In its latest blog post, BWI explores the major river basins of Corsica, often referred to as the “Island of Beauty.” Gain insights into these vital water systems, their significance in supporting the island’s economy and agriculture, and the key challenges they encounter. Read more to learn about the lifeblood of Corsica’s natural landscape and community.
BWI‘s blog post about hydrology in Corsica takes you on a journey through Corsica and its major river basins. Known as the “Island of Beauty,” Corsica features a fascinating river network that plays a crucial role in the island’s economy and agriculture. However, these vital waterways face several challenges. The blog post highlights the importance of these river basins in Corsica and explores the key issues they are encountering.
Corsica, a Mediterranean island located between the southern continental coast of France and Sardinia, boasts 28 principal watersheds. Due to their distribution, eight of these watersheds account for over 72% of the island’s water resources, with an average flow of 76 m³/s. Given the island’s size, its main rivers are relatively short (Donta et al., 2005).
During the summer months, Corsica welcomes over 2 million tourists, which coincides with its Mediterranean climate characterised by a shortage of precipitation. Rainfall mainly occurs in winter and is unevenly distributed across the island, ranging from the coast to the high peaks at elevations of approximately 600 to 1200 meters. This uneven distribution leads to significant water shortages in summer, exacerbated by peak demands from tourism and irrigation.
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(Donta et al., 2005)
Hydrology in Corsica
Location
The largest river basin in Corsica, the Golo River Basin, is located in the northern part of the island, south of Bastia. The main river traversing this basin, the Golo River, is also the longest river on the island. It stretches approximately 89 km and originates in the central mountains near Monte Cinto at an altitude of 2000 meters (Donta et al., 2005). The river drains into the Tyrrhenian Sea near Aléria on the eastern coast.
Importance
The Golo River Basin represents a salient economic pillar for the locals, as it houses a known EDF dam in Calacuccia. It is essential for electricity production, human consumption, and irrigation. Furthermore, it contains several micro-hydropower stations. The Golo River Basin in Corsica is also marked by agricultural activities, although not the most prominent.
Challenges
The Golo River Basin often faces significant water scarcity caused by the variability in water availability and frequent droughts during the summer months. This scarcity affects agriculture, drinking water supply, and natural ecosystems. Additionally, increasing demand for irrigation, particularly for water-intensive crops, further exacerbates water shortages. What’s more, agricultural run-off, due to fertilizers and pesticides, pollutes the river and negatively impacts water quality and aquatic ecosystems.
Noteworthy
The Golo River drains a steep catchment (average gradient of 30 km) in the northern part of Corsica Island. The river’s steep catchment area offers opportunities for adventurous activities like canyoning and white-water rafting, attracting outdoor enthusiasts to this part of the island (In Terra Corsa, 2024).
Hydrology in Corsica
Location
The Tavignano River, the second-largest river in Corsica, originates in the central mountains near Corte and runs eastward, emptying into the Tyrrhenian Sea near Aléria, close to the mouth of the Golo River.
Importance
The Tavignano River Basin plays a vital role in the island’s hydrology, supplying water for drinking, agriculture, and maintaining natural ecosystems. The health of the Tavignano River Basin is integral to sustaining water quality and availability in the region.
Challenges
The Tavignano River Basin undergoes significant seasonal changes in water flow. During winter and spring, the river’s flow is high, with average monthly rates ranging from 13.9 to 19.4 cubic meters per second (m³/s). Flow peaks occur in December, February, and April, while the lowest flow is observed in March. In contrast, summer months from July to September see much lower water levels. The average monthly flow drops to around 1.27 m³/s in August and remains relatively stable through September (Di Rosa et al., 2017; Waymarking, 2022).
Noteworthy
During the devastating flood of 1976, the Tavignano River’s water level was as high as that of the Rhône River. Local elders used to describe the area stretching from the village of Antisanti, located in the lower Tavignano Valley, to the eastern plain, as “the mountain that walks” due to the dramatic changes in the landscape caused by the flood (Faure, 2022).
The Tavignano Basin receives an impressive annual rainfall of 646 millimeters. This is notably higher than the average annual rainfall for France and significantly surpasses that of the Golo catchment area, which sees only 482 millimeters annually.
Hydrology in Corsica
Location
The Prunelli River flows for around 44 km from the mountains to the west coast, emptying into the Mediterranean Sea near Ajaccio, the capital of Corsica. Despite being smaller, this basin is crucial due to its proximity to Ajaccio, the largest city in Corsica (Geocaching, 2016).
Importance
The Prunelli River is regulated by the Tolla Reservoir, created by the Tolla Dam. This reservoir is vital for water supply, hydroelectric power generation, and flood control in the region. The river’s water is extensively used for irrigation in the fertile valleys along its course, supporting local agriculture. The Tolla Dam is also a significant source of hydroelectric power for the region.
Challenges
The Prunelli River Basin is prone to flash floods, especially during heavy rainfall events in the mountainous areas, which can cause rapid increases in river discharge. Recent extreme weather events have led to more frequent overflows, raising concerns about the safety and sustainability of nearby communities. The increasing unpredictability and difficulty in managing the river underscore the need for enhanced flood management strategies and infrastructure improvements to cope with the growing impact of climate change.
