Hydrological signature indicators by e-larose · Pull Request #2267 · Ouranosinc/xclim

e-larose · 2025-11-03T23:29:11Z

Pull Request Checklist:

This PR addresses an already opened issue (for bug fixes / features)
- This PR fixes Hydrological signature Indicators #2266
Tests for the changes have been added (for bug fixes / features)
- (If applicable) Documentation has been added / updated (for bug fixes / features)
CHANGELOG.rst has been updated (with summary of main changes)
- Link to issue (:issue:number) and pull request (:pull:number) has been added

What kind of change does this PR introduce?

Adds Hydrological signature indicator wrapper

Does this PR introduce a breaking change?

Other information:

for more information, see https://pre-commit.ci

…cator # Conflicts: # src/xclim/indicators/land/_streamflow.py

aulemahal

Sorry if I'm late and opiniated...

aulemahal · 2025-12-04T21:41:01Z

To remove before merging!

aulemahal · 2025-12-04T21:42:25Z

+  abstract = {The duration of the seasonal snowpack determines numerous aspects of the
+    water cycle, ecology and the economy in cold and mountainous regions, and is a balance
+    between the magnitude of accumulated snow and the rate of melt. The contribution of
+    each component has not been well quantified under contrasting topography and
+    climatological conditions although this may provide useful insights into how snow cover
+    duration could respond to climate change. Here, we examined the contribution of the
+    annual peak snow water equivalent (SWE) and the seasonal melt rate to define the
+    duration of the snowpack over temperate mountains, using snow data for mountain areas
+    with different climatological characteristics across the Iberian Peninsula. We used a
+    daily snowpack database for the period 1980--2014 over Iberia to derive the seasonal
+    peak SWE, melt rate and season snow cover duration. The influence of peak SWE and melt
+    rates on seasonal snow cover duration was estimated using a stepwise linear model
+    approach. The stepwise linear models showed high R-adjusted values (average R-adjusted
+    = 0.7), without any clear dependence on the elevation or geographical location. In
+    general, the peak SWE influenced the snow cover duration over all of the mountain areas
+    analysed to a greater extent than the melt rates (89.1\%, 89.2\%, 81.6\%, 93.2\% and
+    95.5\% in the areas for the Cantabrian, Central, Iberian, Pyrenees and Sierra Nevada
+    mountain ranges, respectively). At these colder sites, the melt season occurs mostly in
+    the spring and tends to occur very fast. In contrast, the areas where the melt rates
+    dominated snow cover duration were located systematically at lower elevations, due to
+    the high interannual variability in the occurrence of annual peak SWE (in winter or
+    early spring), yielding highly variable melt rates. However, in colder sites the melt
+    season occurs mostly in spring and it is very fast in most of the years. The results
+    highlight the control that the seasonal precipitation patterns, in combination with
+    temperature, exert on the seasonal snow cover duration by influencing the peak SWE and
+    suggest a future increased importance of melt rates as temperatures increase. Despite
+    the high climatological variability of the Iberian mountain ranges, the results showed
+    a consistent behaviour along the different mountain ranges, indicating that the methods
+    and results may be transferrable to other temperate mountain areas of the world.}


Do we need the full abstract here ? For a smaller file and for coherence with the other entires, I think we could remove the abstracts here.

aulemahal · 2025-12-04T21:45:13Z

+days_with_snowpack = Snow(
+    title="Days with snowpack",
+    identifier="days_with_snowpack",
+    units="days",
+    long_name="Days with snowpack",
+    description="The total number of days with snow water equivalent (SWE) above a given threshold.",
+    compute=xci.days_with_snowpack,
+)


This already exists as snw_days_above, no ?

aulemahal · 2025-12-04T22:19:45Z

+@declare_units(swe="[length]", thresh="[length]")
+def days_with_snowpack(
+    swe: xarray.DataArray,


Ah I see the nuance now. I would argue that swe is exactly the same as snw and the difference in variable doesn't justify a new indicator. Also, snw is the CMIP name, which is why we chose it in xclim.

This makes me think of a PR I co-authored with Ludwig, I could dig this up.

There is the special field [precipitation], which can do automatic conversions. Having this with snw -> swe would be dangerous. What you say is that user should do all their work in snw, then convert to swe at the end, correct? snw_to_snd functions already exist, it would be easy to add a new converter with the correct density to have snw_to_swe

In the context of xclim, what I think is that we should try to limit the number of non-conventional variables to a minimum. swe is so close to snw that I don't think it warrants a special treatment.

Also, days_with_snowpack and snw_days_above are two very different names for the same thing. The {var}_days_above construct being the choice made by xclim for clear and systematic naming, unless days_with_snowpack is a jargon term refering to a (domain-)specific algorithm.

