Short answer. No. Article 508 says owning the bed of a rain-water channel does not give you the right to build works whose destruction by floods may cause damage to third persons — a structure flimsy enough to wash out and hurt your neighbor's property falls squarely within what this article forbids.
What the law says
The private ownership of the beds of rain waters does not give a right to make works or constructions which may change their course to the damage of third persons, or whose destruction, by the force of floods, may cause such damage.
Civil Code, Article 508 — Limits On Rain Water Beds. Read the full provision →
Ownership does not authorize damaging works
Article 508 states the limit directly: the private ownership of the beds of rain waters does not give a right to make works or constructions which may change their course to the damage of third persons, or whose destruction, by the force of floods, may cause such damage. Owning the channel bed on your land does not translate into an unlimited right to build on it however you like, if the building itself creates a risk of damage to your neighbors.
Two distinct ways a construction can violate this rule
The article actually describes two separate situations, either of which is enough on its own. The first is a work that changes the water's course to a neighbor's damage while it is standing. The second — the one that fits your question — is a work whose destruction by the force of floods may itself cause damage. The article treats both as forbidden, not just the first.
Building something flimsy does not avoid liability
Because the article expressly covers damage caused by a structure's destruction in a flood, building something deliberately weak or flimsy does not put you outside its reach — if anything, it places you squarely inside the second branch of the rule. A construction that predictably washes out and damages a neighbor's property in a flood is precisely the harm Article 508 was written to prevent, regardless of how sturdy or intentional the original construction was meant to be.
Ownership of your land carries a responsibility to neighbors
The broader point behind this article is that a landowner's rights over a rain-water bed on his property are not absolute where a third person's property is at risk. "It's on my land" is not, by the article's own terms, a complete answer once a construction there is likely to change the water's course or to fail in a flood in a way that damages someone else's property, so it is worth designing and maintaining any such structure with that neighboring risk in mind.