LE2 Flashcards
The Philippines receives an average of ____________. However, this amount is not evenly distributed over time and space.
2,360 mm of rainfall evert year
What is the average annual rainfall is approximately 2,360 mm. but this varies geographically from __________.
960 mm in southeast Mindanao to over 4,050 mm in central Luzon.
What type of Philippine’s Climate is two pronounced season: dry from November to April wet during the rest of the year.
Type 1
What type of Philippine’s Climate is No dry season with a very pronounced rainfall from November to January.
Type II
What type of Philippine’s Climate is Seasons are not very pronounced relatively dry from November to April and wet during the rest of the year.
Type III
What type of Philippine’s Climate is Rainfall is more or less evenly distributed through the year.
Type IV
Any product of condensation of atmospheric water vapor in the free air or at earth’s surface.
Hydrometer
Consists of tiny liquid water droplets, usually with diameters between 0.1 and 0.5 mm, has slow settling rate.
Drizzle or mist
Consists of liquid water drops mostly larger than 0.5 mm in diameter.
Rain
Ice coating formed on exposed surfaces by the freezing of supercooled water deposited by rain or drizzle.
Glaze
White opaque deposit of ice granules more or less separated by trapped air and formed by rapid freezing of supercooled water drops impinging on exposed objects.
Rime
Composed of ice crystals, chiefly in complex branched hexagonal form, and often agglomerated into snowflakes.
Snow
Precipitation in the form of balls of ice, produced in convective clouds.
Hail
Consists of transparent, globular, solid grains of ice formed by the freezing of raindrops or refreezing or largely melted ice crystals falling through a layer subfreezing air near the earth’s surface.
Sleet
Caused by unequal heating of land masses.
Convective Lifting
Mechanical lifting over mountain barriers.
Orographic Lifting
Lifting of warm air on one side of a frontal surface over colder, denser air on the other side (front).
Frontal Lifting
Bounding surface between two distinct air masses.
Frontal Lifting
Lifting of air converging into a low-pressure area.
Cyclonical Lifting
Three (3) rainfall characteristics
- Intensity
- Duration
- Frequency
It is expressed in mm/hr
Intensity
It is period within which magnitude of hydrologic event will be equaled or exceeded once in the average.
Frequency
It is 8” diameter standard rain gage – has a measuring tube 1/10 of the area of the collector.
Non-recording rain gage
It is accumulated rain
Weighing type
Rise of float with increasing catch of rainfall is recorded.
Float recording
The Isohyetal method generally provides a more accurate representation of precipitation distribution, especially in regions with highly variable rainfall.
More Accurate than Thiessen Polygons
It helps estimate precipitation over areas where rainfall stations are few, as long as there’s a reasonable distribution of stations.
Works Well with Sparse Data
Unlike simple methods like Thiessen polygons, which assume a uniform distribution of rainfall within each polygon, the Isohyetal method allows for more detailed and realistic representation of rainfall gradients.
Provides Detailed Distribution
The process by which water on the ground surface enters the soil.
Infiltration
Movement of water through the soil profile going to grounwater.
Percolation
Infiltration per unit time; expressed in volume per unit time per unit area depth per unit time.
Infiltration rate
Velocity of flow caused by a unit gradient; flow through soils in any direction.
Hydraulic conductivity
Used interchangeably with hydraulic conuctivity.
Permeability
The summation of the depth of water absorbed by a soil in a specified elapsed time in reference to the time of initial water application.
Cumulative infiltration
The infiltrated water first meets the moisture deficiency if any excess water moved vertically downwards to reach the ground water table. the vertical water movement is called _________.
Percolation
Often rich in humus and minerals
Topsoil (A horizon)
Poor in humus, rich in minerals
Subsoil (B horizon)
Little or no plant or animal life
Weathered rock fragments (C horizon)
Infiltration is a primary method for replenishing groundwater supplies, which are crucial for drinking water, irrigation, and industrial use.
Groundwater Recharge
By allowing water to enter the soil, infiltration reduces surface runoff, which can help prevent flooding and erosion.
Reducing Runoff
Infiltration helps maintain soil moisture levels, supporting plant growth and sustaining ecosystems.
Supporting Ecosystems
Other importance of soil infiltration:
- Water Conservation
- Reduced soil erosion by runoff
- Irrigation (manner of application)
- Critical and maximum depth determination in water reservoir design
The larger the pore size and the greater the continuity of the pores, the greater is the infiltration rate.
Soil
Formation of thin compact layer on the surface as a result of severe breakdown of soil structure caused by the beating action of raindrops and flow of water over the surface.
Surface sealing or Puddling of soil
The clay surfaced soil are compacted even by the impact of rain drops which reduce infiltratoin.
Soil Characteristics / Compaction
Clay has ______ and ______ slow infiltration compared to sand and gravely soil.
Low and Slow
The more saturated the loose Earth material are, the less infiltratoin.
Soil’s degree of saturation
Typically refers to the collection of standing water at the ground surface due to the presence of an impermeable layer within the soil.
Ponding
The amount, intensity, and duration of precipitation significantly impact infiltration. Heavy, short-duration rainfall can lead to more runoff, while light, long duration rainfall allows more water to infiltrate.
Precipitation
Vegetation and land use affect infiltration. Vegetated areas typically have higher infiltration rates due to root systems creating pathways for water.
Land Cover
_______ vegetation, _______ infiltration
More ; Slower
A portion of the stream flow that is not runoff; it is water from the ground, flowing into the channel over a long time and with a certain delay.
Base Flow
Lateral movement of water
Base Flow
Rivers near city has _______ baseflow because of impervious surface.
Low
Steeper sloped tend to have higher runoff and lower infiltration rates compared to flat areas.
Slope of the land
Chemicals that improve the soil structure hence increase infiltration ; other chemicals cause soil particles to swell and to become hydrophilic hence reduce infiltration.
Use of soil additives
Water first enters the soil at the surface, influenced by gravity and capillary forces.
Surface Entry
Water moves vertically and horizontally through soil layers, filling pore spaces and cracks.
Movement Through Soil
Some infiltrated water reached deeper soil layers and recharges groundwater aquifers.
Recharge of Groundwater
Involves direct measurement of water applied and water flowing from the field.
Direct Measurement
Showed that when the rainfall rate i exceeds the infiltration rate f, water infiltrates the surface soils at a rate that generally decreases in time.
Horton (1933)
The capacity decreases with time and ultimately reaches a constant rate, caused by filling of soil pores with water, which reduces capillary suntion.
Horton infiltration capacity curve
