You’re right: it’s baseless news.
The flood that hit Valencia was not caused by secret cloud-seeding projects or the infamous HAARP. Although cloud seeding exists – and is used in various countries to induce rainfall – there is no evidence linking this technique, which is used in Morocco, to the wave of severe weather in Spain.
Furthermore, there are no scientific studies at all demonstrating a direct link between weather events in the two countries. This is a conspiracy theory that oversimplifies (and distorts) very complex phenomena.