GEOG 1113 NOTES pt 11HYDROLOGIC SYSTEMS** WATER (H2O)* originally formed within the Earth & brought to the surface byoutgassing, which is the release of trapped gasses from rocks, forcedout through cracks, fissures, & volcanoes from within the Earth* collected on the surface after the Earth cooled about 3.8 BYBP* reached present amount, about 1.36 billion km3, about 2 BYBP* covers approximately 71% of the Earth's surface•Other than gravity, water is the major agent of geomorphic change on the earth’s surface* Distribution•97.22 % is in the oceans, 2.78 % is freshwater. * of this freshwater:* of this 77.78% surface water: 99.357% in ice & glaciers,.33% in freshwater lakes & ponds, .003% is in rivers & streams,.28% is in saline lakes, and .03% is in the atmosphere* Properties of water: * occurs in all 3 states (phases) of matter (solid, liquid, gas) at the T°s foundon Earth* undergoes phase changes (melting, freezing, evaporation, condensation,sublimation, & deposition) * to change phase energy is either added or released** HYDROLOGIC CYCLE * the flow of water through the environment* includes all phases, all 4 of Earth's spheres, & various pathways* Basic cycle:* evapotranspiration (evaporation + transpiration by plants): water is converted fromthe liquid form to the gaseous form & rises into the atmosphere
* condensation: water vapor is converted back to the liquid form (cloud and raindrops)* precipitation: water returns to surface as rain, snow, etc.* after precipitation, water either soaks into the surface, infiltration, or isrun-offs(overland flow) into streams, lakes, & other water bodies* Water Balance:the amount of water in an area based on input (precipitation)minus output (usage, evaporation, storage) * hydrologic cycle, if balanced, provides an adequate water supplyfor plants, animals, and various processes* water is a major factor in weathering processes above & below the surface,& thus landform development (Increased water == increased weathering)* How it affects weathering:Infiltration vs runoffsubsurface weathering fluvial landscapesregolith formation degradationkarst formation aggradationoverland flowFLUVIAL SYSTEMS* What is a fluvial system?•Primarily this refers to “running water”* rills, brooks, creeks, streams, rivers, & other water moving in a channel or watercourse* may be a permanent watercourse or temporary (intermittent)* in arid regions intermittent channels are also known as arroyos, wadis, dry gulches,washes, etc.•Running water causes erosion and transport of weather material. * in some cases standing water such as lakes or ponds are included but carryout
more weathering than transport, and are more likely to be areas of aggradation* How do they induce change on the landscape?** 2 main processes by which is induced:Degradation: wear downEarth’s materials and surface: erosion.Aggradation: the build-upof Earth’s surface: deposition.