Water Cycle, Groundwater, Aquifers, Caves Hydrosphere Water Cycle, Groundwater, Aquifers, Caves

Hydrosphere About 97 % of the hydrosphere is in the oceans. Water contained by landmasses—nearly all of it freshwater—makes up about 3 %

Hydrosphere

Water Cycle Water constantly moves among the oceans, the atmosphere, the solid Earth, and the biosphere. This unending circulation of Earth’s water supply is the water cycle.

Water Cycle Processes involved in the cycle include: Precipitation Evaporation Sublimation Infiltration - the movement of surface water into rock or soil through cracks and pore spaces Runoff Transpiration - the release of water into the atmosphere from plants through the ground

Runoff Runoff is water flowing downslope along Earth’s surface. Runoff may reach a stream, river, or lake, may evaporate or accumulate and eventually seep into the ground.

Stream Systems A stream is a channel with permanent water flow. Tributaries are streams that flow into other streams, increasing the size of the stream it is joining. A large stream is called a river, and all its tributaries make up a stream, or river system.

Moving Water Carves a Path A stream channel forms as the moving water erodes a narrow pathway into rock, creating sediment. Stream banks are the ground bordering the stream on each side Hold the moving water within the confines of the stream channel

Formation of Stream Valleys As a stream actively erodes its path through the sediment or rock, a V-shaped channel develops. A stream erodes until its base level, the elevation at which it enters another stream or body of water. Downcutting- wearing away of the streambed, stops when base level is reached, fueled by gravity

Stream Load A stream carries its load in 3 ways: Solution-particles dissolved in water Suspension-particles small enough to stay afloat in water. Bed load-materials that are pushed along bottom of stream

Meandering Streams A stream’s slope, or gradient, decreases as it nears its base level. Sometimes, the water begins to erode the sides of the channel in such a way that the overall path of the stream starts to bend or wind. A meander is a bend or curve in a stream channel caused by moving water.

Meandering Streams Outside of curve-heavy erosion occurs, water moves fastest. Inside of curve-deposition occurs, water moves slowest pg. 225

Meandering Streams It is common for a stream to cut off a meander and once again flow along a straighter path. The cut off meander becomes an oxbow lake, which eventually dries up. At the mouth of the stream, the gradient begins to flatten and the channel becomes wide.

Deposition of Sediments Gradient (slope) decreases, velocity decreases. In dry regions, a stream’s gradient may suddenly decrease causing the stream to drop its sediment at the base of a slope as a fan-shaped deposit called an alluvial fan.

Deposition of Sediments Streams lose velocity when they join larger bodies of quiet water. A delta is the triangular deposit, usually consisting of silt and clay particles, that forms where a stream enters a large body of water.

River Basin Portion of land drained by a river and its tributaries (streams that flow into a larger stream or body of water) Final destination is an estuary or an ocean Everyone lives in a river basin, whether you live near water or not Considered an ecosystem, all living and non-living things are connected and interdependent River basin’s make up many smaller watersheds, land that drains into a stream, lake or wetland

Differences between bodies of water Lake vs. Reservoir Both a depressions in the surface materials that collect and hold water Both accumulate water from streams and runoff Lakes have outlets from which water flows to rivers and to the ocean Reservoirs are lakes made for the primary purpose of storing water for communities use.

Differences between bodies of water Wetlands- land area that is covered with water for a large part of the year Bogs- waterlogged soil from precipitation, NOT stream fed Marshes- marsh grasses, reeds, sedges, and rushes Swamps- shrubs and trees pg. 230

Wetland Importance? Filtering system- trap pollutants, sediments, and pathogenic bacteria Provide vital habitats for migratory water-birds and homes for many other wildlife, as well as plants (NC pitcher plants) BBC LIFE- carnivorous plants

Lakes Undergo Change Eutrophication- process of photosynthesis, plants add oxygen and waste products to lake water Decay process of organisms use up dissolved oxygen supplies Natural process BUT addition of fertilizers (nitrogen and phosphorus) causes algae blooms which depletes oxygen

Poorly sorted sediments Precipitation and Groundwater The rain infiltrates the ground and becomes groundwater. Little precipitation becomes runoff and is returned to the ocean. Porosity is the percentage of pore space in a material. Well sorted sediments High porosity Poorly sorted sediments Low porosity

Water Table The zone of saturation is the depth below Earth’s surface at which groundwater completely fills all the pores of a material. The water table is the upper boundary of the zone of saturation. Area above water table is known as zone of aeration, pores filled with air.

The Water Table The topography of the water table follows the topography of the land above it. Because of its dependence on precipitation, the water table fluctuates with seasonal and other weather conditions.

Groundwater Movement Groundwater flows downhill in the direction of the slope of the water table. Permeability is the ability of a material to let water pass through it. High permeability-large, connected pores Ex sand, gravel Low permeability-tiny pores, fine grained materials, said to be impermeable Ex silt, clay, shale

Groundwater Movement Aquifers are underwater permeable layers where most groundwater flow takes place. Impermeable layers, called aquicludes, are barriers to groundwater flow.

Sinkholes Groundwater’s interaction with limestone, forms karst topography- caves, underground channels, and a rough bumpy ground surface

Spring Formation pg. 250

Hot Springs Emerge from aquifers that descend to great depths in Earth’s crust and allow deep, hot water to rise . Geysers- explosive hot springs that erupt at regular intervals (Old Faithful)

Wells To produce water, a well must tap into an aquifer. Wells are holes dug or drilled deep into the ground to reach a reservoir of groundwater. To produce water, a well must tap into an aquifer.

Wells Overpumping of a well produces a cone of depression around the well. Drawdown is the difference between the original water-table level and the water level in the pumped well. Recharge is the process in which water from precipitation and runoff is added back to the zone of saturation.

Confined Aquifers Water-table aquifers are unconfined and unprotected, and thus, easily polluted. Deeper aquifers, called confined aquifers, are sandwiched between aquicludes. The aquicludes form barriers that prevent pollutants from reaching such aquifers.

Threats to Our Water Supply Human demands for freshwater include household use, agriculture, and industry.

Threats to Our Water Supply Overuse As human population increases, so does the need for abundant water. If groundwater is pumped out at a rate greater than the recharge rate, the groundwater supply will inevitably decrease, and the water table will drop.

Threats to Our Water Supply Subsidence Ground subsidence, or the sinking of land, is a problem caused by the excessive withdrawal of groundwater.

Threats to Our Water Supply Salt The overpumping of wells near the ocean can cause the underlying salt water to rise into the wells and contaminate the freshwater aquifer.

Threats to Our Water Supply Pollution in Groundwater

Threats to Our Water Supply *Point Source Pollution: comes from a single, localized source EX: factory

Threats to Our Water Supply *Nonpoint source pollution - pollution from a general area Ex: runoff from farming area

Protecting Our Water Supply All major pollution sources need to be identified and eliminated.

Protecting Our Water Supply Pollution plumes may be stopped by the building of impermeable underground barriers. Polluted groundwater can be pumped out for chemical treatment on the surface.