Unit 1 Flashcards
What is hydrology?
The science of water, tracking where it falls, flows, hides, or vanishes.
Hydrology encompasses both surface and underground water as well as atmospheric water vapor.
What are the two main branches of hydrology?
- Scientific Hydrology
- Engineering Hydrology
Scientific hydrology focuses on theory, while engineering hydrology is practical and applied.
What does scientific hydrology focus on?
Pure theory, chasing ‘why’ and ‘how’ for the sake of knowledge.
It is more academic and detached compared to engineering hydrology.
What is engineering hydrology?
Applied hydrology focused on practical applications and solving real-world water issues.
It involves bending water to human needs and addressing challenges like floods and droughts.
List three tasks of engineering hydrology.
- Estimate Water Resources
- Decode Processes
- Fight Problems
Each task involves specific methods and data to manage water effectively.
What does estimating water resources involve?
Quantifying rivers, aquifers, and rain using data like MCM, TMC, and CGWB.
This is crucial for understanding available water supply.
What processes does engineering hydrology decode?
- Precipitation
- Runoff
- Evapotranspiration
Understanding these processes helps in managing and predicting water flow.
What are some problems that engineering hydrology aims to fight?
- Floods
- Droughts
Strategies to predict and manage these issues are essential for safety and sustainability.
True or False: Engineering hydrology is only concerned with theoretical concepts.
False
Engineering hydrology is focused on practical applications and real-world issues.
Fill in the blank: This book serves as a _______ for civil engineers dealing with water management.
[field manual]
It combines qualitative and quantitative approaches to water management.
What is the main purpose of the book mentioned in the text?
To provide practical tools for managing water issues like floods and shortages.
It is designed for civil engineers working on infrastructure like dams and bridges.
What is the significance of understanding hydrology in engineering?
It allows engineers to master water processes and effectively address challenges like floods and droughts.
Knowledge of hydrology is crucial for successful water management.
What is transpiration?
Water’s escape act through plants, where roots suck it from the soil and it is released as vapor through leaves.
Transpiration is a biological process and is dependent on the presence of plants.
What are the main components involved in transpiration?
Roots, soil, vapor, leaves, stomata.
Stomata are tiny pores on leaves that allow gas exchange.
How is transpiration measured?
Indirection, as it is hard to isolate.
It represents a significant portion of water loss in ecosystems with vegetation.
Define evapotranspiration.
The total water-to-vapor process, which includes both transpiration and evaporation.
Evapotranspiration is a key concept in understanding water cycles.
What is evaporation?
The process of water lifting off surfaces like soil, puddles, lakes, and rivers, driven by heat, wind, and dryness.
Evaporation does not require any biological processes.
What are PET and AET in the context of evapotranspiration?
PET (Potential Evapotranspiration) is the maximum possible under unlimited water; AET (Actual Evapotranspiration) is the actual amount given the available water.
These terms help in assessing water availability and loss.
How do transpiration and evapotranspiration differ?
Transpiration is a subset involving only plants, while evapotranspiration includes both plants and abiotic surfaces.
Evapotranspiration is broader and encompasses all forms of water vaporization.
In which environments does evaporation dominate?
Deserts.
In arid regions, evaporation plays a more significant role compared to transpiration.
In which environments does transpiration dominate?
Jungles or areas with dense vegetation.
In these ecosystems, plants significantly contribute to water loss through transpiration.
Why is understanding evapotranspiration important in hydrology?
It affects runoff, river health, and water budgets.
Tracking evapotranspiration is essential for managing water resources.
True or False: Transpiration can occur without the presence of plants.
False.
Transpiration is exclusively linked to living plants.
Fill in the blank: Evapotranspiration is the combination of _______ and evaporation.
transpiration.
This highlights the interconnectedness of biological and physical processes in the water cycle.
What are the three key components in the cycle discussed?
Precipitation, runoff, evapotranspiration
Define precipitation in the context of the cycle.
The input—rain, snow, whatever falls. It’s the fuel.
What is runoff?
Water that bolts—rivers, floods, surface chaos.
What does evapotranspiration (ET) refer to?
The vapor thief that feeds on precipitation.
True or False: Precipitation benefits both runoff and evapotranspiration.
True
How do precipitation, runoff, and evapotranspiration interact?
They drive and steal from each other in a zero-sum system.
What happens when evapotranspiration is high?
Runoff decreases.
What can heavy rain on dry ground lead to?
Runoff winning over evapotranspiration.
Fill in the blank: Evapotranspiration _______ on precipitation.
sucks it up
In what conditions does runoff take precedence over evapotranspiration?
