Description
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Source: Guardian
Context
Flash floods began on July 4 and have killed at least 81 people in Texas Hill Country, making it one of the deadliest deluges in the United States in the last century.
What are Flash foods?
- Flash floods are sudden, intense floods that occur within minutes to hours of heavy rainfall, dam break, or rapid snowmelt. Unlike regular floods, flash floods happen quickly and with little warning, often in low-lying areas, dry riverbeds, or urban zones with poor drainage.
- These floods are extremely dangerous due to their speed and force, capable of sweeping away vehicles, damaging infrastructure, and endangering lives. They are commonly triggered by cloudbursts, thunderstorms, or cyclonic systems.
- Flash floods are increasingly frequent due to climate change, deforestation, and unplanned urbanization, making early warning systems and disaster preparedness essential for minimizing damage and casualties.
Geographical Factors
- Texas Hill Country is a semi-arid region with soils that absorb little moisture. Heavy rain swiftly flows off the surface and into small streams.
- These creeks eventually merge into rivers that grow fast. The Balcones Escarpment, a steep geological elevation, causes moist air from the Gulf of Mexico to climb and condense, resulting in heavy rain.
- This region's distinct terrain makes it vulnerable to sudden and catastrophic flash floods.
Climate change
- Climate change has intensified rainfall events around the planet. Warmer air retains more moisture, around 7% more per degree Celsius rise in temperature. As a result, storms become more intense and last longer.
- Warmer waters in the Gulf of Mexico contribute to increased evaporation and moisture movement.
- These factors, together, cause catastrophic rainfall and flooding, as shown in the recent Texas disaster.
Warning Systems and Emergency Response Issues
- Residents in the worst-hit districts reported receiving little or no advance warning of the floods. The National Weather Service (NWS) offered early warnings, but they were too late for an effective evacuation.
- Local emergency alerts were delayed, raising questions about the effectiveness of warning systems.
- Staff reduction at the NWS in prior years have been questioned as a potential impact influencing forecasting and communication.
Source: Indian Express
Practice Question:
Q. The recent Texas Floods highlight the increasing vulnerability of urban areas to extreme weather events. Which of the following factors contribute to urban flooding, both in India and globally?
- Loss of natural drainage systems due to urban expansion
- Climate change leading to extreme rainfall events
- Poor solid waste management and blocked drainage
- Increase in agricultural activities in urban core areas
Select the correct answer using the code given below:
A) 1 and 2 only
B) 1, 2 and 3 only
C) 2, 3 and 4 only
D) 1, 3 and 4 only
Correct Answer:
B) 1, 2 and 3 only
Explanation:
- Statement 1: Correct. Unplanned urban expansion often encroaches on lakes, wetlands, and natural drainage channels, increasing flood risk.
- Statement 2: Correct. Climate change contributes to higher frequency and intensity of extreme weather events, including heavy rainfall.
- Statement 3: Correct. Improper waste disposal blocks drains, worsening waterlogging and floods.
- Statement 4: Incorrect. Increase in agriculture is not typical in urban cores and does not directly contribute to urban flooding.
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