Effects of land use change on the flood hydrology of the Waikato River catchment

Increasing pressure is being exerted for conversion of established areas of forest plantation to pasture in the Waikato River Catchment. Such conversion is already well underway in some parts of the catchment.

Environment Waikato has been aware of the gradual conversion within the upper Waikato catchment over the last several years. Due to the scale of land use change, a policy review for the area above Karapiro is proposed. The review process requires specific steps be followed including scientific investigations of the issues and their effects on current policies and targets, available methods to address the issues and effects including justifications for any policy changes. Stakeholder and public consultation is a legal requirement and is part of the whole review process. The initial assessment of the effects of land use change within the catchment above Karapiro included effects on water quality, soil erosion and flood hydrology. This project is concerned only with understanding the effects of forest plantation to pasture conversion on flood hydrology within the Waikato River Catchment downstream of Lake Taupo.

These areas consist of a variety of geological soils, whose hydrological and erosion characteristics vary with changes in land use. In particular the flood ydrology of the pumice soils of the central North Island is known to be particularly sensitive to changes in land use. Conversion of plantation forested areas to pasture within the Waikato region is currently unregulated by statutory planning instruments and can occur ‘as of right’. Currently known areas of forestry conversion are assessed at up to approximately 70,000ha.

You can download the project brief and plan below (in PDF format) to learn about the effects of land use change on the flood hydrology of the Waikato River catchment between Karapiro and Taupo.

Project brief: Effects of land use change on the flood hydrology of the Waikato River catchment between Karapiro and Taupo
(90 kb, 12 seconds to download, 56k modem)