Ongoing subsidence is an complex problem in the Dutch lowlands for cities and polder land. Old strategies for coping have bottom limits. New strategies will be arranged and the pacing of subsidence mapped and modelled, so that the measures to negotiate and decide on have figures in mm and €.

• prof. mr. dr. Frank Groothuijse
• dr. ir. Dries Hegger
• dr. ir. M.M. (Mariet) Hefting
• prof. mr. Marleen van Rijswick
• prof. dr. Peter Driessen
• dr. Kim Cohen
• prof. dr. Esther Stouthamer
• Ruth de Klerk
• dr. Oscar van Vliet
• Duygu Tolunay
• Kim de Wit MSc
• Bente Lexmond MSc
• Pepijn van Elderen MSc

• Gilles Erkens (Deltares)
• Bernardien Tiehatten (LOSS)
• Prof. Ramon Hanssen (TU Delft)
• J.G. Rots (TU Delft)
• K.G. Gavin (TU Delft)
• Prof. Ekko van Ierland (WUR)
• Prof. Hans-Peter Weikard (WUR)
• Jan Willem van Groenigen (WUR)
• Jan JH van den Akker (WUR)
• Dr. Mandy Korff (TUD
• Deltares)
• Dr. Peter Fokker (TNO Geological Survey of the Netherlands)

This is a pilot project of the UU research focus area Future Deltas. We study subsidence due to peat compaction and oxidation in built-up areas in three villages in the central part of the Rhine-Meuse delta, The Netherlands. Built-up areas are typically avoided because sealed surfaces and restricted property access hamper investigation the subsurface. These areas are however heavily impacted by land subsidence, and therefore, with an increasing number of people living on peaty soils, understanding processes leading to subsidence is critical. 

We made cross sections based on logged borehole data to reveal the lithological composition of the Holocene sequence underlying the villages. At selected sites, representing different land uses and subsurface composition, cores were extracted to determine current compaction conditions of peat layers, based on high-resolution bulk density measurements. Oxidation conditions of selected peat samples were determined based on respiration measurements. Derived information on compaction and oxidation conditions, along with data from previous studies, allowed to assess the relative contribution of both processes under different settings regarding loading and groundwater level. In addition, we assessed the potential for future land subsidence at our study sites under different development scenarios. Ultimately, insights derived from this study can be used for developing sustainable management strategies for inhabited organo-clastic coastal zones worldwide.

• prof. dr. Esther Stouthamer
• dr. ir. M.M. (Mariet) Hefting

This project aims to enhance the capabilities of individuals and organisations to develop sustainable strategies for dealing with groundwater extraction, land subsidence and salt water intrusion in the increasingly urbanising Mekong Delta (Vietnam). We will enlarge the knowledge base of stakeholders (including policy makers, water managers and scientists) and work with them to develop and implement innovative tools and technologies in practice and policy. A new integrated delta model will be developed, linking surface water, groundwater and geo-mechanical models, to analyse the interrelated character of groundwater extraction, subsidence levels and salt water intrusion. Together with stakeholders the new and comprehensive model will be constructed and applied to quantify the effects of water management strategies in the Mekong Delta. Stakeholders will analyse and develop adequate strategies by simulating and demonstrating the effects of development scenarios and policy recommendations, such as expressed in the Mekong Delta Plan (2013).

• dr. ir. Gualbert Oude Essink
• prof. dr. Piet Hoekstra
• prof. dr. Esther Stouthamer
• dr. Maarten van der Vegt
• dr. Carel Dieperink

Delta Evolution is the label we use since 2005, for the Utrecht University research line in Lowland Geomorphology and Quaternary Geology, carried out by the Department of Physical Geography, in cooperation with other institutes. Delta Evolution is also the label put on the strategic research cooperation (since 2008) of the group with departments in Deltares Research Institute and TNO Geological Survey of the Netherlands, that have their offices on the Utrecht science campus too. The Delta Evolution program also connects to the network of alumni of Physical Geographers and Quaternary Geologists active in commercial consultancy companies and governmental agencies in the field of water management, hydrology, civil engineering, nature conservation and archaeology in The Netherlands and to colleagues at other universities - with whom we collaborate in shared projects. Our research and networks extend to deltas internationally - see the pages of the Future Deltas focus area for example. 

