Look at the picture and answer the questions. Material 1: Hunan Province is called Hunan because most of the area is south of Dongting Lake. Dongting Lake used to be the calendar of our country.

Dongting Lake is the second largest freshwater lake in China, located in the north of Hunan Province and on the south bank of the Yangtze River. The tributaries have brought a lot of sediment to the bottom of the lake for a long time, and the average annual sedimentation is ten times larger than that of Poyang Lake. Coupled with the unreasonable reclamation in history, the "Eight Hundred Li Dongting Lake" was divided into many lakes, and its storage capacity for the Yangtze River water was declining. Lakeside plain is rich in water and heat resources and fertile land, which is one of the important commodity grain bases in China. It is one of the important freshwater aquaculture bases in China. At present, China is implementing the methods of returning farmland to lakes, building towns by immigrants and reducing sediment deposition to protect Dongting Lake and protect the ecological environment of the lake area.

So the answer is: (1) Xiangjiang River; (2) Reclaiming land from lakes and silting; (3) Returning farmland to lakes, resettling and building towns to reduce sediment deposition.