Usage guide: toggle between tabs to show maps of key indicators of ecosystem health in relation to the main issues facing Te Awarua-o-Porirua harbour, click and drag the year slider underneath each map to see change over time, and hover over map data to see specific values.
Sediment (particularly muddy sediments) discharged into rivers, streams and harbours can negatively impact a range of values, including ecosystem health and the way people use water for recreational, cultural and spiritual purposes.
The depth of sediment overlying concrete pavers buried at discrete sites provides an indicator of estuary sedimentation. The map shows monitoring site (circles) annual sedimentation over a rolling five year period and the whole harbour average of these values (shaded region). Positive values indicate where there has been net sediment deposition (accumulation) and negative values indicate net erosion.
See Stevens LM, Forrest BM 2020. Te Awarua-o-Porirua Harbour Sediment Plate Monitoring 2019/2020 for technical methods and further information.
Contours displayed at 0.25 m intervals derived from depth databases gridded at 10 m resolution. Bathymetry depths (m) are referenced to Porirua Sounding Datum (SD) which is linked to Porirua Chart Datum (CD), defined as 2.55 m below Land Information New Zealand (LINZ) steel pin C1K1 at the Mana Cruising Clubrooms.
See Waller & Stubbing 2019. Porirua Harbour bathymetric survey 2019 for technical methods and further information.
Contours derived from differencing the 10 m resolution depth databases from each combination of surveys. Red areas indicate sedimentation, while blue areas indicate general harbour erosion. Bathymetry depths (m) are referenced to Porirua Sounding Datum (SD) which is linked to Porirua Chart Datum (CD), defined as 2.55 m below LINZ steel pin C1K1 at the Mana Cruising Clubrooms.
See Waller & Stubbing 2019. Porirua Harbour bathymetric survey 2019 for technical methods and further information.
The main habitats monitored are unvegetated sediments (e.g. mud and sand areas) and areas vegetated with salt marsh and seagrass. Degraded habitat is a major contributor to reduced aquatic ecosystem health.
In terms of estuarine health, a key broad scale focus is on understanding the spatial extent and temporal change in mud-dominated sediment (>50% mud content) across intertidal areas.
See Stevens & Forrest 2020. Broad Scale Intertidal Habitat Mapping of Te Awarua-o-Porirua Harbour for technical methods and further information.