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Natural Hazards and Society > Lecture 4 - Droughts > Flashcards

Lecture 4 - Droughts Flashcards

1
Q

What is a drought?

A

A drought is a natural event that occurs when a period of low rainfall causes a water shortage.

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2
Q

How is drought commonly perceived, and how does it actually develop?

A

Drought is often associated with short spells of hot, dry weather but can actually take time to develop.

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3
Q

Why do dry winters have a significant impact on water resources?

A

Dry winters impact water resources heavily because winter rain typically replenishes groundwater and reservoirs, while summer rain helps maintain these levels and keeps rivers flowing.

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4
Q

How complex is the phenomenon of drought, and what are its impacts?

A

Drought is a complex and poorly understood natural hazard with multi-faceted effects that include socio-economic and environmental impacts.

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5
Q

What is a common element in most definitions of drought?

A

Most definitions include a “temporary reduction in water availability over time and space.”

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6
Q

What are the five categories of drought?

A
  1. Meteorological Drought
  2. Hydrological Drought
  3. Agricultural Drought
  4. Groundwater Drought
  5. Socio-economic Drought
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7
Q

What is drought accumulation, and why are timescales important?

A

Drought accumulation refers to the buildup of drought conditions over time, with timescales being crucial as longer drought periods can have increasingly severe impacts.

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8
Q

How frequent and costly have droughts been in the European Union over the past 30 years?

A

Droughts have become more frequent and widespread in the EU, costing over €100 billion in the past three decades.

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9
Q

By what year is there expected to be a significant change in drought indications across the EU?

A

Significant changes in drought indications are expected across the EU by 2070.

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10
Q

What is the “Blueprint for Safeguarding European Waters”?

A

It is a 2012 EU initiative aimed at protecting water resources and managing water scarcity and drought risks in Europe.

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11
Q

Where can an overview of drought propagation concepts and processes be found?

A

An overview is provided in Van Loon (2015).

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12
Q

What is the goal of drought assessment?

A

Drought assessment aims to quantify drought events and develop a long-term understanding of drought characteristics like frequency and severity.

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13
Q

What are the current limitations of conventional drought risk estimates?

A

Current estimates are uncertain and potentially unreliable, and causal relationships with climate change cannot yet be assessed.

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14
Q

Why is predicting future drought severity and frequency challenging?

A

Due to limitations in current data and models, accurately estimating future drought severity and frequency remains difficult.

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15
Q

What are some instrumental data sources for drought assessment in the UK?

A

Key sources include the NRFA river flow data, Central England Temperature Series, and the British Rainfall Series.

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16
Q

How much river flow data is available in the National River Flow Archive (NRFA)?

A

The NRFA has data covering a total of 50,000 years, including daily and monthly flow records from 200 representative gauging stations.

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17
Q

What is the Central England Temperature Series, and what period does it cover?

A

It is a dataset recording mean monthly temperatures in central England, covering the years 1659 to the present.

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18
Q

What precipitation data is available for England and Wales, and for what period?

A

The England and Wales precipitation series provides data from 1766 to 1995.

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19
Q

What is the MIDAS Land Surface Observations data?

A

MIDAS provides daily measurements of land surface data across 154 UK counties, from 1853 to the present.

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20
Q

What is spatial coherence in the context of droughts?

A

Spatial coherence refers to how droughts can affect different locations similarly, but with variations in severity and duration, such as between Oxford and Chatsworth House, Derbyshire.

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21
Q

What are drought indices?

A

Drought indices are tools used to identify, quantify, and characterize drought events by providing a framework to define, analyze, and monitor droughts.

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22
Q

Why are drought indices important?

A

Due to the complex nature of droughts, indices help in quantifying or describing drought states, making it easier to track and compare drought severity across locations and timescales.

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23
Q

Name three commonly used drought indices

A
  1. Palmer Drought Severity Index (PDSI)
  2. Standardized Precipitation Index (SPI)
  3. Standardized Precipitation Evaporation Index (SPEI)
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24
Q

What is the purpose of the Palmer Drought Severity Index (PDSI)?

A

Developed by Palmer in 1965, the PDSI is used to measure drought severity based on temperature and precipitation data, mainly for assessing long-term droughts.

