Littoral Waterway Defense
The Littoral Waterway Defense uses the compulsory Waterway terrain piece, along with three optional Bad Going Terrain (two Steep Hills and one Woods). The reason this cannot be used for Arable defenders as the Waterway is optional, leaving only two other optional terrain pieces, and this defense requires a Waterway and three terrain pieces.
The figure above shows the terrain placement. The Waterway allows you to remove a section of the board, making it easier to use three pieces of terrain to create anchor points for the flank. As shown in the figure below, this board rotated in every combination still has viable anchor points, either with the terrain pieces, the Waterway, or the board edge.
Some people may prefer not to "turtle" once they have established their battle line between two anchor points, feeling that it gives the initiative over to the enemy. If so, that makes it a good choice for your solo "opponent"; it allows you to try something new that you would not normally do yourself, giving you more experience against that type of defense and foe.
Arable Waterway Defense
The biggest problem with anchoring flanks in Arable home topography's is that you do not have four Bad Going terrain choices to ensure that, no matter which way the board is rotated, the board remains the same. Given that you must use a compulsory piece of terrain - either a BUA or a Road - you can use the BUA to anchor a flank.
I will defer the discussion on using a BUA for the time being, but suffice it to say you can exchange one of the Bad Going terrain pieces for the BUA and achieve the same results, as shown in the figure below.
Note that I have placed the BUA opposite to the Waterway, increasing the odds that the defender will have the waterway to its flank, rather than behind it. The figure below shows the possible battle lines for each way the board can be rotated by the attacker. Note that the attacker will generally favor the baseline opposite the BUA with the Waterway to the left flank (in this case), so the odds are the defender will defend with the lower-right configuration.
So, what if you need to anchor your flanks, have the Arable topography, but don't want to use a BUA? We'll look at that next time.