2015年-世界发展银行全球_Water_and_Climate_Adaptation_Plan_for_the_Sava_River_Basin___Annex_4_Guidance_Note_on_Adaptation_to_Climate_Change_for_Navigation_24页_1mb

Water & Climate Adaptation Plan for the Sava River Basin - Navigation

1. Background

This guidance note is part of the Water and Climate Adaptation Plan (WATCAP) for the Sava River Basin (SRB), prepared by the World Bank under the Water Partnership Program (WPP) and the Trust Fund for Environmentally & Socially Sustainable Development (TFESSD). It focuses on the adaptation needs for inland navigation in the SRB, considering the impact of climate change. The Sava River is a key component of the inland navigation system in Southeast Europe, with navigation possible from the confluence with the Danube in Belgrade up to Sisak, covering a total length of 586 km. The navigation activities are managed by the International Sava River Basin Commission (ISRBC), which has a strategic objective of rehabilitating and developing the Sava River waterway.

2. Present Navigation Conditions

The current navigation conditions on the Sava River are poor and unfavourable due to:

• Limited draft over long periods
• Narrow fairway widths
• Sharp river bends limiting vessel and convoy sizes

The Sava River is classified as 50/50 class III and IV between Belgrade and Sisak. The fairway depth requirements for class IV are:

• 2.3 m for 95% of the time
• 3.3 m for 65% of the time

For class Va, the requirements are slightly more demanding:

• 2.4 m for 95% of the time
• 90 m width in bends
• 55 m horizontal clearance under bridges

The Feasibility Study recommends improving the Sava River to class Va in certain sectors, with a total cost of about 86 million EUR. The project is divided into two sections: 0–211 rkm and 211–594 rkm. The EIA for the upper section is completed, while the lower section is under development.

3. Climate Change Impact on Navigation Conditions

Climate change is expected to affect inland navigation through four main phenomena:

1. Low flows – reduce water depths and fairway widths, increasing the risk of grounding and collisions.
2. High flows – may restrict or suspend navigation.
3. River ice – impacts navigation during winter months.
4. Visibility (fog) – although not analyzed in this document due to lack of data.

3.1 Low Flows

Low flows are characterized by Q65 and Q95, which are the 65th and 95th percentiles of the flow duration curve. These represent the flow rates that are exceeded 65% and 95% of the time, respectively.

• Q65 corresponds to the 65% of the time navigation with maximum draft is possible.
• Q95 corresponds to the 95% of the time navigation with reduced draft is possible.

Hydrologic simulations with five climate models indicate that Q65 and Q95 are likely to decrease slightly in the distant future, with the largest reduction observed downstream of Sisak (up to 6% for Q65 and 11% for Q95). In the near future, the change is minimal, with an average increase of 3 days for n65 and 2 days for n95.

3.2 High Flows

High flows are associated with Q1 and Q3, representing the flow rates exceeded 1% and 3% of the time, respectively. These are used to define thresholds for navigation restrictions.

• Q1 is used to determine the high navigable water level.
• Q3 serves as a compromise between different thresholds set by various authorities.

Simulations show that both Q1 and Q3 exhibit weak changes in the near future, with a gradual increase in the upper parts of the river and a decrease downstream. The magnitude of these changes is smaller than the overall uncertainties in the models, making it difficult to draw firm conclusions.

4. Adaptation Measures

Adaptation measures for the Sava River waterway include:

• Waterway infrastructure improvements: Dredging, training works, and bend modifications.
• Transport operations and vessels: Adjustments in vessel design and operational practices.
• Environmental considerations: Integration of environmental impact assessments (EIA) to ensure sustainable development.

The guidance note emphasizes the need to consider both climate change impacts and existing environmental regulations, particularly in relation to the European Water Framework Directive (WFD). The detailed design of the waterway is currently under development, incorporating additional environmental considerations.

5. Key Tables and Figures

• Table 1: Navigable reaches of the Sava River and its tributaries.

• Table 2: Climate model chains used in the study.

• Table 3: High water levels above which navigation is prohibited.

• Table 4: Possible responses of inland navigation to climate change impacts (source: PIANC, 2008).

• Figure 1: Overview map of the Sava River Basin with major rivers.

• Figure 2: Change in Q65 (flows of 65% duration) in near and distant future.

• Figure 3: Change in Q95 (flows of 95% duration) in near and distant future.

• Figure 4 and 5: Comparison of observed and simulated distributions for Q65 and Q95.

• Figure 6 and 7: Change in the number of days with flows below Q65_base and Q95_base.

• Figure 8 and 9: Change in Q1 and Q3 (flows exceeded in 1% and 3% time during a year) in near and distant future.

• Figure 14: Change in the number of days with negative temperatures as an indicator of ice formation.

• Figure 15: Interconnection of factors relevant for navigation and fairway parameters.

6. Conclusion

The Sava River Basin is at risk from climate change impacts on navigation, particularly low and high flows, ice formation, and fog. The guidance note recommends a comprehensive approach to adaptation, including infrastructure improvements, operational adjustments, and environmental impact assessments. The study highlights the need for further research and data collection, especially regarding visibility and its effects on navigation. The ultimate goal is to ensure the Sava River remains a viable and sustainable waterway for transport in the face of climate change.