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Unlock This CourseWater surplus occurs when an area receives more water than it needs or can effectively use. This might sound like a good problem to have, but too much water can actually cause serious issues for people and the environment. Areas of water surplus are found across the globe, from tropical rainforests to temperate regions with heavy rainfall.
Understanding water surplus is crucial because it affects millions of people worldwide. These areas often face challenges like flooding, waterlogged soils and the need for expensive drainage systems. However, they also provide opportunities for water storage, hydroelectric power and supporting diverse ecosystems.
Key Definitions:
Water surplus areas are typically found in equatorial regions, temperate oceanic climates and monsoon regions. The Amazon Basin, parts of Southeast Asia, the Pacific Northwest of North America and Western Europe all experience regular water surplus conditions.
Several physical factors combine to create areas of water surplus. Understanding these helps explain why some regions consistently have more water than they can use effectively.
Climate is the most important factor determining water surplus. Areas with high precipitation and low evapotranspiration rates are most likely to experience water surplus conditions.
Regions receiving over 1000mm of rainfall annually often experience surplus. This includes equatorial areas with convectional rainfall and temperate regions with frontal rainfall systems.
Cooler temperatures reduce evapotranspiration rates, meaning less water is lost to the atmosphere. This helps maintain surplus conditions even with moderate rainfall.
Monsoon climates create seasonal water surplus during wet seasons, whilst Mediterranean climates may have winter surplus periods.
The physical landscape significantly influences water surplus through its effect on precipitation patterns and water movement.
Orographic Effect: Mountains force air masses upward, causing cooling and increased precipitation on windward slopes. This creates localised areas of high rainfall and potential water surplus.
Drainage Basin Characteristics: Areas with poor natural drainage, such as flat terrain or impermeable rock, are more likely to experience water surplus as water cannot easily flow away or infiltrate into the ground.
The Amazon Basin receives over 2000mm of rainfall annually due to its equatorial location and the recycling of moisture through evapotranspiration. The flat terrain and dense vegetation create conditions where water surplus is maintained year-round, supporting the world's largest tropical rainforest ecosystem.
Human activities can both contribute to and be affected by water surplus conditions. Understanding these interactions is essential for effective water management.
Human modifications to the landscape can alter natural water cycles and create or worsen water surplus conditions.
Urbanisation: Cities create impermeable surfaces that increase surface runoff and reduce infiltration. This can lead to localised flooding and water surplus in urban areas during heavy rainfall events.
Deforestation: Removing forests reduces evapotranspiration and interception, potentially increasing water surplus in affected areas. However, it can also reduce rainfall through decreased moisture recycling.
Agriculture: Intensive farming can compact soils, reducing infiltration and increasing surface runoff. Irrigation systems may also contribute to waterlogging in some areas.
Paradoxically, areas with water surplus may have low population densities due to challenging living conditions such as frequent flooding, waterlogged soils and limited agricultural potential.
Water surplus creates both challenges and opportunities for human activities and natural environments. These impacts vary depending on the severity and duration of surplus conditions.
Water surplus significantly affects natural ecosystems and environmental processes.
Positive Impacts:
Negative Impacts:
Water surplus affects human activities in various ways, creating both costs and benefits for communities.
Frequent flooding damages buildings and transport networks. Construction costs are higher due to the need for flood-resistant designs and drainage systems.
Waterlogged soils can reduce crop yields and limit farming options. However, some crops like rice benefit from surplus water conditions.
Water surplus areas offer excellent potential for hydroelectric power generation, providing renewable energy opportunities.
Bangladesh experiences annual water surplus during monsoon seasons, with 80% of the country consisting of flood plains. Whilst this provides fertile agricultural land, it also displaces millions of people annually and causes significant economic damage. The country has developed sophisticated flood management systems including early warning systems and flood-resistant crops.
Managing water surplus requires a combination of engineering solutions, planning strategies and adaptive approaches. Effective management aims to reduce negative impacts whilst maximising benefits.
Hard engineering approaches use technology and construction to control water surplus.
Drainage Systems: Networks of channels, pipes and pumps remove excess water from urban and agricultural areas. These systems require regular maintenance and can be expensive to install.
Flood Defences: Levees, flood walls and barriers protect communities from flooding. However, these can transfer flood risk downstream and may fail during extreme events.
Reservoirs and Dams: These store excess water during surplus periods for use during drier times. They also provide flood control and hydroelectric power generation opportunities.
Soft engineering and planning approaches work with natural processes to manage water surplus more sustainably.
Sustainable Drainage Systems (SuDS): These use natural processes to manage surface water, including permeable pavements, green roofs and constructed wetlands.
Floodplain Management: Allowing rivers to flood naturally in designated areas reduces flood risk elsewhere whilst maintaining ecosystem services.
Land Use Planning: Restricting development in flood-prone areas and promoting appropriate land uses in water surplus regions.
Natural wetlands and forests in water surplus areas provide valuable services including flood control, water purification and carbon storage. Protecting these areas is often more cost-effective than engineering solutions.
Different regions have developed unique approaches to managing water surplus based on their specific conditions and challenges.
The Netherlands has developed world-leading expertise in water management, with two-thirds of the country below sea level. Their approach combines advanced engineering with innovative planning.
Key Strategies:
The Thames Barrier protects London from tidal surges and river flooding. Completed in 1984, it consists of 10 moveable gates that can be raised to prevent high tides from flooding the city. The barrier has been used over 200 times since opening and is a crucial part of London's flood defence system.
Countries in monsoon Asia have developed strategies to cope with extreme seasonal variations in water availability.
Traditional Approaches:
Modern Developments:
Climate change is altering precipitation patterns globally, creating new challenges for water surplus management. Some areas may experience increased surplus due to more intense rainfall events, whilst others may see reduced surplus as temperatures rise.
Adaptation Strategies:
Managing water surplus often requires international cooperation, especially for shared river basins. Countries must work together to develop sustainable solutions that benefit all parties.