Noteworthy
The Prunelli River Basin is an important agricultural area, particularly known for its vineyards and olive groves. The region produces high-quality wines and olive oil, which are integral to the local economy and culture (Geocaching, 2016)
Hydrology in Corsica
Location
The Gravona River flows through the western part of Corsica, with its basin covering a large portion of the western central region of the island. Originating in the central mountains of Corsica, specifically from the Monte Renoso massif at an elevation of about 2,352 meters, the river flows westward for approximately 46 kilometers before emptying into the Gulf of Ajaccio. The mean annual discharge is around 8 to 10 cubic meters per second (m³/s) (Schubert at al., 2023).
Importance
The Gravona River is a crucial source of freshwater for Ajaccio and surrounding communities. Its water is used for drinking supply, agriculture, and some industrial purposes, making it vital for the local population and economy.
Challenges
The Gravona River Basin is susceptible to significant seasonal variability in river flow due to its mountainous terrain. This results in a high potential for flash floods, especially during the autumn and winter months when heavy rains can cause rapid rises in river levels. These flash floods pose risks to the local infrastructure and communities.
Noteworthy
The Gravona River Basin is home to diverse ecosystems, including riparian forests and various aquatic species. The water quality in the Gravona River is good, thanks to the relatively undeveloped nature of much of its basin. The clear, fast-flowing waters provide a suitable habitat for fish species such as trout, making it an important area for biodiversity and conservation efforts (Schubert at al., 2023).
Hydrology in Corsica
Location
The Taravo River Basin is located in the southwest of Corsica, encompassing one of the island’s most extensive watersheds. The Taravo River originates north of Monte Grosso (1895 meters NGF) and follows a rectilinear course from northeast to southwest, emptying into the Mediterranean Sea at the Gulf of Valinco (Vella, 2023).
Importance
The Taravo River plays a crucial role in local agriculture, providing essential water for irrigation in the surrounding valleys. The river valley is known for its vineyards, olive groves, and other agricultural activities, vital to the local economy and culture.
Challenges
The Taravo River Basin faces challenges such as seasonal drought and water scarcity, which impact water availability for irrigation and other uses. Erosion and sedimentation caused by the river’s flow can affect water quality and agricultural productivity. Additionally, agricultural runoff, including pesticides and fertilizers, contributes to water pollution. Climate change may exacerbate these issues by altering rainfall patterns and increasing the frequency and severity of droughts.
Hydrology in Corsica
Location
The Rizzanese River flows through the southern part of Corsica, extending approximately 44 kilometers before emptying into the Mediterranean Sea near Propriano. Originating from the hills near the town of Quenza at an elevation of around 1,200 meters, the river traverses the southern mountainous region of Corsica and discharges into the Gulf of Propriano (Dawson, 2024).
Importance
A major human intervention in the Rizzanese River’s hydrology is the Rizzanese Dam, completed in 2013. This significant hydroelectric project harnesses the river’s flow to generate a substantial portion of Corsica’s renewable energy. The dam has created a reservoir that regulates the river’s flow, ensuring a more consistent water supply throughout the year, though it has also altered the natural flow regime (Power Technology, 2024).
Challenges
The construction and operation of the Rizzanese Dam have led to ecological impacts, including changes in sediment transport and potential effects on aquatic habitats. Despite measures to mitigate these impacts, such as managing sediment flow and habitat restoration, the river still exhibits a Mediterranean flow regime with high flows during winter and spring due to rainfall and snowmelt, and much lower flows in summer and early autumn. Flash floods are also a risk during heavy rainfall, particularly in autumn.
Noteworthy
The Rizzanese River exemplifies Corsica’s diverse and rugged geography, making it an intriguing subject for natural landscape and environmental studies. It is also popular for outdoor activities like hiking and swimming, attracting visitors who wish to experience its natural beauty and charm.
These river basins are vital to Corsica’s hydrology, agriculture, and ecology. Despite their relatively short lengths, the rivers—each flowing from the island’s rugged mountainous terrain—play essential roles in sustaining local ecosystems, supporting agriculture, and shaping the island’s unique landscape. Their diverse challenges and contributions highlight the intricate relationship between Corsica’s natural environment and human activity.
List of References for ‘Hydrology in Corsica’ :
Dawson, S. (2024). CR Stariz. (online) Available at: http://www.simondawson.com/crstariz.htm (Accessed 5 August 2024).
Di Rosa, M., De Giorgi, A., Marroni, M., and Pandolfi, L. (2017) ‘Geology of the area between Golo and Tavignano Valleys (Central Corsica): a snapshot of the continental metamorphic units of Alpine Corsica.’, Journal of Maps, 13(2), pp. 644–653. Available at: https://www.tandfonline.com/doi/full/10.1080/17445647.2017.1351900#abstract (Accessed: 5 August 2024).
Donta, A.A., Lange, M.A., and Herrmann, A. (2005) ‘Water on Mediterranean Islands: Current Conditions and Prospects for Sustainable Management’, Centre for Environmental Research, 5(1) Available at: https://d-nb.info/113751258X/34#page=97 (Accessed: 5 August 2024).
Faure, V. (2022) ‘En Corse, le combat du fleuve qui parle’, Le Monde, 11 July. Available at: https://www.lemonde.fr/m-le-mag/article/2022/07/11/en-corse-le-combat-du-fleuve-qui-parle_6134229_4500055.html (Accessed: 5 August 2024).In Terra Corsa (2024) Nature Activities in Corsica. Available at: https://interracorsa.com/en/ (Accessed: 5 August 2024).
