Podcast
Questions and Answers
Which satellite sensor is primarily used for measuring soil moisture?
Which satellite sensor is primarily used for measuring soil moisture?
- Geostationary Operational Environmental Satellite (GOES)
- Tropical Rainfall Measuring Mission (TRMM)
- Soil Moisture and Ocean Salinity (SMOS) (correct)
- Advanced Microwave Sounding Unit (AMSU)
Which of the following methods is used to determine the average rainfall over an area by assigning influence zones to each rain gauge station?
Which of the following methods is used to determine the average rainfall over an area by assigning influence zones to each rain gauge station?
- Thiessen polygon method (correct)
- Isohyetal method
- Hyetograph method
- Arithmetic mean method
What does the term 'residence time' refer to in the context of hydrological fluxes?
What does the term 'residence time' refer to in the context of hydrological fluxes?
- The time required for water in a drainage basin to be completely replaced (correct)
- The amount of water that flows out of a region
- The volume of water stored in a control volume
- The rate at which water flows into a drainage basin
What is the primary purpose of a hyetograph?
What is the primary purpose of a hyetograph?
Which of the following satellite missions is designed to measure total water storage, soil moisture, and groundwater?
Which of the following satellite missions is designed to measure total water storage, soil moisture, and groundwater?
If a catchment area of $1 \text{ km}^2$ receives 2 cm of rainfall, what is the volume of water collected?
If a catchment area of $1 \text{ km}^2$ receives 2 cm of rainfall, what is the volume of water collected?
What is the average residence time of water in the atmosphere?
What is the average residence time of water in the atmosphere?
Based on rainfall intensity, how is rainfall classified as 'moderate rain'?
Based on rainfall intensity, how is rainfall classified as 'moderate rain'?
What distinguishes a recording rain gauge from a non-recording rain gauge?
What distinguishes a recording rain gauge from a non-recording rain gauge?
Considering the formula for calculating the mean residence time, $\text{T} = \frac{\text{M}}{\text{F}}$, what does 'M' represent?
Considering the formula for calculating the mean residence time, $\text{T} = \frac{\text{M}}{\text{F}}$, what does 'M' represent?
In the Thiessen polygon method, what does the weightage factor $\frac{A_i}{A}$ represent for a station?
In the Thiessen polygon method, what does the weightage factor $\frac{A_i}{A}$ represent for a station?
What is the difference between a mass curve and a hyetograph in representing rainfall data?
What is the difference between a mass curve and a hyetograph in representing rainfall data?
Based on the information provided, which form of precipitation consists of water drops with sizes larger than 0.5 mm and a maximum size of about 6 mm?
Based on the information provided, which form of precipitation consists of water drops with sizes larger than 0.5 mm and a maximum size of about 6 mm?
Which of the following reservoirs has the longest average residence time for water?
Which of the following reservoirs has the longest average residence time for water?
Assuming a steady-state condition, how is the mean residence time calculated?
Assuming a steady-state condition, how is the mean residence time calculated?
What is the primary advantage of using the Thiessen polygon method over the arithmetic mean method for determining mean precipitation?
What is the primary advantage of using the Thiessen polygon method over the arithmetic mean method for determining mean precipitation?
What information is required to calculate average rainfall using the arithmetic average method?
What information is required to calculate average rainfall using the arithmetic average method?
What climatic condition is most suitable for applying the arithmetic average method to determine average rainfall in a basin?
What climatic condition is most suitable for applying the arithmetic average method to determine average rainfall in a basin?
What is the definition of 'precipitation'?
What is the definition of 'precipitation'?
How are influence zones determined in the Thiessen polygon method?
How are influence zones determined in the Thiessen polygon method?
Which of the following is a characteristic of the influence zones created in the Thiessen polygon method?
Which of the following is a characteristic of the influence zones created in the Thiessen polygon method?
What distinguishes an isohyetal map from a Thiessen polygon map in representing rainfall data?
What distinguishes an isohyetal map from a Thiessen polygon map in representing rainfall data?
Consider five rain gauge stations with the following rainfall measurements: Station A (10 cm), Station B (15 cm), Station C (8 cm), Station D (18 cm), and Station E (20 cm). Using the arithmetic mean method, what is the average rainfall for the catchment?
