South Dunedin water table 2023 model

Raw data stored in piezo_data_points, and transferred to modelpoints for interpolation. Interpolated grids (8 m) generated for model extent using TopotoRaster function. The watertable elevation is stored as either GWL or watertableRL (m NZVD2016). Depth to water is stored in DTW, based on the 2021 LiDAR DEM. The extent of the area of interest is stored in modelling_extent. Layers are in NZTM (NZGD2000 EPSG: 2193) coordinates and NZVD2016 vertical datum (EPSG:7879)