It seems Planet Zoo does not behave the same as Planet Coaster and JWE when it comes to water in the landscape. In Planet Zoo when you add water to the landscape this becomes a fixed feature, updating the landscape elevation around it does not make the existing water adapt to the new landscape but instead highlights a hard edge that contains the water, which tends to look unnatural plus these edges can not be smoothed or adjusted afterwards. The workflow forces you to delete the water and then change the landscape before adding the water again. Having the water dynamically adapt to the landscape elevation changes in real time makes it far easier to sculpt the landscape and feels more seamless. I assume the fact that the behaviour in Planet Zoo is different is due to a technical limitation so maybe we will have to live with it but at least have the border appear more organic.