Consider five rain gauge stations with the following rainfall measurements: Station A (10 cm), Station B (15 cm), Station C (8 cm), Station D (18 cm), and Station E (20 cm). Using the arithmetic mean method, what is the average rainfall for the catchment?
Which of the following statement is correct when considering the application of remote sensing in hydrology?
Which of the following statement is correct when considering the application of remote sensing in hydrology?
Flashcards
Remote Sensing Hydrology
Remote Sensing Hydrology
Using satellite technology to measure different aspects of the hydrological cycle.
Residence Time
Residence Time
The time required to completely replace water in a drainage basin with new water flow.
Precipitation Definition
Precipitation Definition
All forms of water that reach the Earth from the atmosphere.
Light Rain
Light Rain
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Moderate Rain
Moderate Rain
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Heavy Rain
Heavy Rain
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Rainfall Measurement
Rainfall Measurement
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Rain Gauge
Rain Gauge
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Arithmetic Average Method
Arithmetic Average Method
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Thiessen Polygons Method
Thiessen Polygons Method
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Isohyetal Method
Isohyetal Method
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Mass Curve of Rainfall
Mass Curve of Rainfall
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Hyetograph
Hyetograph
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Rain Classification
Rain Classification
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Study Notes
- Hydrogeology is the study of groundwater
Remote Sensing in Global Hydrological Cycles
- Remote sensing is used to observe hydrological variables
- Satellites and their missions measure various hydrological variables over different time periods.
- Geostationary Operational Environmental Satellite (GOES), launched in 1978 is still collecting precipitation data
- TRMM 3B42.v6 three-hourly provides data for average annual precipitation
Fluxes and Residence Times
- Residence time is the time required for complete water replacement in a drainage basin by new water flow
- Mean residence time is the ratio of water volume stored in a control volume to the volume of water flowing into or out of the region per unit of time
Average Residence Time in Reservoirs
- Glaciers: 10 to 10000 years
- Soil Moisture: 2 weeks to 1 year
- Groundwater (Shallow): 100 to 200 years
- Groundwater (Deep): 10000 years
- Oceans: 4000 years
- Lakes: 10 to 100 years
- Atmosphere: 10 days
- Rivers: 2 weeks to 6 months
- Biosphere: 1 week
Precipitation
- Precipitation includes all forms of water reaching the Earth from the atmosphere
Forms of Precipitation:
- Rain
- Snow
- Drizzle
- Glaze
- Sleet
- Hail
- Dew
Rain
- Rain is the primary form of precipitation consisting of water drops larger than 0.5mm, with a maximum raindrop size of about 6mm.
Rainfall Intensity Classification:
- Light rain: trace to 2.5 mm/h
- Moderate rain: 2.5 mm/h to 7.5 mm/h
- Heavy rain: > 7.5 mm/h
Measurement of Rainfall
- Precipitation is measured by the depth that rainfall would cover an area if collected
- 1cm of rainfall over 1 km² represents 10^4 m³ of water
- Precipitation is measured using a rain gauge
Rain Gauges Types
- Nonrecording gauges
- Recording gauges
Mean Precipitation Over an Area
- Rain gauges provide point samples of rainfall distribution
- Hydrological analysis needs rainfall data over an area
- Point rainfall values can be converted to an average using:
- Arithmetic mean
- Thiessen polygons method
Arithmetic Average Method
- Appropriate for physically and climatically homogenous areas with small required accuracy
- Average rainfall is the arithmetic mean of rainfall values recorded at various stations
Weighing Mean Method (Thiessen Polygons)
- Each station is assigned an influence zone, assuming rainfall equivalence
- Influence zones are represented by convex polygons
- Polygons are created using mediators of segments linking each station to neighboring stations
Thiessen Polygons
- Method for determining average precipitation over an area
Mathematical formula for determining average precipitation over an area
- P = (P1A1 + P2A2 + ... + PmA))/(A1 + A2 + ... + Am)
Generally for M stations you perform this calculation
- P= Σ(PiAi)/Atotal = Σ (Pi * Ai/A)
- Ai / A is the weightage factor of station i
Isohyetal lines for determining average precipitation over an area
- Isopleth or isohyet is a line connecting points of equal rainfall depth.
Graphical Representation of Rainfall
- Rainfall variation over time is shown via:
- Mass curve
- Hyetograph
- A mass curve plots cumulative rainfall depth against time
- A hyetograph is a bar graph of rainfall intensity versus time, useful for determining max intensities
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