SPEI
SPEI: A Python package for calculating and visualizing drought indices - Published in JOSS (2025)
Science Score: 98.0%
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✓DOI references
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Published in Journal of Open Source Software
Keywords
Scientific Fields
Repository
A Python package for calculating and visualizing drought indices such as the SPI, SPEI and SGI.
Basic Info
- Host: GitHub
- Owner: martinvonk
- License: mit
- Language: Python
- Default Branch: main
- Homepage: https://martinvonk.github.io/SPEI/
- Size: 46.1 MB
Statistics
- Stars: 95
- Watchers: 2
- Forks: 12
- Open Issues: 3
- Releases: 27
Topics
Metadata Files
README.md
SPEI
SPEI is a simple Python package to calculate drought indices for hydrological time series. This package uses popular Python packages such as Pandas and Scipy to make it easy and versatile for the user to calculate the drought indices. Pandas Series are great for dealing with time series; providing interpolation, rolling average, and other manipulation options. SciPy enables us to use all different kinds of distributions to fit the data. Different popular drought indices are supported such as the SPI (Standardized Precipitation Index), SPEI (Standardized Precipitation Evaporation Index), and SGI (Standardized Groundwater Index).
If you happen to use this package, please cite: Vonk, M. A. (2024). SPEI: A simple Python package to calculate and visualize drought indices (vX.X.X). Zenodo. https://doi.org/10.5281/zenodo.10816741.
Available Drought Indices
| Drought Index | Abbreviation | Literature | | --------------------------------------------- | ------------ | ---------- | | Standardized Precipitation Index | SPI | 1 | | Standardized Precipitation Evaporation Index* | SPEI | 2 | | Standardized Groundwater Index | SGI | 3,4 | | Standardized Streamflow Index | SSFI | 5,6 | | Standardized Soil Moisture Index | SSMI | 7 |
The package is not limited to only these five drought indices. If any of the distributions in the Scipy library is valid on the observed hydrological series, the drought index can be calculated.
*For the calculation of potential evaporation, take a look at pyet. This is another great package that also uses pandas Series to calculate different kinds of potential evaporation time series.
Installation
To get the latest stable version install using:
pip install spei
To get the development version download or clone the GitHub repository to your local device. Install using:
pip install -e <download_directory>
Literature
This list of scientific literature is helpful as a reference to understand the context and application of drought indices.
- Lloyd-Hughes, B. and M.A. Saunders (2002) - A Drought Climatology for Europe. DOI: 10.1002/joc.846
- Vicente-Serrano, S.M., S. Beguería and J.I. López-Moreno (2010) - A Multi-scalar drought index sensitive to global warming: The Standardized Precipitation Evapotranspiration Index. DOI: 10.1175/2009JCLI2909.1
- Bloomfield, J.P. and B.P. Marchant (2013) - Analysis of groundwater drought building on the standardised precipitation index approach. DOI: 10.5194/hess-17-4769-2013
- Babre, A., A. Kalvāns, Z. Avotniece, I. Retiķe, J. Bikše, K.P.M. Jemeljanova, A. Zelenkevičs and A. Dēliņa (2022) - The use of predefined drought indices for the assessment of groundwater drought episodes in the Baltic States over the period 1989–2018. DOI: 10.1016/j.ejrh.2022.101049
- Vicente-Serrano, S. M., J. I. López-Moreno, S. Beguería, J. Lorenzo-Lacruz, C. Azorin-Molina, and E. Morán-Tejeda (2012). Accurate Computation of a Streamflow Drought Index. Journal of Hydrologic Engineering. American Society of Civil Engineers. DOI: 10.1061/(asce)he.1943-5584.0000433
- Tijdeman, E., K. Stahl and L.M. Tallaksen (2020) - Drought characteristics derived based on the Standardized Streamflow Index: A large sample comparison for parametric and nonparametric methods. DOI: 10.1029/2019WR026315
- Carrão. H., Russo, S., Sepulcre-Canto, G., Barbosa, P.: An empirical standardized soil moisture index for agricultural drought assessment from remotely sensed data. DOI: 10.1016/j.jag.2015.06.011s
Publications
These are scientific publications that use and cite this Python package via Zenodo:
van Mourik, J., Ruijsch, D., van der Wiel, K., Hazeleger, W., & Wanders, N. (2025). Regional drivers and characteristics of multi-year droughts. Weather and Climate Extremes, 48, 100748. https://doi.org/10.1016/j.wace.2025.100748
Segura-Barrero, R., Lauvaux, T., Lian, J., Ciais, P., Badia, A., Ventura, S., Bazzi, H., Abbessi, E., Fu, Z., Xiao, J., Li, X., & Villalba, G. (2025). Heat and Drought Events Alter Biogenic Capacity to Balance CO2 Budget in South-Western Europe. Global biogeochemical cycles, 39(1), e2024GB008163. https://doi.org/10.1029/2024GB008163
Adla, S., Šaponjić, A., Tyagi, A., Nagi, A., Pastore, P., & Pande, S. (2024). Steering agricultural interventions towards sustained irrigation adoption by farmers: socio-psychological analysis of irrigation practices in Maharashtra, India. Hydrological Sciences Journal, 69(12), 1586–1603. https://doi.org/10.1080/02626667.2024.2376709
Panigrahi, S., Vidyarthi, V.K. (2025). Assessing the Suitability of SPI and SPEI in Steppe Hot and Arid Climatic Zones in India. In: Sefelnasr, A., Sherif, M., Singh, V.P. (eds) Water Resources Management and Sustainability. Water Science and Technology Library, vol 114. Springer, Cham. https://doi.org/10.1007/978-3-031-80520-2_12
Owner
- Name: Martin Vonk
- Login: martinvonk
- Kind: user
- Location: Netherlands
- Company: @tudelft, @ArtesiaWater
- Repositories: 7
- Profile: https://github.com/martinvonk
JOSS Publication
SPEI: A Python package for calculating and visualizing drought indices
Authors
Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, South Holland, The Netherlands, Artesia B.V., Schoonhoven, South Holland, The Netherlands
Editor
Mengqi Zhao
Tags
hydrology drought time seriesCitation (CITATION.cff)
cff-version: "1.2.0"
authors:
- family-names: Vonk
given-names: M. A.
