Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar)

Tinahindraza Mampionona Albertin

doi:doi:10.11648/j.earth.20261501.13

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Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar)

Tinahindraza Mampionona Albertin^*

Published in Earth Sciences (Volume 15, Issue 1)

Received: 4 January 2026 Accepted: 15 January 2026 Published: 2 February 2026

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Abstract

The Menarandra River, located in the Androy region of southern Madagascar, flows through a semi-arid environment characterized by severe water stress, a long dry season lasting seven to nine months, and a short, highly variable rainy season concentrated between December and March. Rainfall records from the Bekily meteorological station over 2000–2017 highlight pronounced interannual variability, with alternating wet years (e.g., 2001, 2005, 2011, annual totals >1,000 mm) and deficit years with totals below 700 mm (e.g., 2002, 2004, 2016, 2017). To better link raw rainfall data to effective rainfall in terms of hydrological response, the analysis incorporates the Turc formula, widely used in water balance studies to estimate potential evapotranspiration and effective rainfall. This approach allows a more precise characterization of hydrological conditions associated with rainfall variability and their potential role in riverbed drying. Rainfall analysis is complemented by qualitative interpretation of Google Earth satellite images processed in QGIS, together with field observations. Comparison of images from December 2014 and October 2018 reveals marked reduction and fragmentation of water-covered areas, indicating increasing spatial discontinuity of surface flow. While the temporal correspondence between rainfall variability and riverbed drying suggests a strong association, river intermittency likely reflects the combined influence of seasonal and interannual rainfall patterns and local hydrological controls. Overall, results indicate a progressive shift of the Menarandra toward a more intermittent flow regime, improving understanding of river drying dynamics in semi-arid southern Madagascar and informing sustainable water resource management under increasing drought conditions.

Published in	Earth Sciences (Volume 15, Issue 1)
DOI	10.11648/j.earth.20261501.13
Page(s)	30-43
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

Menarandra River, Rainfall Variability, Prolonged Drying, Minor and Middle Riverbed, Hydrological Regime, Southern Madagascar

References

[1]	Région Androy. (2013). Monograph of the Androy Region. Ministry of Interior and Decentralization, Republic of Madagascar, Antananarivo.
[2]	Acuña, V., Datry, T., Marshall, J., Barceló, D., & Sabater, S. (2014). Why should we care about temporary waterways? Science of the Total Environment, 486, 1–7. https://doi.org/10.1016/j.scitotenv.2014.03.077
[3]	Clicours. (n.d.). Hydrography of Madagascar: Rivers and hydrological regimes. Online geographic resource. https://www.clicours.com
[4]	Battistini, R. (1965). Morphological and hydrological issues of southern Madagascar. Annals of Géography, 74(402), 1–28.
[5]	Chaperon, P., Danloux, J., & Ferry, L. (1993). Rivers and streams of Madagascar. ORSTOM, Paris, 874 p.
[6]	PRD Androy Region. (2024). Regional Development Plan (PRD) of the Androy Region. Androy Regional Council, Madagascar.
[7]	Donque, G. (1975). Climate and hydrology of southern Madagascar. University of Madagascar, Department of Geography, Antananarivo.
[8]	Randriamahefasoa, H., Rajerison, M., & Rasolofo, J. (2012). Cyclones and hydrological impacts in southern Madagascar. Malagasy Journal of Geography, 6(2), 45–58.
[9]	Nicholson, S. E. (2000). The nature of rainfall variability over Africa on time scales of decades to millennia. Global and Planetary Change, 26(1–3), 137–158. https://doi.org/10.1016/S0921-8181(00)00040-0
[10]	IPCC. (2014). Climate Change 2014: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, UK.
[11]	Datry, T., Larned, S. T., & Tockner, K. (2014). Intermittent rivers: A challenge for freshwater ecology. BioScience, 64(3), 229–235. https://doi.org/10.1093/biosci/bit027
[12]	Republic of Madagascar – Prime Minister’s Office / CPGU – GEO & ECO Consult. (2014). Development of flood prevention standards for road infrastructure in Madagascar. Hydrological characteristics of southern rivers, p. 51.
[13]	Rodríguez-Blanco, J. D., Walling, D. E., & He, Q. (2010). Rainfall–runoff–sediment transport relationships in semi-arid Mediterranean catchments. Journal of Hydrology, 386(1–4), 221–234. https://doi.org/10.1016/j.jhydrol.2010.03.022
[14]	Boulton, A. J., Rolls, R. J., Jaeger, K. L., & Datry, T. (2017). Hydrological connectivity in intermittent rivers and ephemeral streams. In T. Datry, N. Bonada, & A. Boulton (Eds.), Intermittent Rivers and Ephemeral Streams: Ecology and Management (pp. 79–108). Academic Press / Elsevier. https://doi.org/10.1016/B978-0-12-803835-2.00004-8
[15]	Larned, S. T., Datry, T., Arscott, D. B., & Tockner, K. (2010). Emerging concepts in temporary river ecology. Freshwater Biology, 55(4), 717–738. https://doi.org/10.1111/j.1365-2427.2009.02322.x
[16]	Google Earth. (2023). Menarandra River Basin, Southern Madagascar. Satellite imagery. Google Earth Pro.

