Climate Risk Assessment: A Comprehensive Analysis of Spain’s Meteorological Hazards
Climate Risks:
Temperatures
Normally, all organisms adapt to ambient temperatures. Increases or decreases constitute thermal hazards. Globally, approximately one thousand deaths annually result from cold waves and heat. In Spain, heat waves frequently occur in mid-July due to the Azores anticyclone. Cold waves typically arrive in the first months of the year, originating from northern Europe.
Wind
Winds exceeding 70 km/h are considered highly dangerous. More intense winds—tropical cyclones, hurricanes, tornadoes, and typhoons—originate from large depressions in the lower atmosphere. The resulting turbulent air movements cause catastrophic effects, particularly in less developed countries lacking protective measures. Main impacts include:
- Direct damage to the population
- Destruction of buildings and forests
- Dispersion of arable land, causing crop destruction and soil loss
Precipitation
Storms
Storms cause:
- Flooding from rising river levels
- Crop loss (especially with hail)
- Soil loss from raindrop impact and runoff
- Traffic accidents
Rainfall also occurs as snow or hail. Snow accumulation on slopes risks landslides or avalanches.
Lightning
Thunderstorms produce lightning, posing a significant risk. Even dry thunderstorms can cause damage. Lightning causes:
- Injuries
- Forest fires
- Death of livestock
- Human fatalities
Cold Drop
A cold drop, primarily affecting Spain’s Mediterranean coast, involves a mass of cold air descending from upper atmospheric layers. This causes significant temperature drops and heavy rainfall.
Barometric Swamp
A transient atmospheric situation between two fronts (warm and cold), temporarily retaining cold air.
Convective Systems
Large storm clouds from converging subtropical and polar currents cause significant precipitation and flooding. Floods lead to:
- Human and animal deaths
- Crop destruction
- Building destruction
- Levee breaches and erosion
- Increased risk of epidemics
Rambla
Mediterranean streams with sporadic, high-flow courses through narrow channels, often overflowing.
Drought
Meteorological and agricultural droughts are characterized by decreased precipitation over time and area. Causes include:
- Topographical: mountains drying out moist air
- Climatic: anticyclonic cells, lack of atmospheric disturbances
- Marine-continental influences: cold ocean currents, monsoons
- Soil: reduced soil moisture, increased ground reflectivity
- Atmospheric: dust reducing radiation, temperature inversions
- Anthropogenic: greenhouse effect from increased CO2
Drought causes:
- Reduced crop and livestock production
- Water supply problems
- Decreased resource availability
- Increased risk of forest fires
Climate Risk Planning
Predictive measures involve continuous observation of meteorological variables, particularly in high-risk areas identified through risk mapping. Short- and medium-term weather forecasts aid in predicting potentially catastrophic events. Preventive and corrective mechanisms include structural and functional measures.
Structural Measures
These aim to stabilize river flow through dams (hydraulic lamination), canals, and levees. However, dam failure, increased flows, and land impermeabilization can have negative consequences. Reforestation and soil conservation are crucial for water retention and runoff prevention.
Functional Measures
These involve civil protection plans (warnings, evacuations) based on risk maps. Regional planning is essential, especially in fertile river terraces often used for agriculture. Dry riverbeds frequently contain roads, settlements, and recreational areas, making unexpected flooding extremely dangerous. Spanish legislation (Water Act) establishes occupation zones in river terraces to mitigate flood risk:
- Servitude Area: 5m from the riverbank—all actions prohibited.
- Police Area: 100m from the margins—authorization needed for activities.
- Inundable Zone: theoretical flood zone with a 500-year return period (probability of a flood every 500 years). Use should be limited for safety.