Unit 1 Flashcards
What is meant by the term drainage basin system as it applies to a river basin?
Original Answer: A drainage basin is an area of land where all water drains into one river and its tributaries. It includes inputs like rain, flows like runoff, and outputs like evaporation and river discharge.
Simple Terms: A drainage basin is where all the water in an area collects and flows into one main river.
What is meant by the term interception storage?
Original Answer: Interception storage is when water is temporarily held on plants, like leaves or stems, before it evaporates or drips to the ground.
Simple Terms: Interception storage is water that gets caught on plants and doesn’t reach the ground right away.
What are the zones found in an aquifer and its water table?
Original Answer: 1) The saturated zone: where all the spaces in the rock/soil are filled with water. 2) The water table: the top of the saturated zone. 3) The unsaturated zone: the area above the water table with air and water in the soil.
Simple Terms: The aquifer has: 1) Saturated zone: fully filled with water. 2) Water table: the top level of underground water. 3) Unsaturated zone: area with both air and water above the water table.
Define the terms interception and stemflow.
Original Answer: Interception is the process where precipitation is caught and temporarily stored on vegetation surfaces before reaching the ground. Stemflow is the process where water runs down the stems or trunks of plants and trees to the ground.
Simple Terms: Interception is when plants catch rain. Stemflow is when rain runs down plant stems or tree trunks to the ground.
Define the terms throughfall and throughflow.
Original Answer: Throughfall is precipitation that drips off leaves, branches, or other vegetation to the ground. Throughflow is the lateral movement of water through the soil, often moving towards a river or stream.
Simple Terms: Throughfall is when rain drips through leaves. Throughflow is when water flows sideways through soil to a river.
Define the terms water table and springs.
Original Answer: The water table is the top level of underground water where the ground is fully saturated. Springs are places where groundwater naturally flows out onto the surface.
Simple Terms: The water table is the top of underground water. Springs are where underground water comes out to the surface.
Identify and briefly describe two stores found in a river basin.
Original Answer: 1) Soil moisture: Water held in the soil, available for plant uptake or movement into groundwater. 2) Groundwater: Water stored in the saturated zone of rock or soil, forming part of the aquifer system.
Simple Terms: 1) Soil moisture: Water stored in soil. 2) Groundwater: Water stored deep underground.
Describe how groundwater recharge occurs.
Original Answer: Groundwater recharge occurs when water from precipitation or surface sources infiltrates the soil, moves through the unsaturated zone, and percolates into the saturated zone, replenishing aquifers.
Simple Terms: Groundwater recharge happens when water soaks through the soil and refills underground water storage.
Describe how and when overland flow may occur.
Original Answer: Overland flow occurs when rainfall intensity exceeds the infiltration capacity of the soil, causing water to flow over the land surface. This often happens during heavy rain, on impermeable surfaces, or when the soil is saturated.
Simple Terms: Overland flow happens when the ground can’t absorb water fast enough, so rain flows over the surface.
Explain how throughflow and groundwater flow (baseflow) occur.
Original Answer: Throughflow is water moving sideways through soil towards rivers. Baseflow is water flowing slowly through underground rock to rivers.
Simple Terms: Throughflow is water moving sideways in the soil. Baseflow is underground water flowing to rivers.
Describe the difference between infiltration and percolation.
Original Answer: Infiltration is the process where water enters the soil from the surface. Percolation is the downward movement of water from the unsaturated zone to the saturated zone, replenishing aquifers.
Simple Terms: Infiltration is water soaking into the ground. Percolation is water moving deeper underground.
Briefly indicate how rates of infiltration might vary with the intensity of rainfall.
Original Answer: Light rain soaks into the soil slowly, allowing for infiltration. Heavy rain can overwhelm the soil, causing water to run off instead of soaking in.
Simple Terms: Light rain soaks into the ground. Heavy rain causes water to run off the surface.
Explain how precipitation received by a river basin may reach the river channel.
