Video Walk throughs
Below are a series of short videos you can watch to achieve a specific task. These bite size videos are meant to fast track you into the many functions of RivEX. Don't worry if you miss the beginning, they are on a constant loop!
•Building topology for the first time
•Running Quality control tools
•Generate network attributes such as Strahler order or catchment ID
•Creating the segment ID table
•Creating reaches from sampling points
•Transfer metrics from network to sites
Building topology for the first time
You have installed RivEX, loaded your river network into ArcMap and ready to go! The first thing you must do is extract the topological information of the river network. To do this you must specify a unique numeric ID field and Node fields. But what if these do not exist yet? No problem let RivEX create these for you as shown below.
Running quality control tools
It is strongly recommended you run ALL quality control tools to ensure your river network is topologically correct and ready for processing. Below shows an example of running a subset of the quality control tools.
Create nodes
You will often want to create nodes from the network, this will help you understand the topology of the network and identify errors. Three types of nodes are extracted and symbolized in the example below.
Generate network attributes such as Strahler order or catchment ID
RivEX can generate many attributes and other tools in RivEX rely on you computing these first. Assuming no errors exist in the network it is as easy as clicking several buttons. Below several key attributes are created and then network is finally symbolized by Strahler order.
Creating the segment ID table
Many tools in RivEX rely on the Segment ID table to have been built. Do this only when you have completed all your error checking and are happy that the network is correct and ready for RivEX. The following video shows that to create reaches you need the source ID encoded into the network, to do that you need the segment ID tables built so the source ID tool can work. Sequences have been shortened as building these tables for large networks can be time consuming.
Generating sampling points
RivEX provide a suite of tools for generate sampling points along your river network. Such points can feed into a survey campaign for network analysis. The video below shows a method of generating a stratified sample, 3 points in every cell of a grid with a 50Km cell size.
Creating reaches from sampling points
RivEX can generate reaches (polylines) along river networks in an upstream or downstream direction based upon a field in the sampling point dataset. Each point could potentially be identifying a different reach length based on some criteria (e.g. strahler order). The lengths encoded into the point dataset must be in the same units as the river network. For example you are trying to map zones of impact and are recording these in metres (e.g. a zone of impact downstream of a weir) but your river network is in WGS84 and therefore in units of decimal degrees, you will need to project your network into a coordinate system using metres. The video below shows a selected set of sampling points being used to create 10Km downstream reaches. The final selection of one such reach demonstrates a reach being truncated as the tool is honouring clip to source ID.
Find downstream sites
RivEX has several tools for searching for sites in a variety of ways, one such tool is find downstream sites. These tools typically generate a table of data which you can use in your analysis. May be you are analysing your river network and attempting to quantify impassibility for fish migration? Knowing how many barriers and their distance from the river mouth will help you in your analysis. The video below shows some sites representing fictitious barriers and the final output table, site 141 indicates it has 3 barriers downstream of it and you know their relative positions because you can see the distance from mouth field (DSSite_D2M). Sequences have been shortened for this video.
Transfer metrics from network to sites
Often you will want to analyses your site data in another application but some of the information is encoded in the network. RivEX provides a tool for transfering network data to the site data. Distance fields created by RivEX are automatically adjusted whilst other fields are simply transferred. The video below shows this tool in action and the resulting updated site layer. Sequences have been shortened for this video.
Link all sites
RivEX can link any site to any other site using an implementation of the Dijkstra shortest path algorithm. The output is a polyline showing the routes between sites. This gives you a distance and a geometry that could feed into further spatial analysis or simply used to visualise the route. The following video shows you the tool being used and then the data queried. Sequences have been shortened for this video.
