SJI Year 4 IP Geography: Land and Water Interactions

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Questions and Answers

What is the primary reason for sediment accumulation at the river mouth?

High tidal currents

Limited vegetation growth

Calm coastal waters (correct)

Increased wave activity

Which type of delta typically shows a triangular or fan shape?

Bird's foot delta

Arcuate delta (correct)

Estuarine delta

Submerged delta

Which delta type is characterized by having a long narrow estuary and is affected by wave and current activity?

Bird's foot delta

River mouth delta

Arcuate delta

Estuarine delta (correct)

What does river discharge refer to?

The volume of water flowing through a river at a given point Signup and view all the answers

Which of these rivers is commonly associated with an arcuate delta?

Mississippi River Signup and view all the answers

Which soil type is most likely to reduce the risk of flooding?

Sandy soils Signup and view all the answers

How does vegetation contribute to reducing flood risk?

Intercepts rainfall and increases infiltration Signup and view all the answers

What is a significant effect of urbanization on flood hazards?

Increases impermeable surfaces Signup and view all the answers

What usually happens when river channels are straightened?

Flood risk increases due to faster water flow Signup and view all the answers

What impact does deforestation have on flood risk?

Decreases infiltration and increases flooding Signup and view all the answers

How do straightened rivers affect water flow and flood risk?

Decrease the river's capacity to hold water Signup and view all the answers

What role do gutters and drains play in urban flooding?

Carry water quickly to rivers, increasing flood risk Signup and view all the answers

What effect does afforestation have on flood likelihood?

Reduces flood likelihood through increased interception Signup and view all the answers

Which of the following is an erosional feature created by river processes?

Gorges Signup and view all the answers

What is the primary cause of the formation of a floodplain?

The gentle slope and sediment deposition during floods Signup and view all the answers

Which landform is typically found in the lower course of a river?

Alluvial fans Signup and view all the answers

How do ox-bow lakes form in relation to river processes?

By the river changing its course and leaving a bend cut-off Signup and view all the answers

Which statement correctly describes a cause of flooding in river valleys?

Heavy rainfall that raises river levels significantly Signup and view all the answers

What feature is formed as a result of repeated flooding and deposition of sediments?

Floodplains Signup and view all the answers

Which of the following is NOT associated with river processes?

Mountain peaks Signup and view all the answers

What is a common characteristic of the Ganges Plain in India?

Extensive floodplains due to sediment deposition Signup and view all the answers

What is the primary cause of flooding due to persistent precipitation?

Long periods of heavy rainfall Signup and view all the answers

How does the slope of a basin affect the hydrograph?

Steep-sided valleys cause quicker water reach to the river. Signup and view all the answers

What happens when intense storms occur?

River levels may rise rapidly due to runoff. Signup and view all the answers

Which type of rock is classified as impermeable?

Granite Signup and view all the answers

What effect does spring snowmelt have on rivers?

Contributes additional water, possibly causing flooding. Signup and view all the answers

Which property of porous rocks helps in storing water?

They contain numerous fillable pores. Signup and view all the answers

What weather events contribute notably to flooding in rivers?

Torrential rains from hurricanes Signup and view all the answers

What characterizes pervious rocks?

They allow water to flow through bedding planes. Signup and view all the answers

What is characteristic of a hydrograph with a steep rising limb and high peak discharge?

The area experiences more urbanization. Signup and view all the answers

How does rock permeability affect the shape of a hydrograph?

Permeable rocks lead to shorter lag times. Signup and view all the answers

Which factor contributes to a slow return to normal flows in a hydrograph?

Gentle slopes. Signup and view all the answers

What does a hydrograph with a gentle falling limb indicate about the drainage basin?

The area has a dense forest cover. Signup and view all the answers

Which of the following features is most likely found in a drainage basin that produces a hydrograph with a high peak discharge?

Urbanized areas with impermeable surfaces. Signup and view all the answers

What type of vegetation is likely to result in a shorter lag time on a hydrograph?

Sparse vegetation that prevents water absorption. Signup and view all the answers

What impact does urbanization generally have on hydrographs?

Decreases lag time due to faster runoff. Signup and view all the answers

What is a significant characteristic of a rural drainage basin compared to an urban one in terms of hydrograph shape?

Rural basins often have longer lag times. Signup and view all the answers

Study Notes

Hydrographs

Hydrographs illustrate river discharge over time, showing how different factors affect the response to rainfall.
Steep rising limbs indicate a short lag time, typically associated with urbanized areas and impermeable rock.
Gentle rising limbs signify a longer lag time, often occurring in rural areas with permeable rocks.

Drainage Basin Characteristics

Features such as impermeable rocks lead to rapid runoff and quick peak discharge.
Urban areas typically present more runoff than rural regions due to infrastructure.
Vegetation influences water absorption; less vegetation increases flooding risk.

River Landforms

Erosional features include V-shaped valleys, gorges, and river terraces, shaped by the force of flowing water.
Deposition features consist of alluvial fans, meanders, ox-bow lakes, deltas, and floodplains formed by sediment accumulation.

Floodplains

Floodplains form where rivers overflow, depositing sediments that create flat, fertile land.
Repeated flooding builds up alluvium, leading to the gradual creation of floodplain features like levees and ox-bow lakes.
Notable examples of floodplains include the Ganges Plain in India and the Mississippi Plain in the USA.

Types of Deltas

Arcuate deltas are triangular-shaped with many distributaries and are often made of coarse sediments; examples include the Mississippi Delta.
Bird’s foot deltas extend out to sea and appear narrow, usually composed of fine silt and sand; significant examples include the Seine Delta.
Estuarine deltas do not grow beyond the coastline due to erosion from waves and currents.

River Discharge

River discharge is measured in cubic meters per second, calculated by multiplying water velocity with cross-sectional area.
River response to rainfall is influenced by watershed characteristics and slope steepness; steeper slopes lead to faster runoff.

Factors Influencing Flooding

Prolonged rainfall saturates ground, leading to surface runoff.
Intense storms can cause rapid rises in river levels due to overwhelming rainfall.
Snowmelt in spring contributes additional water to rivers, risking floods when combined with heavy rains.

Rock and Soil Types

Permeable rocks (e.g., sandstone) allow rapid water infiltration, reducing surface runoff; impermeable rocks (e.g., granite) increase flooding risk.
Sandy soils promote rapid infiltration, while clay soils hinder it, causing surface runoff and flooding.

Role of Vegetation

Vegetation intercepts rainfall and aids in water absorption, reducing surface runoff.
Deforestation increases flooding risk, as seen in regions like Bangladesh, where tree removal contributes to higher runoff rates.

Urbanization Impacts

Urban development replaces permeable surfaces with impermeable materials, increasing surface runoff and flood risk.
Infrastructure can expedite water flow into rivers, reducing lag time and exacerbating floods.

River Channel Modifications

Altering river courses by straightening or shortening increases flooding likelihood due to reduced flow areas.
Reservoirs and dams may unintentionally increase downstream flooding risk if they fail or release excessive water.

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Description

Explore the effects of vegetation, rock permeability, and urbanization on storm hydrographs through this quiz. Understand how these factors influence river landforms and the interaction between land and water. Test your knowledge of key geographic concepts relevant to Year 4 studies.