starttime from forcing.nc and fews_run

Change `starttime` from forcing.nc: first timestep in forcing.nc minus 1 model timestep, so the first forcing timestep is included in the Wflow run. For a  `fews_run` the `starttime` is equal to the first forcing timestep (first forcing timestep is excluded).

Author: vers-w

docs/src/user_guide/additional_options.md

@@ -267,8 +267,10 @@ specified in the main section of the TOML configuration file:
 fews_run = true  # optional, default value is false
 ```
 
-This ensures that a different format for the log file is used such that each log message
-takes up only one line. That meets the [General Adapter
+This ensures that Wflow offsets the time handling, to meet the expectations of Delft-FEWS.
+
+It also uses a different format for the log file such that each log message takes up only
+one line. That meets the [General Adapter
 logFile](https://publicwiki.deltares.nl/display/FEWSDOC/05+General+Adapter+Module#id-05GeneralAdapterModule-logFile)
 expectations, which then can get parsed with these Delft-FEWS log parsing settings:
 

src/Wflow.jl

@@ -58,7 +58,7 @@ function Clock(config, reader)
     # and add them to the config
     starttime = get(config, "starttime", nothing)
     if starttime === nothing
-        starttime = first(nctimes)
+        starttime = first(nctimes) - Δt
         config.starttime = starttime
     end
     endtime = get(config, "endtime", nothing)
@@ -68,6 +68,10 @@ function Clock(config, reader)
     end
 
     calendar = get(config, "calendar", "standard")::String
+    fews_run = get(config, "fews_run", false)::Bool
+    if fews_run
+        config.starttime = starttime + Δt
+    end
     starttime = cftime(config.starttime, calendar)
 
     Clock(starttime, 0, Δt)

test/io.jl

@@ -71,11 +71,11 @@ end
     pop!(Dict(config), "timestepsecs")
     clock = Wflow.Clock(config, reader)
 
-    @test clock.time == DateTimeProlepticGregorian(2000, 1, 2)
+    @test clock.time == DateTimeProlepticGregorian(2000, 1, 1)
     @test clock.iteration == 0
     @test clock.Δt == Second(Day(1))
     # test that the missing keys have been added to the config
-    @test config.starttime == DateTime(2000, 1, 2)
+    @test config.starttime == DateTime(2000, 1, 1)
     @test config.endtime == DateTime(2001, 1, 1)
     @test config.timestepsecs == 86400
 

test/run.jl

@@ -46,6 +46,24 @@ config.output.path =
 model = Wflow.initialize_sbm_model(config)
 Wflow.run(model)
 
+
+# second half of January, warm start, fews_run set to true, and starttime set one day earlier
+# to match endtime of part 1
+config.starttime = DateTime("2000-01-14T00:00:00")
+config.endtime = DateTime("2000-02-01T00:00:00")
+config.model.reinit = false  # warm start
+config.fews_run = true
+config.state.path_input =
+    joinpath(dirname(tomlpath), "data/state-test/outstates-moselle-january-1of2.nc")
+config.state.path_output = joinpath(
+    dirname(tomlpath),
+    "data/state-test/outstates-moselle-january-2of2-fews_run.nc",
+)
+config.output.path =
+    joinpath(dirname(tomlpath), "data/state-test/output-moselle-january-2of2-fews_run.nc")
+model = Wflow.initialize_sbm_model(config)
+Wflow.run(model)
+
 # verify that there are minimal differences in the end state of the two runs
 endstate_one_run_path =
     joinpath(dirname(tomlpath), "data/state-test/outstates-moselle-january.nc")
@@ -64,3 +82,22 @@ varnames = setdiff(keys(endstate_restart), keys(endstate_restart.dim))
         @test maxdiff < 1e-9
     end
 end
+
+# the fews_run restart should match the other restart exactly
+endstate_fewsrun_path = joinpath(
+    dirname(tomlpath),
+    "data/state-test/outstates-moselle-january-2of2-fews_run.nc",
+)
+endstate_restart_path =
+    joinpath(dirname(tomlpath), "data/state-test/outstates-moselle-january-2of2.nc")
+endstate_fewsrun = NCDataset(endstate_fewsrun_path)
+endstate_restart = NCDataset(endstate_restart_path)
+
+varnames = setdiff(keys(endstate_restart), keys(endstate_restart.dim))
+@testset "fews_run" begin
+    for varname in varnames
+        a = endstate_fewsrun[varname][:]
+        b = endstate_restart[varname][:]
+        @test all(skipmissing(a) .== skipmissing(b))
+    end
+end