Beach change in the Auckland region: current state and trends. State of the environment reporting

Executive summary

Te Kaunihera o Tāmaki Makaurau / Auckland Council’s Coastal Processes Monitoring Programme provides essential long-term information on coastal change across the region. The programme has been monitoring coastal change at key beaches across Tāmaki Makaurau since the 1960s. Through the regular and long-term collection of beach profile surveys, the programme provides valuable data on erosion and accretion rates, which supports our understanding of natural coastal dynamics, informs adaptation planning, and enables effective management responses to coastal hazards and climate change. This report provides detailed beach profile analyses of 12 beaches, with beaches categorised into four groups (west coast, open east coast, inner Hauraki Gulf, and Tāmaki Strait) representing distinct wave climates around Tāmaki Makaurau. The analysis evaluates long- and short-term beach state and trends by assessing variations in beach envelope, beach volume, beach width, and for certain beaches, dune dynamics and beach rotation. Several important patterns emerge providing valuable insights into our region’s dynamic coastlines.

1. Site-specific beach dynamics

The beaches of Tāmaki Makaurau exhibit considerable diversity in their long- and short-term trends, despite similarities in geographic setting and wave climate within each coastal group. Notably, Piha and Muriwai, both exposed to the high-energy west coast wave climate, demonstrate opposing long-term trends (1980s - 2025): Piha has experienced substantial accretion and widening across all profiles, whereas Muriwai has undergone significant sand volume loss and foredune retreat. These contrasting behaviours highlight the site-specific nature of sand transport, deposition and accommodation space along Auckland’s west coast.

Inter-beach variability is observed across all groups, where adjacent beaches often exhibit contrasting trends. For example, the open east coast beaches Pākiri and Omaha exhibit opposing patterns of beach change, with Pākiri undergoing long-term erosion (1970s -2025) while the majority of Omaha Beach has accreted during the same period. As well as differences in sediment dynamics and accommodation space, these variations are largely influenced by differing beach management practices at these sites. As illustrated with these examples, variability in natural and human-influenced drivers of coastal change throughout the region underscores the necessity for continued site-specific monitoring to inform targeted coastal management at key locations.

2. Changes to long-term trends

Since the last State and Trends Assessment, published in 2016, the long-term trend at many beaches has altered considerably. The previous assessment reported relative long-term stability at both Pākiri Beach and Maraetai Beach. However, this report reveals the emergence of long-term erosion trends at both sites, with Pākiri, in particular, exhibiting accelerated erosion over the past decade. These changes highlight the dynamic nature of Auckland’s beaches and emphasises the necessity to continue monitoring these beaches to detect and respond to any significant changes to the long-term trend. 

3. Human interventions

Human activities such as sand mining, beach renourishment, dune planting, and the construction of coastal structures can strongly influence beach states in Tāmaki Makaurau, having the potential to mask or exacerbate natural trends. At Omaha Beach, human activities such as groyne construction and dune planting programmes have contributed to the long-term accretive trend at the beach by helping to trap sand within the beach and dune system. Similar impacts are observed at Muriwai and Piha beaches, where restoration initiatives – including dune reshaping and replanting – have supported dune stabilisation and accretion. Continued monitoring of these beaches is essential to better understand the long-term effects of human activities and restoration efforts.

4. Vulnerability of urban beaches

The inner Hauraki Gulf beaches are characterised by high intra-annual variability, with all monitored sites exhibiting substantial event and seasonal-scale fluctuations in beach profile position, volume, and width. Most inner Gulf beaches are ‘urban beaches’ that are predominantly backed by seawalls or rock revetments. They are also considered closed systems, with limited sediment typically present on the beaches and little inputs of sediment into the nearshore system. As such, these beaches are particularly vulnerable to erosion during high-energy events. 

Notably, recent years have seen many sites exceed historic lower limits of beach elevation, suggesting a potential emerging trend of sediment loss. Ongoing monitoring will determine whether these changes represent short-term responses to recent storm activity or indicate a long-term trend of sediment loss at these beaches. The contrasting response of Ōrewa Beach and Takapuna Beach to Cyclone Lola that impacted Auckland in October 2023, is investigated in this report as a case study in Section 6.

5. Cyclical patterns of beach change

Several beaches in Tāmaki Makaurau exhibit cyclical patterns in beach volume, beach width or beach rotation that may correspond to major climatic oscillations such as the El Niño Southern Oscillation, Interdecadal Pacific Oscillation or Southern Annual Mode. Beaches such as Pākiri Beach, Omaha Beach, and Long Bay exhibit cyclical patterns of beach change occurring on five- to ten-year cycles, coinciding with sustained periods of sand accumulation or loss. Understanding the drivers of these cycles at different beaches is critical for anticipating future beach change and appropriate coastal management.

These patterns collectively highlight the necessity of maintaining long-term, site-specific monitoring to track beach evolution, detect emerging issues, and inform proactive coastal management. Monitoring results also help prioritise resource allocation by identifying beaches that may require more frequent monitoring and those where reduced effort may be appropriate. Given resource constraints, strategic prioritisation of key sites is essential.

The high variability of beach change across Tāmaki Makaurau reflects a complex interplay of local drivers – including wave climate, sediment supply, bathymetry, geographic setting, and human interventions. Improving understanding of these drivers at the site level will be key to managing future coastal change.

The Coastal Processes Monitoring Programme continues to evolve, integrating long-term datasets with new technologies. New initiatives outlined in this report, including nearshore bathymetry surveys, a pilot drone monitoring programme, wave buoys, coastal monitoring cameras, and efforts to improve public access to coastal data, will strengthen Auckland’s ability to protect and adapt its coastline in response to future environmental challenges.

Auckland Council technical report, TR2025/13

September 2025

See also

Te oranga o te taiao o Tāmaki Makaurau. The health of Tāmaki Makaurau / Auckland’s natural environment in 2025. A synthesis of Auckland Council’s state of the environment reporting