ENSV 101 1st EditionExam # 2 Study Guide Lectures: 10 - 17Lecture 10 (February 17th)What exactly makes water so important? The distinctive chemical properties of water itself, are what make the very existence of life possible. Among other things, water:- Dissolves and transports elements- Water also dilutes and transports wastes- It is also a key element in supporting biologic structuresWater and the Hydrologic Cycle: The overall movement of water throughout the hydrologic cycle is powered by the Sun, and occurs in the following process:- Evaporation, or Transpiration- Condensation- Precipitation- Surface runof- Infiltration- Ground waterThe largest reservoir that can be found in the Hydrologic cycle by far, is the ocean. The ocean actually contains the vast majority of Earth’s water, around 97.5% of it!Another interesting aspect of this natural process, is that most of the water in this cycle is saline, making it unusable by humans.The largest reservoir of freshwater on Earth is the polar sheets, which contain approximately 74% of the Earth’s fresh water. The largest reservoir of the unfrozen fresh water that can be found on Earth is groundwater.Water on the Ground: After precipitation occurs, water moves downhill, initially as overland flow, or sheet flow, and then it collects into small channels that are called gullies or rills. After collecting into these small channels, the water then gets concentrated into stream flow.Discharge: Is the rate of water movement (volume per time), units: cfs (ft3 per second), cumecs (m3 per second)Load: A stream’s total sediment and dissolved matter that it is transportingWater on the Ground:- Bed Load: consists of 5-50% of total sediment load, and moves by rolling, sliding, or saltation.- Suspended Load: Particles of silt and clay efectively provide the muddy characteristics of various streams- Comprised Load: Is comprised primarily of seven diferent ions (bicarbonate, magnesium, calcium, sulfate, chloride, sodium and potassium)Stream Flow: Consists of the following elements- Storm flow: “extra” water that ends up running of after precipitation- Base flow: water flowing between storms usually supplied by groundwaterStreams that have no base flow are ephemeral, while streams with base flow are perennial.The size and shape of a stream channel are actually controlled by several factors, including: - The erodibility of rock- The steepness of descent - Volume of waterGradient: The vertical distance that a stream channel descends along its course. Overall, this undergoes a decrease as it goes downstream, but this is not a change which occurs very smoothly.Overall, stream behavior is controlled by five distinctive factors, including:1. Average channel width and depth2. Channel gradient, or slope3. Discharge4. Channel pattern 5. Sediment loadAll streams on Earth undergo a diferent amount of combined efects from the interactions which occur among these distinctive factors.Lecture 11 (February 19th)Downstream: width and depth increase gradient decreasesflow velocity and discharge also undergo an increaseLoad particle size decreasesalluvium: sediment that is deposited by a riverBedrock channels often have the rarely sighted straight channels, river banks that resemble a straight line.In the Meandering channels: Straight channels are rareLow gradient dreams typically assume a sinuous shape, each bend is a meander velocity is lowest along inside meanderpoint bar deposition commonly occursVelocity is at its highest along the outside meanders, and because of this, cut bank erosion can occur, because the water efectively cuts away at the outside edges of a meandering channel. By way of this erosion, meanders have a tendency to migrate, and oftentimes, a stream will bypass a channel loop, efectively cutting it of and forming an oxbow lake. Braided Channel: A stream with many interlacing channels and bars will be categorized as a braided channelStraight channels These channels are often in bedrock. or very steep areas, anthropogenicThey also have a tendency to be highly erosiveContinental Divide: A line which separates the drainage basins that flow into diferent oceans Continental divides will often coincide with the crests of mountains, the result of uplift, we know that there is a close relationship that occurs between plate tectonics as well as the locations of stream basins.Landforms of Streams:Floodplain: broad deposit of fine sediment beyond the channel made during a floodTerrace: old floodplains abandoned as stream incises and cuts down over timeAlluvial Fan: a fan-shpaed deposit at the base of an upland or mountainous areaDelta: a triangular shaped deposit that is formed when a stream ends up entering standing water, which can pertain to either a sea or a lake. Flood Prevention:River channels are oftentimes channelized and or dammed for the purpose of flood controlFlood prevention comes at a price, however:- It interferes with the ecosystems which are present along a river environment- It can aggravate the efects of pollution around the area- Flood prevention does not always protect against the efects of flooding, at may actually increase the chances of a flood occurring- It can also lead to subsidence, or sinking.Lag time: time between break precipitation and peak flowLecture 12 (February 24th) Groundwater typically flows from high water table areas to low water table areas in response to the efects of gravity on Earth. Thus, water that is on high mountain tops, will typically find its way down towards the bottom of the mountain, towards lower altitudes.Infiltration of precipitation is a means of “recharging” the groundwater sourcesIn general, water typically moves to areas of discharge, where it will end up meeting the surface, and water sources such as streams, lakes, ponds, or wetlands.Groundwater flow depends on the porosity and permeability of the rock it moves through.Porosity: the percentage of the total volume of rock that consists of open pore spacesPermeability: a measure of how easily a solid allows fluids to pass thorough it.Resource: a source or supply that can be used beneficially or for profit.Aquifer: a body of rock or regolith porous and permeable enough to be used as a resource.Confined aquifer: bounded above and below by impermeable rock layers called aquicludes. (Hasa potentiometric or piezometric surface rather than a water table where it would be confined bysomething impermeable).Artesian wells: where