Hydrology & Water Resources Exam 2

What is the relationship between increasing greenhouse gas concentrations and air temperature?

Increasing greenhouse gas concentrations lead to increasing air temperature.

How much does moisture-holding capacity increase for every 1°C warming in air temperature?

Moisture-holding capacity increases by about 7% for every 1°C warming.

What is the role of the Intergovernmental Panel on Climate Change (IPCC)?

The IPCC synthesizes and explains the science of climate change and its impacts through Assessment Reports every five years.

What are the three working groups of the IPCC?

The three working groups focus on science

What is the main focus of the IPCC's AR6 WG I Report (2021)?

The Physical Science Basis of climate change.

What does the IPCC's AR6 WG II Report (2022) address?

Impacts

What is the significance of warmer air in relation to precipitation?

Warmer air holds more moisture

What percentage of U.S. cities experienced an increase in wettest-day rainfall according to the study analyzed?

79% of cities experienced an increase in wettest-day rainfall.

What is the impact of warming over land on evaporation?

Warming over land drives an increase in atmospheric evaporative demand and severity of droughts.

What are the observed hydrological changes mentioned in the IPCC reports?

Changes in precipitation

What is the impact of deforestation on Brazilian drought?

Deforestation causes drought by disrupting moisture recycling and leading to dried rivers and fires in tropical wetlands.

What are the drivers of drought and reduced water availability?

Precipitation and evaporation drivers lead to meteorological and hydrological drought.

What is the projected impact of climate change on glaciers by 2100?

75% of glaciers in the Himalayas are projected to melt

How does climate change affect the timing of ice cover on lakes?

causes later onset and earlier breakup of lake ice, shortening the ice season.

What are some indirect effects of climate change on precipitation and evapotranspiration?

Indirect effects include changes in ice cover

What is the importance of water security in the context of climate change?

crucial for managing observed hydrological changes and adapting to future risks.

What is the significance of the Clausius-Clapeyron graph in climate studies?

It helps interpret the relationship between temperature and moisture capacity in the atmosphere.

What are the projected sectoral water-related risks due to climate change?

Projected risks include impacts on agriculture

What adaptations are necessary for achieving water security?

Adaptations include understanding the limits and trade-offs of water-related strategies.

What is the impact of increased CO2 levels on plant growth?

Increased CO2 may enhance plant growth but also leads to challenges in water availability.

What are the observed sectoral impacts of current hydrological changes?

Impacts are seen in agriculture

What is the expected trend in heavy precipitation events as climate warms?

The frequency and intensity of heavy precipitation events are expected to increase.

What is the significance of the term 'cascading moisture recycling' in the context of climate change?

It describes how moisture from the Atlantic contributes to rainfall over the Amazon

How does evaporation rate in spring/summer affect ice season?

A low ice year leads to a high-ice year due to its impact on water temperature.

What are some disasters that serve as the public face of climate change?

Floods

What is the process for attributing weather events to climate change?

Combine weather observations with climate models to assess the role of climate change.

What key questions are asked when attributing events to climate change?

1. How did climate change influence the intensity of the event? 2. How did climate change influence the likelihood of the event occurring? 3. How did pre-existing vulnerability worsen the impacts?

What were the key findings from Typhoon Gaemi in July 2024?

Rainfall intensity increased by 14% in Taiwan and 9% in Hunan

What was the impact of Typhoon Gaemi on rural communities?

communities with climate-sensitive livelihoods and urban poor in low-lying areas were most affected. intense rainfall, increased flood and landslide risk

What was the increase in the number of storms as a result of climate change observed in the findings from Typhoon Gaemi?

A 30% increase in the number of storms of that strength.

What was the measured storm severity index for UK and Ireland from October 2023 to March 2024?

A 20% increase in average stormy-day precipitation due to climate change.

What was the likelihood of rainfall in 2023-24 compared to previous years?

Rainfall was 10 times more likely due to climate change.

What is the significance of the IPCC's Assessment Reports?

They provide periodic evaluations of climate change science and impacts.

When was the first IPCC Assessment Report published?

1990.

What major recognition did the IPCC receive in 2007?

The Nobel Peace Prize

What are some observed hydrological changes in the U.S. since 1901?

Annual precipitation has decreased in many areas

What has been the trend in mesoscale convective storms since 1979?

Increased occurrence and rainfall.

What has been observed regarding extreme snowfall in the northern U.S.?

Extreme snowfall has increased.

What projections are made regarding future heavy precipitation events?

The frequency and intensity of heavy precipitation will continue to increase.

What is expected for forest fires in the western U.S. due to climate change?

An increase in forest fires with profound changes to ecosystems.

What changes are projected for snowpack in the western U.S.?

Large declines in snowpack are expected.

What is the anticipated impact of climate change on hurricanes and typhoons?

Increased intensity and frequency.

What does the term 'atmospheric rivers' refer to in the context of climate change?

Increased frequency and severity of atmospheric rivers on the west coast.

What are the expected changes in spring melt and snow water equivalent (SWE) in the western U.S.?

Earlier spring melt and reduced SWE.

What is the projected impact of climate change on precipitation types in the central/eastern U.S.?

