Glossary

Berm is a barrier separating two areas, in this case it separates the lagoon from the ocean. A coastal berm is built up by wave action, pushing and depositing marine sand on the shore, building a mound, or small sand dune. This can be washed away in time of large waves and high tide from the ocean side, or an increase in the level of the lagoon due to high rainfall.

Catchment is a natural area which drains to a waterway. Catchments come in many sizes, from an area that drains into a small creek, to a larger system of waterways that all feed into a single major river. The boundary of a catchment is always bordered by a raised area such as a ridge line. In the case of the Manly Lagoon catchment all the rain that falls in an 18 square kilometre catchment runs downhill to a final point at the opening of the Lagoon at Queenscliff Beach.

Dredging is the removal of accumulated sediment from the bottom of a waterway.

Ecology is the relationship of living organisms to each other and their surroundings.

Environmental Corridors are continuous areas of open space through developed areas, often urban or farmland. They are often designed to connect other natural areas, such as national parks, or maintain the health of valuable, vulnerable areas, such as a creek system. 

Floodplain is a flat area surrounding a waterway. In a natural system, in times of high rainfall, it is common that a waterway will reach the limits of the banks and flow over onto this area.   

Hydrology is the study of the occurrence, movement, circulation and distribution of water.

Infiltration in hydrology refers to the movement of water down into the soil. From here the water may be stored in the soil as ground water, or move downhill with gravity, below the surface level, until it reaches a water way, such as Manly Lagoon.

Micro pollutants are not readily visible and include nutrients, heavy metals, oil, grease and bacteria.

Macro pollutants are easily visible and include rubbish, organic matter and sediment.

Organic matter is that that has come from a once living organism. This includes plant and animal material and waste. 

Pathogens are infectious agents that cause disease to a host. These include bacteria, viruses, and protozoa.

Riparian vegetation is a broad term referring to all vegetation that is impacted on, or impacts an adjoining waterway.

Runoff is the rainfall falling on a land surface that is not infiltrated, evaporated or stored, and drains or flows off.

Scouring is the abrasion or movement of particles.  In this case it relates to water from the lagoon moving marine sand away from the entrance berm, to form a wider channel for the lagoon to drain to the ocean.

Sediments are materials that have been broken down by weathering and erosion from parent materials and are then transported by wind or rain. This process is usually very gradual, yet with urbanization we are accelerating it. Urban stormwater creates high amounts of erosion particularly on exposed land and construction sites, carrying the eroded sediments quickly over hard surfaces and through storm water drains into water ways, such as Manly Lagoon. 

Water clarity is a measure of how much sunlight can penetrate through water. Generally, clearer water is better for the health of the Lagoon system. Amongst other things it means light can reach sea grasses on the bottom, and indicates nutrient levels are not too high.