ta1.2: Function to return the TA1 and TA2 hydrologic indicator...

In jlthomps/EflowStats: Returns HIT/HAT Hydrologic Indicator stats for a given set of data

Description

This function accepts a data frame that contains a column named "discharge" and calculates TA1; Constancy. Constancy is computed via the formulation of Colwell (see example in Colwell, 1974). A matrix of values is compiled where the rows are 365 (no February 29th) days of the year and the columns are 11 flow categories. The cell values are the number of times that a flow falls into a category on each day. The categories are: log(flow) < 0.1 ? log(mean flow), 0.1 ? log(mean flow) ??? log(flow) < 0.25 ? log(mean flow) 0.25 ? log(mean flow) ??? log(flow) < 0.5 ? log(mean flow) 0.5 ? log(mean flow) ??? log(flow) < 0.75 ? log(mean flow) 0.75 ? log(mean flow) ??? log(flow) < 1.0 ? log(mean flow) 1.0 ? log(mean flow) ??? log(flow) < 1.25 ? log(mean flow) 1.25 ? log(mean flow) ???log(flow) < 1.5 ? log(mean flow) 1.5 ? log(mean flow) ??? log(flow) < 1.75 ? log(mean flow) 1.75 ? log(mean flow) ??? log(flow) < 2.0 ? log(mean flow) 2.0 ?log(mean flow) ??? log(flow) < 2.25 ? log(mean flow) log(flow) ??? 2.25 ? log(mean flow) The row totals, column totals, and grand total are computed. Using the equations for Shannon information theory parameters, constancy is computed as: 1- (uncertainty with respect to state)/log (number of state) TA2; Predictability. Predictability is computed from the same matrix as constancy (see example in Colwell, 1974). It is computed as: 1- (uncertainty with respect to interaction of time and state - uncertainty with respect to time)/log (number of state) where uncertainty with respect to state = sum((YI_sub/Z)*log10(YI_sub/Z)) where YI_sub = the non-zero sums of the 11 categories and Z = the sum total of the Colwell matrix and where uncertainty with respect to time = sum((XJ_sub/Z)*log10(XJ_sub/Z)) where XJ_sub = the non-zero sums of the 365 days and where uncertainty with respect to interaction of time and state = sum((colwell_sub/z)*log10(colwell_sub/Z)) where colwell_sub = the non-zero sums of the entire matrix and where number of state = number of categories = 11

Usage

  ta1.2(qfiletempf)

Arguments

qfiletempf

data frame containing a "discharge" column containing daily flow values

Value

ta1.2 list containing TA1 and TA2 for the given data frame

Examples

qfiletempf<-sampleData
ta1.2(qfiletempf)

jlthomps/EflowStats documentation built on May 19, 2019, 12:48 p.m.