Parent Layer: Gisborne OLFP's and Depressions

Name: OLFPs Catchment Area

Display Field: AREA_HA

Type: Feature Layer

Geometry Type: esriGeometryPolyline

Description: Overland flow paths were derived from a flow accumulation surface that was extracted from a hydrologically corrected DEM. Flow paths were defined using a flow accumulation threshold of 500 cells, i.e. to qualify for inclusion in the flow path network, a minimum catchment area of 2,000 m2 was required (500 cells x 4 m2 each). OLFPs were delineated iteratively, with additional burn lines created with each iteration to correct flow paths that spill out of their channels and follow an incorrect trajectory. This is often caused by manmade structures such as bridges but also natural features such as dense vegetation incorrectly included within the DEM (as opposed to the surface model or DSM). Several iterations using this approach were conducted until a fair representation of the flow paths was obtained. Flow paths were first converted to vector polylines and smoothed to give a more appropriate visual representation. The resulting feature class can be visualised by symbolising on the catchment area field using the break values shown below.DiscalimaerThis overland flow path layer provides a high-level understanding of routes where surface stormwater may flow during rainfall events. It is subject to the following limitations:The layer uses a surface generated by LiDAR only and does not account for the stormwater reticulation network or for any surface obstructions such as buildings or fences.The layer is subject to limitations in the LiDAR data. These include lower precision under dense foliage and lack of LiDAR data in some rural areas in the District.The layer is generated through a GIS algorithm which divides terrain into a grid of squares. Water is modelled to flow from each grid square to the lowest adjacent grid square. This method means that fine features such as kerbs may not be accurately represented.The layer does not include any assessment of depth, width, or rate, of flows.In some locations, change to landform since LiDAR was generated will have altered overland flow paths from those displayed on the layer.These limitations mean that overland flow paths represented on the layer should not be considered definitive and are subject to further investigation. Likewise, flow paths that exist in reality, may not be represented on this layer.A draft disclaimer for the depression storage layer is provided as follows for your consideration.The depression storage layer provides an indicative extent of where ponding may form during prolonged rainfall.It is subject to the following limitations:It is assumed that the depression storage areas shown would fill to capacity prior to spillingThe depression storage areas shown exceed the following minimum criteria regarding ponding area, storage volume and depth.Surface area > 100 m2 Maximum depth > 0.20 m Volume > 30 m3The layer uses a surface generated by LiDAR only and is subject to the limitations of LiDAR. In some locations, change to landform since LiDAR was generated will have altered the potential depression storage area from those displayed on the layer.

Copyright Text: Morphum Environmental

Default Visibility: true

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:

XMin: 2026434.0001220703
YMin: 5702234.000122072
XMax: 2044530.0001220712
YMax: 5714924.000122071
Spatial Reference: 2193  (2193)

Drawing Info:

Renderer:
Unique Value Renderer:
Field 1: AREA_HA
Field 2: N/A
Field 3: N/A
Field Delimiter: ,
Default Symbol:
N/A
Default Label: N/A
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Transparency: 0
Labeling Info:

Advanced Query Capabilities:

Supports Statistics: true
Supports OrderBy: true
Supports Distinct: true
Supports Pagination: true
Supports TrueCurve: true
Supports Returning Query Extent: true
Supports Query With Distance: true
Supports Sql Expression: true
Supports Query With ResultType: false
Supports Returning Geometry Centroid: false
Supports Binning LOD: false
Supports Query With LOD Spatial Reference: false

HasZ: false

HasM: false

Has Attachments: false

HTML Popup Type: esriServerHTMLPopupTypeAsHTMLText

Type ID Field: null

Fields:

• OBJECTID ( type: esriFieldTypeOID, alias: OBJECTID )
• Shape ( type: esriFieldTypeGeometry, alias: Shape )
• arcid ( type: esriFieldTypeInteger, alias: arcid )
• grid_code ( type: esriFieldTypeInteger, alias: grid_code )
• from_node ( type: esriFieldTypeInteger, alias: from_node )
• to_node ( type: esriFieldTypeInteger, alias: to_node )
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• Shape_Length ( type: esriFieldTypeDouble, alias: Shape_Length )

Supported Operations:   Query   Query Attachments   Generate Renderer   Return Updates

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