Drainage Basin System Review

These flashcards cover key concepts related to the drainage basin system, river processes, hydrographs, and flood management.

What are the three main components of the drainage basin system?

Outputs, Stores, Flows.

What is defined as the area drained by a river and its tributaries?

Drainage basin.

What is the boundary of a drainage basin called?

Watershed.

What process involves the change of water from liquid to gas?

Evaporation.

What is the combined process of evaporation and transpiration called?

Evapotranspiration.

How is river discharge measured?

In cubic metres per second (Cumecs).

What is interception in the context of the drainage basin system?

Water intercepted by plant branches and leaves before reaching the ground.

What is the term for water stored in the upper levels of the soil, utilized by plants?

Soil water.

What type of flow occurs when water moves over the ground rather than infiltrating?

Overland flow.

What is infiltration?

The movement of water from above ground into the soil.

What does percolation refer to?

Water flowing from the ground or soil into porous rock or rock fractures.

What is baseflow?

The level of channel flow when there is no overland flow, made up entirely of groundwater.

What percent of the Earth's freshwater is made up of underground water?

Approximately 30%.

What is an aquifer?

An underground water store.

What is the water table?

The level at which the ground becomes saturated with water.

What causes groundwater to recharge?

Precipitation infiltrating the ground.

How does the type of precipitation affect groundwater recharge?

Storm events can saturate the ground quickly, increasing overland flow instead of groundwater recharge.

What is a spring?

A natural outlet of groundwater where it flows out onto the surface.

What does a hydrograph show?

How river discharge changes over time.

What represents the time between peak rainfall and peak discharge on a hydrograph?

Lag time.

What is stormflow in hydrology?

The additional water in the river during a storm, including overland flow and throughflow.

What is bankfull discharge?

The maximum capacity of the river before it spills over the banks.

What is a flashy hydrograph?

Characterized by a short lag time and high peak discharge.

What is the critical erosion velocity curve?

The minimum velocity needed for material to be picked up and then eroded.

How does vegetation affect river discharge during spring and summer?

More vegetation leads to higher interception and lower soil saturation.

What is drainage density?

The total length of rivers and streams in a drainage basin divided by the total area of the basin.

How does soil type influence infiltration rates?

Sandy soils allow faster infiltration than clay soils due to larger pore sizes.

What is the effect of urbanization on the drainage basin?

Increased overland flow and reduced infiltration due to impermeable surfaces.

What happens to the river channel when it is straightened?

Water flows faster, which can lead to flooding further downstream.

How can afforestation affect river flow?

It can decrease surface runoff and channel flow, leading to lower river levels.

What is the main cause of river flooding?

Heavy rainfall or prolonged periods of rainfall that saturate soils.

What technology can be used to predict flooding risk?

Modeling software that calculates the risk based on environmental factors.

What is a flood recurrence interval?

The probability of a flood of a given size occurring in a specified timeframe.

What do levees do in relation to flooding?

They provide a raised embankment to prevent river water from spilling onto the floodplain.

What is river restoration?

The process of restoring a river to its original state before alteration.

How can wetlands help reduce flood risk?

They can hold excess floodwater and limit flooding elsewhere.

What effect does livestock farming have on river banks?

It can trample soil, reducing infiltration and increasing flooding risk.

What is the relationship between temperature and evaporation in the hydrological cycle?

Higher temperatures lead to increased evaporation rates.

What structural issues might arise from dam construction?

Dams can displace communities, disrupt ecosystems, and be expensive to build.

What is a point bar?

A deposit of fine sediment on the inside of a meander bend.

How does antecedent moisture affect river discharge?

Highly saturated soils increase overland flow, while dry soils may lead to more infiltration.

What is an oxbow lake?

A lake formed when a river meander is cut off from the main channel.

How do natural flood defenses work?

They use vegetation and land management to absorb and slowly release floodwater.

What impact does agricultural land use have on flood risk?

It leads to compaction of soil and can decrease infiltration, increasing runoff.

How do storms impact river hydrographs?

Storms increase discharge rapidly, affecting both the rising limb and the lag time.

What is the function of diversion spillways?

To direct excess water away from flooded areas.

How can river channel processes affect sediment transport?

Erosion and deposition shape the river channel, influencing load movement.

What is the main effect of ice on soil permeability?

Frozen ground is impermeable, increasing overland flow.

What strategies can be used to manage flood risks in urban areas?

Improving green spaces, using permeable materials, and conserving riverbanks.