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25
What does the Standardized Precipitation Index (SPI) measure?
The SPI quantifies drought based solely on precipitation over different timescales, making it versatile for analyzing short-term to long-term drought conditions.
26
What is the Standardized Precipitation Evaporation Index (SPEI)?
Developed by Vicente Serrano et al. in 2010, the SPEI considers both precipitation and evaporation, allowing it to assess droughts influenced by temperature changes as well.
27
Name three additional drought indices beyond PDSI, SPI, and SPEI.
1. Surface Water Supply Index 2. Reconnaissance Drought Index 3. Crop Moisture Index
28
According to Friedman (1957), what are the four requirements of a good drought index?
1. Appropriate timescale for the current situation 2. Quantitative measure of large-scale, long-term drought conditions 3. Relevance to the specific problem being studied 4. A long, accurate past record of the index should be available
29
What is a key feature of drought indicators?
Drought indicators can quantify drought at various timescales and enable comparisons of drought severity across different locations, regardless of local climate differences.
30
What does the Palmer Drought Severity Index (PDSI) measure?
The PDSI measures dryness based on recent precipitation and temperature, assessing regional moisture levels.
31
For what purpose was the PDSI originally developed?
The PDSI was initially created for the US Weather Service as the first comprehensive method to assess regional moisture conditions.
32
33
What is a key advantage of the PDSI?
The simplicity of the PDSI allows for the extension of data series, making it possible to generate long-term records.
34
How does the revised version, scPDSI, improve upon the original PDSI?
The scPDSI (Standardized PDSI) allows for comparison across different sites by standardizing the data, as noted by Wells et al. (2004).
35
What is the Standardized Precipitation Index (SPI) based on?
The SPI is based on transforming time-series rainfall data into a normal distribution, fitting a cumulative probability distribution to precipitation data.
36
What range of values does the SPI use to characterize conditions, and what do these values represent?
The SPI uses values from -3 to +3, where negative values indicate dry conditions and positive values indicate wet conditions.
37
Over what timescales is the SPI typically applied, and why?
The SPI is applied over timescales of 1 to 24 months, reflecting different water sources: soil moisture (1-3 months) and streamflow, groundwater, lakes, and reservoirs (3-24 months).
38
Why is the SPI recommended by the World Meteorological Organization (WMO)?
The SPI is the WMO’s recommended indicator for national meteorological and hydrological services due to its adaptability for drought monitoring across different regions (WMO, 2012).
39
40
What is the Standardized Precipitation Evaporation Index (SPEI)?
The SPEI is a drought index similar to the SPI, but it also accounts for evaporation, which is especially important in semi-arid and arid climates and for studying climate change impacts on drought.
41
Why is the SPEI particularly useful for climate change studies?
The SPEI includes the role of temperature in drought formation, making it useful for assessing how climate change affects drought conditions.
42
What approach to potential evapotranspiration (PET) is recommended when calculating the SPEI?
The Thornthwaite approach to PET is recommended for calculating the SPEI.
43
What is a key difference between the SPI and SPEI?
A key difference is the theoretical probability distribution used to fit the climatic water balance data in the SPEI, incorporating evaporative demand.
44
Why are meteorological drought indices like the SPI and SPEI limited in hydrological drought analysis?
Only surface and groundwater variables can accurately quantify and characterize hydrological droughts, as SPI and SPEI do not directly measure these.
45
Name three established hydrological drought indicators.
1. Palmer Hydrologic Drought Index (PHDI) 2. Surface Water Supply Index (SWSI) 3. Streamflow Drought Index (SDI)
46
Why is groundwater often overlooked in drought research?
Groundwater is one of the least studied variables in drought research, despite its importance in long-term drought analysis.
47
What is the Standardized Groundwater Index (SGI), and how is it calculated?
The SGI is a drought index specifically for groundwater, calculated on a 1-month timescale and based on the SPI approach.
48
What is the most challenging aspect of drought prediction?
Predicting drought termination is the most challenging yet critical aspect of drought prediction.
49
How are numerical and process models used in drought management?
These models are widely used worldwide to monitor drought progression, predict termination, and assess impacts.
50
What is "The Long Drought" (Marsh et al., 2007)?
A period of prolonged droughts, interspersed with wetter episodes, that occurred from 1890-1910, primarily affecting Central England with some spatial variability.
51
What was the central region affected during "The Long Drought" period of 1890-1910?
Central England, though drought conditions showed some spatial variability across other regions.