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Albertin, T. M. (2026). Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar). Earth Sciences, 15(1), 30-43. https://doi.org/10.11648/j.earth.20261501.13

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Albertin, T. M. Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar). Earth Sci. 2026, 15(1), 30-43. doi: 10.11648/j.earth.20261501.13

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AMA Style

Albertin TM. Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar). Earth Sci. 2026;15(1):30-43. doi: 10.11648/j.earth.20261501.13

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@article{10.11648/j.earth.20261501.13,
  author = {Tinahindraza Mampionona Albertin},
  title = {Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar)},
  journal = {Earth Sciences},
  volume = {15},
  number = {1},
  pages = {30-43},
  doi = {10.11648/j.earth.20261501.13},
  url = {https://doi.org/10.11648/j.earth.20261501.13},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.earth.20261501.13},
  abstract = {The Menarandra River, located in the Androy region of southern Madagascar, flows through a semi-arid environment characterized by severe water stress, a long dry season lasting seven to nine months, and a short, highly variable rainy season concentrated between December and March. Rainfall records from the Bekily meteorological station over 2000–2017 highlight pronounced interannual variability, with alternating wet years (e.g., 2001, 2005, 2011, annual totals >1,000 mm) and deficit years with totals below 700 mm (e.g., 2002, 2004, 2016, 2017). To better link raw rainfall data to effective rainfall in terms of hydrological response, the analysis incorporates the Turc formula, widely used in water balance studies to estimate potential evapotranspiration and effective rainfall. This approach allows a more precise characterization of hydrological conditions associated with rainfall variability and their potential role in riverbed drying. Rainfall analysis is complemented by qualitative interpretation of Google Earth satellite images processed in QGIS, together with field observations. Comparison of images from December 2014 and October 2018 reveals marked reduction and fragmentation of water-covered areas, indicating increasing spatial discontinuity of surface flow. While the temporal correspondence between rainfall variability and riverbed drying suggests a strong association, river intermittency likely reflects the combined influence of seasonal and interannual rainfall patterns and local hydrological controls. Overall, results indicate a progressive shift of the Menarandra toward a more intermittent flow regime, improving understanding of river drying dynamics in semi-arid southern Madagascar and informing sustainable water resource management under increasing drought conditions.},
 year = {2026}
}

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TY  - JOUR
T1  - Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar)
AU  - Tinahindraza Mampionona Albertin
Y1  - 2026/02/02
PY  - 2026
N1  - https://doi.org/10.11648/j.earth.20261501.13
DO  - 10.11648/j.earth.20261501.13
T2  - Earth Sciences
JF  - Earth Sciences
JO  - Earth Sciences
SP  - 30
EP  - 43
PB  - Science Publishing Group
SN  - 2328-5982
UR  - https://doi.org/10.11648/j.earth.20261501.13
AB  - The Menarandra River, located in the Androy region of southern Madagascar, flows through a semi-arid environment characterized by severe water stress, a long dry season lasting seven to nine months, and a short, highly variable rainy season concentrated between December and March. Rainfall records from the Bekily meteorological station over 2000–2017 highlight pronounced interannual variability, with alternating wet years (e.g., 2001, 2005, 2011, annual totals >1,000 mm) and deficit years with totals below 700 mm (e.g., 2002, 2004, 2016, 2017). To better link raw rainfall data to effective rainfall in terms of hydrological response, the analysis incorporates the Turc formula, widely used in water balance studies to estimate potential evapotranspiration and effective rainfall. This approach allows a more precise characterization of hydrological conditions associated with rainfall variability and their potential role in riverbed drying. Rainfall analysis is complemented by qualitative interpretation of Google Earth satellite images processed in QGIS, together with field observations. Comparison of images from December 2014 and October 2018 reveals marked reduction and fragmentation of water-covered areas, indicating increasing spatial discontinuity of surface flow. While the temporal correspondence between rainfall variability and riverbed drying suggests a strong association, river intermittency likely reflects the combined influence of seasonal and interannual rainfall patterns and local hydrological controls. Overall, results indicate a progressive shift of the Menarandra toward a more intermittent flow regime, improving understanding of river drying dynamics in semi-arid southern Madagascar and informing sustainable water resource management under increasing drought conditions.
VL  - 15
IS  - 1
ER  -

