INTRODUCTION

The Ord River Irrigation Scheme is located in the northern part of Western Australia and the Northern Territory (Figure F.1). The region experiences the tropical climate of the Kimberley region with a wet and a dry season. Average annual rainfall at Kununurra is 793 mm. Its mean daily maximum temperature ranges from 30.7°C in July to 38.9°C in November, while the mean daily minimum temperature varies from 15.4°C in July to 25.6°C in December (Australian Bureau of Meteorology website).

Interest in the Kimberley region of Western Australia, including the Ord River Valley, began with Alexander Forrest's report of his exploration of the Fitzroy and Ord River Valleys between 1875 and 1879. The potential of the Ord River Valley for irrigated agriculture was first recognised in the late 1930s (Department of National Resources, 1976; Young, 1979). In 1941 a party of engineers and scientists explored the area and established that the Ord River could be dammed at one of many sites and provide water to a large fertile plain. In the same year, a small experimental farm was established on the banks of the Ord River near the off-take of the present M1 Supply Channel (Figure F.1). In the next four years, the Western Australian Government sponsored more detailed investigations. These concluded that 22 000 ha of land could be irrigated, and a further 50 000 ha extending into the Northern Territory, warranted further examination.