Please enable JavaScript.
Coggle requires JavaScript to display documents.
Hydrological Hazards - Key Terms and Flood Hazards lecture 1-4 - Coggle…
Hydrological Hazards - Key Terms and Flood Hazards lecture 1-4
Introduction to flood risk
Lecture 3
TYPES OF FLOODS = Pluvial, Fluvial/ Riverine, Flash/ Rapid-onset, Lowland/ slow rise
(focus flooding)
coastal, groundwater, non-natural = dam break and pipe bursts
Pluvial
is where the flooding is associated with surface water divided from rainfall - tend to be less problematic
Fluvial or riverine flooding
main causes are widespread/ long-duration precipitation and melting snow
this can take hours, day to weeks depending on river basin size
flash flooding
is rapid-onset, short duration flooding, the main causes is intense heavy rain fall and catchment conditions eg steepness
Coastal flooding
is when low lying coastal areas experience tides, storm surges, tropical cyclones, high wind and tsunami
New Zealand
floods are mostly rivering flooding which is very common. Nz disasters of floods are bias towards south Island because of the southern alps
3 categories for floods - Tangible/ intangible , Direct/ indirect or Primary/ secondary
Risk and Risk Management
4 basic rules
risk Avoidance
risk reduction
risk Retention
risk transfer
risk avoidance
is not investing in property ect however, with that you are also avoiding reward in this case there is (acceptable risk) ISSUE WITH THIS some people don't understannd if it is a risk or not
risk reduction
is methods to reduce the likelihood and/or severity of loss ISSUES WITH THIS is to be effective the risk must be properly understood
risk retention
is accepting loss when it occurs and have "self insurance" your own equity ISSUES WITH THIS is the issues need to be understood to know how much money to put aside
risk transfer
is causing another party to accept the risk eg insurance and payouts ISSUES WITH THIS is some insurance company wont pay you out fully so the risks need to be understood
WHAT IS RISK =(the likelihood of a hazard occurring) x (the consequences of that hazard occurrence) - Good risk
management
might aim to reduce the likelihood of the hazard and reduce the consequences
Risk, Vulnerability and resilience
Lecture 2
Hazard severity- what could happen but hasn’t happened yet.
Controls = Duration, predictably, frequency, extent, magnitude, speed of onset, spatial concentration and number
Hazard prevention = Risk management (before event), Emergency management (during the event)
Prevention
is a misnomer, and may lead to complacency eg. flooding CANNOT be prevented (but we can manage it better)
Risk management
is what we do
before
the event, and
emergency management
is what we do
during
the event
natural disasters
- the term natural is a misnomer: Events are not hazards or disasters without human involvement
Vulnerability is social
Reducing vulnerability is requires
Economic development, better risk management and better emergency management
vulnerability
increases due to poor risk management or poor emergency management - It also changes through time
KEY TERMS
Hazard
= A dangerous phenomenon, substance, human activity or condition that
may
cause loss of life, injury or other heath impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage
Disaster
= A dangerous phenomenon, substance, human activity or condition that
has
cause loss of life, injury or other heath impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage
Hazard Management
= What humans do, or should do, to minimise the effects of hazards
Risk
the potential loss of life, injury, or destroyed or damaged assets which could occur to a system, society or a community in a specific period of time, determined probabilistically as a function of hazard, exposure, vulnerability and capacity
Vulnerability
the characteristics of a person or group and their situation that influence their capacity to anticipate, cope with, resist and recover from the impact of a natural hazard
Lowland and flash flooding
lecture 4
Low-land river flooding
- a larger and less dynamic event then flash flooding and more downstream. It is caused by excessive precipitation, which may have fallen hundreds of Km upstream
Lowland river flooding is associated to
flood plains
- which are natural and dynamic systems that are areas of common flooding connected to a river. They are historically known to be an advantage for human settlements
Case example=
mississippi usa
- this drain 2/3 of usa and some parts of Canada and one of the worlds most managed river Systems
Flash flooding
- rapid localised flooding of low lying areas , caused mostly by intense rainfall events and tends to cause a-lot of economic damage
they are hard to predict eg thunderstorms and can be random and usually small in scale
causes include reduced or insufficient drainage system efficiency and the volume of water may be to much for the drainage network to carry
case examples include UK Boscastel - a huge amount of rainfall and a small amount of time
a-lot of drainage had been blocked due to vegetation
Floods risk in Christchurch
a major hazard is the Waimakariri bursting its banks and chch is prone to tidal flooding along the coast Christchurch also know to have events with extreme rain fall in short amounts of time
Over time there has been a change in flood risk and much more area of the
avon
river is susceptible to flooding
climate and river flooding
in a warmer climate which is creating more volume and intense storms and the mountain areas have high average temps which increases run-off
climate change me we are adding energy into the atmosphere