Podcast
Questions and Answers
What is the primary method by which water infiltrates into the subsurface?
What is the primary method by which water infiltrates into the subsurface?
Soil saturation does not affect the availability of water to plants.
Soil saturation does not affect the availability of water to plants.
False
What percentage of precipitation typically infiltrates the subsurface?
What percentage of precipitation typically infiltrates the subsurface?
76%
The top of the saturated zone where soil spaces are completely filled with water is known as the ______.
The top of the saturated zone where soil spaces are completely filled with water is known as the ______.
Signup and view all the answers
Match the following components with their descriptions:
Match the following components with their descriptions:
Signup and view all the answers
Which of the following impacts does vegetation have on the water budget?
Which of the following impacts does vegetation have on the water budget?
Signup and view all the answers
Groundwater flow is typically slower compared to surface water flow.
Groundwater flow is typically slower compared to surface water flow.
Signup and view all the answers
What can a water budget result in if the precipitation and evaporation needs are not met?
What can a water budget result in if the precipitation and evaporation needs are not met?
Signup and view all the answers
What percentage of global irrigation and drinking water is supplied by groundwater?
What percentage of global irrigation and drinking water is supplied by groundwater?
Signup and view all the answers
Overconsumption of groundwater has no impact on its depletion rates.
Overconsumption of groundwater has no impact on its depletion rates.
Signup and view all the answers
What is the primary source of groundwater?
What is the primary source of groundwater?
Signup and view all the answers
The upper limit of the saturation zone is known as the _________.
The upper limit of the saturation zone is known as the _________.
Signup and view all the answers
Match the types of aquifers with their descriptions:
Match the types of aquifers with their descriptions:
Signup and view all the answers
Which statement correctly describes groundwater use in some U.S. states?
Which statement correctly describes groundwater use in some U.S. states?
Signup and view all the answers
Rural areas in the U.S. commonly use groundwater for 100% of their water supply.
Rural areas in the U.S. commonly use groundwater for 100% of their water supply.
Signup and view all the answers
What happens when groundwater is extracted at a rate higher than its natural replenishment?
What happens when groundwater is extracted at a rate higher than its natural replenishment?
Signup and view all the answers
What does ∆S represent in the soil water change equation?
What does ∆S represent in the soil water change equation?
Signup and view all the answers
Evapotranspiration includes both evaporation and transpiration from the soil and plants.
Evapotranspiration includes both evaporation and transpiration from the soil and plants.
Signup and view all the answers
What does PE stand for in the context of water demand?
What does PE stand for in the context of water demand?
Signup and view all the answers
The process that provides moisture to Earth’s surface is called __________.
The process that provides moisture to Earth’s surface is called __________.
Signup and view all the answers
Match the terms with their correct definitions:
Match the terms with their correct definitions:
Signup and view all the answers
A rain gauge is used to measure only the volume of rainfall.
A rain gauge is used to measure only the volume of rainfall.
Signup and view all the answers
What is the significance of using a wind shield with a rain gauge?
What is the significance of using a wind shield with a rain gauge?
Signup and view all the answers
Which method is used by Thornthwaite's indirect approach to estimate potential evapotranspiration?
Which method is used by Thornthwaite's indirect approach to estimate potential evapotranspiration?
Signup and view all the answers
Study Notes
Water in the Subsurface
- Water infiltrates through percolation, slowly passing through porous materials.
- Soil-moisture zone provides subsurface water for plant roots.
- Bound water in soil impacts plant water availability.
- 76% of precipitation infiltrates the subsurface; 85% returns to the atmosphere through evaporation or transpiration.
- Gravitational water percolates deeper during soil saturation.
- Water table marks the upper limit of the saturated zone, fully filled with water.
- Base flow occurs where the water table intersects stream channels, contributing to stream flow.
- Streams and groundwater flow into oceans, sustaining the hydrologic cycle.
- Some streams feed into closed lake basins, leading to evaporation or underground seepage.
- Groundwater flows slowly toward the sea, often intersecting the surface.
Water Budgets and Resource Analysis
- A water budget can be established for any area on Earth's surface.
- Evaluates the input and distribution of precipitation and evapotranspiration.
- Factors include evaporation, transpiration, surface runoff, and soil moisture storage.
- Timeframes for water budgets can range from minutes to years.
- Functions similarly to a financial budget, balancing inputs (precipitation) and outputs (evaporation, transpiration, runoff).
- Soil-moisture acts as a savings account, allowing for temporary storage and withdrawal of water.
- Water budget deficits or surpluses can affect crop yields.
- Thornthwaite developed methodologies to address irrigation and water use challenges based on climate influence on water supply and demand.
Groundwater Resources
- Groundwater supplies 80% of global irrigation and drinking water.
- Groundwater pollution threatens water quality and food security.
- Overconsumption leads to depletion beyond natural replenishment.
- 50% of the U.S. population relies on groundwater for freshwater access.
- In some states, groundwater meets 85% of water needs; rural areas may rely entirely on it.
- Groundwater withdrawal in Canada and the U.S. rose over 150% from 1950 to 2000.
The Groundwater Environment
- Precipitation is the primary groundwater source, moving down as gravitational water.
- Water travels through the unsaturated zone, where some pore spaces hold air.
- The saturated zone stores water completely filling soil pore spaces, bounded by an impermeable layer.
- The upper limit of the saturation zone is called the water table, which directs groundwater flow.
Aquifers and Wells
- Aquifers are permeable subsurface materials allowing groundwater flow.
- Unconfined aquifers have permeable layers above and impermeable rock below.
- Confined aquifers are surrounded entirely by impermeable layers.
- Aquitards are low-permeability layers that cannot conduct usable water.
- Humans extract groundwater through wells drilled until the water table is reached.
Components of the Water Budget
- Soil Water Change Rate Formula:
∆S = P - ET
where ∆S is soil moisture change, P is precipitation, ET is evapotranspiration, and ∆t indicates time change.
Water Supply: Precipitation
- Precipitation occurs in various forms, including rain, snow, and hail.
- Rain gauges measure rainfall and snowfall depth, weight, or volume.
- Wind shields are used to measure precipitation accurately by minimizing losses from angular raindrops.
Water Supply: Precipitation Measurements Worldwide
- Over 100,000 locations monitor global precipitation levels.
- Maps display global annual precipitation averages.
Water Demand: Potential Evapotranspiration
- Evapotranspiration represents actual water loss to the atmosphere.
- Potential evapotranspiration (PE) indicates water loss under ideal moisture conditions.
- A dry bowl analogy illustrates that if replenished, total demand equals PE; if not, the deficit forms.
- Actual evapotranspiration (AE) equals PE minus any deficit.
Water Demand: Potential Evapotranspiration Measurement Tools
- Evaporation pans or evaporimeters measure evapotranspiration, with automatic water replacement.
- Lysimeters are used to isolate soil and measure moisture.
- Rain gauges can record precipitation next to lysimeters.
Thornthwaite's Methodology
- Thornthwaite's indirect method estimates PE for midlatitude locations using mean air temperature and day length.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the critical concepts of subsurface water management, including infiltration, percolation, and the significance of the soil-moisture zone. Understand how soil composition affects plant water availability and the role of precipitation in subsurface water dynamics. This quiz provides a comprehensive overview of water's journey beneath the surface.
