ERTH 330 Final Study Guide

Fluxes in the hydrologic water cycle

Movement of water

Storage in the hydrologic water cycle

Where water is held

What is the importance of fluxes reservoirs within the hydrologic cycle

precipitation, evaporation, infiltration, runoff

What is the important of storage within the hydrologic cycle

Oceans, glaciers, ground water, lakes

Why is precipitation important for Californias water resources

California depends heavily on winter precipitation and Sierra Nevada snowpack which acts as a natural reservoir

What are the spatial and temporal patterns of percipitation in California

1. Northern CA generally gets more precipitation then Southern California

2. Mountains receive more precipitation than valleys/deserts

3. Most precipitation occurs during winter months

Why does California have dry summers

High pressure systems that block storms

Why does California have wet winters

The jet streams shift south so it allows Pacific storms to reach California

What is Orographic Effect

Most air rises over the mountains, cools, and causes precipitation

What is Rain Shadow

Dry area on the leeward side of mountains after moisture is lost

How does California Topography affect precipitation

Mountains like the Sierra Nevada increase precipitation on western slopes and create dry deserts east of the mountains

What is EL Nino

Weak trade winds and warmer Pacific waters, wetter CA winters

What is La Nina

Stronger trade winds cooler Pacific waters, drier CA winters

What role do trade winds play

They move warm surface water across the Pacific and Influence ENSO patterns

What are normal conditions and the role of trade winds

Balanced trade winds and oceam temperatures

What is the connection between ENSO and weather patterns

ENSO influences storm tracks which affects precipitation and drought patterns in CA

What is the gradient of a stream

The slope of a river channel

How does the stream gradient change downstream

Gradient decreases from steep headwaters to the rivers mouth

What is a rivers base level

The lowest point of. a river can erode to. (usually sea level)

What is the discharge equations

Q=Width x Depth x Velocity

How do rivers characteristic change downstream

1. Channel widens,

2. depth increases,

3. velocity increases,

4. discharge increases,

5. sediment becomes finer

How is discharge measure

By measuring the rivers width, depth, and velocity

What is a hydrograph

A graph that shows a rivers discharge over time

How is flood frequency calculated

based on historical discharge records and ranking flood events

What is recurrence interval (R)

The average time between flood of a certain size

What dies R=100 mean

“100 yr flood” has a 1% chance of occurring each year

What is the probability equation

Probability % = 1/R x 100

What does P=1% mean

100 yr flood

What does P=10% mean

10 year flood

What does P=0.2% mean

500 year flood

What is interpolation from a discharge fruquency curve

Estimating flood recurrence or discharge values between unknown data points

What is an example of a sinkhole lake

Devils Hole Sinkhole Florida

How are sinkhole lakes created

Because of subsidence

What is an example of a river that forms an oxbow lake

Itkillik River Alaska

Trophic status

A measure of a lakes productivity and nutrient levels

Eutrophic Lakes

Nutrient rich, High algae, lower dissolved oxygen lakes

Oligotrophic lakes

Nutrient poor, clear water, high dissolved oxygen lakes

Mesotrophic lakes

In between eutrophic and oligotrophic

What is an example of a Eutrophic lake

Lake Merced it has high algal production and decomposes organic debris

What is an example of an Oligotrophic Lake

Crater Lake it has few small fish and low vegetation

What are the two most important nutrients for water

Nitrogen and Phosphorus

What is Eutrophication

Excess nutrients cause algae bloom which consumes oxygen depletion

What is DO

Dissolved Oxygen

What causes lakes to form from Glacial Activity

Glacial melts and the water forms lakes

What is an example of glacial formed lake

Columbia Ice field Athabasca Glacier

Proglacial Lake

Formed by the damming action of moraine or ice during the retreat of a melting glacier

What is an example of a Proglacial Lake

Schoolroom Glacier Wyoming

What causes lakes to form from Volcanic Activity

Volcano calderas rims that form from the volcano collapse and gets filled with rain water

What is an example of a Volcanic Activity lake

Crater Lake, Oregan

How are Lakes formed by Tectonic Activity

By the movement of the earths crust rift (fissures in rocks) that fill up with water

