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During the year two hydraulic survey parties were established, one based on Palmerston North to cover the southern half of the North Island, and the other based •on Blenheim to cover the northern half of the South Island. These parties are employed full time and continuously on the inspection, selection, and surveys of river-gauging stations, and on the making of river-discharge measurements, particularly at low and flood stages. They will move from district to district on an approved itinerary by means of their own transport. By this continuity of work it is felt by the Council that the personnel of the parties will become more proficient, while far more data of a higher standard will become available to those requiring it than if this work was left to be performed intermittently by district staffs. Each party is fully equipped with various types of current meters and miscellaneous gauging aids, so that the most accurate .discharge measurements may be made under almost any adverse conditions, including night work during storms. The North Island party has made intensive reconnaissance surveys of the Waipaoa, Tutaekuri, Ngaruroro, Tuki Tuki, and Rangitikei Rivers and certain sites are under -consideration for adoption as gauging-stations, while detailed surveys have been made of several sites, and proposals for gauging-stations are in hand. The South Island party has concentrated on survey of gauging-station sites for hydro-electric purposes in Nelson, Upper Buller, and Marlborough districts, while both parties have made many standard discharge measurements, particularly of important streams during the phenomenally long, dry season. Towards the end of the year both parties were concentrated on Methven, the centre of the South Canterbury irrigation scheme, and made new surveys .and discharge measurements at the various gauging-stations operated by the Irrigation Division, Ministry of Works, while the opportunity was taken to perfect and standardize >eqnipment and techniques. It was also found necessary to establish a similar, but district, mobile hydraulic survey party in the Hamilton works district, and since December this party has been working intensively on the Lower Waikato River and on the Bay of Plenty rivers locating .satisfactory gauging-sites, carrying out surveys of those sites, and making discharge measurements. The Council is confident that the successful and continuous establishment of these survey parties, the data they will collect, and the derived fundamental run-off information which will thereby be obtained will be of the utmost value to the Dominion in the future. All hydraulic works such as highway and railway bridges, hydro-electric development, irrigation, airfield and municipal storm-water drainage, water-supplies, river control, .and soil conservation schemes require as close and perfect a knowledge as possible of precipitation and run-off. No remarkable flood occurred on any of the larger rivers, the greatest floods occurring ■on the Manawatu and Tuki Tuki Rivers on the 9th August. In minor catchments the most spectacular flooding occurred at Marton from the 'Tutaenui Stream, a tributary of the Rangitikei River, on 13th February. During the five previous days over 7 in. of precipitation was recorded in the catchment. On the morning of the 13th February not less than 2 in. fell during a thunderstorm in two hours, with a further 1 in. in the following two hours, resulting in the highest flood and greatest ■depth of flooding within living memory. It has been calculated that at the peak some 10,000 cusecs were discharged from a catchment of 27 square miles. This same storm -caused lesser flooding in the adjoining catchment, the Makirikiri Stream, a tributary of -the Turakina River, resulting in a peak discharge of 2,300 cusecs from 13 square miles.

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