LAND DRAINAGE.

Hauraki Plains Gazette, Volume XXXIII, Issue 4431, 23 June 1922, Page 1

LAND DRAINAGE.

NEW ZEALAND AND AMERICA. MR J. B. THOMPSON’S REPORT. No. 8. FUTURE OF LAND DRAINAGE. Pas'. History.—ln the initial, stages of the movement comparatively small areas of swamp lands were being drained by community or private enterprise working under the Land Drainage Act. The reclamation of large areas could not well: be financed without Government aid, and finally parliamentary sanction was obtained to the proposed development of what was then known as the Piakc Swamp, but now as the Hauraki Plains. An enabling Bill was brought down for this particular area, an'l later for the Rangitaiki Plains area, and the results obtained by the: drainage operations called forth applications from many districts for similar aid.

The - old procedure of individual empowering Bills was then decided to be too cumbersome, and the Government of the day decided to bring down a measure which would enable it to handle subsequent, applications. This measure was finally placed on the statute-book as the Swamp Drainage Act, 1915, the Hon. Minister cf Lands being the administrative authority. The Future. —To date the drainage operations carried out under Government control have resulted in. bringing previously useless swamp land to profit, and expectations have been more than realised. These operations are incomplete as regards present undertakings, and there aye many areas untouched which it will pay to take in hand. One cannot be too enthusiastic in the matter, of land reclamation, and the watching of seemingly irreclaimable areas coming to profit is very heartening. There is a big field of undeveloped possibilities in New Zealand that can, be best carried out by the Government under, its own Swamp Drainage Act, 1915, or by community enterprise working under the machinery of the Land Drani.age Act, 1908.

There are many purely swamp areas throughout the Dominion, perhaps small individually, but large in the aggregate, which must, in the ordinary course of events, be reclaimed. Then come the large tracts of marsh lands 'on the foreshores of the coast. The periodically flooded bottom lands' in t,he flopdrplane slopes of rivers is another avenue for development. -Fortunately gravity drainage governs the larger proportion of future possible reclamation projects.

Installation of low'-lift pumps will be necessary to deal with certain of the areas. Generally the field is a broad one, and offers every inducement for investigation. There will without doubt come a time when necessity will demand intensive cultivation of swamp and marsh areas; holdings will become smaller, and the necessity for close drainage of sarnie will arise. To jneet these conditions tile drains will be required, in sizes of 6in and upwards. Their use has been most successful, and they will eventually largely replace open ditches, which occupy so much land. Investigations Necessary.—lt -is recognised in Canada and in the United States that practical assistance by the respective Governments is required in the direction of providing reliable data for information of drainage boards, settlers, and engineers, and t’k this end there exists an investigation staff. The Drainage Investigations Bureau bf the United States is a most valuable branch of the Federal Government, and might well be aodpted a.-; a'model for requirements in New Zealand and elsewhere.

Field of. Investigation.—Although practically all officers of the Land Drainage branch are construction I men, yet it should be possible to in- ' corporate with their duties some measure of investigational research, provided junior assistance is given them in th,.- way of l avoiding, the personal daily round of visits to the various instruments, recorders, test-pits, etc. It is suggested that the time is ripe to undertake local investigations in regard to the following: Precipitation (rainfall) ; run.-|off ; evaporation ; soil moisture ; subsidence of drained land; flow of water in artificial canals and ditches; saturation; water-table research. At present our means of determining the run-off of any particular watershed are meagre, and the approximate deductions arrived at unreliable. This branch should be in a position to offer sound advice to drainage districts upon these most important questions, for upon it depends the size of ditches necessary to accommodate storm-water, the spacing of same, and the depths necessary to enable as low a water-table as possible being, maintained. The value of sue!? work would be greatly enhanced by the issue off bulletins from time to time.

In the event of the foregoing recommendations regarding drainage investigations being approved it is not suggested that they take effect immediately, but rather that the principle be affirmed and action taken; as soon as conditions return to normal.