Information on Climate and Geology

CLIMATE

The area is located in the sub-humid temperate zone. Summers are short and mild and winters long and cold. Mean monthly maximum temperatures vary from 25.4 degrees Celsius in February to 11.7 degrees Celsius in July. Mean monthly minimum temperatures vary from 12.5 degrees Celsius in February to minus 2.9 degrees Celsius in July. Frosts occur throughout the year beginning in March and ending in December and it is not uncommon to have temperatures drop to minus 10 or 14 degrees Celsius during winter on the lower areas of Walcha. Snow also occurs an average of two (2) days per year. In January to April winds blow most frequently from the north-east while in May to December from the west to north-west.

The average annual rainfall is 815mm with December and January the wettest months and April and May the driest.

GEOLOGY

Geologically the Walcha district is part of the New England Region consisting of extensive sedimentary rocks with granite intrusions to the north-east. Basalt rock dominates the centre of the district.

The district is largely made up of a plateau forming part of the Great Dividing Range. The maximum elevation is 1,463m at Grundy Trig, 38km south of Walcha. To the east of Walcha the plateau is steeply dissected by spectacular gorge country which is readily seen at the Apsley Falls, 18km east of Walcha. The first drop of the falls is 114m and the second, 1km further on, is 195m. The gorge is 360m deep. The district forms part of the catchment of four major river systems. The westward flowing Namoi River and the eastward flowing Macleay, Hastings and Manning Rivers.

Rainfall in the district ranges from 700 to 1200 mm annually with approximately 60% falling in the summer and 40% in the winter. Temperatures are low and Walcha often features as having the lowest minimum in the State. Walcha has an average frost period of 240 days.

Soils of the district are predominantly Krasnozems, Chocolate and Solod soils. Over one third of the district is covered by shallow soil types.

The eastern and southern areas of the district are covered with wet sclerophyll forests which yield large quantities of valuable hardwood timber. The central and north-western areas consist of open woodland which has been extensively cleared. Altogether about half of the district is under native timber.

The large areas of native forest and the long history of pasture improvement on the cleared lands has resulted in the district having experienced little soil erosion. At least half of the district is largely un-eroded and the remainder experiences either slight to moderate sheet erosion or occasional gullying of drainage lines.