Increases in water, snow or ice extent, depth, flows or debris/sediment loads are associated with flooding, inundation, snow fall, water logging and sea level rise whilst decreases are linked to drought and snow melt. Over the longer term, changes in hydroperiod occur. Human-induced changes include dam creation, land drainage and pollution.
Water
Drying
Prolonged shortage of water that dries out environments that require water. It can be human or climate induced. Time period: weeks to years.
Snowfall
Precipitation of ice crystals, most of which are branched (sometimes star shaped). Time period: hours to days.
Net snow gain
The cumulative gain of snow cover. Can remain non-vegetated, or move from vegetated (level 1). Level 3: anything turns into NW (P2). Time period: years to decades.
Snow accumulation
The overall accumulation of snow in a region Time period: hours to months.
Net snow loss
The cumulative loss of snow cover. From non-vegetated to potentially vegetated (level 1). Level 3: NW (P1) to anything. Time period: years to decades.
Abstraction
Withdrawal of water from the environment for human use. Remains non-vegetated (level 1). Level 3: remains NW. Time period: years to decades.
Algal bloom
A sudden proliferation of algae (microscopic plants) that occurs near the surface of a body of water. Blooms can occur due to natural nutrient cycles, or can be in response to eutrophication or climate variations. Time period: hours to years.
Blackwater event
When organic material is inundated or washed into waterways and consumed by bacteria, leading to a sudden depletion of dissolved oxygen in the water. Remains non-vegetated (level 1). Level 3: shift from NW (P1) to AW (P2). Time period: days to weeks.
Surface water change
Damming is known to be one of the most important anthropogenic impacts on freshwater ecosystems. Dams fragment river systems and potentially block migration routes, leading to the loss of megafauna. They change the downstream flooding patterns and sediment deposition leading to the loss of floodplains, riparian zones and wetlands. It is important to note that…
Flood
A flood occurs when water inundates (covers) land which is normally dry. Vegetated to non-vegetated (level 1). Level 3: NTV or NS (P1) to NW (P2). Time period: days to months.
Flash flood
Flood of short duration with a relatively high peak discharge. Occurs within about six hours of rain, usually the result of intense local rain and characterised by rapid rises in water-levels. Remains non-vegetated, unless the land flooded is vegetated (level 1). Time period: hours or days to weeks.
Coral bleaching
When the coral host expels its zooxanthellae (marine algae living in symbiosis with the coral) in response to increased water temperatures, often resulting in the death of the coral. Remains non-vegetated (level 1). Time period: months to decades.
Modification of costal environments
Includes clearing and modifying coastal habitats and artificial barriers to flow. Changes to coastal habitats and reductions in connectivity as a result of land use change affect the region’s ecosystem.
Land-based run-off
Land-based run-off affects the quality of water entering coastal environments. Inshore areas suffer from poor water quality due to an influx of nutrients from run-off, sediments from run-off, pesticides from run-off and marine debris. Time period: weeks months to years.
Coastal hazards
As sea levels rise, coastal areas are likely to experience increased erosion and inundation, which poses a threat to communities, infrastructure and coastal ecosystems. The effect of storm surges and waves will amplify these impacts, which vary from place to place.