It is not good to build a park in a riverbed. There are the following bad reasons for building a park in a riverbed:

1. Damage to the ecological environment: The riverbed is an important component and part of the natural water system. The park may need to carry out filling, masonry and other projects, which will destroy the original ecosystem and harm the natural functions of the river. River beds are biological habitats, and the construction of parks will destroy or destroy the habitats of wild animals and plants, which will have a negative impact on biodiversity.

2. Increased flood risk: The river bed is a natural water channel. If a park is built on the river bed, it may hinder the smooth flow of water and increase the risk of floods. Especially in flood-prone areas, parks on riverbeds may become obstacles to floods, exacerbating flood hazards.

3. Land use issues: The river bed is a limited natural resource. If it is used to build a park, it will occupy land resources that could be used for farmland, ecological protection and other purposes. Especially in densely populated urban areas, where land resources are already tight, using riverbeds for park construction may lead to a waste of land.

4. Social and economic costs: Building a park on the riverbed requires land acquisition, construction and other work, which requires a large investment of funds and human resources. Moreover, the river bed is low-lying and may require drainage, reinforcement and other projects, increasing construction costs. In addition, the maintenance and management of the park also require certain funds and manpower investment.