What is an example of a Tectonic Lake

Lake Baikal Serbia

What is Groundwater

water stored underground in soil and rock

Where does groundwater come from

Precipitation infiltrating into the ground

What is recharge

The process of precipitation becoming ground water

What is an aquifer

Rock or sediment that stores and transmits ground water

Unconfined Aquifer

An aquifer with no barrier above it

Confined Aquifer

An aquifer trapped beneath a confining layer

Perched Aquifer

A small isolated water pocket above the main water table

What is the water table

The boundary between the two zones the top of the saturated table

What is Vadose Zone

Unsaturated zone of aeration it is above the water table

What is an Influent stream

A stream that loses water to groundwater

What is the saturated zone

The underground zone completely filled with water

What is an Effluent stream

A Stream that gains ground water

What drives groundwater movement

Hydraulic gradient

What is Porosity

The amount of empty space in sediment or rock

What Is permeability

The ease with which water will flow through a porous material

When porosity is higher Permeability is _____

Lower

When Porosity is lower, Permeability is ____

High

What percentage of freshwater is groundwater

About 30%

What is fossil water

Very old groundwater stored for thousands of years

What is a cone of depression

circular inverted cone shaped drop that happens when a well is pumped, water flows towards the well from storage

What is Subsidence

Land sinking because of too much groundwater removal

Why does susidence occur

Decreased pore space so there is less storage for groundwater due to over pumping pore spaces collapse

What is an example of Major Subsidence

San Joaquin Valley sank up to ~28ft it had a permanent loss of groundwater storage

Why is subsidence Dangerous

It Damages infrastructure and permanently reduces aquifer storage

How does Droughts affect Ground water

It cause more pumping and ground water decline

What is fracking

Injecting high pressure fluid into rock to extract oil and gas

What is fracking fluid made of

Water, Sand, and chemicals

Why is sand used

by keeping the fractures open and letting everything into the well and be pumped to the surface

Why is fracking needed in shale

because shale is a “tight” rock with extremely low permeability and fracking increases surface area, improves flow, and males extraction possible

Conventional Reservoir

Easy to extract and high permeability

Non Conventional Reservoir

requires fracking and low permeability

How is oil and gas formed

Formed over millions of years from buried plants & microorganisms by Heat and pressure leading to oil & gas which has been stored in underground rock layers

Why has U.S oil/gas production increases

due to fracking and horizontal drilling it allows access to previously unreachable resources

What percentage of global energy comes from fossil fuels

80%

What are major environmental concerns with fracking

1. water contaminations,

2. air pollution,

3. high water use,

4. wastewater disposal challenges,

5. regional stress from multiple wells

What are contamination pathways from fracking

1. surface spills (transport/storage accidents)

2. well failure (bad casing/cement

3. improper injection

4. wastewater leaks

5. migration through old/abandoned wells

What did EPA studies conclude about fracking contamination

No evidence of widespread contamination but localized impacts exist risks are link too poor practices and specific conditions

Why is Fracking controversial

1. Provides energy benefits

2. but has environmental & health risks

3. debate is influenced by: Media, Politics, and Scientific uncertainty

What is Risk

1. Probability x consequences

2. public perception influenced by emotion/media

3. “no evidence” doesn’t mean “no risk”

Where does drinking water come from

1. Surface water: Rivers, Lakes, Reservoirs

2. 2. Groundwater: aquifers

Where does EBMUD water come from

90% from Mokelumne River watershed during drought it may come from other sources like the Sacramento River

How does Water get contaminated At the Source

1. Air pollution

2. Human activity (oil, pesticides, sewage)

3. Animal waste, Microbes

4. Natural Materials (sediment, metals)

How does water get contaminated during Transport

1. Pipe corrosion

2. Open aqueduct exposure

How does water get contaminated In Distribution System

1. Pipes

2. Storage Tanks

3. Local Infrastructure

Can safe drinking water still contain contaminants

yes, at levels below harmful levels (dose matters

What does “the dose makes the poison” mean

Toxicity depends on concentration and the amount of water

What does the Safe Drinking Water Act do

Protects public health and allows EPA to set drinking water standards

What is MCLG

Maximum Contaminant Level Goal which is the idea health goal no risk

What is MCL

Maximum Contaminant Level which is the legal limit of contaminants water can have based on cost/ technology