a. What is the problem/issue being addressed?
Groundwater has been implicated as a factor in landscape development both onshore and offshore. However, this association has been the subject of considerable debate. Experiments and numerical models studying groundwater erosion have been based on simple assumptions, whilst observations of groundwater processes in the field and the laboratory are lacking. As a result, we do not have a good understanding of how groundwater can erode sediments and rocks. This is particularly the case for seafloor settings.
For 80% of the last 2.6 million years, sea levels have been lower than today, and groundwater systems extended beyond today’s coastlines. Remnants of these systems have been documented in many parts of the world’s seafloor. We know very little about the characteristics of this offshore groundwater because most of the information we have is derived from incidental and sporadic discoveries during drilling campaigns. Since offshore groundwater systems are rarely in equilibrium with sea levels, our understanding of seafloor evolution by groundwater processes can only be understood in terms of lower sea levels and more extensive groundwater systems than we have today.
b. What are the overall objectives?
MARCAN addresses the hypothesis that groundwater plays a key role in the seafloor evolution. The objectives of MARCAN are to:
(i) Quantify the characteristics of offshore groundwater systems.
a. Define the 3D geometry, extent and characteristics of offshore groundwater systems and their evolution in response to changing sea levels through time.
b. Determine how offshore groundwater systems and their characteristics are controlled by seafloor and sub-seafloor structures.
(ii) Demonstrate that offshore groundwater is an important factor in seafloor evolution.
a. Identify and quantify the processes through which groundwater erodes sediments and rocks.
b. Evaluate if, and under which conditions, offshore groundwater can modify seafloor landscapes.
c. Why is it important for society?
Offshore groundwater systems are clearly of interest as a source of drinking water, especially in islands and densely populated coastal regions. MARCAN has contributed new tools and knowledge to make the EU a leader in the assessment and environmentally-sustainable exploitation of these valuable offshore resources. Sectors involving seafloor engineering, carbon dioxide sequestration, and ore deposit and petroleum exploration will also have a direct interest in MARCAN because it places better constraints on how fluids have flowed in the past and improve risk assessments. MARCAN also contributes essential environmental baseline data, scientific knowledge, observational tools and quantitative models that will help decision-makers on their design of environmental policy and management of water resources.
