ABSTRACT:

Quantifying water sources to rivers and streams is critical for managing water resources globally. Endmember mixing analysis (EMMA) is a commonly applied method to water sources to streams that uses tracers for hydrograph separation. Most EMMA applications follow similar methods, but several choices must be made such as selecting tracers, endmembers, and stream locations for mixing. With no standardized EMMA approach, these choices may be made subjectively with little regard for resulting errors. We created an open-source software program called EMMALAB, developed in MATLAB App Designer, to simplify and standardize the workflow associated with EMMA. EMMALAB guides the user through a uniform process to visualize and select endmembers via principal component analysis, calculate the fractional contribution of each endmember, and calculate errors in the mixing analysis. The files in this HydroShare resource include: EMMALAB v. 1.2 installers for Mac and PC, a dataset template, two example Provo River datasets (Soapstone and nested catchment), and the transcript for a YouTube video (https://www.youtube.com/watch?v=_oOI6bqL5a4) that provides instructions for using the software. The Provo River nested catchment dataset is the example data used in the training video. The newest release of EMMALAB contains more detailed residual analysis, the ability to calculate orthogonal projections for the endmembers, a convexity test, and minor bug fixes to the custom script DataEMMA.m. A web version of the software is available at: https://geologymatlab.byu.edu:9988/webapps/home/.