River Environment Classification (REC2) New Zealand

REC2 (River Environment Classification, v2.5) - June 2019 [Hosted Feature Layer]This service depicts rivers as lines and catchments as polygons The River Environment Classification (REC) is a database of catchment spatial attributes, summarised for every segment in New Zealand's network of rivers. The attributes were compiled for the purposes of river classification, while the river network description has been used to underpin models. Typically, models (e.g. CLUES and TopNet) would use the dendritic (branched) linkages of REC river segments to perform their calculations. Since its release and use over the last decade, some errors in the location and connectivity of these linkages have been identified. The current revision corrects those errors, and updates a number of spatial attributes with the latest data. REC2 provides a re-cut framework of rivers for modelling and classification. It is built on a newer version of the 30m digital elevation model, in which the original 20m contours were supplemented with, for example, more spot elevation data and a better coastline contour. Boundary errors were minimised by processing contiguous areas (such as the whole of the North Island) together, which wasn't possible when it was originally created.Major updates include the revision of catchment land use information, by overlaying with the land cover database (LCDB3, current as at 2008), and the update of river and rainfall statistics with data from 1960-2006. The river network and associated attributes have been assembled within an ArcGIS geodatabase. Topological connectivity has been established to allow upstream and downstream tracing within the network. REC2 can be downloaded or streamed and used directly in ArcMap. (A file geodatabase version for ArcGIS of REC2 can be downloaded as a zip file and used directly for analyses in ArcMap from here)This layer is using Esri's ArcGIS Online Optimizations for fast rendering.This is REC2 (Version 5) , June 2019 - a publicly available dataset from NIWA Taihoro Nukurangi.NIWA acknowledges funding from the MBIE SSIF towards the preparation of REC v2.5Coordinate Reference System: NZTM (New Zealand Transverse Mercator, EPSG: 2193)Geometric Representation of Rivers: LinesExtent (Bounding Box):

Top(Latitude) -33.9534Bottom(Latitude) -47.4867

Left (Longitude) 166.2634

Right (Longitude) 178.9733

Riverlines table Attributes associated directly with network:

Field Type Description

Catarea Real Watershed area in m2 CUM_Area Real Area upstream of a reach (and including this reach area) in m2. Nzsegment Integer Reach identifier to be used with REC2 (supercedes nzreach in REC1).

Lengthdown Real The distance to coast from any reach to its outlet reach, where the river drains (m). Headwater Integer Number (0) denoting whether a stream is a “source” (headwater) stream. Non-zero for non-headwater streams.

Hydseq Integer A unique number denoting the hydrological processing order of a river segment relative to others in the network.

StreamOrder Integer A number describing the Strahler order a reach in a network of reaches.

euclid_dist Real The straight line distance of a reach from the reach “inlet” to its “outlet”. upElev Real Height (asl) of the upstream end of a reach section in a watershed (m). downElev Real Height (asl) of the downstream end of a reach section in a watershed (m).

upcoordX Real Easting of the upstream end of a river segment in m (NZTM2000). upcoordY Real Northing of the upstream end of a river segment in m (NZTM2000). downcoordX Real Easting of the downstream end of a river segment in m (NZTM2000).

downcoordY Real Northing of the downstream end of a river segment in m (NZTM2000). sinuosity Real Actual distance divided by the straight line distance giving the degree of curvature of the stream nzreach_re Integer The REC1 identifiying number for the corresponding\closest reach from REC1 (can be used to retrieve the REC management classes) headw_dist Integer Distance of the furthermost “source” or headwater reach from any reach (m). Shape_leng Real The length of the reach (vector) as calculated by ArcGIS. Segslpmean Real Mean segment slope along length of reach. LID Integer Lake Identifier number(LID) of overlapping lake.

Reachtype Integer A value of 2 is assigned if the segment is an outlet to the lake, otherwise 0 or null. nextdownid integer segment number of the most downstream reach

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