Between the Tangla Mountains, whose south slopes drain into the Tsang-po and the Salwin Rivers, and the Kuenlun Mountains, which form the south buttress of the Tsaidam steppes, the Yangtse Chiang, even at its source near the 90th meridian, draws on a basin nearly 240 miles in depth from north to south. Below the confluence of the three main streams this basin is somewhat contracted by the north-west south-east trend of the Baian Kara range, and the river is gradually deflected southwards. From the 99th meridian its course is almost due south, passing through the country of the Tanguts, or St. Fans, until at last it enters China.
This part of its course is, roughly speaking, parallel with the Mekong and Salwin Rivers. Penned in by high mountains, which form an extension of the great plateau of Central Asia, these rivers continue in close proximity to each other for nearly two hundred miles.
The immense depth of the gorges through which the Yangtse Chiang has cut its way in Yun Nan and west Sze Chuen, and the extraordinary freaks played by its tributaries on the right bank, have prevented the course of the Yangtse Chiang below the Ya-lung from being thoroughly ascertained. Its course, as laid down by the Jesuits, appears to have been mainly mere guesswork, and some corrections have recently been made. Apparently it here attains its lowest latitude--26° north. The strength of the stream and the height of the banks above the river prevent much use being made of it for boat traffic, even in the few portions where no dangers exist. The grandness of these gorges culminates in the “Sunbridge,” Tai-yang-chiao, a mountain at least 20,000 feet high, “which falls to the Yangtse Chiang in a series of terraces, which from below appear like parallel ridges, and abuts on the river into a precipice or precipices, which must be 8,000 feet above its waters. The main affluent on the right bank received in this part of its course is the Niu-lan River, the gorges of which are also very grand.
Ping-shan is generally regarded as the head of continuous navigation, but Mr. Hosie descended the river by boat from Man-i-sau, forty _li_ higher up.
The Fu-ling, Chien Chiang, Kung-t’an or Wu-chiang, which joins the Yangtse Chiang at Fu-Chau on the right bank, is the last considerable tributary received before reaching the gorges leading to Ichang. This river is important as the first of the streams which form the great network of water-communication which binds Peking and Canton with Central China. By the Fu-ling Canton can be reached with only two short portages, and a certain amount of trade with Hankau is carried on by this and the Yuan River in preference to taking goods up the Yangtse Chiang.
The gorges which have shut in the Yangtse Chiang almost from its source close in upon it again below Fu-Chau, and continue to within a few miles of Ichang, contracting the river at one or two points to a width of 150 yards.
In the autumn of 1896, some forty miles below Wan Hsien, a landslip occurred, which carried down into the river a portion of the mountainside, estimated by Mr. Bourne at 700 yards by 400 yards. This at present forms a complete obstacle to any hope of steam navigation between Ichang and Chung-King, and is much more formidable than the Yeh-tan, Hsin-tan, or any of the other rapids which had hitherto been in question. The Ching-tan, or Hsin-tan, was similarly formed some two hundred and fifty years ago, and it is probable, therefore, that other rapids originated in the same way.
Many rivers are received on either bank before Ichang is reached, of which the most important is the Ching-Chiang, which enters the Yangtse Chiang on the right bank below Ichang.
At Sha-shih, the port of Chong-Chau Fu, the character of the country changes, and an extensive embankment thirty feet high, and from seventy feet to three hundred feet wide at the base, is necessary to protect the country from inundation. The inland water communication extending from Ching-chau to Hankau, on the east, and connecting with the higher parts of the Han River, exposes an immense area to suffering from floods, and the city itself was almost destroyed on one occasion by freshets in the inland waters. The facilities of communication afforded by these routes make Sha-shih a centre of great commercial value, for, independent of the great highway of the Yangtse Chiang and of the canals already mentioned, there are also two large canals on the right bank of the river connecting with the Tung-ting Lake.
Driven onwards by the immense pressure from behind, the waters of the Yangtse Chiang, though moving in an almost perfect plane, have an average surface current throughout the year of two knots at Hankau, where the river is 1,450 yards broad, and has an average depth of forty-two feet. In their course to the sea, the entrance to the Poyang Lake is almost the only place below Wuhsueh at which a passenger on a steamer can detect the influx of any other river. The main river, its tributaries, and the inland canals all form a part of one great network, which proclaims the delta of the river. The rivers of East Hu Peh, North Kiang Si, An Hui, and Kiang Su, which enter the Yangtse Chiang, are very scarcely recognizable as fresh contributions. Even the waters of the Yellow River drained into the Yangtse Chiang in 1889 without for some time exciting any comment on the addition to its volume.
The coal fields of Hu Nan have of late concentrated attention on the Tung-ting Lake and the valley of the Hsaing as the future trade route between South and Central China; but until recently the valley of the Kan, which is navigable by boat from near the Mei-ling Pass on the frontier of Kwang-Tung to the Poyang Lake, was the great official waterway from Canton to Peking.
The Shu or Chin Chiang, which passes Nan-Chang-Fu to the north-west of the lake, and the Chin or Chin-Chia Chiang, which descends from Kwang-Hsin-Fu on the north-east, are the largest of the other rivers which drain into the Poyang Lake, but part of the waters of Hui-chu-Fu in An Hui are also received by it, and it is noteworthy how many routes exist through the mountains on the east to the Che Kiang and Fu Kein.
The lake, which is reported to be 1,800 square miles in extent, acts, like the Tung-ting Lake, as a great reservoir to check inundations.
On leaving Kiang Si and entering An Hui, the river at Wuhu reaches the point where a branch in olden days made its way southwards to the Chien-tang Gulf, near Hang-Chau Fu. Its course is conjectured to have been through a series of lagoons, known in ancient times as the five lakes (the Chen-tse) and its delta is presumed not to have extended further east than the Lang-shan Hills, but the whole subject has been a fertile source of controversy. Another branch must have passed by Sung-kiang Fu, and thence near to Shanghai. The south bank of the present course of the river seems to give indications that its bed was in former days on a higher level than now, but at the present day it is only by embankments that the Yangtse Chiang is prevented from finding a way for some of its surplus waters by the Tai Hu and Su-chau to the sea.
The area of the Tai-Hu and the other lakes in the southern delta of the Yangtse Chiang has been estimated at 1,200 square miles (out of a total area of 5,400 square miles), and the total length of the small channels used for irrigation and navigation at 36,000 miles. But these figures are based upon imperfect maps of the country, and therefore not thoroughly trustworthy.
On the north bank of the river an even more marvellous system of artificial waterworks exists. The Huai River, which, with its seventy-two tributaries, is a most important commercial route to north An Hui and Ho Nan, used to find a natural course to the sea to the south of Shan Tung, but has been diverted by a double series of lakes and innumerable canals, and has now no existence as a river east of the Grand Canal. The enlargement of some lakes and the excavations of others were carried out with a view to preventing too great a pressure on any one point of the Grand Canal south of the old course of the Yellow River. The greater part of the Huai now finds its way to the Yangtse Chiang through different openings in a large canal, which runs almost parallel with the river for a distance of 140 miles. North of this canal lies an immense parallelogram, estimated by Père Gandar at 2,300,000 hectares (8,876 square miles) in extent, which is below the water-level. This is intersected by a series of waterways kept under the most careful control, and constitutes one of the most valuable rice fields in the country. To protect it from inundations by the sea, immense dykes and a large canal stretch north and south between the Yangtse Chiang and the old course of the Yellow River. Through these dykes are eighteen openings for canals to the sea, but the main drainage is southwards to the Yangtse Chiang. Between the dykes and the sea lie the flats which form the great salt-fields of Central China.