In the construction of the Four Modernizations

there are nine types of soil erosion and water loss by human. It is mainly caused by road buil ding and construction of factories houses in mountain and plain or table areas in the loess plateau

by mining and exploiting and by massed spoils in the development for conservancy and hydroelectric construction. For the more

a great quantity of industry dust and waste from town-run enterprises pollutes water resourse and increases Sediment concentration of rivers and channels. Deforestation for farming and cultivating on grass land and steeper slopes leads to erosion. And it is accelerated by the old traditional faming system which is extensive seeding and worse harvesting

planting along a slope recultivating on economic forest land and so on. People in mountain and table region sin the loess plateau develop the sideline production such as Fungus

the tuber of elevated gastrodia (gastrodia elate)

which destroys vegetation and results in more severe erosion. And rubbish and coal ash piled and placed any where in a city increases sediment concentratiou of rivers and channels. Such nine mentioned above would become more worse as the construction develops rapidly.