52
What was a key focus of the "Understanding Drought Risk" project?
Developing Drought Management Plans with extended, robust rainfall records to help reconstruct historical drought patterns across Britain.
53
How do Drought Management Plans benefit utility companies?
They allow utility companies to reassess water resource models that were based on a limited set of recent droughts, enhancing the development of Water Resource Management Plans for reliable service levels.
54
Why are longer drought records important for water resource modeling?
Longer records provide a more accurate basis for planning water supply and service restrictions by capturing a wider range of historical drought events.
55
What is the purpose of drought reconstruction in the UK?
To use historical records to create a continuous timeline of drought events, improving understanding of past drought patterns and informing future water management.
56
What data sources were used for drought reconstruction in Norwich?
Continuous instrumental records from 1836 onwards, a wine pints series from 1750-1762, and additional shorter series from 1788-1798 and 1791-1799
57
How can historical drought reconstructions support modern water resource management?
By providing a long-term perspective, these reconstructions help water managers plan for future droughts and evaluate the resilience of current water resources
58
What does the utility reconstruction of UK droughts reveal about drought frequency?
Severe and extreme droughts are a recurrent feature of the UK climate and are not limited to the 20th or 21st centuries
59
What challenge exists in characterizing UK droughts?
While major droughts are spatially coherent, the unique characteristics of individual drought events are poorly understood and difficult to define.
60
How has the UK benefited from extended drought reconstructions?
Extended reconstructions improve the historical baseline of drought events, allowing for broader applications in studying drought characteristics, spatial coherence, and impacts.
61
What has been discovered about drought climate drivers in the UK?
Although there is an interrelationship between the AMO and NAO, there is no consistent link between these drivers and UK drought occurrence, reflecting the complexity of climate and drought processes.
62
What is the relationship between the North Atlantic Oscillation (NAO) and UK droughts?
There is no significant relationship between the NAO and UK droughts, showing that drought drivers are complex and not solely dependent on NAO phases.
63
Why is water increasingly viewed as a manageable resource?
Rising demands from agriculture, industry, and population growth are driving changes in global water management practices for both clean and waste waters.
64
How does UK and EU legislation impact water rights?
UK and EU laws enshrine individual rights to potable water, but this level of protection may vary outside the EU.
65
How does the provision of potable water vary internationally?
Standards for potable water quality, such as the addition of fluoride, vary regionally and internationally, reflecting differing public health standards.
66
What role does international aid play in potable water access?
Organizations like the World Bank support the development of water supplies in international aid efforts, although success has been varied.
67
What is the current focus of drought monitoring advancements?
Advances are focused on real-time drought monitoring, which is critical for agriculture and water resource planning.
68
Why is real-time drought monitoring important?
It enables timely drought mitigation planning, essential for managing agricultural needs and water resource demands
69
What is a key need in drought monitoring from a water resources perspective?
There is a need to apply improved understanding of drought propagation to enhance early warning and monitoring systems.
70
Is groundwater considered a renewable or non-renewable resource?
Groundwater is not non-renewable like minerals or petroleum, but it is not fully renewable in the same way as solar energy. It is recharged by precipitation at rates that are often slower than withdrawal rates.
70
What is a key consideration in groundwater management strategies?
Strategies must account for both current and future groundwater development, as its effects can unfold over many years.
71
Why do the effects of groundwater pumping take time to become apparent?
The full impacts, particularly on surface-water resources, may not be evident for years after pumping begins, due to the slow response of groundwater systems
72
How should losses from groundwater storage be viewed in terms of sustainability?
Losses should be considered within the context of achieving sustainability over a long period, allowing for temporary withdrawals balanced by periods of recharge.
73
What makes groundwater withdrawals and recharge variable?
Seasonal changes and annual fluctuations cause variability in both groundwater withdrawals and recharge rates.
74
What is a crucial attribute of groundwater sustainability?
The concept promotes a long-term management perspective, essential for balancing usage and replenishment.
75
What is a priority for groundwater management in the United Kingdom?