orcid: "https://orcid.org/0009-0007-3528-2991"
doi: 10.5281/zenodo.16441123
message: If you use this software, please cite our article in the
Journal of Open Source Software.
preferred-citation:
authors:
- family-names: Vonk
given-names: M. A.
orcid: "https://orcid.org/0009-0007-3528-2991"
date-published: 2025-07-29
doi: 10.21105/joss.08454
issn: 2475-9066
issue: 111
journal: Journal of Open Source Software
publisher:
name: Open Journals
start: 8454
title: "SPEI: A Python package for calculating and visualizing drought
indices"
type: article
url: "https://joss.theoj.org/papers/10.21105/joss.08454"
volume: 10
title: "SPEI: A Python package for calculating and visualizing drought
indices"
GitHub Events
Total
- Create event: 12
- Release event: 4
- Issues event: 25
- Watch event: 19
- Delete event: 6
- Issue comment event: 19
- Push event: 222
- Pull request review comment event: 9
- Pull request review event: 6
- Pull request event: 21
- Fork event: 6
Last Year
- Create event: 12
- Release event: 4
- Issues event: 25
- Watch event: 19
- Delete event: 6
- Issue comment event: 19
- Push event: 222
- Pull request review comment event: 9
- Pull request review event: 6
- Pull request event: 21
- Fork event: 6
Issues and Pull Requests
Last synced: 4 months ago
All Time
- Total issues: 25
- Total pull requests: 59
- Average time to close issues: 17 days
- Average time to close pull requests: about 9 hours
- Total issue authors: 15
- Total pull request authors: 1
- Average comments per issue: 1.28
- Average comments per pull request: 0.05
- Merged pull requests: 56
- Bot issues: 0
- Bot pull requests: 0
Past Year
- Issues: 16
- Pull requests: 22
- Average time to close issues: 21 days
- Average time to close pull requests: about 11 hours
- Issue authors: 8
- Pull request authors: 1
- Average comments per issue: 1.06
- Average comments per pull request: 0.0
- Merged pull requests: 19
- Bot issues: 0
- Bot pull requests: 0
Top Authors
Issue Authors
- martinvonk (10)
- filipematos95 (2)
- cherryleh (1)
- luizfiscina (1)
- Appleweier (1)
- 1JunGu (1)
- simoonoses1 (1)
- xiaoqi1010 (1)
- Mahsabzg (1)
- shirazi25 (1)
- agnespeltan (1)
- mengqi-z (1)
- mahronid (1)
- juliammassing (1)
- njdepsky (1)
Pull Request Authors
- martinvonk (59)
Top Labels
Issue Labels
Pull Request Labels
Packages
- Total packages: 1
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Total downloads:
- pypi 902 last-month
- Total dependent packages: 0
- Total dependent repositories: 1
- Total versions: 25
- Total maintainers: 1
pypi.org: spei
A simple Python package to calculate drought indices for time series such as the SPI, SPEI and SGI.
- Documentation: https://spei.readthedocs.io/
- License: MIT License Copyright (c) 2022 Martin Vonk Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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Latest release: 0.8.0
published 5 months ago
Rankings
Maintainers (1)
Dependencies
- actions/checkout v3 composite
- actions/setup-python v4 composite
- actions/checkout v3 composite
- actions/setup-python v4 composite
- matplotlib *
- numpy *
- pandas *
- scipy *
- toshimaru/auto-author-assign v1.6.2 composite