Surface Water Movement

Hydrologic Cycle Earth’s water supply is recycled in a continuous process

Hydrologic Cycle Evaporation-Movement of water from Earth’s surface to atmosphere Condensation- Movement from water vapor to clouds Precipitation- water falls back on Earth Infiltration- Water soaking into the Earth Runoff- water on earth’s surface that flows downslope into lakes, streams, rivers, oceans, or puddles Transpiration- water vapor from plants; Similar to evaporation

Runoff A number of conditions determine whether water on Earth’s surface will infiltrate the ground or become runoff. Vegetation causes the soil to hold more water water flows slower down plants allowing the ground to soak in more Rate of Precipitation- More water enters ground if rainfall is gentle During heavy downpours , the rate of precipitation may exceed the rate of infiltration

Runoff Soil Composition: Determines how much water soil can hold Slope: the steeper the slope, the less water is allowed to soak into the ground

Stream Systems Stream System- Large river and all of its tributaries Water flows downslope to lower elevations Can flow into lakes, oceans and other streams

Stream Systems Tributaries Rivers that flow into other streams Example: Missouri river is a tributary for the Mississippi

Stream Systems Watersheds All of the land whose water drains into a stream Divide A high land that separates one watershed from another

Stream Systems Stream Load: the material that a stream carries. Stream load is carried in 3 ways: solution: material dissolved in water 2. suspension: particles small enough to be held up by the turbulence of moving water (silt, sand, clay) 3. bed load: sand pebbles and cobbles that are rolled and pushed along the stream bed by water

Stream Velocity and Carrying Power Carrying power: streams ability to transport material; this is dependent on stream velocity and volume Stream velocity: effected by slope, depth, width of the stream Discharge: width x depth x velocity When discharge increases, carrying power increases Increases during heavy rain, rapid snowmelt, and flooding

Floodplains Flood- water spills over the sides of stream banks and onto adjacent lands Floodplain- the area of land covered with stream water during times of floods When water recedes off the floodplain, sediments are deposited on the land making the soil very fertile

Floods Upstream flood: the flooding of a small area (localized) caused by a sudden rainstorm dropping large amounts of time (flashflood); short-term events.

Floods Downstream flood: heavy accumulation of excess water due to prolonged rain or extensive snowmelt; longer lasting.

Streams, Wetlands, and Lakes

Stream Development Stream formation relies on adequate water supply As a stream develops it changes width and size, and shapes the land over which it flows

Formation of Stream Valleys Driving force of a stream- gravity Stream actively erodes a path through the sediment or rock, a V-shaped channel develops

Meander As stream channels develop into broader valleys , the volume of water and sediment that they can carry increases. Sometimes the water begins to erode the sides of the channel in such a way that the overall path starts to bend and wind. A bend or curve is called a meander.

Meander

Origins of Lakes Lakes can form from many different sources Stream flows become blocked Glacial origins (melted glaciers) Dissolving of limestone cavern Water from precipitation , runoff, and underground sources can maintain a lake’s water supply

A stream meander that no longer has access to water and eventually dries up. Oxbow Lake

Lakes Undergo Change Eutrophication: when a watershed enriches bodies of water with nutrients that stimulate excessive plant growth Can be positive or negative

Wetlands Wetland: low lying area that is periodically saturated with water and support a specific plant species Areas include bogs, marshes, or swamps