Finally, if we really need to keep this indicator, I would suggest removing the compute function nonetheless and simply creating a day_with_snowpack in indicators/land/_snow.py instead.

But outside of the context of xclim, in my very personal opinion, I find talking about snow in terms of liquid water a bit weird. You don't need to melt it to study it on a computer.

I forgot about the distinction and already removed it.

aulemahal · 2025-12-04T22:20:05Z

+@declare_units(swe="[length]", q="[discharge]")
+def lag_snowpack_flow_peaks(
+    swe: xarray.DataArray,


Same. Please use snw.

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coxipi · 2026-02-05T21:12:48Z

 docs/paper/tmp_saved_input_paper.bib
+docs/tmp_saved_input_references.bib


Suggested change

docs/paper/tmp_saved_input_paper.bib

docs/tmp_saved_input_references.bib

docs/tmp_saved_input_references.bib

docs/paper/tmp_saved_input_paper.bib

revert unneeded change

coxipi · 2026-02-05T21:19:27Z

+@declare_units(swe="[length]", thresh="[length]")
+def days_with_snowpack(
+    swe: xarray.DataArray,


This makes me think of a PR I co-authored with Ludwig, I could dig this up.

There is the special field [precipitation], which can do automatic conversions. Having this with snw -> swe would be dangerous. What you say is that user should do all their work in snw, then convert to swe at the end, correct? snw_to_snd functions already exist, it would be easy to add a new converter with the correct density to have snw_to_swe

Signed-off-by: Trevor James Smith <10819524+Zeitsperre@users.noreply.github.com>

for more information, see https://pre-commit.ci

Zeitsperre · 2026-02-06T16:02:48Z

@coxipi I performed a merge of main, but I found that there were quite a few conflicts from the previous hydro indice PR (as though this branch was based off an older version before it was merged to main).

I may have totally botched the merge, so apologies.

coxipi · 2026-02-06T17:11:02Z

~~@Zeitsperre am I in charge of this PR now 😆 ?~~ oh wait, are your referring to a conflict from a change I made in another PR?

Anyways, we can discuss what to do with this in the next meeting. I'm not sure what your botched merge entails, but we'll figure something out

Zeitsperre · 2026-02-06T21:23:14Z

~~@Zeitsperre am I in charge of this PR now 😆 ?~~ oh wait, are your referring to a conflict from a change I made in another PR?

Nope, just the last merge commit I performed this morning. I have some time to see if I can clean it up before Miller Time.

Update: Managed to clean up the mess. Testing is failing as sen_slope is not a resampled indicator, but otherwise PR is looking reasonable.

Signed-off-by: Trevor James Smith <10819524+Zeitsperre@users.noreply.github.com>

…xclim into hydro_indicator

Zeitsperre · 2026-04-16T14:41:47Z

 v0.60.0 (2026-01-23)
 --------------------
-Contributors to this version: Éric Dupuis (:user:`coxipi`), Trevor James Smith (:user:`Zeitsperre`), Juliette Lavoie (:user:`juliettelavoie`), Ève Larose (:user:`e-larose`), Faisal Mahmood (:user:`faimahsho`), David Huard (:user:`huard`), Pascal Bourgault (:user:`aulemahal`).
+Contributors to this version: Éric Dupuis (:user:`coxipi`), Trevor James Smith (:user:`Zeitsperre`), Juliette Lavoie (:user:`juliettelavoie`),  Faisal Mahmood (:user:`faimahsho`), David Huard (:user:`huard`), Pascal Bourgault (:user:`aulemahal`).


Ève's other PR made it into the last version ;)

Suggested change

Contributors to this version: Éric Dupuis (:user:`coxipi`), Trevor James Smith (:user:`Zeitsperre`), Juliette Lavoie (:user:`juliettelavoie`), Faisal Mahmood (:user:`faimahsho`), David Huard (:user:`huard`), Pascal Bourgault (:user:`aulemahal`).

Contributors to this version: Éric Dupuis (:user:`coxipi`), Trevor James Smith (:user:`Zeitsperre`), Juliette Lavoie (:user:`juliettelavoie`), Ève Larose (:user:`e-larose`), Faisal Mahmood (:user:`faimahsho`), David Huard (:user:`huard`), Pascal Bourgault (:user:`aulemahal`).

Zeitsperre · 2026-04-16T14:42:48Z

Don't forget to remove the print calls!

