Cartographer calculates River Condition outputs by correlating groups of 5 MoRPh surveys (collectively referred to as a MoRPh5) with a single River Type survey. The correlation is based on five fields from the survey forms:

• MoRPh Correlation Code
• River Name
• Reach Name
• Subreach Name
• Module Number

This page describes how these fields are used and provides some best practices for completing them in complex situations.

How MoRPh5s are Calculated

When you enter five MoRPh surveys in close proximity to one another, Cartographer automatically generates a marker on the MoRPh5 map. It uses the following rules to work out whether surveys should be grouped together:

• the surveys must be recorded within 2 weeks of one another;
• the surveys must be recorded within 5km of one another;
• the surveys must either have module numbers 1 to 5 or module numbers 6 to 10;
• the surveys must have the same river name, reach name, subreach name, and correlation code fields.

How River Condition is Calculated

When you enter five MoRPh surveys and a matching River Type survey, Cartographer automatically generates a marker on the River Condition map containing outputs for the Biodiversity Metric. It uses data from the MoRPh5 map, which is correlated with data from the River Type map using the following rules:

1. the MoRPh5 and River Type surveys must refer to locations within 50km of each other;
2. the surveys must have the same correlation code fields.

Rule 1 casts a wide net that compares surveys in the right general area. Rule 2 prevents accidental correlation between different river reaches and projects.

How to use MoRPh Correlation Codes

As described above, Cartographer calculates MoRPh5 and River Condition outputs by grouping MoRPh and River Type surveys. For simple cases, it’s easy to do the grouping based on GPS location, timestamp, and subreach name.

In more complex cases, you may have multiple River Condition Assessments going on in the same location at the same time. For example, this is common in training courses where multiple trainees are analysing the same river subreaches, and in scenario modelling where multiple scenarios are being considered at the same location.

In these situations, you need a way to tell Cartographer which surveys to include and exclude in each set of RCA calculations. You can do this using the optional field MoRPh Correlation Code, which appears on both the MoRPh and River Type survey forms:

Cartographer will only group MoRPh surveys to calculate MoRPh5 outputs if they all have the same values for River Name, ReachName, Subreach Name, and Correlation Code. Similarly, it will only group MoRPh5s and River Types to calculate River Condition outputs if they have the same Correlation Code.

This means you can use Correlation Codes as follows:

1. If you only have one River Condition Assessment going on at a particular location and time, you can ignore Correlation Codes altogether.
2. If you have multiple River Condition Assessments going on, allocate a different correlation code to each (in a training workshop you can use the trainee’s initials; in scenario modelling you can use the scenario name).
3. Make sure that all of the MoRPh and River Type surveys in a particular River Condition Assessment have the same Correlation Code. This tells Cartographer that it’s ok to group them when calculating outputs. You can read more on debugging grouping problems on the How to Fix Missing MoRPh5s page.
4. Make sure that different overlapping River Condition Assessments have different Correlation Codes. This will prevent Cartographer accidentally mis-grouping surveys when computing outputs.