Water Systems and Hydrological Processes

Flashcards about Water Systems, Hydrological Cycle, Human Impacts, Properties of Water, Carbon Sequestration, Ocean Acidification, Water Stratification, Upwellings, and Ocean Circulation.

What percentage of the Earth's water is freshwater?

Approximately 2.5%

Where is the majority of freshwater stored?

Glaciers and ice sheets (approximately 69%)

Besides glaciers, where is the next largest store of freshwater found?

Groundwater (approximately 30%)

Name the two driving forces of the hydrological cycle.

Gravity and solar radiation

What transformation process is driven by the Sun heating water?

Evaporation

What force pulls condensed water back to Earth as precipitation?

Gravity

Is the global hydrological cycle considered an open or closed system?

Closed system

What are the main stores within the hydrological cycle?

Oceans, glaciers/ice caps, groundwater/aquifers, surface freshwater, atmosphere

Give an example of a transformation flow in the hydrological cycle

Evaporation, condensation, melting, freezing, evapotranspiration, sublimation

Give an example of a transfer flow in the hydrological cycle

Surface runoff, infiltration, percolation, stream flow, groundwater flow, advection, precipitation

Define evaporation.

The process by which liquid water changes into a gaseous state and enters the atmosphere.

Define transpiration.

The process by which plants release water vapor through stomata in their leaves.

Define melting.

The process by which ice or snow changes into liquid water.

Define evapotranspiration.

The combined process of evaporation and transpiration.

Define freezing.

The process by which liquid water changes into a solid state.

Define advection.

The wind-blown movement of water vapor or condensed/frozen water droplets (clouds).

Define sublimation.

The direct transition of water from a solid to a vapor state.

Define condensation.

The process by which water vapor transforms into liquid water.

Define precipitation.

The process of water falling from the atmosphere to the Earth's surface.

Define surface runoff.

The movement of water over the Earth's surface.

Define infiltration.

The process of water seeping into the soil from the surface.

Define percolation.

The downward movement of water through the soil and rock layers.

Define stream flow.

The movement of water in streams, rivers, or other water bodies.

Define groundwater flow.

The movement of water through pores and spaces in underground soil and rock.

Name three human activities that significantly impact the hydrological cycle.

Agriculture (irrigation), deforestation, and urbanization

How does irrigation impact the hydrological cycle?

Modifies water distribution and availability, increases evapotranspiration, can lead to increased surface runoff, water pollution and nutrient imbalances.

How does deforestation impact the hydrological cycle?

Increases surface runoff, reduces evapotranspiration, increases erosion, reduces groundwater recharge, and alters stream flow.

How does urbanization impact the hydrological cycle?

Replaces permeable surfaces with impermeable surfaces, reduces groundwater recharge, increases flooding, diminishes water availability, increases surface runoff, and may increase local temperatures.

What is meant by steady state of a water body?

The balance between inputs and outputs, ensuring water level remains constant over time.

Give examples of water inputs for a water body.

Precipitation, surface runoff, groundwater inflow

Give examples of water outputs for a water body

Evaporation, river outflow, groundwater outflow, agricultural extraction

What is meant by sustainable water harvesting?

Taking water from a water body at a rate that does not exceed the rate of natural replenishment

What happens if total outputs are greater than total inputs in a water body?

The water body will decrease in size, leading to a water deficit.

What is polarity in water molecules?

Uneven distribution of charge with a slight positive charge near hydrogen atoms and a slight negative charge near the oxygen atom.

What is the role of polarity in making water the universal solvent?

It allows water to dissolve many substances, especially salts and polar molecules, which aids in the transport of nutrients and minerals.

Describe cohesion in water.

Hydrogen bonding between water molecules, making them 'stick' together, forming droplets and surface tension.

Describe adhesion in water.

Water molecules sticking to other materials, aiding water movement through narrow spaces like in capillary action.

Why is transparency an important property of water?

Allows sunlight to penetrate underwater, enabling photosynthesis in aquatic plants and algae which supports aquatic food webs

Define specific heat capacity.

The amount of heat energy required to raise the temperature of a substance by a certain amount.

How does water's high specific heat capacity affect the environment?

Regulates environmental and body temperatures, maintaining stable conditions for life. Oceans absorb heat during the day and release it slowly at night, moderating coastal climates.

At what temperature is water most dense?

4°C

Why is it important that ice is less dense than liquid water?

Ice floats, providing habitat and insulation for aquatic life in cold environments.

