Page images

of cubic feet, being sufficient to cover the entire level to a depth of 24 inches. The principal portion of the district lies below the level of high water spring tides in the Humber, being in some places as much as 9 feet below that level. From a map of the valley published in Dugdale, and bearing date in 1640, it appears that the course of the Ancholme was originally very tortuous, being probably enfeebled and choked up by the alluvial deposits from the overflowing of the Humber. At that time, however, a straight channel had been cut, extending from the Humber to Glentham Bridge (a distance of 18 miles), and several drains formed, leading to the new Channel. Figs. 13 and 14, which are reduced sketches of the plan and section given by Dugdale, show the general direction of the old and new channels, and the drains as they existed in 1640. In the previous year Sir John Munson became the undertaker for improving the draining works of this district, having a period of six years allotted for their execution, and a part of the lands, extending to 5827 acres, assigned to him, free of all commons, titles, charges, interest, and demand, of all or any persons whatsoever.

64. In the year 1801, the late Mr. Rennie reported upon the best means of completing the drainage and navigation of the level; and recommended that the drainage of the high lands should be separated from that of the low lands by main drains, commonly called catch-water drains, formed at a higher level than the others, and arranged with separate sluices for discharging into the Humber. This recommendation was well founded on the observation that the greater force and rapidity with which the waters from the upper districts reached the river than those from the lower,

[merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

had the effect of driving the latter over the level, the sluices being inadequate to discharge the entire bulk of water during the periods while the river-tide permitted the sluice doors to remain open. Another and highly important purpose which the catch-water drains fulfil, is that of providing a reserve supply of water which, during dry seasons, may be applied to the lower lands, thus promoting the objects which in those districts are usually associated with drainage, viz., irrigation and navigation. Mr. Rennie had already adopted a similar system of drainage on a more extensive district, that of the East, West, and Wildmore fens, near Boston; but his Report upon the Ancholme level was not then adopted. Twentyfour years later, however, an act was obtained, viz. in 1825, for effecting improvements then recommended by Sir John Rennie, and comprising the formation of the catch-water drains, as proposed in 1801. Sir J. Rennie advised that the river Ancholme should be straightened, widened, and deepened, so as to double its capacity; that a new sluice be formed at Ferraby, having its cill 6 ft. lower than the old one; together with a new lock, 20 ft. wide, so as to serve the double purpose of admitting larger vessels, and affording a greater discharge for the drainage waters during floods. That all old bridges which obstructed the flow should be removed, and a new lock be formed 18 miles above Ferraby sluice. These several works were executed accordingly, and the entire level of Ancholme has been converted into a rich arable district, capable of producing superior crops of every kind. Sir John Rennie also recommended the formation of reservoirs, with overfalls and weirs to receive the sand and mud brought down from the upper part of the country, and thus prevent its accumulation in the river.

65. Fig. 15 will give a general idea of an arrange

[merged small][graphic][ocr errors][subsumed][ocr errors][subsumed]

ment of drains, which will be suitable for a level district with high land behind it. In this Fig. A B is the river, and CD the high land. EFG represent a catch-water drain for receiving the waters from the high land. HIJ, a parallel main drain for the level, with another main drain I K. Between the main drains the level is intersected with minor drains, which have a fall either way towards the mains. The catch-water drain is adapted to discharge directly into the river, or by closed sluices at E G, and an open one at F, its contents may be directed into the main level drain at 1, and made to assist the irrigation of the level in dry seasons. Sluices will be required at E, F, G, H, I, J, and K, by the regulation of which the water may be collected and disposed of in any manner required for the preservation and improvement of the district.

66. Figs. 16, 17, and 18 represent sections of drains of

[blocks in formation]

large size, adapted for works of the kind here referred to. Drains of these sections, formed with a fall of 18 in. per mile, will discharge as follows: Fig. 16, 10-ft. drain, will discharge 1193-4 cubic feet per minute. Fig. 17, 15-ft. drain, 2880 cubic feet per minute; and Fig. 18, 18-ft. drain, will discharge 4642 cubic feet per minute. A good section for an embankment against the sea for

Fig. 19.


« PreviousContinue »