North Marlborough is characterised by a wet climate while south Marlborough has a dry climate. Annual rainfall ranges from 600 mm in the south to 2,600 mm in the north. The Richmond Ranges, Bryant Ranges and the Marlborough Sounds dominate North Marlborough, much of which is covered in native forest with some exotic forestry. The Marlborough Sounds are an example of a drowned mountain valley known as a ria. The Marlborough Sounds coastline accounts for approximately 20% of New Zealand’s entire coastline.
Small steep rivers and streams are characteristic of the Sounds while South Marlborough is mainly dry tussock-covered mountain ranges which include the Inland Kaikouras and the Raglan Ranges. The highest peaks in Marlborough, including the highest peak outside of the Southern Alps, lie in these ranges.
Water quality is monitored on a monthly basis at 34 sites as part of the region’s state of the environment (SoE) monitoring of surface water. Two of these sites, on the Wairau River, are monitored by NIWA. Sites are located at the bottom of catchments where possible in order to take account of the cumulative effects of land-use within the catchment. Land-use pressures in the region include dairying and exotic forestry in North Marlborough and viticulture and dryland pastoral farming in South Marlborough, particularly along the Wairau plains and east coast.
During the summer there is weekly monitoring at some sites. See the Marlborough District Council website for details.