Understanding the Drainage Basin Hydrological Cycle

Drainage basin

An area drained by a river and its tributaries, defined by a watershed marking the boundary between two separate basins.

Open systems

Systems that receive both inputs and outputs.

Main input in the drainage basin hydrological cycle

Precipitation, such as rain, snow, or hail.

Channel flow

The flow of water in the channel.

Surface runoff or overland flow

Water flowing over the land where it can infiltrate into the soil.

Infiltration

The process where water soaks into the soil.

Soil type and saturation

Factors that determine the rate of infiltration.

Throughflow

The movement of water downhill through the soil, fastest at points with cracks.

Percolation

The movement of water from the soil down to the water table.

Groundwater flow

The slowest flow in the cycle, occurring through permeable rock below the water table.

Baseflow

The water feeding into the river through the banks and beds.

Interception

Rain falling on vegetation, buildings, or roads before reaching the soil.

Forms of water storage in the hydrological cycle

Vegetation storage, surface storage (puddles, ponds, lakes), and groundwater storage in aquifers.

Evapotranspiration

The combination of evaporation and transpiration of water from plant leaves.

Water stored in the soil calculation

Using the equation P = Q + E + S, where P is precipitation, Q is runoff, E is evapotranspiration, and S is storage.

Water balance or water budget graph

Shows seasonal patterns of water storage and balance, with precipitation and evapotranspiration trends.

Source of a river

The start of a river journey, often found high in the mountains or hills.

Upper course of a river

The first part of a river's journey, where water rushes downhill over rocks and boulders.

Formation of valleys and canyons

Water wears away the rock beneath it over many years if the rock is soft.

Formation of waterfalls

Created where hard rock meets soft rock, with the soft rock eroding faster.

Middle course of a river

The part of the river where it slows down upon reaching flatter ground.

Tributaries

Small rivers or streams that feed into larger, wider rivers.

Lower course of a river

The part where the river widens out into estuaries or deltas.

Role of sediment in the lower course

Sediment slows the river's flow and provides nutrients for plants and animals.

Mouth of a river

The end of the river where it flows into the ocean or sea.

Three courses of a river

Upper course, middle course, and lower course.

Natural features created by rivers

Waterfalls and valleys.

Confluence

The place where a tributary meets the main river.

Floodplain

A flat area of land around the river that is covered during times of flood.

Levees

Raised riverbanks created by the buildup of alluvium on the floodplain after a river floods.

Estuary

The area where a river meets the sea, where saltwater mixes with freshwater.

Delta

A landform created at the mouth of a river, where material carried by the river is deposited.

Importance of trees to humans

Trees produce oxygen, clean the air by removing pollutants, filter rainwater, and protect us from outdoor elements.

Purpose of measuring and inventorying trees

To identify where trees are located, damaged, cut down, or growing strong.

Earth's surface covered by trees

Nearly 1/3, which is about 29.5% or 9.5 billion acres.

Remote sensing technology

A method to observe and measure objects from afar.

LiDAR

Light Detection and Ranging.

How LiDAR works

Uses light energy emitted from a laser to scan the Earth's surface.

Active remote sensing system

A system that actively produces light energy using a laser to gather data.

Earliest use of laser remote sensing systems

In the 1960s, with LiDAR being used to measure ground elevation by the 1970s.

Early use of LiDAR

Focused on producing high-resolution elevation maps.

Vegetation data in early LiDAR

Considered 'noise' because it interfered with refined topographic maps.

Valuable information in early LiDAR data

Data about vegetation, such as tree height, density, and cover.

Modern LiDAR data in ecology

Used to measure topography, vegetation, and buildings, and to estimate ecological metrics.

LiDAR and ecological issues

Helps estimate the number of trees that remain after a fire.

NEON and LiDAR

The National Ecological Observatory Network collects LiDAR data every year over its core sites for 30 years.

LiDAR data and ecosystem study

Allows scientists to create maps and visual animations showing changes in vegetation through time.

Height of waves in the 2004 Indian Ocean tsunami

Waves were as high as 30 meters tall.

Casualties of the 2004 Indian Ocean tsunami

Approximately 230,000 people across 14 countries.

Difference between tsunamis and normal waves

Tsunamis are caused by large displacements of water, often from undersea earthquakes.

Cause of the 2004 Indian Ocean tsunami

A 9.2 magnitude undersea megathrust earthquake along a subduction zone.

Water displaced by the 2004 earthquake

Approximately 30 cubic kilometers of water.

Speed of tsunami waves

About 500 miles per hour.

Surprise of countries hit by the tsunami

There were no tsunami warning systems in the Indian Ocean at the time.

Detection of tsunamis in deep water

Tsunamis appear as low, broad humps that are barely noticeable.

Behavior of tsunami waves approaching the coastline

The waves slow down and grow taller, becoming destructive.

Primary tsunami warning system in the Pacific Ocean

The National Tsunami Warning Center, run by the US National Oceanic and Atmospheric Administration (NOAA).

DART system

Uses sea-floor pressure recorders and surface buoys to measure water pressure and detect potential tsunamis.

Creation of the Indian Ocean Tsunami Warning System

Prompted by the 2004 Indian Ocean earthquake and resulting tsunami.

Modern tsunami warning systems alerts

Alerts are transmitted via satellite to tsunami warning centers.

Number of DART stations in the global tsunami warning network

Nearly 40 DART stations in the Pacific, Caribbean, Atlantic, and Indian Oceans.