GEOL 107 GENERAL GEOLOGY STUDY GUIDE PART 2 Hydrologic Cycle and River Systems Interlude F and Chapter 17 in Earth Portrait of a Planet Know the relative distribution of water on the Earth Oceans 96 5 Glaciers and Polar Ice 1 7 Groundwater 1 7 Lakes and Rivers 0 013 Atmosphere 0 0001 Biosphere 0 00001 Understand the hydrologic cycle What are the main parts of the cycle evaporation liquid gas water vapor driven by heat of sun condensation gas liquid vapor moves through troposphere and is cooled precipitation condensed water vapor falling back to Earth s surface as rain snow runoff water flowing on land surface oceans groundwater transpiration What are the excesses in evaporation vs precipitation for the oceans and for land What balances these excesses Ocean doesn t dry up more evap less precip land doesn t flood less evap more precip surface runoff of excess precip is equivalent to excess amount of evap over ocean exception glacial ice What is a drainage basin a drainage divide watershed drainage basin area which precip falls from the sky it would be drained by rivers in that watershed drainage divide separates watersheds Know the five patterns of river drainage and the geologic setting in which they occur 1 dendritic 2 rectangular like branches of a tree that have tributaries rock of similar types created when flows through similar rock types bend or cuve at nearly right angles follows pathways along fractures or joints in rockes old rocks fractured long ago white clay creek 3 trellis 4 radial rivers and tributary flow parallel to each other for long distances occurs when rivers flow in valleys or folded rocks flow away from a central uplift such as volcano What is a longituidinal profile How does the longituidinal profile of a river or stream change from its headwaters to its mouth LP cross sectional image showing the variation in the rivers elevation along its length steeper near its headwaters source than near its mouth near its headwater an idealized stream flows down deep valleys or canyons whereas near its mouth it flows down deep valleys or canyons plot of elevation from head mouth gradient change in elevation as a function of distance from head mouth rivers and streams end when velocity 0 decreases from head to mouth change in elevation change in distance What is discharge How is discharge related to channel width channel depth channel shape and water velocity amount of water flowing past a given point in a given amount of time increases from head to mouth Know that the velocity of a stream is dependent upon both discharge and the stream gradient higher steeper the gradient the faster the velocity since G V higher discharge the faster the velocity since D V factors G D compete in terms of impact on velocity from head to mouth Head Velocity b c gradient more important Mouth Velocity b c discharge is more important near head and mouth velocity is increasing WE CARE BC IT EFFECTS THE COMPETENCE OF THE RIVER STREAM What are the typical downstream changes in discharge stream gradient and velocity Know the ways that a river or stream carries the debris of erosion 1 bed and saltation load bouncing along the bottom 2 suspended load along with water 3 dissolved load dissolved in water Rainfall V and carries particles in suspended loads makes rivers and streams cloudy What is competence What is capacity competence is the max grain size that a transport agent can carry V Co capacity how much material can be transported D Ca What is a floodplain What is a meander area over which river streams meanders can be covered during a flood bends or curves in a river or stream velocities lower on the inside and higher on the outside of the meander less water on the inside more friction and slower water deposition occurs outside erosion occurs How are point bars formed How are oxbow lakes formed inside deposition occurs forming point bars bigger stuff that low velocity can carry erosion occurs on the outside which can cause oxbow lakes abandoned meaners in rivers or streams What is a natural levee deposits that occur along the banks of a river created during floods when the water overflows its banks How do you determine the recurrence interval for floods determined by measuring max discharge from a rivers floods over a long period of time What does it mean to have a 10 year flood x year floods probability that only once in the next x years will a flood with a discharge equal to or greater than the flood will occur again During what flood cycle does the river do most of its work of erosion and transport What is a delta deposits that occur when a river stream flows into standing water everything drops What is an alluvial fan deposits that occur in sudden decrease of gradient mountain valley Know that in terms of the features formed at the surface of the Earth water is the most important agent of transportation erosion and deposition for weathered material Groundwater Chapter 19 in Earth Portrait of a Planet What are permeablilty and porosity porosity measure of amount of void spaces in a material permeability measure of interconnectedness of void spaces in a material What is an aquifer an aquiclude aquifer material through which water can easily flow sandstone high perm and poros aquiclude material through which water cant easily flow shale low permeability What is the water table horizon that separates the unsaturated zone above from the saturated zone below boundary between zone of aeration and saturation does not always stay in same position higher rainfall higher water table What are the zone of aeration unsaturated or vadose zone and the zone of saturation saturated zone zone of aeration pores filled with air or partially filled with water zone of saturation filled with water What is a perched water table due to lens of sediments acting as aquiclude a secondary water table created above the main water table What is hydraulic head the potential energy available to drive the flow of a given volume of groundwater at a location groundwater flows from regions where it has higher HH to regions where it has lower HH How fast does groundwater move groundwater moves very slow cm day What is a confined aquifer an unconfined aquifer unconfined aquifer not overlain by an aquiclude can infiltrate down from surface confined aquifer water isolated from the ground surface lies beneath aquiclude What is a cone of depression if groundwater is extracted faster than it can be replaced a cone of depression