More precipitation is expected as rain rather than snow.

What is the significance of understanding Shared Socioeconomic Pathways (SSPs)?

They provide scenarios for future socioeconomic conditions and their impact on climate change.

What do the SSPs illustrate regarding global population and GDP?

They show projections of global population growth and GDP changes over time.

What is a watershed?

A defined area of land that drains to a selected outlet.

What defines the boundary of a watershed?

The boundary is defined by elevation.

What is an endorheic basin?

A watershed that drains to an internal location

What is the significance of watersheds in hydrologic systems?

They allow for the accumulation of processes to be measured at a single outlet.

What is the Strahler Stream Order?

A method for classifying streams based on their hierarchy

What happens when two streams of the same order join?

The resulting stream is assigned the next higher order (n+1).

What is drainage density?

The total channel length divided by the watershed area

What are the characteristics of high drainage density?

Shorter hillslopes

What are the characteristics of low drainage density?

Longer hillslopes

What is the watershed mass balance equation?

O = P - E - Q_out

What is the role of rivers in shaping landscapes?

Rivers contribute to erosion and sediment transport

What is a hydrograph?

A visual representation of streamflow over time

What is the importance of lakes in hydrologic systems?

Lakes serve as reservoirs for water storage and play a crucial role in local ecosystems.

What are the projected impacts of climate change according to the IPCC?

Risks and adverse impacts from climate change escalate with every increment of global warming.

What is the significance of the statement 'There is a rapidly closing window of opportunity to secure a liveable and sustainable future for all'?

It emphasizes the urgent need for action to mitigate climate change effects.

What does the term 'megadrought' refer to?

A prolonged period of drought that may last for decades

What factors influence surface runoff?

runoff mechanism, drainage density, land cover, topography, soil properties, rainfall characteristics

What challenges do international watersheds face?

Issues such as transportation

What is the role of dams in flood mitigation?

Dams help control water flow and reduce the risk of flooding downstream.

What is the importance of assessing flood-frequency and risk?

It helps in planning and implementing measures to protect communities from flooding.

What is the impact of agricultural runoff on watersheds?

It can introduce pollutants and nutrients that degrade water quality.

What is the significance of the Danube Watershed?

It faces challenges related to transportation

What does the term 'climate change' encompass?

Long-term changes in temperature

Why is it important to understand watershed characteristics?

Understanding these characteristics aids in effective water resource management and environmental protection.

What are the two factors used by the IPCC to estimate confidence levels?

Agreement and evidence

What information is needed on a map to outline a watershed?

Elevation, locations, topographic contours, land area boundaries: to define the extent of land draining to a common outlet

What happens to precipitation after it hits the ground?

It can either infiltrate into the soil or run off along the ground surface.

What are the two mechanisms of runoff?

Infiltration-excess runoff (IER) and saturation-excess runoff (SER)

What is infiltration-excess runoff (IER)?

Occurs when rain falls at a higher intensity than it can infiltrate into the soil.

What conditions lead to saturation-excess runoff (SER)?

Occurs when the ground is saturated at the surface.

What is a hydrograph?

a graph that shows how stream discharge (flow rate) changes over time

What are the two main components of a hydrograph?

Stage (elevation of river surface) and discharge (volumetric flow rate of water).

What does the rating curve show in relation to hydrographs?

The relationship between stage and discharge.

What are the three hydrograph characteristics of interest?

Magnitude of peak discharge

How does drainage density affect runoff velocity?

High drainage density → steep slopes, impermeable soils → rapid concentration of flow → flashier hydrographs. (faster runoff velocity)

Low drainage density → flatter terrain, permeable soils → slower runoff → delayed peak flow

How does basin steepness influence runoff?

Steeper basins lead to faster runoff and less time for water to infiltrate.

What is the impact of urbanization on stormwater runoff?

Increased impervious surfaces lead to a 'flashy' response to rainfall.

What is the significance of measuring streamflow?

It indicates how much water is in the channel and how quickly it enters.

What do USGS stations measure?

Water level (gage height or stream stage)

What is the formula for calculating discharge?

Q = velocity × area

How do you construct a discharge rating curve?

By measuring discharge at different flows and extrapolating between measured values.

What is the ideal depth for measuring velocity in a stream?

60% of the total depth from the surface

What is the relationship between peak flow and basin shape?

Basin shape influences the magnitude and timing of peak flow.

What is the effect of impervious surfaces on runoff volume?

They increase runoff volume due to reduced infiltration.

What is the role of soil characteristics in infiltration?

Different soil types have varying infiltration capacities.

What is the significance of lag time in hydrographs?

It indicates the time taken for peak flow to occur after rainfall.

What does the area under the hydrograph curve represent?

The total volume of runoff.

What happens to subsurface runoff during storms?

It contributes to base flow between storms.

What is the difference between runoff and streamflow?

Runoff is how quickly water reaches a stream channel

What are the vertical-axis units on a stage hydrograph?

Stage height

What are the vertical-axis units on a discharge hydrograph?

Discharge

What causes the decrease in infiltration capacity during a storm?

Soil saturation and compaction reduce the soil's ability to absorb water.

Which runoff mechanism is based on rainfall intensity?

Surface runoff