Searching for "alameda canals" or "alameda artificial canals" won't get you very far because the weird finger lakes in the middle of the island are called the Alameda Lagoons.
If you're heading to the south part of the island, you may find yourself hitting some deadends that hit the lagoons. There are only two streets that go through them - Grand and Willow. You can also take 8th St. (which is the first street to the west after the lagoons end) and Park St (the first street to the east after the lagoons end).
Most of the lagoons border private property, but there are some places that are open to the public. The easiest way to get a look at them is to take one of the above-mentioned deadends.
The lagoons used to be the south shore of the island! But "Fifty years ago, Alameda was split by the most bitter land-use fight in its history when developers proposed using millions of tons of sand to fill in the south shore along San Francisco Bay." [source]. The proposal was that what was once bay-front property would be filled in all the way, but the lagoons were created instead to maintain some of the waterfront element. Apparently there was no compensation for people whose houses went from bay-front to lagoon-front. Here's an excellent blog post about the lagoons (history, comparing architecture and urban landscape on both sides of the lagoons) with many pictures. And here's a great article in Alameda Magazine about the history of the lagoons.