Zeitsperre · 2026-04-16T14:43:22Z


 import numpy as np
 import pytest
+import xarray as xr


Suggested change

import xarray as xr

from xarray import DataArray

Zeitsperre · 2026-04-16T14:43:31Z

+    out = land.days_with_snowpack(swe, freq="YS")
+
+    assert out.attrs["units"] == "days"
+    assert isinstance(out, xr.DataArray)


Suggested change

assert isinstance(out, xr.DataArray)

assert isinstance(out, DataArray)

e-larose and others added 30 commits August 6, 2025 11:51

season_an_rr and tot_rr added

2b1b836

streamflow_elasticity added

6fb3968

days_with_snowpack added

dfceed1

aridity index added

5db5f85

Correction of Runoff Ratios

4a312a6

unit corrections

8a7e5af

lag_snowpack_flow_peaks added

6b01b09

SS_an_season added

5e4aac0

signature names added to list

d536cf2

grammar corrections

799f3e6

corrections added

7760834

improvements to days_with_snowpack

38bf019

TestDaysWithSnowpack added

fadca60

swe_series added

f6ff973

[pre-commit.ci] auto fixes from pre-commit.com hooks

c0588aa

for more information, see https://pre-commit.ci

Add details to AUTHORS.rst

66631a6

Add details to zenodo

64768b6

annual_maxima added

08cfcd8

area_series added

ac97278

area series added

b3a86f3

Notes and detailed def for RR

a442eb9

Notes and detailed def added for Elasticity index

a75afdf

function name clarification

067376a

ajusted from 1st PR comments

488d873

Notes added to days_with_snowpack

3b812d9

Notes added to annual_aridity_index

0b25a70

Notes added to lag_snowpack_flow_peaks

6bfb0c8

thresh correction

d2fee82

annual_maxima correction

2bb2bf1

Merge branch 'main' into HS_eve

df3bf0b

e-larose added 4 commits November 27, 2025 17:47

modifications for indicator tests

19df40c

Merge remote-tracking branch 'origin/hydro_indicator' into hydro_indi…

ae53243

…cator # Conflicts: # src/xclim/indicators/land/_streamflow.py

indicator tests added

6c58fcc

FIXME added

2adcfe5

github-actions bot added the docs Improvements to documenation label Dec 4, 2025

aulemahal reviewed Dec 4, 2025

View reviewed changes

Zeitsperre and others added 2 commits December 12, 2025 21:21

Merge branch 'main' into hydro_indicator

de87041

[pre-commit.ci] auto fixes from pre-commit.com hooks

8720153

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coxipi reviewed Feb 5, 2026

View reviewed changes

Zeitsperre and others added 2 commits February 6, 2026 16:00

Merge branch 'main' into hydro_indicator

2f595c9

Signed-off-by: Trevor James Smith <10819524+Zeitsperre@users.noreply.github.com>

[pre-commit.ci] auto fixes from pre-commit.com hooks

659b0b7

for more information, see https://pre-commit.ci

Zeitsperre added 2 commits February 6, 2026 16:56

fix bad merge

ca48a51

Signed-off-by: Trevor James Smith <10819524+Zeitsperre@users.noreply.github.com>

Merge branch 'main' into hydro_indicator

186eaec

Signed-off-by: Trevor James Smith <10819524+Zeitsperre@users.noreply.github.com>

Zeitsperre requested a review from coxipi April 14, 2026 14:30

Zeitsperre assigned Zeitsperre and coxipi and unassigned Zeitsperre Apr 14, 2026

coxipi added 8 commits April 14, 2026 10:38

clean references

1793b61

remove unecessary change

8a585a9

put back cfcheck in Streamflow

e0829ac

remove aridity index tables

074dd6e

remove table in French too

bb5889b

again, remove AI tables

51bd50e

remove days_with_snowpack (redundant, snw_days_above already exists)

599d1b9

Merge branches 'hydro_indicator' and 'main' of github.com:Ouranosinc/…

d2663e2

…xclim into hydro_indicator

Zeitsperre reviewed Apr 16, 2026

View reviewed changes

use snw, not swe

6f4f5d7

		docs/paper/tmp_saved_input_paper.bib
		docs/tmp_saved_input_references.bib

	Contributors to this version: Éric Dupuis (:user:`coxipi`), Trevor James Smith (:user:`Zeitsperre`), Juliette Lavoie (:user:`juliettelavoie`), Faisal Mahmood (:user:`faimahsho`), David Huard (:user:`huard`), Pascal Bourgault (:user:`aulemahal`).
	Contributors to this version: Éric Dupuis (:user:`coxipi`), Trevor James Smith (:user:`Zeitsperre`), Juliette Lavoie (:user:`juliettelavoie`), Ève Larose (:user:`e-larose`), Faisal Mahmood (:user:`faimahsho`), David Huard (:user:`huard`), Pascal Bourgault (:user:`aulemahal`).

	assert isinstance(out, xr.DataArray)
	assert isinstance(out, DataArray)

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e-larose commented Nov 3, 2025

Pull Request Checklist:

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Does this PR introduce a breaking change?

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