Chapter 5 Flashcards
What is hydrology
-it is the science that looks at understanding, describing and predicting how water moves through the landscape and through the atmosphere
Describe the importance of the Colorado river
- it flows out of the central Rocky Mountains
- > flows through Colarodo, Utah, Nevada, etc and into Mexico
- > it flows through an extremely arid region with few other sources of water
- > but the areas it flows through has intensive agriculture and growing urban populations
- this river is dammed for msot of its length
- > almost every drop of water is allocated to different states for different usages
- > to the point that 90% is diverted before it reaches the Mexican border
- > the river rarely reaches its delta in the Gulf of California
What is the most sacred river to Hindus
-the Ganges river that flows through India and Bangladesh is the most sacred river to all Hindus
What is meant by the term debris flows
-these are fast moving masses of saturated rocks and sediment and organic material
How do mountains store water
- they store water as ice and snow
- >they are essentially the water towers of the world
Where do rain, snow, glacial melt water and ground water originating in the mountains end up
- they end up in rivers
- >rivers transport the water from mountain ranges to the lowlands and back to the seas and oceans
What is a watershed
- the land that drains into a common water body si called a water shed
- > healthy watersheds perform important regulating ecosystem services that influence water quality and quantity
What is the role of soil in watersheds
- they act as a sponge
- > soaking up precipitation through a process called infiltration
- note vegetation in watersheds increases infiltration
- > because it slows surface runoff
- > allowing more water to seep into the ground
Does infiltration minimize erosion and prevent flash floods
- yes
- > some of the water that is absorbed into the soil through infiltration replenishes ground water stores
- > which in turn recharges lakes and streams
Do watersheds slow run off and regulate the release of water
- yes
- >this process also helps to maintain consistent stream flow and water supplies during dry periods
How do watersheds play a crucial role in cleaning and filtering out water supplies
- as water moves through the soil, microbes remove harmful pollutants, toxins, pesticides and heavy metals
- power plants also purify water by taking up excess nutrients
- > like those released from fertilizers
Is rain mostly during the summer in the mountains
- yes
- > it is too cold at other times of the year
- > so it falls as snow
What is frontal rainfall
-low pressure systems move in from elsewhere and are forced to travel over the mountains
How long does rain last from frontal rainfall
- it can be prolonged
- > it may last for days or even weeks
- > as witnessed on the west coast of Canada
What are convective storm rainfalls
- or the rain may be from locally formed convective storms
- > these storms form in afternoons and evenings from strong daytime heating on the landscape
- occur on a much shorter timeframe than frontal rainfall
- > lasting mere minutes to hours
- > includes solid precipitation like hair as well as storng winds
Does convective precipitation occur at any time of the year like frontal precipitation
- no
- > it is limited to periods when it is hot enough to cause strong evaporation during the day
- > such as during late spring, summer and early fall
- they are common in continental areas
- > and are often seen in places like the Canadian Rockies throughout the summer
What are the several routes once convecting storm current rain falls on the ground
- it can take on several routes once it falls on the ground
- > runoff can be direct, moving downslope on the surface from the minute it hits the ground
- > or runoff can be delayed, absorbed into the ground
How does direct and delayed runoff contribute to the river runoff
Direct runoff
->can have an almost immediate impact on the stream and river runoff
Delayed runoff
- > may also contribute to river runoff
- > but over a period of days to weeks
How does intense rainfall compare to long lasting rain in terms of absorption of water into the soil
- intensity of the rainfall often controls how well the rain is absorbed into the ground
- > during intense rainfall events, the top portion of the ground will become saturated, causing surface runoff
- > steady rain that is not as intense will allow the water to percolate deeper
What does fresh snowfall contain
- it contains upwards of 90% trapped air
- > it is a very good insulator
- > the upper 30 to 40 centimeters will be colder
- > the snow resting directly on the ground will often tend to be warmer than the surface snow
Does the insulating ability of snow decreases as its density increase
-yes
Does the ground being frozen determine how the melt will flow
- yes
- > if the ground under the snow is frozen, surface runoff will dominate
- > leading to water quickly finding its way into streams
-in conditions where the ground is frozen, any late winter rain on snow events cal easily lead to flooding
Does the initial energy in the Spring from the Sun contribute to massive amounts of melting
- no
- > much of the initial energy from the Sun contributes to warming the snow pack
- > with only minimal melt occuring
- > so there tends to be a laf between warming of the atmosphere and melting of the snow
Does positive feedback develop once the snow begins to melt
-yes
Why would the albedo of snow decrease as it melts
- because water starts to build up in the snow pack
- also airborne particulates including soil, dust, smoke and organic material which falls with the snow is exposed and increasingly concentrated as snow melts
- > darker snow is less reflective
- > so more heat from the sun is absorbed
Is the water coming from the glacier cold
- yes
- > not so much above freezing
- > this keeps the stream and river temperatures quite low(important for trout)
- > so glaciers serve as a thermal buffer
How does runoff move through the mountains
-common theme is for the runoff to find its way down the slopes
- it can move as:
1) overland flow where the water flows over the ground surface(eventually forming streams)
2) Percolate into the ground and make its way to local streams
3) Water becomes part of the groundwater system
What is groundwater
- it is water that fills the pore spaces and fractures in rocks and sediment
- > the saturated zone is where all available fractures and pore space is filled in the sediment and the rock
What sits on top of the saturated zone
-on top of the saturated zone is the water table
What is the purpose of ground water in the winter
- it maintains streams and rivers in high elevation areas in the winter
- during the winter, there is little rainfall and the snow isn’t melting and neither are the glaciers
- > so ground water is essential for maintaining flow into rivers and streams
What controls how runoff moves across mountain landscapes
- the steepness of the slope and the material it is comprised of is critical
- > steep slopes made up of bare rock or bare rock covered in sparse soil with patchy or little vegetation will favor rapid and intense runoff
- vegetation plays several roles in determining how runoff moves through the mountain landscape
- > leaves and branches filter the water coming from the sky by capturing it directly
- > this reduces the amount that hits the ground
- > vegetation also removes water from the ground through their roots
- > this removed water is eventually released back into the atmosphere through transpiration
What is transpiration
-the process by which water is taken in by plants and evaporated out of their leaves and stems
Do alpine plants and forests help with water storage, preventing over saturation
- yes
- >it can also delay runoff
Which mountains will have higher rates of erosion
- mountains with high energy environment, exposed bedrock, loose sediment and patchy vegetation will have higher rates of erosion
- process of erosion is led by water
Are glacier lake outburst floods occurrence risk increasing
- yes due to global climate warming acceleration
- >eg; Imja Tsho has been identified as one of the potentially dangerous leaks in the Himalayas
What have the High Mountain Glacier Watershed Program have done regarding the risks that Imja Tsho poses
- they have met with village leaders
- discussed some options for managing the risks that Imja Tsho poses
- > these included accepting the risk of a possible flood, relocating to higher elevations and constructing controlled drainage canals
Has there been reconstruction of arched bridges over the Nepal-China highway to avoid glacial outburst flood levels
-yes
Have glacial lakes been drained and dammed in Peru
-yes
What are legacy pollutants
- contaminant that accumulate in glaciers
- >once the ice melts, it will release these pollutants back into the environment
