add interflow

[peterlafollette]

This PR adds the capacity for interflow, such that water stored in the vadose zone (LGAR domain) can contribute directly to streamflow. A WF contributes to streamflow if its capillary head is above a new specified parameter, lateral_flow_psi_threshold, and another new parameter lateral_flow_factor modifies lateral flow contributions to streamflow. Interflow is proportional to the hydraulic conductivity of a wetting front. Interflow is enabled only when both parameters are specified. Flux caching is disabled during timesteps where lateral flow is active and eligible fronts are present. The lateral_flow_factor parameter should be interpreted as a lumped effective lateral conductance term that can include anisotropy, hydraulic gradient, drainage length, and catchment connectivity effects.

Additions

Removals

Changes

Testing

1. Stable for more than 20,000 core hours (of simulations using NOM + CASAM + troute or PET + CASAM + troute) using PSO - generated parameter sets and various forcing datasets

Screenshots

Notes

Todos

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Visually tested in supported browsers and devices (see checklist below 👇)
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

Testing checklist

Target Environment support

• Windows
• Linux
• Browser

Accessibility

• Keyboard friendly
• Screen reader friendly

Other

• Is useable without CSS
• Is useable without JS
• Flexible from small to large screens
• No linting errors or warnings
• JavaScript tests are passing

[ajkhattak]

Peter, thanks for adding the lateral flow process to CASAM. From a technical standpoint, it looks solid overall. There are a few sections that I wasn't able to fully follow, so let's tag up to briefly discuss them.

One suggestion I have is to use more descriptive variable names and add documentation/comments for the new functions you've implemented. This would make the code easier to understand and maintain.

Thanks!

[peterlafollette]

Replied to / resolved all comments and met about them -- most salient changes are updated clearer naming conventions, better guard to prevent interflow from extracting too much water for any given time step, more commenting in code, and updated readme documentation.