Humans are changing the water cycle in multiple significant ways, both directly and indirectly. Major human activities altering the water cycle include:

• Damming rivers for hydroelectric power and water storage, which disrupts the natural flow of water, affects aquatic ecosystems, and changes sediment and water distribution upstream and downstream.
• Withdrawing water from lakes, rivers, and groundwater for domestic, agricultural (irrigation), and industrial use, which decreases natural runoff and alters local water availability.
• Deforestation, which reduces transpiration (the release of water vapor from trees), leading to drier local atmospheres and changes in precipitation patterns.
• Agriculture, especially irrigation, changes water distribution by moving large volumes of water from natural sources to farms, increasing runoff and salinity.
• Contributing to climate change through greenhouse gas emissions, which intensifies the water cycle by increasing evaporation, altering precipitation patterns, accelerating glacial melt, and causing more frequent droughts and floods.

These human impacts affect local and global water availability, ecosystem health, and water management practices, sometimes causing significant regional shifts in the water cycle beyond natural variability.

Direct Changes

• Constructing dams alters water flow, ecosystem connectivity, and sediment transport.
• Water withdrawals for irrigation decrease river flow and groundwater levels.
• Deforestation reduces atmospheric moisture and affects rainfall.

Indirect Changes via Climate Change

• Increased temperatures raise evaporation rates.
• Altered precipitation patterns lead to more intense storms and prolonged droughts.
• Melting ice sheets raise sea levels and impact water storage.

Regional Examples

• In North China, drought conditions persist due to over-pumping groundwater for irrigation, which affects water cycle variables like evapotranspiration and runoff.

Human activities have thus significantly modified the natural water cycle, requiring adaptive management and conservation efforts to reduce negative impacts and maintain water sustainability.