Cyanobacteria Abundance Modeling: Development and Assessment of Season- Ahead Forecasts To Improve Beach Management on Lake Mendota
Abstract
As eutrophication and the associated dominance of cyanobacteria continue to increase
across inland waterbodies, local officials are seeking novel methods to proactively
manage water resources. Presently, however, there is no long-term cyanobacteria
forecast that can provide advance warning of a potential threat in the upcoming season
for beach managers. In this study, a statistical model is developed utilizing local and
global scale season-ahead hydro-climatic predictors to evaluate the potential for
informative cyanobacteria biomass forecasts across the June-August (JJA) season to
aid in beach management. Model skill is quite strong in comparison to JJA
cyanobacteria observations (R2=0.52, RPSS=0.64). Cyanobacteria predictions are in
turn used to inform categorical forecasts of JJA beach days closed, specifically the
probability of normal (0-2 days closed) and above normal (> 2 days closed). Forecast
categories and observed categories tend to correlate strongly, with 70% to 90% of
predictions falling into the correct category across the six beaches modeled,
demonstrating encouraging prediction skill.
To assess the potential application and value of the forecasts developed, local
stakeholders, including non-profit organizations, University of Wisconsin – Madison
affiliates, and government agencies that are involved in various aspects of water
resources research and management, were asked to participate in a qualitative study
consisting of an online survey and focus group discussion session. From both the
survey and the focus group discussion session we identified an expressed interest from
stakeholders for integrating season-ahead cyanobacteria and beach closing forecasts
into current beach management practices, particularly for the purposing of improving
public safety and increasing public awareness. However, there were alternative
stakeholder visions of the value of the forecasts, likely due to the absence of real world
examples. Nonetheless, we conclude that there is clear untapped potential for the
application of season-ahead forecasts to local beach management.
Subject
beach management
season-ahead forcast
cyanobacteria