expuh3s {hydromad} | R Documentation |

A unit hydrograph with a quickflow pathway and two layered slowflow pathways modelling recharge to groundwater in order to allow modelling of long-term disconnection of slowflow stores from streamflow.

expuh3s.sim(U, delay = 0,v_s, tau_s = 0, tau_q = 0, tau_g = 0, R,G_1=0,loss,G_2, Xs_0 = 0, Xq_0 = 0, X3_0 = 0, pars = NULL, return_components = FALSE, na.action = na.pass, epsilon = hydromad.getOption("sim.epsilon"))

`U` |
input time series (units below assume ML/day) |

`delay` |
lag (dead time) between input and response, in time steps. |

`v_s` |
Fraction of effective rainfall that goes to groundwater |

`tau_q` |
Recession coefficient for quickflow (days) |

`tau_s` |
Recession coefficient for soil store (G_1) discharge (days) |

`tau_g` |
Recession coefficient for groundwater store (G_2) discharge (days) |

`R` |
Maximum recharge from G_1 to G_2 (ML/day) |

`G_1` |
storage threshold to stop recharge (ML) (less than zero) |

`loss` |
Groundwater loss (ML/day) |

`G_2` |
storage threshold to stop groundwater loss (ML) (less than zero) |

`Xs_0, Xq_0, X3_0` |
initial values of the exponential components. |

`pars` |
the parameters as a named vector. If this is given, it will over-ride the named parmameter arguments. |

`return_components` |
whether to return all component time series. |

`na.action` |
function to remove missing values,
e.g. |

`epsilon` |
values smaller than this in the output will be set to zero. |

The `expuh3s`

model consists of a single quickflow pathway
modelled as an exponential store, and a slowflow pathway comprised of
two layered stores.

Each slowflow store is modelled as a `leakyExpStore`

, which has a
loss term, has no flow when the store drops below a given level, and
can therefore model longer-term disconnection of a store from streamflow.

Adapted from Herron and Croke (2009):

The upper store, G1, receives rainfall inputs and discharges to the
stream, Qs and recharges the lower store. G1 has a lower limit of 0,
where flow ceases representing the fully 'drained' condition. Conceptually, the upper
store can be viewed as a perched water table, which develops in
response to rain and tends to be relatively short-lived, perhaps
seasonal. Thus the time constant, `tau_s`

, for discharge from the
'soil' store will be somewhere between that for quickflow,
`tau_q`

and the groundwater discharge constant, `tau_g`

.

G2 is recharged from G1 when `G1>G_1`

and discharges to the
stream `Q_g`

when `G2>0`

. The sum of `Q_s`

and
`Q_g`

represents the total slowflow pathway. We assume that all
extraction and natural groundwater losses (`loss`

) are from
G2. The approach avoids the need to specify a maximum capacity for
either storage, but the introduction of a recharge term, `R`

between the stores adds a new parameter.

Recharge is represented by a constant rate `R`

which ceases
when `G1<G_1`

, diminishing linearly to that point when
`thres<G1<thres+loss`

. Setting `G_1=0`

(the default) ceases recharge when flow ceases.

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`

, `Xq`

and `Xg`

.

Joseph Guillaume joseph.guillaume@anu.edu.au

Herron, N.F. and B.F.W. Croke (2009). IHACRES-3S - A 3-store formulation for modelling
groundwater-surface water interactions. In Anderssen, R.S., R.D. Braddock and L.T.H. Newham (eds) *18th World IMACS Congress and MODSIM09 International Congress on Modelling and Simulation.* Modelling and Simulation Society of Australia and New Zealand and International Association for Mathematics and Computers in Simulation, July 2009, pp. 3081-3087. ISBN: 978-0-9758400-7-8. http://www.mssanz.org.au/modsim09/I1/herron.pdf

[Package *hydromad* version 0.9-18 Index]