Rivers/Groundwater Flashcards
How do you calculate stream gradient?
The change in elevation over the change in distance.
How does stream gradient affect velocity and erosion?
If there is a higher gradient, there is a higher velocity and erosion
How do you find stream discharge?
You multiply the average velocity, which is found at six tenths of the depth, and multiply it by the area of the river cross section.
What are the different types of springs?
An ordinary spring, a perched water table, and a hot spring/geyser.
What is an ordinary spring?
It depends on precipitation to flow.
What is a perched water table?
It is water above the existing water table due to an aquiclude.
What is a hot spring and a geyser?
A hot spring occurs when water fills into cracks in between rock Slash magma below. Pressure builds up in chambers. When the water escapes, the pressure drops, and steam occurs. A geyser is like a hot spring, but it has a constriction.
What are the types of wells?
Ordinary and artesian wells.
What is an ordinary well?
This water has to be pumped and occurs in unconfined aquifers.
What is an artesian well?
They occur in artesian springs, and water flows from pressure. It may not need pumping, and it occurs in a confined aquifer.
What is an aquifer?
Any material that can store and transmit water.
What is an aquiclude?
Rock that is impermeable to water.
What is a watershed?
A basin where all water that falls and it goes to one river system.
What is a drainage divide?
A drainage divide divides water sheds.
What is stream piracy?
Stream piracy is when one river steals water from another.
What problems can be caused by over pumping?
A cone of depression and saltwater intrusions. A cone of depression occurs around a well and The water table dips around the well causing a change in direction of groundwater flow. Salt water intrisions happen in coastal areas. Salt water gets drawn into the well to replace freshwater.
What are sources of groundwater contamination?
Salt water intrusion, pesticides, road runoff, landfills, and weather material.
What is the water table?
The surface of ground water.
What is the zone of aeration?
The area with air in pores of rock.
What is the zone of saturation?
The area where groundwater fills the Pores of rocks.
How can we use topography to see how ground water flows?
Ground water flows downhill, and the water table mimics topography.
What is porosity?
Porosity is the amount of air between grains.
What is capillary water?
The amount of water that remains between grains after most water has moved out.
What is permeability?
The speed at which water can move between grains.
What factors affect porosity?
The shape of the grains (angular=less porosity) and sorting (poorly sorted=less porosity).
What factors affect capillary water?
If the grains are more angular, capillary water increases.
What factors affect permeability?
Grain shape (angular=decreases), grain sorting, and grain size (bigger=more permeable).
What are the characteristics of young rivers?
fast, v-shaped valley, straight, erosion, steep, rapids, high bedload and competency
What are the characteristics of mature rivers?
graded stream, slightly meandering, more features, delta develops, tributaries, small floodplain
What are the characteristics of old rivers?
deposition, low grade, meandering, low competency, slow, wide floodplain, many features, mostly dissolved and suspended load.
Why do rivers get more curvy?
Rivers get curvier because of the cutbank and point bar. The cutbank is where the water is deeper and faster with more erosion than the point bar. Over time, the point bar has deposition and the cutbank experiences erosion and meanders form.
What is the cutbank?
The cutbank is the deeper side of the river and it experiences more erosion.
What is the pointbar?
The pointbar is the shallower side of the river and it experiences more deposition.
What happens to a river if the base level changes?
If the base level goes up, the river slows down and deposits sediment. If the base level goes down, the river speeds up and erodes.
How do you find the probablity of a flood occurring?
First, divide the number of years on record+1 by rank to get the recurrence interval(RI). Then, 1/RI x 100= % chance of it occurring each year.
