floods in Europe

I have resolved to stick to the narrow issue of land rent in its simplest form. That is, governments raise taxes from land values more than anything else. (Ultimately land values should be the ONLY thing taxed, but that would require some adjustment, so let's keep it simple.) Today's news shows once again where this would be a Good Thing. The floods will caused tremendous harm to land values (who wants to live where you might be flooded?) But under land rent, taxes (which is based on land prices) are automatically reduced. Land values go down when people move elsewhere, meaning the other land values go up, so the government does not lose out either.