UAF: Urban adjustment factor (UAF)

In UKFE: UK Flood Estimation

Urban adjustment factor (UAF)

Description

UAF from catchment descriptors for QMED estimation in ungauged urban catchments

Usage

UAF(CDs = NULL, URBEXT, BFIHOST, IF = 0.3, PRimp = 70)

Arguments

CDs	catchment descriptors derived from either GetCDs or CDsXML
URBEXT	quantification of catchment urbanisation and suburbanisation (URBEXT2015) - used when CDs is NULL.
BFIHOST	baseflow index as a function of hydrological soil type of the catchment (BFIHOST19scaled) - used when CDs is NULL)
IF	Impervious factor. The default is 0.3
PRimp	The assumed percentage runoff for impermeable areas. The default is 70 percent.

Details

The urban adjustment factor is to adjust the rural QMED estimates (as estimated using the QMED function) to urban estimates. This is necessary because the QMED equation is calibrated on rural catchments. The assumption is that the magnitude of QMED is impacted by urbanisation and that this impact can be modelled as a function of the catchment descriptors URBEXT and BFIHOST. This UAF function is based on URBEXT2015 and BFIHOST19scaled.

Value

The urban adjustment factor

Author(s)

Anthony Hammond

Examples

# Get some catchment descriptors for an urban catchment and calculate the UAF
cds_53006 <- GetCDs(53006)
UAF(cds_53006)

# Calculate UAF using a user input URBEXT2015 and BFIHOST19scaled
UAF(URBEXT = 0.1138, BFIHOST = 0.3620)

UKFE documentation built on Nov. 5, 2025, 6:25 p.m.