Floods in Shrimp Ponds: Mitigating Risks and Ensuring Resiliency

Floods pose a significant threat to shrimp farming, especially during the rainy season. For shrimp farmers, these events can lead to extensive damage, loss of stock, and a decline in overall productivity. Understanding the causes, impacts, and prevention strategies for floods in shrimp ponds is crucial to safeguarding both the environment and the livelihoods of aquafarmers.

The Impact of Floods on Shrimp Aquaculture Systems

Floods in shrimp ponds can disrupt operations and cause extensive damage, affecting the infrastructure, water quality, and shrimp health. The primary ramifications are outlined below:

1. Damage to Infrastructure Floodwaters can weaken pond embankments, damage irrigation networks, and disrupt the overall structure of shrimp ponds. These damages increase maintenance costs and operational challenges.
2. Decreased Water Quality Floodwaters often carry sediments, pathogens, and pollutants into shrimp ponds, leading to poor water quality. This can stress shrimp, slow their growth, and increase mortality rates.
3. Loss of Stock Shrimp can escape from ponds during floods, leading to significant economic losses. Strong currents can also physically harm the shrimp, reducing their marketability.
4. Increased Operational Costs Post-flood recovery efforts, such as infrastructure repairs and water quality restoration, add to the operational costs.
5. Higher Pathogen and Pest Populations Floodwaters can introduce harmful microorganisms and pests, increasing the risk of disease outbreaks and further affecting shrimp health.

The impact of floods on shrimp aquaculture systems

Flood Mitigation Strategies for Shrimp Ponds

To minimize the impacts of floods, shrimp farmers can implement several mitigation strategies:

1. Installing Nets Around Ponds

Installing nets with a width of 1–1.5 meters around ponds prevents shrimp from escaping during floods. These nets should be securely tied to withstand strong currents.

2. Systems designed for effective water removal

Drainage systems help channel excess water away from ponds, reducing the risk of flooding. Overflow channels can be strategically placed on embankments to handle water surges during heavy rains.

3. Liming

Applying lime helps maintain the pH balance in pond water. Rainwater or floodwaters often reduce the pH, stressing the shrimp. Regular liming ensures a stable environment for shrimp growth.

4. Planned Harvesting

In cases of severe flooding, early harvesting minimizes losses. This is particularly useful when flood risks are unpredictable or escalating.

Flood Mitigation Strategies for Shrimp Ponds

Post-Flood Pond Management

After a flood, shrimp farmers must take immediate action to restore pond conditions:

Performing a Full Evaluation

The first step in post-flood management is to evaluate the current state of the pond. Farmers need to assess the physical condition of the pond infrastructure, including embankments, drainage systems, and levees. Any significant damage should be documented, and repairs prioritized to prevent further water intrusion or structural failure. If the pond's location has become prone to recurrent flooding, relocating to a safer site may be necessary.

Regular Outlet Inspections and Maintenance

Floodwaters often carry debris that can clog outlets, hindering the effective flow of water. Outlets must be checked and cleared regularly, especially after a flood. Cleaning these channels at least once a month helps maintain efficient water circulation, reducing the risk of water stagnation and associated problems like pathogen proliferation.

Raising Pond Chambers

Increasing the height of pond chambers can be a simple yet highly effective way to protect shrimp from future flooding. Elevated chambers prevent shrimp from escaping and safeguard against water pressure that could cause breaches in pond barriers. This strategy is especially beneficial in regions prone to heavy rainfall.

Using Overflow Systems

Installing overflow systems can help manage excess water during floods. These systems enable controlled water drainage when levels exceed the pond's capacity, minimizing the risk of infrastructure damage and shrimp loss. However, overflow systems are most effective when floodwaters are confined to the pond and not the surrounding areas.

Building an Efficient Drainage System for Shrimp pond

A robust drainage system is crucial for mitigating the impact of excessive water. Drainage systems should be designed to efficiently channel water away from the pond and surrounding areas. Farmers should also consider integrating sediment traps to reduce the accumulation of harmful debris.

Improving Water Quality

Floodwaters can introduce contaminants and disrupt the delicate balance of pond ecosystems. After a flood, liming and partial water replacement are essential to restore pH levels and overall water quality. These measures help create a conducive environment for shrimp recovery and growth.

Preventive Strategies for Flood Formation

Preventing floods in shrimp ponds requires a proactive approach and careful planning:

1. Selecting Flood-Safe Locations

Choose sites with:

• Coastal areas experiencing tidal fluctuations of 2–3 meters.
• Clay or sandy clay soil with less than 20% sand content.
• Green belts or mangrove forests acting as natural barriers.

2. Utilizing Tidal Calendars

Adjust farming cycles based on tidal calendars to avoid high-risk periods of heavy rainfall and flooding.

3. Installing Water Pumps

Water pumps effectively control pond water levels, reducing the risk of overflow.

4. Cleaning intake and discharge channels

Regular cleaning ensures smooth water flow and prevents debris buildup that could obstruct drainage during floods.

5. Strengthening Pond Embankments

Build strong embankments to withstand water pressure. Use materials that resist erosion and leaks.

6. Implementing Overflow Systems

Design ponds with effective overflow mechanisms to handle sudden water surges.

7. Creating Sub-Soil Layers

Adding sub-soil layers prevents soil erosion and plastic swelling during floods, enhancing the durability of pond structures.

Preventive Strategies for Flood Formation

Farm Design Improvements to Mitigate Flood Risks

Farm designs play a crucial role in flood prevention. Key recommendations include:

1. Building Strong Levees

Levees should meet the following criteria:

• Main Levee: Top width of 2–2.5 meters, slope of 2:1, and freeboard of 60 cm.
• Partition Levee: Top width of 1–1.5 meters, slope of 2:1, and freeboard of 30 cm.

2. Constructing Recirculation Canals

Recirculation canals surrounding ponds help hold water during heavy rains. These canals should have a height of at least 1.8 meters above mean sea level in low-lying areas.

3. Incorporating Reservoir Ponds

Reservoir ponds store treated water for distribution to culture ponds. Approximately 40% of the farm’s water volume should be allocated to reservoirs and canals.

4. Enhancing Pond Depth and Drainage

Maintain pond depths of 1.2–1.4 meters to support higher shrimp stocking densities. Use central drainage systems to remove sludge and improve water quality.

Farm Design Improvements to Mitigate Flood Risks

Climate Change and Shrimp Farming Resiliency

The frequency and intensity of floods are being aggravated by climate change. Southeast Asia, a key region for shrimp farming, is particularly vulnerable. Adopting climate-resilient designs and management practices can help farmers cope with these challenges.

Different Viewpoints and Long-term Advantages

Investing in flood prevention and resilient farm designs offers numerous benefits:

• Protects farm structures from extreme events.
• Minimizes disease outbreaks by controlling water quality.
• Reduces operational costs through improved infrastructure.
• Enhances sustainability by integrating lessons from past climate extremes.

Community-based approaches, combined with scientific farm designs, can ensure sustainable shrimp farming even in flood-prone areas. By adopting these strategies, farmers can safeguard their livelihoods and contribute to a more resilient aquaculture sector.