Layer: Lake Flood Levels 1% AEP (BOPRC) (ID: 300)

Parent Layer: Flood Modelling 1%AEP

Name: Lake Flood Levels 1% AEP (BOPRC)

Display Field: Name

Type: Feature Layer

Geometry Type: esriGeometryPolygon

Description: <DIV STYLE="text-align:Left;"><DIV><DIV>Design levels (1%) for the twelve Rotorua Lakes have originally been contained in the Regional Council’s Environmental Data Summaries – Air Quality, Meteorology, Hydrology and Water Temperature, Environmental Report 2001/01. They were subsequently updated in Environmental Data Summaries – Air Quality, Meteorology, Hydrology and Water Temperature, Report to 31 December 2005 (published) and again in Environmental Data Summaries 2010 (audited but not published).The most recent analysis using recorded data and standard frequency analysis up to 31 December 2020 is contained within this report. The derived design levels include a freeboard to account for estimate imprecision; local wind set up; wave run-up; seiche; construction tolerances; and the likely joint probability of the above factors. All recorded levels and design levels are to Moturiki Datum (1953)Flood analysis methodolgyLake level data is available for the twelve Rotorua Lakes (Figure 1). Records began as early as 1925. Some of the lakes have natural surface outlets, some have controlled surface outlets, and some have no surface outlets.The data used in this analysis is the annual maximum level record for the period of time since the recorder was installed, or since outlet control was put in place. The annual maxima and frequency analyses are presented in Parts 3 to 14.A number of analysis methods were used. At site flood frequency analyses were applied to:• The continuous series of annual maxima for the period of record, or since lake level controlwas installed.Analyses of statistical gauged data involved plotting calendar year annual maxima from the gauged level data. Event probability positions were plotted based on Gringoten formula as follows:F(Qi) = (i - 0.44) / (n + 0.12)Where i is the rank of each flood in the order of flow magnitude, and n is the total number of years in the record.A range of methods were used to calculate the annual exceedance probability, these include the EV1, GEV, Log Pearson 3, Generalized Pareto and the Generalized Logistic. Probability distributions were then fitted to plotted points by the method of L-Moments (Hosking, 1990).Exceedance probabilities for annual (AEP) probabilities were plotted using the Gumbel reduced variate, described by McKerchar and Pearson (1989) as follows:Annual Probability: y (Qi) = -ln [- ln (1-1/T)]Where T is the desired recurrence interval. The resulting Gumbel plots were assessed by means of visual comparison for best fit.The best fitting distribution was selected based on visual inspection of the analysis plots. Where the analysis did not include the large flood events of the early 1960s (either because no recorder was in place at the time or outlet controls were installed later) an EV1 distribution was selected.Dataset creation methodolgyElevation data - DEM created from BOPLASS 2011 LiDAR - both at 2K and 1K. Lake Rotorua heights generated with the 1K DEM whilst all other lakes from the 2K DEM. 1K DEM has a 1m cell size, 2K DEM 2m cell size.All data is NZTM and Moturiki 1953All lakes had the lake level generated with freeboard added - lake level FBRotorua, Rotoiti and Tarawera had lake level generated minus 0.3m + 0.1m (climate change value) - lake level 200All other lakes minus 0.3m - lake level 300Extent boundaries between lakes Rotorua and Rotoiti is the State Highway over the Ohau ChannelLake level data sourceTable 25, pg 37Rotorua Lakes Design Levels Technical report 2022 ISSN: 1176-5550 (Print) ISSN: 1179-9587 (Online)</DIV></DIV></DIV>

Service Item Id: ab638295e74843ddaaaa0705b8223b95

Copyright Text:

Default Visibility: false

MaxRecordCount: 2000

Supported Query Formats: JSON, geoJSON, PBF

Min Scale: 0

Max Scale: 0

Supports Advanced Queries: true

Supports Statistics: true

Has Labels: false

Can Modify Layer: true

Can Scale Symbols: false

Use Standardized Queries: true

Supports Datum Transformation: true

Extent:

Drawing Info:

Renderer:

Unique Value Renderer:

Field 1:

Field 2:

Field 3:

Field Delimiter:

Default Symbol:

N/A

Default Label:

UniqueValueInfos:

Value: -300
Label: Level >0.3m Depth
Description: N/A
Symbol:
Value: -200
Label: Level >0.3m Depth
Description: N/A
Symbol:
Value: FB
Label: Level with Freeboard
Description: N/A
Symbol:

Transparency:

Labeling Info:

Advanced Query Capabilities:

HasZ: false

HasM: false

Has Attachments: false

HTML Popup Type: esriServerHTMLPopupTypeAsHTMLText

Type ID Field: null

Fields:

OBJECTID ( type: esriFieldTypeOID, alias: OBJECTID )
ContourMin ( type: esriFieldTypeDouble, alias: Contour minimum )
ContourMax ( type: esriFieldTypeDouble, alias: Contour maximum )
Name ( type: esriFieldTypeString, alias: Name, length: 100 )
Elevation ( type: esriFieldTypeDouble, alias: Contour )
AEP ( type: esriFieldTypeString, alias: AEP, length: 10 )
NZVD ( type: esriFieldTypeString, alias: NZVD, length: 50 )
Source ( type: esriFieldTypeString, alias: Source, length: 50 )
Height ( type: esriFieldTypeString, alias: Height, length: 10 )
Shape ( type: esriFieldTypeGeometry, alias: Shape )
Shape.STArea() ( type: esriFieldTypeDouble, alias: Shape.STArea() )
Shape.STLength() ( type: esriFieldTypeDouble, alias: Shape.STLength() )

Supported Operations: Query Query Attachments Query Analytic Generate Renderer Return Updates

Iteminfo Thumbnail Metadata