Original Answer: Precipitation reaches the river channel through various pathways: 1) Direct surface runoff during overland flow; 2) Infiltration and throughflow through the soil; 3) Groundwater flow (baseflow) from aquifers; and 4) Direct rainfall onto the river.
Simple Terms: Rainwater reaches the river by running over the surface, soaking into the ground, or flowing underground.
Explain how water reaches, is stored in, and removed from an aquifer.
Original Answer: Water enters aquifers by soaking through the soil (infiltration and percolation). It is stored in the saturated zone of the aquifer. Water is removed through springs, wells, or baseflow to rivers.
Simple Terms: Water soaks into the ground to fill aquifers, is stored underground, and leaves through springs, wells, or rivers.
What is meant by inputs and outputs within a drainage basin system?
Original Answer: Inputs are additions to the system, such as precipitation. Outputs are losses, including evaporation, transpiration, and water leaving the basin via river discharge.
Simple Terms: Inputs are water entering (like rain). Outputs are water leaving (like evaporation or rivers).
With the help of a labeled diagram, show how water makes its way through a drainage basin system.
Original Answer: Water enters the basin as rain (input), moves through it as surface runoff, infiltration, or underground flow, and leaves as river discharge or evaporation (output).
Simple Terms: Water enters as rain, moves through soil or over the ground, and leaves in rivers or as evaporation.
Explain how water from surface storage reaches groundwater storage.
Original Answer: Water from surface storage infiltrates into the soil, moves down through the unsaturated zone by percolation, and enters the saturated zone of the aquifer, contributing to groundwater storage.
Simple Terms: Water on the surface soaks into the soil and moves underground to fill aquifers.
Define the terms precipitation intensity and infiltration capacity
Original Answer: Precipitation intensity is how fast rain falls (e.g., mm/hour). Infiltration capacity is how much water the soil can soak up before runoff starts.
Simple Terms: Precipitation intensity is how fast rain falls. Infiltration capacity is how much water the ground can absorb.
Describe how precipitation intensity might affect the surface flow of water in a river basin.
Original Answer: High precipitation intensity can exceed the infiltration capacity of the soil, leading to overland flow and increased surface runoff. Low intensity allows more water to infiltrate, reducing surface flow.
Simple Terms: Heavy rain causes water to flow on the surface. Light rain soaks into the ground.
What situation may cause a rise in the baseflow level on a storm hydrograph?
Original Answer: A rise in baseflow may occur due to prolonged rainfall saturating the soil, which increases infiltration and groundwater flow into the river. This results in more consistent and elevated baseflow levels.
Simple Terms: Long-lasting rain can soak into the ground and add more water to underground sources, which then flow into the river steadily.
Define the hydrological terms “lag time” and “rising limb.”
Original Answer: Lag time is the duration between the peak rainfall and the peak discharge. The rising limb is the part of the hydrograph that shows the increase in river discharge following rainfall.
Simple Terms: Lag time is the delay between heavy rain and the river flooding. The rising limb is the part of the graph that shows the river flow getting higher.
How can the pattern of discharge in a river basin be affected by the size and shape of the drainage basin?
Original Answer: Larger drainage basins tend to have a slower response time and more prolonged discharge, while smaller basins respond more quickly to rainfall. Circular-shaped basins produce faster runoff and higher peak discharges, as water reaches the main channel more simultaneously.
Simple Terms: Big basins take longer to flood, while small ones flood faster. Round basins cause water to flow to the river quickly, making it flood sooner.
How does drainage density affect river discharge?
Original Answer: High drainage density, characterized by a greater number of tributaries, leads to faster water transfer to the main channel, causing steeper hydrographs and higher peak discharges. Low drainage density slows the transfer of water, resulting in flatter hydrographs with lower peaks.
Simple Terms: More streams mean faster flooding and higher peaks. Fewer streams slow down the water, so the river floods less.
