Walawe River

  

The Walawe Ganga is a significant river that flows through the southern and central parts of Sri Lanka, originating from the central hills near the Udawalawe National Park. As it courses through the landscapes of Ratnapura, Matara, and Hambantota, the river provides vital water for the agricultural areas of Sri Lanka's southern and dry zones. Its journey through scenic valleys, plains, and lowlands makes it an important natural feature in the region, particularly for communities relying on its waters for farming and daily use.

The Walawe River is a crucial source of irrigation, supporting large-scale agricultural production in the southern part of the island. The river's flow nourishes vast fields of paddy, fruits, and vegetables, ensuring food security for many rural families. Moreover, the Udawalawe Reservoir, formed by the Walawe River, is vital for regulating the region's water supply and providing electricity through the Udawalawe Hydroelectric Power Plant, making it a key resource for both agriculture and energy production in Sri Lanka.

Ecologically, the river supports diverse habitats, particularly around the Udawalawe National Park, which is a major wildlife sanctuary in the country. The river's waters feed wetlands and riverbanks, making them essential for supporting biodiversity, including elephants, water buffalo, birds, and other wildlife species. The Walawe Ganga contributes to the park's rich ecosystems, which are a popular destination for eco-tourism, wildlife photography, and safaris. The river's ecological importance is thus intertwined with conservation efforts in the region.

Culturally, the Walawe Ganga has shaped the history of the southern province, playing a vital role in the development of irrigation systems dating back to ancient Sri Lanka. The river continues to be integral to the local population's way of life, supporting rural settlements, farming communities, and providing water for daily consumption. As an essential water source, it also has significant cultural and spiritual value for communities living along its banks.

Flood Risk & Hydrological Importance

The Walawe Ganga, while essential for agriculture and energy generation, is also susceptible to flood risks during heavy monsoon rains. Understanding its hydrological behaviour is crucial for effective flood management in the southern and central regions of Sri Lanka.

• Current Hydrological Readings (Official Report):
  Moraketiya Station – Alert Level: 3.00 m, Minor Flood Level: 5.00 m, Major Flood Level: 7.00 m, Current Level: 4.78 m (Alert, rising).
• Flood-Prone Areas: Low-lying settlements and farmlands near Ratnapura, Moraketiya, and surrounding regions are vulnerable to flooding during heavy rainfall events.
• Catchment Sensitivity: The river's catchment area, including the central highlands, can experience rapid runoff during intense monsoon showers, which significantly increases water flow downstream.
• Effect on Agriculture: Sudden surges in the river's water levels can overflow irrigation channels, damaging crops and causing waterlogging in fields.
• Slow Drainage in Coastal Zones: As the river approaches the coastal plain, water disperses slowly, increasing the chances of prolonged flooding in agricultural areas.
• Urban Risk: The town of Matara and surrounding urban settlements are at risk from elevated water levels during the rainy season, requiring effective flood management strategies.
• Need for Continuous Monitoring: Monitoring water levels at the Moraketiya station is vital for predicting flooding events and managing the impacts on surrounding communities.

Despite its essential role in sustaining agriculture and generating power, the Walawe Ganga's sensitivity to rainfall and flood risks means that ongoing monitoring and flood management strategies are crucial to mitigate the risks for communities and industries depending on it.