---
title: "Time.R"
author: "Alonso Arriagadada M.  <alonso.arriagada@usach.cl>"
version: "0.1.0"
date: "2026-05-27"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Time.R}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

## Time.R
R package for estimating and compare time of concentration and lag time of watersheds

## Requirements
Dependencies:
  ggplot2, readxl, utils

## Installation
You can install the currently-released version of **Time.R** from CRAN with this R command:
```
install.packages("Time.R")
```
Alternatively, you can install the development version from GitHub with:
```
# install.packages("remotes")
remotes::install_github("Alobondo/Time.R")
library(Time.R)
```

## Usage
Functions | Description |
--- | --- |
```Time.R_calc()``` | Apply functions to estimate the time of concentration and lag times for watersheds based on their morphometric characteristics. It includes various methods for calculation and offers plotting functionalities for comparative analysis. |


```Time.R_calc()``` works with a dataframe with columns: ID, Area_km2, Slope_perc, BasinLength_km, Z_max_masl, Z_min_masl, Z_ave_masl, CurveNumber, ManningCoeff, Paved (ID character type and Paved logical type, numeric the rest). 

## Reporting bugs
If you find an error in some function, want to report a typo in the documentation or submit a recommendation, you can do it [here](https://github.com/Alobondo/Time.R/issues)

## Keywords
Hydrology, R package, Time of Concentration, Lag Time, Watersheds

## References
**Time of Concentration Methods**

-   Bransby-Williams: Bransby-Williams, G. (1922). Discussion of “Flood Discharges”. Proceedings of the ICE, London.
-   Kirpich: Kirpich, Z.P. (1940). Time of Concentration of Small Agricultural Watersheds. Civil Engineering, 10(6): 362.
-   Kerby: Kerby, W.S. (1959). Time of Concentration for Overland Flow. Civil Engineering, ASCE, 29(3): 174.
-   Johnstone-Cross: Johnstone, D., & Cross, W.P. (1949). Elements of Applied Hydrology. New York: Ronald Press.
-   California Culverts Practice: California Division of Highways (1942). Hydraulic Design of Highway Culverts. California Department of Public Works.
-   Clark: Clark, C.O. (1945). Storage and the Unit Hydrograph. Transactions of the American Geophysical Union, 20: 141–150.
-   Giandotti: Giandotti, M. (1934). Previsione delle piene e delle magre dei corsi d’acqua. Annali dei lavori pubblici, 72: 449–479.
-   Passini: Passini, F. (1972). Manual de Hidrología Aplicada. Ministerio de Obras Públicas, España.
-   Temez: Témez, J.R. (1978). Cálculo Hidrometeorológico de Caudales Máximos en Pequeñas Cuencas Naturales. Dirección General de Carreteras, Madrid.
-   Pérez: Pérez, G. (1962). Método para el cálculo del tiempo de concentración en cuencas pequeñas. Revista de Obras Públicas, España.
-   Pilgrim: Pilgrim, D.H. (1977). Isochrones of Travel Time and Distribution of Flood Storage from a Tracer Study on a Small Watershed. Water Resources Research, 13(3): 587–595.
-   USBR (U.S. Bureau of Reclamation): Bureau of Reclamation (1973). Design of Small Dams. U.S. Department of the Interior, Washington, D.C.
-   Valencia-Zuluaga: Valencia-Zuluaga, F. (1983). Método empírico para el cálculo del tiempo de concentración en cuencas colombianas. Universidad Nacional de Colombia.
-   Ventura-Heras: Ventura, J., & Heras, J. (1964). Método empírico para el cálculo del tiempo de concentración en cuencas mediterráneas. Revista de Obras Públicas, España.
-   SCS (Soil Conservation Service): SCS (1972, 1986). National Engineering Handbook, Section 4 Hydrology; and Technical Release 55: Urban Hydrology for Small Watersheds. USDA, Washington, D.C.
-   US Navy: U.S. Navy (1972). Design Manual DM-26: Runoff from Small Drainage Areas. Naval Facilities Engineering Command.
-   Federal Aviation Administration (1970). Advisory circular on airport drainage. Washington, DC: DOT.


**Lag Time Methods**

-   NERC: Natural Environment Research Council (1975). Flood Studies Report. London: NERC.
-   Mimikou: Mimikou, M. (1984). Lag Time Estimation in Greek Catchments. Journal of Hydrology, 70: 231–246.
-   Watt–Chow: Watt, W.E., & Chow, K.C.A. (1985). A General Expression for Basin Lag Time. Canadian Journal of Civil Engineering, 12(2): 294–300.
-   Haktanir–Sezen: Haktanir, T., & Sezen, N. (1990). Flood Frequency Analysis of Turkish Rivers. Hydrological Sciences Journal, 35(2): 167–178.
-   SCS Lag Equation: Mockus, V. (1957). Hydrology. In: National Engineering Handbook, Section 4 Hydrology. USDA Soil Conservation Service.

## Example
```
# Load example data
data("Example_TimeR")

# Calculate time of concentration and lag time
Time.R_calc(Example_TimeR, plot_watershed = FALSE, plot_formulas = FALSE)

# Plot results by watersheds
Time.R_calc(Example_TimeR, plot_watershed = TRUE, plot_formulas = FALSE)

# Plot results by formulas
Time.R_calc(Example_TimeR, plot_watershed = FALSE, plot_formulas = TRUE)

```
