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Estimate change in flooding

Source: R/estimate_flood_delta.R
estimate_flood_delta.Rd

Interprets sequence of Water Tracker data in each unit to estimate whether the change in the extent of flooding from the previous observation represents a substantial increase or decrease.

Usage

estimate_flood_delta(df, delta = 0.2)

Arguments

df

Input tibble from estimate_flood_extent().

delta

Numeric proportion change representing significant increase or decrease in flooding.

Value

tibble with added fields: flood_delta and flood_trend

Details

For each unit, the proportion change in flooded area from the previous observation date is calculated (flood_delta) and the direction and magnitude of change is categorized (flood_trend) based on the input value for delta provided, as:

  • INCREASE: flood_delta >= delta

  • up: delta > flood_delta > 0

  • 0: flood_delta = 0

  • down: 0 > flood_delta > -delta

  • DECREASE: -delta >= flood_delta

Examples

df = format_watertracker(sampledat) |> estimate_flood_extent()
estimate_flood_delta(df)
#> # A tibble: 5,474 × 25
#>    wateryear month month_name  year obsdate    unit        WETLAND CLASS AREA_HA
#>        <dbl> <dbl> <fct>      <dbl> <date>     <chr>       <chr>   <chr>   <dbl>
#>  1      2013     5 May         2013 2013-05-11 SampleWetl… Sample… mana…    37.1
#>  2      2013     5 May         2013 2013-05-27 SampleWetl… Sample… mana…    37.1
#>  3      2013     6 Jun         2013 2013-06-12 SampleWetl… Sample… mana…    37.1
#>  4      2013     6 Jun         2013 2013-06-28 SampleWetl… Sample… mana…    37.1
#>  5      2013     7 Jul         2013 2013-07-14 SampleWetl… Sample… mana…    37.1
#>  6      2013     7 Jul         2013 2013-07-30 SampleWetl… Sample… mana…    37.1
#>  7      2013     8 Aug         2013 2013-08-10 SampleWetl… Sample… mana…    37.1
#>  8      2013     8 Aug         2013 2013-08-19 SampleWetl… Sample… mana…    37.1
#>  9      2013     8 Aug         2013 2013-08-26 SampleWetl… Sample… mana…    37.1
#> 10      2013     9 Sep         2013 2013-09-04 SampleWetl… Sample… mana…    37.1
#> # ℹ 5,464 more rows
#> # ℹ 16 more variables: AREA_AC <dbl>, Mosaic <chr>, MosaicDateStart <date>,
#> #   MosaicDateEnd <date>, ObservedPixels <dbl>, WaterPixels <dbl>,
#> #   ObservedAreaHa <dbl>, ObservedAreaWaterHa <dbl>, PercentObserved <dbl>,
#> #   PercentWater <dbl>, ObservedAreaWaterHa_pq <dbl>,
#> #   ObservedAreaWater_adjust <dbl>, flood_prop <dbl>, flood_status <chr>,
#> #   flood_delta <dbl>, flood_trend <chr>