TRUE
, it will have multiple
columns named Xs
and Xq
.
Felix Andrews felix@nfrac.org
...
expuh
,
lambda.inverse.sim