Map of Sichuan landform

Sichuan has a complex and varied topography. The east and west of Sichuan is significantly different in landscape. The terrain of China's mainland forms a flight of three steps in terms of altitude, and Sichuan just lies between the first step and the second step, namely between the Qinghai-Tibet Plateau (the first step) and the Plain of the Middle-and-lower Reaches of Yangtze River (the second step).

It is higher in the west than in the east, demonstrating a distinct disparity in terms of altitude. Plateau and mountainous areas can be seen in west Sichuan with elevations of over 4,000 meters above sea level, while basins and hilly areas can be found in the east, with elevations of 1,000 to 3,000 meters above sea level. The whole province can be divided into three parts: the Sichuan Basin, Sichuan Northwest Plateau and Sichuan Southwest Mountains.

The Sichuan Basin is one of the four basins in China, with an area of 165,000 square kilometers. The Basin is surrounded by the Qinling range to the north, Mt. Micang and Mt. Daba to the east, Mt. Dalou to the south and Mt. Longmen and Mt. Qionglai to the northwest. It experiences a warm and humid subtropical monsoon climate with warm winters and hot summers. The rainfall annual total in most of the region approximates between 900 to 1,200 mm. The vegetation here is subtropical evergreen broadleaved forest. Agricultural crops mature twice every year.

The west of the Basin is Sichuan West Plain with fertile terrain of high productivity irrigated by the Dujiangyan. The middle of the Basin is purple hilly area with an elevation of about 400 to 800 meters above sea level and sloping slightly towards the south. There the Minjiang River, Tuojiang River and Jialingjiang River flow from the mountains in the north towards the south and join the Yangtze River. The east of the Basin is Chuandong parallel ridges and valleys which consist of Mt. Huaying, Mt. Tongluo and Mt. Mingyue.

The northwest Sichuan is Sichuan Northwest Plateau, the southeastern part of the Qinghai-Tibet Plateau, with an average elevation of 3,000 to 5,000 meters. Here it has an alpine climate with alpine meadow vegetation.

The southwest Sichuan is the northern part of the Hengduan Ridge, with high mountains and deep valleys. Mountains stretch and rivers flow from the south to the north. From east to west, mountains and rivers are as follows: Mt. Minshan, Minjiang River, Mt. Qionglai, Daduhe River, Mt. Daxueshan, Yalongjiang River, Mt. Shalulishan and Jinshajiang River. Climate and vegetation change vertically. Vegetation is mostly alpine coniferous forests and alpine shrubs and meadows.

The overall characteristics of Sichuan's climate can be summarized as follows:

a. monsoon climate is obvious and rain and heat happens in the same seasons;
b. regional climate difference is prominent in that the east is characterized by warm winters, early springs, hot summers, autumn rains, much cloud and fog, little sunshine and a long growing season; while the west is characterized by coldness, long winters, almost no summer, sufficient sunshine, concentrated rainfall and distinct dry and rain seasons;
c. vertical climate changes are significant and climate types are varied, which are good for the comprehensive development of agriculture, forestry and husbandry; and meteorological disasters happen in various forms with a high frequency and large scope, which are mainly droughts, rainstorms, floods and cold weather.

sc.gov.cn