Mapping Salinity in the South Old River Aaron Cuthbertson, ES, O&M Barry Montoya, Staff ES, O&M

SWRCB has set salinity objectives for the South Delta South Old River at times exceeds salinity objectives set by SWRCB The objective of the study is to gain a better understanding of the sources of salinity in the South Old River Background – Salinity in SOR

Lead Scientist – Barry Montoya Began doing transects of SOR in 2009 Salinity is typically measured by Electrical Conductivity (EC) – the more conductive a solution is, the saltier. Seawater conducts electricity very well; distilled water conducts very poorly.

Background – Sampling Equip 6 MPH EC Sensor GPS Datalogger

Background – Transect route

Background – Lots of Data Many transects recorded Under different tidal conditions During different times of the year

Problem – GPS (XY) Coordinates How do we compare one transect with another based on GPS coordinates? How do we compare transect data to fixed features along the river?

Problem – GPS (XY) Coordinates

USS Enterprise GIS

What do we want? Ability to easily compare different transects based on location of data points Ability to compare transects to important features on river, such as discharge pipes

Solution: Simplify the data

Simplify the data

How do we convert XY to dist?

Linear Referencing in ArcGIS

Route feature class route = polyline feature class with an embedded measurement system In ArcGIS, the term route refers to any linear feature, such as a city street, highway, river, or pipe, that has a unique identifier and a common measurement system along each linear feature.

Create a reference line (route)

Linear Referencing - process XYEC Route Feature Class Point Feature class Locate features along routes tool DistanceEC Event Table