Abstract: The Liyang plain, located in the northwest of Hunan province, is part of the plain on the north of Dongting Lake. It is situated at longitude 111°22′30″E to 111°51′30″E, and latitude 29°35′31″N to 29°47′30″N. It is made up of the Li River, its tributaries and the alluvial plain, and occupies about 600 sq. km in area (FIGURE 1). The plain is saucer-shaped and surrounded by small hills on three sides, joined at the eastern part to the plain north of Dongting Lake. The area is a classic ‘plate-basin’ structure. Inside its boundaries, the land is broad and flat, with small streams winding in different directions, and lakes and ponds dotting the landscape. It is 32–45 m above sea level, with an incline of 2° to 3°.