r.Water.WaterMesh.MaxDimensionInTiles

Maximum dimension of a water mesh in tiles (max of either X or Y). If a water mesh attempts to generate a quadtree with more than this many tiles in X or Y, it will be biased back below this threshold via the same process as the LODScaleBias (iteratively dividing tile size by 2 until compliance). Having too many tiles can create very large GPU allocations.