Vanessa Brunner Hey @burton21, the author might be able to answer this a bit more specifically, but my guess is that there's some kind of gutter/drainage area to the left of this area. Unless you're putting a lot of water into this section, most of it will probably seep into the ground underneath anyways.
I love this neat, simple structure - it provides just the right amount of shelter and its minimal style is a great match for the cool checkerboard yard.
1. Consider the Grid. Because you live in California in a modern house, always keep the grid and playing off lines in mind. Whether things are lining up with a door, window, post, et. al., making connections with lines and a grid base is a good way to get started with your style of house.
I couldn't talk about positive-negative spaces without showing you at least one checkerboard. It's a favorite design theme, and here it is quite successful. Imagine this veranda planted with only grass or paved with only concrete. Neither solution would be as effective as this one, where a functional walkway becomes a work of art. Another reason this design works so well is that the bold squares are in proportion to the architecture. There's nothing tiny here.
I couldn't talk about positive-negative spaces without showing you at least one checkerboard. It's a favorite design theme, and here it is quite successful.