BMI: bug fixes and updates

docs/src/changelog.md

@@ -11,10 +11,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Documentation: add leakage term to the wflow\_sbm figure, document external input
   parameter `ksathorfrac` and fix description of adding external `inflow` to the kinematic
   wave.
+- Fixed BMI functions (e.g. `BMI.get_value`) that deviated from BMI specifications
+  (BasicModelInterface.jl), including function arguments, return types and the BMI
+  specification that arrays are always flattened (this was not the case for variables stored
+  as 2-dimensional arrays or as vector of SVectors).
 
 ### Changed
 - For cyclic parameters different cyclic time inputs are supported (only one common cyclic
   time (for example daily or monthly) was allowed).
+- BMI: 1) added grid information (type and location) and whether a variable can be exchanged
+  to metadata Structs, 2) extend model grid functions for Wflow components that store
+  variables on `edges` (local inertial model) with `get_grid_edge_count` and
+  `get_grid_edge_nodes`.
+
+### Added
+- Functions for loading and saving states and getting the `starttime` in Unix time format.
+  This is convenient for coupling with OpenDA (and other external) software. The set states
+  functionality from the initialization function has been moved to a separate `set_states`
+  function for each `Model` type, to support loading states independent of initialization.
 
 ## v0.7.2 - 2023-09-27
 

docs/src/user_guide/additional_options.md

@@ -191,10 +191,10 @@ in the [Julia programming language](https://julialang.org/), makes use of the fo
 version.
 
 For the BMI implementation of Wflow all grids are defined as [unstructured
-grids](https://bmi-spec.readthedocs.io/en/latest/model_grids.html#unstructured-grids). While
-the input (forcing and model parameters) is structured (uniform rectilinear), internally
-wflow works with one dimensional arrays based on the active grid cells of the 2D model
-domain.
+grids](https://bmi-spec.readthedocs.io/en/latest/model_grids.html#unstructured-grids),
+including the special cases `scalar` and `points`. While the input (forcing and model
+parameters) is structured (uniform rectilinear), internally wflow works with one dimensional
+arrays based on the active grid cells of the 2D model domain.
 
 ### Configuration
 The variables that Wflow can exchange through BMI are based on the different model
@@ -219,6 +219,12 @@ Wflow.BMI.initialize
 Wflow.BMI.get_input_var_names
 ```
 
+Variables with a third dimension, for example `layer` as part of the vertical `SBM` concept,
+are exposed as two-dimensional grids through the Wflow BMI implementation. For these
+variables the index of this third dimension is required, by adding `[k]` to the variable
+name (`k` refers to the index of the third dimension). For example, the variable
+`vertical.vwc[1]` refers to the first soil layer of the vertical `SBM` concept.    
+
 ### Couple to a groundwater model
 For the coupling of wflow\_sbm (SBM + kinematic wave) with a groundwater model (e.g.
 MODFLOW) it is possible to run:

src/Wflow.jl

@@ -22,7 +22,11 @@ using Polyester
 using LoopVectorization
 using IfElse
 
-@metadata get_units "mm Δt-1"
+@metadata get_units "mm Δt-1" String
+# metadata for BMI grid
+@metadata exchange 1 Integer
+@metadata grid_type "unstructured" String
+@metadata grid_location "node" String
 
 const BMI = BasicModelInterface
 const Float = Float64