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A dendritic drainage pattern resembles a tree with many branches, where many tributaries join into one main river.

The three major stores of water on Earth are:

1. Ocean or Sea
2. Land (including lakes/ponds, vegetation, snow and ice as surface stores, and soils or rocks as subsurface stores)
3. Atmosphere (as water vapor or tiny water droplets in clouds)

The process of water moving from one store to another in the water cycle is called transfer.

Water changes state in the water cycle through the following processes:

• From liquid to vapor (evaporation)
• From vapor back to liquid or solid (condensation, forming clouds, or precipitation as rain, snow, etc.)

This change of state repeats continuously throughout the cycle.

The total amount of water within the water cycle remains constant, but its distribution among various stores and processes is continually changing.

Overland flow takes the shortest time to reach a river because it moves directly across the surface of the ground. Groundwater flow is the slowest due to its movement through soil and rock layers, which can take a significant amount of time.

During dry periods, rivers can receive water from groundwater flow, which continues to feed the river even when there is little or no precipitation. Additionally, stored water in soil moisture can contribute to river flow through throughflow and overland flow when conditions allow.

Water reaches a river through several pathways:

1. Direct precipitation - Water falls directly onto the river.
2. Overland flow - Water flows over the ground surface.
3. Throughflow - Water moves laterally through the soil.
4. Groundwater flow - Water moves through underground layers of soil and rock.
5. Stem flow - Water runs down the stems of plants.
6. Drip flow - Water drips from leaves to the ground.

1. Rainwater reaches the ground.
2. Stored on the earth's surface as surface store (e.g., in ponds, vegetation).
3. Flows downslope in sheets as overland flow (surface run-off).
4. Seep into the soil through infiltration.
5. Stored in unsaturated rock/soil as soil moisture store.
6. Moves further down into rocks through percolation.
7. Stored in rocks as groundwater store.
8. Flows downhill slowly in the soil as throughflow (subsurface run-off).
9. Flows downslope in the rock as groundwater flow (base flow).

• Overland Flow: Water flows downslope in sheets as surface run-off, directly from the surface to the river.
• Throughflow: Water flows downhill slowly in the soil, moving through the unsaturated zone before reaching the river.

Infiltration is the process where rainwater seeps into the soil, allowing water to be stored in the soil moisture store and eventually move further down into rocks through percolation.

• Groundwater Flow: Water flows downslope in the rock as subsurface run-off, moving slowly through the groundwater store.
• Channel Flow: Water flows within the river channel as surface run-off, directly contributing to river flow.

A steep slope gradient leads to less infiltration.

Dense vegetation cover generally leads to higher infiltration, while sparse cover leads to lower infiltration.

A steep slope gradient results in more overland flow.

Factors affecting throughflow include slope gradient (gentle or steep), soil porosity (high), and soil moisture storage (high). A steep slope gradient leads to more throughflow.

An area with a steep slope has a low infiltration rate compared to an area with dense tree cover.

High soil moisture can lead to reduced infiltration due to saturation.

Low land surface permeability, such as surfaces covered with concrete, leads to less infiltration.

High soil porosity increases throughflow due to more pore space for water movement.

High rock porosity leads to more groundwater flow due to increased space for water storage.

A drainage basin, also known as a river basin or catchment area, is the area drained by a main river and its tributaries. It is bounded by a watershed, and all precipitation falling on the basin drains into the main river, contributing to the water cycle.

In a trellis drainage pattern, tributaries join the main river at right angles, creating a trellis-like structure, often found in areas with parallel ridges and valleys.

A rectangular drainage pattern is characterized by tributaries that join one another and the main river at roughly right angles, forming a grid-like network.

In a centripetal drainage pattern, rivers flow down the sides of hills in all directions towards a central lake located in inland basins.

A radial drainage pattern occurs when rivers flow in all directions from a central point at the top of a hill, typically a cone-shaped hill.

The main processes involved in the water cycle include:

1. Precipitation - Water falls from clouds to the land surface.
2. Interception - Some precipitation is intercepted by vegetation.
3. Surface Storage - Water is stored on the surface or absorbed by unsaturated rock and soil.
4. Infiltration - Water infiltrates into the soil, becoming soil moisture.
5. Percolation - Water percolates through saturated rock, becoming groundwater storage.
6. Groundwater Flow - Groundwater flows through base flow and throughflow.
7. Run-off - Water exits as subsurface run-off or surface run-off into channels.
8. Evapotranspiration - Water evaporates from the sea and other surfaces into the atmosphere.
9. Condensation - Water vapor condenses in the atmosphere to form precipitation, completing the cycle.

A drainage basin is an area of land where all precipitation collects and drains off into a common outlet, such as a river, lake, or ocean. It includes:

• Surface Water: Rivers, lakes, and streams that collect water.
• Groundwater: Water that infiltrates the soil and rock layers.
• Run-off: Water that flows over the surface towards the outlet.

The boundaries of a drainage basin are defined by watersheds, which are elevated areas that separate different drainage basins.