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Author Information

Tinahindraza Mampionona Albertin

Doctoral School of Geosciences (GPCEHP), University of Toliara, Toliara, Madagascar

Contact Email

http://orcid.org/0009-0001-8207-8519

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APA Style

Albertin, T. M. (2026). Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar). Earth Sciences, 15(1), 30-43. https://doi.org/10.11648/j.earth.20261501.13

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ACS Style

Albertin, T. M. Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar). Earth Sci. 2026, 15(1), 30-43. doi: 10.11648/j.earth.20261501.13

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AMA Style

Albertin TM. Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar). Earth Sci. 2026;15(1):30-43. doi: 10.11648/j.earth.20261501.13

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@article{10.11648/j.earth.20261501.13,
  author = {Tinahindraza Mampionona Albertin},
  title = {Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar)},
  journal = {Earth Sciences},
  volume = {15},
  number = {1},
  pages = {30-43},
  doi = {10.11648/j.earth.20261501.13},
  url = {https://doi.org/10.11648/j.earth.20261501.13},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.earth.20261501.13},
  abstract = {The Menarandra River, located in the Androy region of southern Madagascar, flows through a semi-arid environment characterized by severe water stress, a long dry season lasting seven to nine months, and a short, highly variable rainy season concentrated between December and March. Rainfall records from the Bekily meteorological station over 2000–2017 highlight pronounced interannual variability, with alternating wet years (e.g., 2001, 2005, 2011, annual totals >1,000 mm) and deficit years with totals below 700 mm (e.g., 2002, 2004, 2016, 2017). To better link raw rainfall data to effective rainfall in terms of hydrological response, the analysis incorporates the Turc formula, widely used in water balance studies to estimate potential evapotranspiration and effective rainfall. This approach allows a more precise characterization of hydrological conditions associated with rainfall variability and their potential role in riverbed drying. Rainfall analysis is complemented by qualitative interpretation of Google Earth satellite images processed in QGIS, together with field observations. Comparison of images from December 2014 and October 2018 reveals marked reduction and fragmentation of water-covered areas, indicating increasing spatial discontinuity of surface flow. While the temporal correspondence between rainfall variability and riverbed drying suggests a strong association, river intermittency likely reflects the combined influence of seasonal and interannual rainfall patterns and local hydrological controls. Overall, results indicate a progressive shift of the Menarandra toward a more intermittent flow regime, improving understanding of river drying dynamics in semi-arid southern Madagascar and informing sustainable water resource management under increasing drought conditions.},
 year = {2026}
}

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TY  - JOUR
T1  - Rainfall Variability and Prolonged Drying of the Menarandra Riverbed (2000–2017) in the District of Bekily (Southern Madagascar)
AU  - Tinahindraza Mampionona Albertin
Y1  - 2026/02/02
PY  - 2026
N1  - https://doi.org/10.11648/j.earth.20261501.13
DO  - 10.11648/j.earth.20261501.13
T2  - Earth Sciences
JF  - Earth Sciences
JO  - Earth Sciences
SP  - 30
EP  - 43
PB  - Science Publishing Group
SN  - 2328-5982
UR  - https://doi.org/10.11648/j.earth.20261501.13
AB  - The Menarandra River, located in the Androy region of southern Madagascar, flows through a semi-arid environment characterized by severe water stress, a long dry season lasting seven to nine months, and a short, highly variable rainy season concentrated between December and March. Rainfall records from the Bekily meteorological station over 2000–2017 highlight pronounced interannual variability, with alternating wet years (e.g., 2001, 2005, 2011, annual totals >1,000 mm) and deficit years with totals below 700 mm (e.g., 2002, 2004, 2016, 2017). To better link raw rainfall data to effective rainfall in terms of hydrological response, the analysis incorporates the Turc formula, widely used in water balance studies to estimate potential evapotranspiration and effective rainfall. This approach allows a more precise characterization of hydrological conditions associated with rainfall variability and their potential role in riverbed drying. Rainfall analysis is complemented by qualitative interpretation of Google Earth satellite images processed in QGIS, together with field observations. Comparison of images from December 2014 and October 2018 reveals marked reduction and fragmentation of water-covered areas, indicating increasing spatial discontinuity of surface flow. While the temporal correspondence between rainfall variability and riverbed drying suggests a strong association, river intermittency likely reflects the combined influence of seasonal and interannual rainfall patterns and local hydrological controls. Overall, results indicate a progressive shift of the Menarandra toward a more intermittent flow regime, improving understanding of river drying dynamics in semi-arid southern Madagascar and informing sustainable water resource management under increasing drought conditions.
VL  - 15
IS  - 1
ER  -

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