Hydrology and the Hydrologic Cycle Quiz

Hydrology and the Hydrologic Cycle

• Hydrology studies the occurrence, distribution, and disposal of water on Earth.
• The hydrologic cycle refers to the continuous movement of water through various phases in nature.

Precipitation

• Precipitation includes rainfall, snow, hail, fog drop, slush, and sleet, with rain being predominant.
• Approximately 505,000 km³ (121,000 mi³) of water falls as precipitation annually.
• Of this, 398,000 km³ (95,000 mi³) falls over oceans, while land receives 107,000 km³ (26,000 mi³) in rainfall.
• Philippines experiences an average mean rainfall of 2,030 mm yearly, with a range from 965 to 4,064 mm.

Infiltration and Percolation

• Infiltration is the process of water entering the soil, crucial for irrigation and flood control.
• Replenishes soil moisture and supports streamflows during dry periods.
• Water travels through soil, termed percolation, and can be absorbed by plants, evaporate, or recharge groundwater.

Surface Runoff

• Surface runoff is precipitation excess flowing over the landscape when it exceeds infiltration rates.
• It directs water to urban sewers, retention basins, rivers, lakes, and wetlands.

Groundwater

• Groundwater moves under gravity from high to low elevations and contributes to baseflow in springs, lakes, and rivers.

Evaporation and Transpiration

• Evaporation transforms water from liquid to gas, influenced by air dryness and temperature differences.
• Transpiration involves water escape from plants through stomata, tiny openings on leaves.

Evapotranspiration

• Evapotranspiration is the combined process of evaporation and transpiration, essential in determining irrigation needs and water availability.

Importance of Hydrology in Engineering

• Hydrology is critical for managing water, influencing fields from geology to engineering.
• Applications include flood and drought forecasting, climate change assessments, and reservoir management.

Vulnerability of the Philippines to Natural Disasters

• Ranked 4th most vulnerable nation to natural calamities from 1995-2015.
• The country faces severe drought approximately every 4 to 5 years, impacting crop production significantly.

Climate Change Impact on Agriculture

• Projected declines in corn yield: 44% by 2020 and 35% by 2050 due to temperature and rainfall fluctuations.
• Significant rice yield declines attributed to El Niño events and rising seasonal mean temperatures, resulting in economic losses of PHP163.6 billion in agriculture (2011-2015).