2
Inclosure 3 in No. 1.
Memorandum on the Removal of the Artificial Obstructions in the Canton River, especially
regarding the scope of the work now undertaken.
(Written for the information of the British authorities.)
MERELY to indicate the scope of the work now undertaken could hardly meet the purposes for which this Memorandum has been written. It is necessary to justify that scope, and this can only be done by viewing what the Treaty calls for and what wa propose to do by the light of practical considerations.
At first sight it appears that the removal of the artificial obstructions in the Cantor River is a specific undertaking about which there can be no misunderstanding. But is this really so? The literal meaning of the expression is the removal of all the piles, stones, and sunken vessels which have been placed in the river during the last fifty years or more,
Now, if this were done, it is not improbable that it would cause a serious apse of the equilibrium of forces maintaining existing channels. New channels would be cu out, masses of silt would be put in motion, and new banks would be formed. Probably years would elapse before a new state of comparative equilibrium was brought about, and in the meantime navigation might be seriously embarrassed.
Even, however, were it otherwise--if the total removal would, on the whole, bef beneficial-the value of the work could not but be incommensurate with its cost. It would be a most ineffective way of spending for the benefit of shipping, say, 1,000,000 dollars.
It is plain, then, that the carrying-out of works in accordance with the literal It should be interpretation of the Treaty stipulation is almost out of the question. remembered, too, that the literal meaning is almost certainly not the meaning that those who were concerned in making the Treaty intended to convey.
Their meaning could not but be a very indefinite one. They were dealing with a matter about which they knew but little-about which bat little was known by any one. The expression which they used may be said to have connected what they required should be done It did not denote it. Had it been put to them, I take it, they would have agreed to the following:
It This Treaty has to do with the old-standing grievance of the barriers.
What we intend is impossible that we should specify what can or should be done. that the matter be dealt with as it would be in a progressive country by a river authority having ample funds. And this, I consider, should be the guiding principle in coming to a conclusion as to what is to be done. In dealing with the barriers on these lines there are two main considerations:-
1. To what extent do the barriers embarrass navigation, and what is necessary id remedy this ?
2. To what extent do the barriers affect the river from a conservancy point of view, ie, to what extent are they detrimental to the approaches to Canton and to the harbour itself, and what should be done in this connection?
The answer to the first consideration is easy enough. The barriers in the navigable approaches embarrass navigation merely by reason of the narrowness of the channe through them.
The widths of the ship channels at the various barriers are as follows:-
Bridge Barrier
Iron Barier
Back Reach
Frout Reach
Taishek Barrier Cambridge Barrier Whampoa Barrier
Feet.
150
200
100
300
200
There is ample depth in the channels through all the barriers except at Taishe where there is only 11 feet at low-water spring tide. This, however, does not limit t
3
256
draught of vessels going to Canton, as a natural barrier exists at Taighei with only 10 feet at low-water spring tide.
The accompanying plan (1) shows the position of the various barriers. Considering the Back Reach, i.e., the principal approach to Canton, it will be seen from the foregoing that, so far as navigation alone is concerned, the embarrassment will be removed by widening the channels through the barriers to a width of, say, 400 feet, and providing a depth of, say, 16 feet at the iron and bridge barriers, and of 12 feet at Taishek. The depth, 16 feet, is such as would allow the passage of an upward vessel which had scrape l over the second bar with a falling tide.
In the front reach things are somewhat different. There are there, in addition to the two artificial barriers which embarrass navigation by the narrowness of the channel through them, natural barriers at Sulphur Point and the Salt Flats, which have only about 6 feet on them at low-water spring tide. So far as foreign interests are concerned in this channel, only the river steamers are affected. To these this channel is a con- venience in so far as it is 4 miles shorter than the Back Reach, and in so far as in certain states of the tide its use renders coming to and leaving a berth more easy. I do not wish to minimize the convenience which this channel is to river steamers, but it is proper to realize that it is not a necessary channel, and it is therefore a matter for corsideration as to what sum can advisedly be spent on removing impediments to navigation in it.
1 anticipate no difficulty in widening the channel at the Cambridge Barrier, but as regards the Whampoa Barrier it is different. Here, in order to obtain a condition in which the barrier did not embarrass navigation, it would be necessary to remove a very large quantity-not yet calculated--of stone and sand; and the stone here is to a con- siderable extent embedded in the sand, which has formed an almost dry bank immediately below, and extending for, as yet, an unknown distance down.
For the present navigation here has been assisted by the placing of an additional lighted beacon--not as part of the harrier scheme, but as an ordinary lighting item.
Before entering into what it is proposed to do in this reach, I will proceed with a consideration of the conservancy aspect of the barriers.
It was, I consider, a reasonable presumption that the barriers had caused and were causing a steady deterioration in the approaches to Canton and to the harbour itself. I started with this presumption myself, but I have since come to the conclusion that there is no evidence to show that any such deterioration is taking or has taken place.
The deterioration in the waterway, as a whole, would manifest itself in a lessened tidal range, and in a raising of the low-water level; and a deterioration of the harbour would manifest itself in a lessened depth-in a lessened volume contained therein. But what do we find ? We find that in the years 1892, 1896, 1902, and 1904, the dates of the only existing surveys for examination, the low-water volumes of water in that part of the harbour which is common to all these surveys are respectively 178, 16·2, 17·6, and 17.4 millions of cubic feet.
There is nothing significant of deterioration in these figures.
We find also that there is no appreciable difference in the tidal range or in the level of low water.
Plans 2, 3, 4, and 5 are reductions of the above surveys to an uniform scale of 500 feet to the inch. Appendix (A) gives a summary of my tidal investigations.
I do not pretend that these investigations are exhaustive, nor that the data on which I base my conclusion are altogether satisfactory either in quantity or quality. But I maintain that a study of such data as is available brings to light no evidence pointing to deterioration.
The available data is weak in the following points: The surveys go back for only twelve years, and the extent to which they are reliable is not known except as regards the last one.
It is practically certain that the zero of the standard tide-gauge used in the various surveys has not varied more than half a foot, but notwithstanding this there is no certainty that the various surveys are strictly comparable, on account of the difficulty that exists in reducing soundings in a river, the slope of which at low water varies considerably from time to time.
Then as to tidal data. The absence of old Whampoa records precludes a study of the rate of the travel of the tidal wave, which would have been valuable; and we have to rely solely on the records of the Canton gauge. The fact that on one occasion the Canton gauge was allowed to be 6 inches out (as will be seen in the Appendix) is a weak point, but it does not follow that it happened on any other occasion. The argument as to the stability of the Canton zero by comparison with the Whampoa one is