The Daba: a range that divides two rivers

The Daba Mountains cut through Sichuan, Chongqing, Shaanxi and Hubei and span about 1,000 kilometres, running between the watersheds of the Yellow and Yangtze rivers. The range belongs to the same orogenic belt as the Qinling, and the narrow Daba is about 1,300 to 2,000 metres high. Its highest ground lies in the Shennongjia massif in Hubei, in the forestry district of that name, and those mountains are often treated as the easternmost section of the range. For Chongqing the range is the northern wall, and Chengkou, the municipality's northernmost county, sits on its southern foot.

What the range does with water is simple and enormous. Its southern slope drains into the Sichuan Basin or straight into the Yangtze by short streams, and its northern side drains to the Han, which reaches the Yangtze only some hundreds of kilometres east. Because the Daba shares its orogenic belt with the Qinling, the pair together separate the Yellow River basin from the Yangtze basin. The ridge line is therefore a boundary between two drainage systems rather than a line between provinces, and rain falling a few kilometres apart on either side of it ends up in different rivers.

The Chongqing end of the Daba is Chengkou, where the county is mountainous and covers most of the Daba inside the municipality. The Dabashan National Nature Reserve lies in that Chongqing part of the range, and the county's forests hold the dawn redwood, endemic to the Daba Shan and thought extinct outside California until stands were found there in the 1940s. The range's evergreen forests are listed by the WWF among 200 ecoregions that should be a priority for conservation. Lower down, terraced farming is expanding and the eucommia tree, a medicinal plant, is a widely planted cash crop.