Water in the Subsurface
24 Questions
0 Views

Water in the Subsurface

Created by
@IllustriousCarnelian1231

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary method by which water infiltrates into the subsurface?

  • Evaporation
  • Percolation (correct)
  • Transpiration
  • Surface runoff

    • Soil saturation does not affect the availability of water to plants.

    False

    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 ______.

    <p>water table</p> Signup and view all the answers

    Match the following components with their descriptions:

    <p>Soil-moisture zone = Subsurface water accessible to plant roots Base flow = Water discharging from groundwater to streams Water budget = Balancing input and output of water resources Thornthwaite's methodology = Used to solve irrigation and water use problems</p> Signup and view all the answers

    Which of the following impacts does vegetation have on the water budget?

    <p>Affects both evaporation and transpiration</p> Signup and view all the answers

    Groundwater flow is typically slower compared to surface water flow.

    <p>True</p> Signup and view all the answers

    What can a water budget result in if the precipitation and evaporation needs are not met?

    <p>Surplus or deficit</p> Signup and view all the answers

    What percentage of global irrigation and drinking water is supplied by groundwater?

    <p>80%</p> Signup and view all the answers

    Overconsumption of groundwater has no impact on its depletion rates.

    <p>False</p> Signup and view all the answers

    What is the primary source of groundwater?

    <p>Precipitation</p> Signup and view all the answers

    The upper limit of the saturation zone is known as the _________.

    <p>water table</p> Signup and view all the answers

    Match the types of aquifers with their descriptions:

    <p>Unconfined Aquifer = Bounded by an impermeable layer below Confined Aquifer = Bounded by impermeable layers above and below Aquitard = Layer with low permeability that does not conduct usable water</p> Signup and view all the answers

    Which statement correctly describes groundwater use in some U.S. states?

    <p>Some states rely on groundwater for 85% of their water needs.</p> Signup and view all the answers

    Rural areas in the U.S. commonly use groundwater for 100% of their water supply.

    <p>True</p> Signup and view all the answers

    What happens when groundwater is extracted at a rate higher than its natural replenishment?

    <p>Depletion of groundwater resources</p> Signup and view all the answers

    What does ∆S represent in the soil water change equation?

    <p>Change in soil moisture</p> Signup and view all the answers

    Evapotranspiration includes both evaporation and transpiration from the soil and plants.

    <p>True</p> Signup and view all the answers

    What does PE stand for in the context of water demand?

    <p>Potential Evapotranspiration</p> Signup and view all the answers

    The process that provides moisture to Earth’s surface is called __________.

    <p>precipitation</p> Signup and view all the answers

    Match the terms with their correct definitions:

    <p>Precipitation = Water supplied to the Earth's surface Evapotranspiration = Total water expenditure to the atmosphere Potential Evapotranspiration = Water that would evaporate and transpire under optimal conditions Soil Moisture Change = Net moisture change in the soil over time</p> Signup and view all the answers

    A rain gauge is used to measure only the volume of rainfall.

    <p>False</p> Signup and view all the answers

    What is the significance of using a wind shield with a rain gauge?

    <p>It reduces underestimation by catching raindrops that arrive at an angle.</p> Signup and view all the answers

    Which method is used by Thornthwaite's indirect approach to estimate potential evapotranspiration?

    <p>Mean air temperature and daylength</p> 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.

    Quiz Team

    Related Documents

    Geosystems: An Introduction to Physical Geography PDF

    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.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser