DRAINAGE OF PLAINS.

Hauraki Plains Gazette, Volume XXXIV, Issue 4607, 28 September 1923, Page 4

DRAINAGE OF PLAINS.

THE NORTHERN AREA. . TOUR OF INSPECTION. Though little is heard of the activities of the delegates elected to further the scheme for the proposed Drainage Board to operate between the Piako and Waihou Rivers much is being done. With a view to ascertaining the requirements of the district, several tours of inspection have been arranged. On Monday last one such tour was made of the Kopuarahi-Shelly Beach area. As the key to the system is the outlets the tour was made around the stopbank. The party assembled at (he corner of the Turua-Kerepeehi-Kopuarahi Roads where the culverts were inspected. It was found that the water from the southern side of the Turua Road and the eastern side of the Kerepeehi Road could cross by a 4ft square culvert, and join the water from the western side of the kerepeehi-Kopuarahi Road to proceed do.wn the shell bank drain to the outlet at Bond’s wharf, where a 3ft circular flood-gate is installed. It would be advisable to have another culvert across the road at that corner to take the water from the northern side of the Turua Road. It was this water that was largely the cause of the disastrous flooding at Kopuarahi recently, where, meeting the water from the western side of the Kopua-rahi-Orongo Road and being unable to get away fast enough through a 3ft. culvert at the school corner, it overflowed the land for miles. The shell bank drain, being undermined and .slipped in many places, would require to be laid back to a one to one batter, and another 3ft. floodgate installed at Bond’s wharf. From Bond’s wharf the party proceeded along the stop-bank to Millers’ outlet,, where a 3ft circular flood-gate is installed. The drain, though at one time flumed, has - slipped so badly that for a short distance the Lands Drainage Department recently laid back the batter to about one to one. This drain has never taken the water from the upper area as it should have done, and would require improving to become satisfactory. Proceeding north along the stop-bank two 3ft wooden gates were noticed to have been removed. A small drain runs along inside the stop-bank, and has an outlet at a wooden flood-gate. This gate, while bf excellent design and having ah opening of 27 square feet, has been in operation for ten years or so, and if left much longer may break up, A concrete gate is suggested. This cotild be made more effective by being placed 18 inches or 2ft lower.

Approaching Kopuarahi wharf two more discarded gates were passed. At the wharf there is a 3ft concrete outlet, and this would probably suffice if the water were diverted as suggested. However, it would be wise to protect the end of the outlet and the gate by putting in some piles. Proceeding towards Sihelly Beach a discarded outlet for the roadside drain was passed; also one for the Bond-O’Carroll drain. The water has to go by the roadside drain to the Kopuarahi wharf or back along the Shelly Beach road. A flood-gate is needed. Continuing on the first outlet was arrived at about a mile from the wharf. This drains the roadside drain, but the gate is not in the most suitable place. At Shelly Beach wharf the stopbank leaves the river and passes between native land and the Hauraki Plains drainage area. There are two concrete road culverts and abandoned flood-gates within a chain or so. The last outlet, like many of. the others, is very inadequate considering the area draining into it. Water from beyond the Kopuarahi-iOrongo road flows down the factory drain, meets the water from the eastern side of the Shelly Beach road, and has to flow through a 2ft pipe culvert where it meets at right .angles the flow of water from the west side Shelly Beach road drain. This drain is about five miles loijg, for it commences near the Ngataipua East road, flows along between the Ngataipua and Maioro blocks and the Hauraki Plains drainage area, to join the Shelly Beach road. The outlet for this enormous area is a 3ft pipe flood-gate. At one time the drain alongside the Ngataipua block was continued out into the Gulf, but as the mudbank is exposed at low water for about three miles it can easily be understood why this would not work satisfactorily. At one time the Drainage Department proposed to open a drain across the Maioro block to the river, and this appears to be the only solution of the problem. The land outside the stop-bank is covered at high. tide. Since the stopband was erected the land outside has become over a foot higher than that within the stop-bank. This mud has been surveyed and is shown on some plans as section 4. The whole of the stop-bank traversed by the party showed the effect of much trampling by stock. If this is allowed to continue the bank will be rendered useless. In parts it is undermined and requires attention, and in other places it is very low and should be built up. The Shelly Beach road is in winter a road in name only. Spoil from the roadside drains has been placed on the sides of the road, thus confining the rain water to the middle. The whole country thereabouts is sodden. Weeds are taking .the place of the grass. That grass grows at all is only explainable by the amazing fertility, for the land is probably the best on the whole of the Hauraki Plains. Leaving the stoprbank at the boundary of the Hauraki Plains drainage area the party waflked across Mb) J. C. Miller’s property to the KopuarahiOrongo road. Water was lying in the paddocks almost up to their boot-tops. There are many drains on this property, which was the first section tc be ppened up for settlement on the Plains, but owing to the distance to the outlet the water in the drains is practically stagnant. It »s the intention of the owner to have a stopbank erected all round his farm. In

his opinion this is the only solution, for after heavy rain he is flooded by the-water from the higher land on the other side of the O Hon go road until such time as the water from nea’~ er Kopuarahi can get away through the 3ft flood-gate at the end of the factory drain. Reviewing the whole area, it appear® that the drainage operations have been carried out in a slipshod manner and without any reference to a comprehensive scheme. Much work will have to be done to rectify the mistakes of the past. Similar inspections will be made in the other areas within the next few days, and a meeting will be held shoitly to discuss what action to take,