Effects of climate change and erosion mitigation on suspended sediment loads and visual clarity in the Wairoa catchment, Hawke’s Bay

The Wairoa River is significant to the iwi and hapū of Te Rohe o Te Wairoa. An important threat to the health of the river is from sediment entering the water.

The Wairoa Tripartite (Wairoa District Council, Tātau Tātau o Te Wairoa, Hawke’s Bay Regional Council) and the Whitiwhiti Ora project (part of the Our Land and Water National Science Challenge) have formed a partnership to jointly guide the direction and delivery of a project focused on understanding cultural values related to the river and the impact of sediment on these values.

The objective of this report is to model erosion and suspended sediment loads in the Wairoa catchment under a ‘best-efforts’ erosion mitigation scenario and assess reductions required to meet National Policy Statement for Freshwater Management 2020 (NPS-FM) fine suspended sediment attribute bands for visual clarity at State of Environment (SOE) sites. This will be assessed under contemporary and future climate scenarios. This information will inform work assessing sediment impacts on the river’s cultural values.