What are the water conservancy projects? Why should water conservancy projects relocate residents and flood cultivated land?

Water conservancy projects include different types of hydraulic structures, such as dams, dikes, spillways, sluices, canals and aqueducts. If the reservoir dam project is built, all the residential areas and cultivated land in the reservoir area will be flooded. Therefore, before the construction, the immigrants in the reservoir area will be relocated, and the flooded farmland in the reservoir area will be compensated for land acquisition.