Attribution of Forest Fires in Europe to Climate Change

Context and challenges

Human activities have been steadily increasing since the 20^th century, leading to a deterioration in the quality of water resources. Agricultural and industrial activities in watersheds produce nutrients that are carried into lakes by rivers. This accumulation of nutrients leads to significant algal growth, particularly cyanobacteria, which depletes the lake’s ecosystem in a process known as eutrophication. Cyanobacteria have a direct impact on the ecosystem by affecting the biodiversity of lakes, although the damage is also economic in nature. In fact, since cyanobacteria can produce cyanotoxins that are hazardous to human health, excessively high levels of cyanobacteria can lead to the closure of swimming and fishing areas in lakes, resulting in a decline in visitor numbers and, consequently, negative economic effects.

Goals

The goal of this thesis is to develop computational tools to aid in the management of eutrophic lakes.

A partial differential equation (PDE) model of the dynamics of a eutrophic lake will be used to identify necessary socioeconomic and ecological trade-offs between nutrient input and the impact on lake users. In preparation of this work, the structure of the PDE model and the theoretical feasibility of the approach were validated in a recent study by the principal investigator (Choquet and Comte, 2023). The issue will be addressed as an optimal control problem under constraints involving the coupled dynamics of nutrients and cyanobacteria in lake waters, with the control variable being the incoming nutrient load into the lake.

The primary goal of this thesis is to enhance the aforementioned mathematical model by incorporating key factors related to eutrophication. These can include meteorological parameters such as temperature or cloud cover. Their significance will be validated and quantified using time series of satellite data through image processing and analysis tools. The aim is also to identify potential specific areas targeted by cyanobacteria and to relate them to bathymetry, inflowing currents, and wind forcing.

Several realistic management scenarios will be proposed and computationally tested in order to provide decision-makers involved in lake management with governance support tools in the form of a “serious game.”

INRAE structure

Non-INRAE partner