Wet soil, cool air.
What tools do engineers use to track the interaction between these components?
- CN (runoff potential)
- AET (real vapor loss)
What does a big storm hitting imply for the cycle?
Precipitation is huge; ET grabs what it can, infiltration takes a bite, and runoff claims the rest.
What is the relationship between evapotranspiration and flood risk?
More ET means less flood.
What is the relationship between runoff and vapor storage?
More runoff means less vapor or storage.
Describe the dynamic between precipitation, runoff, and evapotranspiration.
They are rivals eating the same pie; when one grows fat, the other shrinks.
What is meant by ‘predatory balance’ in the context of these components?
They clash and feed off each other in a competitive cycle.
What is the first step of the hydrologic cycle?
Precipitation
Includes rain, snow, and hail falling from clouds onto various surfaces.
What processes are driven by precipitation?
- Runoff
- Infiltration
- Evapotranspiration (ET)
Precipitation acts as the starting point for these processes.
What is interception in the context of the hydrologic cycle?
Water caught by plants, leaves, roofs before it hits the ground
Delays infiltration and runoff, with some water evaporating back.
What factors dictate the amount of water that infiltrates into the soil?
- Available moisture content (AMC)
- Capillary number (CN)
- Soil type (pervious material)
These factors influence how much water sinks versus stays on the surface.
What is transpiration?
Plants pulling water from soil and exhaling it as vapor
It is part of the evapotranspiration process.
What drives transpiration in plants?
- Sun’s heat
- Plant health
No infiltration means no transpiration can occur.
What is evaporation from land?
Water lifting off bare soil, puddles, and surfaces without the need for life
It feeds clouds and combines with transpiration to form total ET.
What is surface runoff?
Water racing off into rivers, streams, and floods
It occurs when infiltration and ET do not capture all the water.
What is the largest source of evaporation in the hydrologic cycle?
Evaporation from the ocean
It significantly contributes to global evapotranspiration.
What is groundwater flow?
Water creeping underground, fed by infiltration
It is vital for maintaining streams and ocean levels.
What is deep percolation?
Water plunging deeper into aquifers and rock fractures
It is part of infiltration’s long-term process of recharging water reserves.
Fill in the blank: The hydrologic cycle is also known as the _______.
Water cycle
It describes the continuous movement of water on, above, and below the Earth’s surface.
True or False: Evapotranspiration (ET) is the sum of evaporation and transpiration.
True
ET combines both processes to represent total water loss to the atmosphere.
What is the hydrologic cycle?
Water’s endless war—shapeshifting (liquid, solid, gas) and moving relentlessly across oceans, land, and air.
Where does the hydrologic cycle start?
Oceans—solar radiation rips water into vapor via evaporation (step 7), the biggest ET source.
How does vapor become clouds?
Winds haul ocean vapor skyward, forming clouds that move over land.
What losses occur during precipitation?
Mid-air evaporation and interception by plants or roofs (step 2) steal water before it lands.
What are the three fates of water hitting land?
Infiltration (sinks into soil), evapotranspiration (stolen by sun and plants), runoff (races to streams).
What controls infiltration?
Soil type (pervious material), wetness (AMC), and rain intensity—CN models the split to groundwater .
Why is the hydrologic cycle complex?
It’s chaotic—no start, no end—spanning transportation, storage, and state changes across endless paths and timescales.
What is transportation in the cycle?
Water moving—rain falling, rivers rushing, groundwater creeping.
What is storage in the cycle?
Water parking—soil, aquifers, lakes, ice
What are the state changes in the cycle?
Liquid to vapor (evaporation), vapor to liquid (rain), liquid to solid (snow), solid to liquid (melt).
What is depression storage?
Surface traps—ponds, lakes, reservoirs—holding water.
What is soil moisture storage?
Water in soil—pre-infiltration, post-rain—fuels transpiration, delays runoff.
What is groundwater storage?
Aquifers and deep rock —slow, hidden reserves
What keeps the cycle’s resources constant?
Earth’s water is fixed—sun drives, gravity enforces, no new water, just recycling.
How do humans mess with the cycle?
Dams trap runoff, irrigation taps groundwater, paving kills infiltration, vapor suppression fights ET.
What’s the role of the cycle in water power?
Dams harness stream flow—runoff’s the fuel.
What is the difference between drainage area, drainage basin, watershed and catchment area
They are all the same, different names given to the same concept, - land area draining to a specific point or land surface that collects and funnels water to a specific point, like stream or lake.
