Scale Hydrograph

Scales inflow hydrograph given a sampled inflow volume from the volume-frequency curve. Scale factor is defined by the sampled inflow volume and the maximum volume of the corresponding duration. If the native hydrograph timestep differs from the target routing timestep, resampling is applied prior to scaling: finer-to-coarser uses block averaging; coarser-to-finer uses linear interpolation.

Usage

scale_hydrograph(
  hydrograph_shape,
  observed_volume,
  sampled_volume,
  routing_dt = 1
)

Arguments

hydrograph_shape

Data frame with two columns: time (hours) and inflow (cfs). Must be in that order.

observed_volume

Maximum n-day inflow volume from input hydrograph shape.

sampled_volume

Sampled inflow volume from volume-frequency curve.

routing_dt

Target routing timestep in hours. Supported values are 0.25 (15-min), 1 (1-hour, default), 6 (6-hour), and 24 (24-hour).

Value

A data frame with two columns: time_hrs and inflow_cfs, at the target routing timestep, with time starting at hour 0.

Examples

# Example hydrograph. Requires pre-processing
hydro_example <- hydrograph_setup(jmd_hydro_jun1965_15min, critical_duration = 2, routing_days = 10)
hydrograph_shape <- hydro_example[[1]][, 2:3]

# Default 1-hour routing timestep
scaled <- scale_hydrograph(hydrograph_shape,
                           observed_volume = 50000,
                           sampled_volume = 55000)

# 15-min input hydrograph, 1-hour routing timestep
scaled <- scale_hydrograph(hydrograph_shape,
                           observed_volume = 50000,
                           sampled_volume = 55000,
                           routing_dt = 1)