Ensuring sustainable long-term use of groundwater resources by carefully balancing withdrawals with recharge rates.
76
Why is it important to understand how reservoirs respond to drought in the Severn Trent Water (STW) area?
Understanding reservoir response is essential for developing effective drought plans and ensuring reliable water supply during droughts.
77
Which recent drought events highlighted the UK's vulnerability to water shortages?
The droughts of 2004-2006 and 2010-2012 demonstrated the ongoing vulnerability of UK water resources.
78
How many people were affected by water use restrictions during recent UK droughts?
Approximately 26 million customers experienced water restrictions, such as hosepipe bans.
79
What historical data is being reconstructed to improve UK water resource assessments?
Historical droughts (pre-1920) are being reconstructed to enhance water resource assessment and drought management.
80
How are drought indices used in UK water resource management?
Drought indices are applied to support operational drought management, providing insights for planning and response
81
What is the service capacity of Severn Trent Water (STW)?
STW provides 1.8 gigalitres of water daily to approximately 7.4 million people
82
What area and supply sources does Severn Trent Water cover?
STW serves a 21,000 km² area with a water supply split equally among river abstractions, reservoirs, and groundwater.
83
What types of data are crucial for understanding drought in Severn Trent Water’s area?
Key data includes rainfall, streamflow, and reservoir levels, which are essential for monitoring and managing drought.
84
What is the purpose of the Drought Plan Regulations (2005) and Drought Plan Direction (2011) in the UK?
These regulations define the legal obligations of water companies regarding the development and implementation of drought plans.
85
What are water company drought plans?
Statutory documents outlining how a company will ensure water supply to customers during droughts while minimizing negative impacts.
86
What operational steps must be included in a water company drought plan?
The plan should detail short-term actions to be taken before, during, and after a drought to manage water resources effectively.
87
What agency provides guidance for water company drought plans in the UK?
The Environment Agency offers guidance to help water companies structure and implement their drought plans (Environment Agency, 2011b).
88
What are two key components considered in the organizational structure of drought plans?
Priorities for action and thresholds for responses to drought conditions.
89
How are thresholds used in water company drought plans?
Thresholds help determine the appropriate responses to different levels of drought severity to ensure timely and efficient action.
90
What are the socio-cultural impacts of drought?
Droughts lead to extensive and complex socio-cultural impacts that are often not reflected in instrumental records.
91
How can human activities influence drought impacts?
Human actions or inactions can exacerbate the effects of drought, making the situation more severe.
92
What is the current understanding of water availability and use in drought research?
Drought research should recognize the interactions between natural water availability and socioeconomic factors, rather than viewing them as separate phenomena.
93
How did severe droughts in the mid-1800s impact reservoir construction in the UK?
Severe droughts led to the expansion and construction of reservoirs to secure water supplies, especially for urban areas.
94
What was the primary purpose of many early reservoirs built in the UK?
Many early reservoirs were constructed to support the canal network during low-flow periods.
95
How many large reservoirs have been constructed in the UK since 1900, and what is the largest?
Since 1900, 46 large reservoirs have been built; the largest is Kielder Water in Northumbria, completed in 1981.
96
What was the Elan Valley Reservoir built to address?
The Elan Valley Reservoir was developed to provide clean water for Birmingham, addressing outbreaks of waterborne diseases due to inadequate water supply.
97
What challenges exist for constructing new reservoirs in the UK today?
Few suitable locations for new reservoirs exist, and building them would be extremely costly.
98
What historical conflicts have been linked to water resources?
Conflicts such as the war between Lagash and Umma over irrigation rights and the Kashmir dispute highlight the historical significance of water as a resource leading to conflict.
99
What is the significance of drought in climate history?
Drought has historically threatened large populations and posed serious risks to life, continuing to be a significant climate concern.
100
What challenges remain in predicting drought termination?
Predicting when a drought will end is difficult, complicating water resource planning and management.
101
Predicting when a drought will end is difficult, complicating water resource planning and management.
There is no evidence to suggest that droughts are increasing in frequency in the UK, though there is concern over increased stress on water resources.
102

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