TGPC: Greater Wellington letter to Chair, PCTG BOI - Attachment 2

,,Literature review of Porirua Harbour and catchmentAppendix 2: Annotated Bibliographyhowever nutrient and chlorophyll-a concentrations were not measured, and the flushinginfluence of the large tidal wedge was not considered. POTirua Harbour is mainly subtidal,making it unique compared with other New Zealand estuaries which empty almostcompletely at low tide. Classes estuarine areas for habitatloss however data across yearsis not compared so classification is fairly unfounded. Seagrass beds extensive andhealthy, whilst terrestrial buffer is rarely natural, and often separated physically fromestuary. This separation may contribute to 'coastal squeeze' as saltmarsh species respondto sea levelrise. Large amount of litter noted in Onepoto Arm. List of all saltmarshspeciesSwales, A. , S. I. Bentley, M. S. MCGlone, R. Ovenden, N. Hermanspahn, R. Budd, A. Hill, SPickmere, R. Huskew and M. Okey (2005). Pulloitthunui Infoi. ' ayecis of historicol calchnien!landcover chuitges on nileisedrinenin!ion. National Institute of Water and Atmospheric ResearchLtd. , Prepared for Greater Wellington Regional Council and POTirua City Council, NIWA ClientReport: HAM2004-149.Sedimentation history of Pauaiahanui Inlet based on radioisotopes and pollen analysis ofsediment cores. These methods are used to calculate sediment accumulation rates(SARS). Nine cores were taken, five near sub-catchment outlets and four in the centralbasin. Detailed description and interpretation of each core. Determines spatial variationsin SARS, grain size and metal concentration and relates them to changes in catchmentuse. Averaged across all sites, SARS have been increasing since European arrival andsubsequent deforestation and urbanisation. "C dating shows a SAR of ~0.7mnVyr for thelast 2,000 years' ' Pb dating shows a SAR at 2.4mm/yr for the last 150 years '''csshows a SAR of 3.4mnVyr from 1950 onwards, whilst pollen analysis shows that SARSfrom the 1980's onwards are at 4.6mnVyr. This last average is particularly influenced bythe core taken at the HOTokiri catchment outlet: in the last 20 years this area has receiveddouble the sediment than locations elsewhere (loinnVyr). The high yield of sandysediment is most likely sourced from the HOTokiri catchment, which is large and steepand has a large area of pine plantations. Browns Bay also has a high SAR: this areaappears to act as a sink for sediment derived elsewhere. Sites located at sub-catchmenioutlets have higher SARS than those of the central mud basin, indicating that the sourceof sediment is eroded soils, and that the supply rate exceeds ability of estuarine processesto redistribute sediment. Browns Bay site has a SAR higher for the last 50 years than thelast 20 years, reflecting the influence of 1970s urban developments, and the stabilising ofthose developments in the last 20 years. Future SARS are likely to equal and exceed2.4mnVyr. Pollen profiles are characterised by a loss of native species, rise in exoticgrass and weed species and a huge increase in pine pollen in the late 1970s. Wavesappear to erode, redistribute, winnow and mix sediment to a depth of ~5cmConcentration of zinc, lead and copper were below ANZECC (2000) IsQG for allsitesWRC (1989a). Eiivironnien!all, lipact reporifuiwre Sidle Highway I Foule. Wellington RegionalCouncil.Extensive investigation and assessment of coastal and land resources, water resources,and landscape characteristics in the whole Porirua Basin and Pauatahanui catchment, inrelation to potential impacts of State Highway I route options. Accompanied by 10technical reports, of which the most relevant are Landscape Assessment (V01. 6), Landand Coastal assessment(V01. 7) and Water Resources Impact Assessment(V01. 8)Report for Porirua City Council & Welling ton City CouncilBlaschke and Rutherford Environmental ConsultantsFebruary 20105