How does temperature affect gas solubility in water?

Cold water generally holds more dissolved oxygen than warm water.

Explain why oceans are considered a carbon sink.

Oceans absorb large amounts of carbon dioxide (CO₂) from the atmosphere, helping to slow the increase of CO₂.

What is ocean acidification?

As CO₂ is absorbed by the ocean, it reacts with seawater to form carbonic acid, lowering the pH of the water.

How does ocean acidification affect marine life?

It harms marine life, especially species with calcium carbonate shells, by reducing their ability to form and maintain their shells.

What is short-term carbon sequestration in the ocean?

CO₂ dissolving in seawater, contributing to ocean acidification.

What is long-term carbon sequestration in the ocean?

The accumulation of carbon in sediments and organisms, such as organic and inorganic carbonates, over geological time.

What is water stratification?

The layering of water in a body of water due to differences in temperature and density.

How does temperature affect water density?

Warmer water is less dense and stays on the surface, while colder water is denser and sinks to the bottom.

What is the thermocline?

A transition layer in a body of water where temperature drops rapidly with increasing depth.

How do stratified water layers differ in oxygen and nutrient content?

Surface water is usually oxygen-rich, while deep colder layers may be oxygen-poor. Deep water often contains higher concentrations of nutrients.

How does global warming affect ocean stratification?

Warming surface waters are becoming less dense, increasing the separation between layers and reducing vertical mixing.

How does salinity affect water stratification?

Higher salinity makes water denser, while lower salinity makes water less dense, intensifying ocean stratification in polar regions due to ice melt.

What are upwellings?

Areas in oceans and freshwater bodies where cold, nutrient-rich water rises from deep below to the surface.

How do wind-driven upwellings occur?

Strong winds blow across the surface of the ocean, pushing warm surface water away from the coast, allowing cold water from the deep to rise.

What are the benefits of upwellings?

Nutrient-rich water supports large populations of phytoplankton, attracting fish, marine mammals, and seabirds.

What are some limitations and risks of upwellings?

Overfishing can deplete fish populations, and climate change could disrupt upwelling cycles and alter nutrient availability.

What is thermohaline circulation?

The global ocean current system driven by variations in temperature and salinity, affecting water density, also known as the ocean conveyor belt.

How does thermohaline circulation work?

Cold, salty water sinks in polar regions and flows southward, pulling surface water along, creating a continuous flow that transfers heat around the globe.

What is the role of the Gulf Stream in thermohaline circulation?

It brings warm water from the Gulf of Mexico up the eastern coast of the US and across to Western Europe, moderating the climate.

How does climate change threaten thermohaline circulation?

Melting ice caps in Greenland and Antarctica are adding freshwater to the oceans, reducing salinity and density of surface waters, potentially slowing down or stopping the conveyor belt.

How does increased irrigation impact evapotranspiration rates?

Artificially high evapotranspiration rates

What leads to higher surface run-off rates in agriculture?

Water is supplied faster than the soil can absorb it

What term refers to the clearing or removal of forests?

Deforestation

What role do forests play in the hydrological cycle?

Act like natural sponges and absorb rainfall

What do forests facilitate in the hydrological cycle?

Infiltration

What is released into the atmosphere as trees are removed?

Reduced moisture

What is the name for the process of transforming natural landscapes into urban areas?

Urbanization

What is replaced by impermeable surfaces?

Permeable surfaces, such as soil and vegetation

What do impermeable surfaces prevent?

Inflitration

What do urban areas typically have that are designed to quickly remove excess water?

Efficient drainage systems

What effect increases evaporation rates?

The urban heat island effect

What are the components of sustainable water harvesting?

Total inputs and outputs of a water body

What must happen to prevent aquifer depletion?

Groundwater extraction must be balanced with recharge rates

What is the uneven distribution of charge in a water molecule called?

Polarity

What is the result of hydrogen bonding between water molecules?

Cohesion

What does hydrogen bonding result in within a plant?

Flow of water molecules through the plant in a continuous stream

What does the depth sunlight penetration determine?

The zone where photosynthetic organisms can survive

How is carbon sequestered in the ocean long-term?

Through biological processes using marine organisms and sediment

What does warming surface water prevent between water layers?

Mixing of oxygen and nutrients

What is the result when ice caps melt in polar regions?

Less concentrated salinity

What bodies of water are strongly affected when seasonal winds blow across them?

Stratified lakes and oceans