Lesson 10 - Impacts of Climate Change on the Hydrological Cycle Flashcards
Positive and negative feedback describe how a system does what?
Positive and negative feedback describe how a system (for example a drainage basin and its rivers) responds to a change in inputs.
What is negative feedback?
In any system processes at work help to regulate the system and help to keep it in a state of balance. A period of heavy rainfall may result in increased overland flow and channel flow above the surface and greater throughflow and groundwater flow below the surface. These processes help remove extra water from the drainage basin and return it to its normal state. Regulating processes like these are referred to as negative feedback.
What is positive feedback?
In some situations, perhaps if the rainfall is particularly heavy or lasts a long time, the usual feedback processes may not be able to work effectively. Instead the changes have a ‘knock-on’ or ‘snowballing’ effect, which can cause permanent or long term changes in the system. This is referred to as positive feedback.
Give some of the impacts of climate change?
- Wetlands will dry up
- Drier soils due to increased temperatures
- Lower water availability
Give some ways to adapt to changes to the climate?
- Maintain plant cover and replant hedges
- Reconnect wetlands to the river
- Repair drainage systems
- Urban areas need to adapt to offset the effect of impermeable surfaces
Explain how climate change will affect the hydrological cycle?
Climate change will enhance, intensify or accelerate the global hydrological cycle. Temperature variations and precipitation variations will increase globally. Furthermore, countries will have to cope with changes to water budgets. The way in which the hydrological cycle will operate within the world’s drainage basins will change as a result of climate change.
What is happening to the rate of evaporation as a result of climate change?
In large areas of Asia and North America actual evaporation is increasing.
Is there a definitive link between climate change and the rate of groundwater flow?
There is no definitive link between climate change and the rate of groundwater flow. Human abstraction is the dominant factor which impacts groundwater supplies.
How has climate change affected the precipitation input to the hydrological cycle?
Widespread increases in intense rainfall events have occurred although the overall amount of precipitation has remained steady or even decreased. Areas of precipitation increase include the tropics and high latitudes. Additionally, the length, frequency and intensity of heat waves has increased widely, especially in southern Europe and southern Africa. More precipitation now falls as rain rather than snow.
How has climate change affected ice stores?
Glaciers have retreated globally since the end of the ‘ Little Ice Age’. Additionally, thinning of the glacier due to melting ice has accelerated since the 1970s. This is due to rapid temperature increase and changes in precipitation type.
How is climate change likely to impact the volume of surface runoff and stream flow?
More climatic extremes will lead to an increase in hydrologic extremes with more droughts and floods. An accelerated cycle with more intense rainfall means that surface runoff rates will become higher and infiltration rates will become lower.
How is climate change likely to impact the oceans?
In areas of ocean warming, increased evaporation will occur. There is limited evidence that more cyclones are being generated.
How has climate change affected lakes and reservoirs?
Regional variations in lakes and reservoirs have been linked to regional variation in climate. There has been changes in wetland storage however there is not enough evidence to suggest that this is the result of climate change.
How is climate change affecting permafrost?
Changes in the physical climate at high latitudes, primarily increasing air and ocean temperatures, are leading to permafrost degradation in northern areas. This has an impact on groundwater supplies.
How is climate change likely to impact soil moisture?
Soil moisture is likely to increase due to increases in precipitation.
