The water logging and soil salinization disasters in northeast of China

The damage on the production of crops caused by the ponding of farmland is called the water logging disaster. It's called the collapse disaster if the ponding area is lower than the ground, and is called the flooding disaster if the ponding area is higher than the ground. And it's called the soil salinization disaster if the ponding occurs in the saline area and have caused the reduction of output. All these disasters can happen together or separately in the same place, so they make up the definition of water logging and soil salinization disasters and are combined into studying.

The water logging and soil salinization disasters can be divided into 4 types according to the occurrence areas.

The plain area

This type of disaster usually occurs in the plain area because of the poor drainage of low-lying land. The main occurrence areas are the Songnen Plain, Liaohe plain and the West Liaohe plain, and these areas are often also the salinization areas.

The plain depression area

This type of disaster refers to the water logging occurs in the depressions -its height is higher than the flood level of rivers and lakes and it will flow backward when the level is too high. Some depressions in cold areas with poor drainage will freeze in the winter and the ice-melting water can not be drained away in the next spring which will cause a grater loss to people alongside. It mainly occurs in the Nenjiang, Taoerhe River, and the lower reaches of the Liaohe River.

The valley area

This type of disaster refers to the intrusion of groundwater caused by low topography which usually occurs in the valley area -the southeast of Greater Khingan, the upper reaches of the West Liaohe River and Changbai Mountain District with a not large and scattered distribution.

The swamp depression area

This type of disaster refers to the floods caused by the flatness, the high groundwater level and the poor drainage of the marsh or swamp area. It often occurs in Sanjiang plain (Heilongjiang, Wusuli River and Songhua River plain). The flood in one year will make a continuous impact on the next year. The reclamation of lowlands with a poor condition for draining has resulted in the rapid expansion of such disasters since 70s. In recent years, people replant some lands with rice and effectively reduce the disasters.

The information is provided by Disaster Risk Reduction Knowledge Service.