Check for discharge unit compliance in streamflow statistical indicators

HISTORY.rst

@@ -4,6 +4,11 @@ History
 
 0.40.0 (unreleased)
 -------------------
+Contributors to this version: Trevor James Smith (:user:`Zeitsperre`)
+
+Bug fixes
+^^^^^^^^^
+* Streamflow indicators relying on indices defined in `xclim.indices.stats` were not checking input variable units. These indicators will now raise an error if input data units are not m^3/s. (:issue:`1130`, :pull:`1225`).
 
 Internal changes
 ^^^^^^^^^^^^^^^^

xclim/data/variables.yml

@@ -4,6 +4,11 @@ variables:
     cell_methods: "area: sum"
     description: Cell area (over the ocean).
     standard_name: cell_area
+  discharge:
+    canonical_units: m3 s-1
+    cell_methods: "time: mean"
+    description: The amount of water, in all phases, flowing in the river channel and flood plain.
+    standard_name: water_volume_transport_in_river_channel
   evspsblpot:
     canonical_units: kg m-2 s-1
     cell_methods: "time: mean"

xclim/indicators/land/_streamflow.py

@@ -79,7 +79,7 @@ def cfcheck(self, **das):
     "distribution.",
     abstract="Streamflow frequency analysis on the basis of a given mode and distribution.",
     units="m^3 s-1",
-    compute=declare_units(da=None)(frequency_analysis),
+    compute=declare_units(da="[discharge]")(frequency_analysis),
 )
 
 rb_flashiness_index = Streamflow(
@@ -101,7 +101,7 @@ def cfcheck(self, **das):
     long_name="Daily flow statistics",
     description="{freq} {op} of daily flow ({indexer}).",
     units="m^3 s-1",
-    compute=declare_units(da=None)(generic.select_resample_op),
+    compute=declare_units(da="[discharge]")(generic.select_resample_op),
 )
 
 fit = Fit(
@@ -113,7 +113,7 @@ def cfcheck(self, **das):
     long_name="{dist} distribution parameters",
     description="Parameters of the {dist} distribution.",
     cell_methods="time: fit",
-    compute=declare_units(da=None)(_fit),
+    compute=declare_units(da="[discharge]")(_fit),
 )
 
 
@@ -124,7 +124,7 @@ def cfcheck(self, **das):
     long_name="Day of the year of the maximum streamflow over {indexer}",
     description="Day of the year of the maximum streamflow over {indexer}.",
     units="",
-    compute=declare_units(da=None)(generic.select_resample_op),
+    compute=declare_units(da="[discharge]")(generic.select_resample_op),
     parameters=dict(op=generic.doymax),
 )
 
@@ -136,6 +136,6 @@ def cfcheck(self, **das):
     long_name="Day of the year of the minimum streamflow over {indexer}",
     description="Day of the year of the minimum streamflow over {indexer}.",
     units="",
-    compute=declare_units(da=None)(generic.select_resample_op),
+    compute=declare_units(da="[discharge]")(generic.select_resample_op),
     parameters=dict(op=generic.doymin),
 )

xclim/testing/tests/test_land.py

@@ -1,8 +1,10 @@
 from __future__ import annotations
 
 import numpy as np
+import pytest
 import xarray as xr
 
+import xclim.core.utils
 from xclim import land, set_options
 
 
@@ -55,6 +57,12 @@ def test_empty(self, ndq_series):
         )
         assert np.isnan(out.values[:, 0, 0]).all()
 
+    def test_wrong_variable(self, pr_series):
+        with pytest.raises(xclim.core.utils.ValidationError):
+            land.freq_analysis(
+                pr_series(np.random.rand(100)), mode="max", t=2, dist="gamma"
+            )
+
 
 class TestStats:
     def test_simple(self, ndq_series):