Example - Create reaches for a walk-over survey

Scenario

You are working on a river restoration project that requires a walk over survey to collect in-channel and riparian data. Each survey reach is 500m long and you need to stop every 50m to do a transect across the channel. With RivEX its easy to create this base dataset that will become the "framework" for collecting, mapping and analysing your data. The output can be uploaded to ArcGIS Online to create an off-line field map. Using your devices inbuilt GPS this would help locate your reaches and ensure you are standing at the correct spot check.

Warning The following guide is using a fictitious field survey scenario along the River Axe, UK.

Workflow

Step	Processing Task
1	You have prepared your river network and now ready to create the route that will be segmented into 500m reaches. The route is a single polyline and can be created using the Link Sites tool. Before you create the route you must first create 2 point layers that are points representing the UPSTREAM and DOWNSTREAM limits of your river survey.
2	Create two point layers, they must be in the same coordinate system as your river network, snapped to the river and both contain a numeric ID field, in this worked example this field is simply called ID. Each point is assigned the ID number of 1. The ID number can be any integer value as long as they are both the same value. The attribute tables of the upstream and downstream survey limits, note they both share a common ID of 1. The River Axe, UK. The start and end of the survey has been marked by the green and red points. These are separate datasets and have been snapped to the network when they were created and share a common ID number. WARNING: If you have been supplied these point layers do not assume they align with the network, they might require snapping using RivEX.
3	Run the Link sites tool to generate the route, take note of the optional setting. The completed tool is shown below using the worked example data. The output is a single polyline marking the route from the upstream site to the downstream site limit.
4	You can now call the Segment routes tool. A completed example is shown below, creating 500m reaches and 50m spaced points along each reach.
5	The outputs of the segment routes tool with optional spaced points are shown below. The 500m segments or "reaches" are colour code by their reach ID. In this zoomed-in screen shot you can see reaches 41 - 46. The spaced points are labelled with their distance along their segment. The point layer was duplicated and a definition query created to show only the 0m and 500m points, these are symbolised as red squares to indicate the reach limits
	If you review the outputs section of help page for the Segment routes tool, you will see they are richly attributed with ID numbers and distances. By ensuring the field data you capture is tagged with the ID of the reach, you can join and map your field data. The reach polylines can be used in spatial analysis such as determining river slope or be buffered and intersected with habitat data and results summarised by reach ID.