DESIGN METHODOLOGY FOR CULVERTS WITH FISH PASSAGE

G.A. Kikkert & E.P. Vodjansky (Bloxam Burnett & Olliver Ltd, BBO), P.A. Franklin (National Institute of Water and Atmospheric Research, NIWA), E. Gee (Waikato Regional Council, WRC) & S. Bowie (Department of Conservation, DOC)

ABSTRACT

Introduction

Fish passage requirements for culverts were introduced as part of the Freshwater Fisheries Regulation in 1983 and its enforcement has been a responsibility of DOC. Under the RMA (1991), control of the environmental effects of culverts became the responsibility of Regional Councils. In practice, the impact of the above on culvert design was relatively small. Guidelines for fish passage at culverts continued to focus primarily on the swimming characteristics of fish. Engineering design guidelines for achieving culvert hydraulics that support passage of New Zealand native fish were not well defined and lacked measurable design criteria. The introduction of the New Zealand Fish Passage Guidelines (Franklin et al., 2018) aimed to fill this gap. The guidelines included an approach for obtaining suitable hydraulic parameters for meeting fish passage. However, in practice, the approach did not provide clear quantitative design requirements that can easily be included in a design methodology. As a result, confirming that a culvert design meets fish passage requirements, particularly the new National Environmental Standards for Freshwater 2020 (NES-F), is difficult. To better align the Fish Passage Guidelines with the new policy requirements set out in the NES-F and the information required for quantitative design, NIWA is currently in the process of updating the document. In support of the updated Fish Passage Guidelines, this paper reports on a methodology for detailed design of culverts with fish passage.

The full abstract can be downloaded below