Read the following materials and answer the questions. Reservoir migration is a big problem that many countries encounter when building reservoirs. At present, the main ways of reservoir resettlement

Read the following materials and answer the questions. Reservoir migration is a big problem that many countries encounter when building reservoirs. At present, the main ways of reservoir resettlement are (1) Policy factors?

(2) First, changes in the natural environment and socio-economic environment. Many immigrants can't adapt to the environment where they move, or the economic situation of immigrants is not good; Second, the life or occupation of immigrants in the immigration area does not meet their personal requirements.

(3) Local resettlement has aggravated the contradiction between population and land shortage in the reservoir area, and land reclamation has caused the deterioration of the ecological environment, such as the reduction of forest area, the intensification of soil erosion, the seasonal change of rivers, and the easy flooding of rivers.