Metocean conditions study to optimise marine operability at Punta Chungo, Chile

Last year, Latin America’s leading company in marine exploration, BENTOS, commissioned MetOcean Solutions to provide a summary of metocean conditions at Punta Chungo, Chile. 

Punta Chungo is the maritime terminal of Los Pelambres copper mine from where their 364 .000 Ton/yr of copper concentrate are exported to international markets. Punta Chungo is located in the central Chilean coast. The port is configured in a way that the terminal is directly affected by regional windseas and swell waves incoming from the Pacific Ocean.  

Dr Séverin Thiébaut, MetOcean Solutions’ Oceanographer in charge of the project, says the characterisation of ambient and extreme metocean conditions are crucial to optimise marine operability and port safety. 

“Plus, it identifies potential hazards and documents important aspects of the environmental conditions and long-term trends that may require further attention at Punta Chungo.”  

The wave model implementations were led by MetOcean’s wave expert Dr Henrique Rapizo who explains “We set up a 20-year multi-nest SWAN wave hindcast model to replicate the ambient and extreme wave climate in Punta Chungo. 

“Our approach fully captured details of the coastal line and bathymetry in the area. The finest nest had approximately 50 m resolution to resolve small-scale bathymetric features between each point of interest." 

The Simulating WAves Nearshore (SWAN) model was used for the work. A 4-level dynamical nesting approach was applied to downscale wave spectra from the global implementation of the WaveWatchIII model to the shallow nearshore locations of interest. The model was forced by wind fields from the Climate Forecast System Reanalysis (CFSR), and tidal constituents from the Oregon State University Tidal Inverse Solution (OTIS).  

Analyses were carried out at four sites along the port berth to extract ambient and extreme wave statistics to assess the workability, extreme metocean statistics and long-term trend of storm events. 

“Based on a co-temporal criterion, we presented annual and monthly workability statistics for the operational area in Punta Chungo,” explains Séverin. “For example, we were able to define the month with highest/lowest workability; durations of consecutive workable hours; and number of workable events. 

“Extreme metocean statistics were also analysed for each location. The estimation of likelihood and intensity of long‐term extreme events have been a key consideration in the design of marine infrastructure, but also supports operational safety and helps to avoid unnecessary infrastructure costs.” 

Figure 1 - Example of time series of offshore wind speed storm peaks (top) and significant wave height storm peaks (bottom) represented by the blue starts, linear trend shown in the red line.

In addition, we produced an analysis of storm event frequency and severity on a yearly basis from 2000-2019 based on several metocean parameters, as illustrated in Figure 1 for wind speed and significant wave height. Results indicate a decreasing trend in the storm wind intensity and frequency, while storm Hs intensity and frequency increased from 2000 to 2019 (Figure 2).

Figure 2 - Number of storms per year above the 95th percentile level based on wind speed (red) and Hs (blue).