The Netherlands and the Rhine-Meuse delta in it are strongholds for our research. Our scientific research treats this delta as the mega-case, to draw smaller cases from - and to compare with other delta systems (other mega-cases) to test and validate what part of our insights are delta-specific and what is generic. The lowlands that the program focuses on include: delta plains, coastal plains, larger river valleys, peat wetlands, lagoon and fenlands and so on. These areas connect to upstream catchments and coastal marine systems downstream. Besides holding sedimentary and geomorphic record of their dynamic formation (lowland genesis, natural and human impacts thereon), the lowlands are also archives that recorded change of the upstream catchment (size of floods and amounts of sediment received), the coastal system (transgression, tides, barrier coasts, storms), the climate system (storms, precipitation, temperature), the biological system (vegetation and fauna, aquatic, riparian, terrestrial), the deeper earth (neoteconics, glaciohydro-isostasy), and archeological history (finds, sites, use of landscape). This feeds interdisciplinary and multidisciplinary research. Also, the better the build-up, making-of and age of the lowlands is understood (data integration, synthesis), the better the archives and science based on becomes (duplication, cross-validation, stacking). This is a main reason to carry-over mapping and dating knowledge from individual projects to Delta Evolution's living datasets, that in turn feed into new projects.

Delta Evolution as an umbrella programma, bundles series of PhD/Postdoc projects and contract-research projects and includes long-term dataset management from and between these projects. Goals in Delta Evolution at present are:

1. Perform novel scientific research in Geomorphology and Quaternary Geology of lowland areas,

• by using and expanding the present datasets (already huge and of high quality) and knowledge (from several disciplines), 
• by exploring the limits of our process-understanding and innovate the techniques of modelling geomorphology to cover longer timescales (1000-100,000 years), 
• by pushing the resolution and accuracy of our mapping and dating, and innovate the techniques that combine these (GIS palaeogeography, 3D/4D geomodelling),
• by striving to time-slice the evolution of deltas and quantify rates of morphological, sedimentary and hydrological change as they were changing over time (thus documenting shifts in controls)
• by addressing research questions on the delta system at nested spatial, temporal and functional scales (whole delta, individual branches and swamps, fluvial vs. tidal affected reaches, human-impacted, semi-natural, natural parts of the system's suites of environments and processes; transgressive vs high-stand periods).
• by combining new-collected data from field- and lab work with existing data, statistical analysis and physical numerical modelling.

2.  Synchronize the academic delta research with applied research activities

• by valorizing new scientific insights early on in national mapping projects and geological/geotechnical/geohydrological advice.
• by making early use of data-collection opportunities arising from larger infrastructural projects in the Netherlands delta, in academic research.
• by topping up scientific research with contract-research and vice-versa: have exchange of input data, syncing the interpretation, and reviewing the data output.
• by releasing high-quality data-sets and update these from time to time: take-in, monitoring and review of applied and academic research results from 3rd parties.
• by taking up advisory roles, if possible in early stages, in projects that demand geological-geomorphological  information for plannig and decision making.
• by connecting the Delta Evolution research output to internationally actual themes such as: global change, sustainability, climate change, sea-level change and land subsidence, delta urbanisation, environmental pressure, groundwater demand, hydrocarbon demand, ecological demand, interdisciplinarity science demand. See the pages of the Future Deltas focus area for examples. 

• dr. Kim Cohen
• prof. dr. Esther Stouthamer
• prof. dr. Hans Middelkoop
• dr. Wim Hoek
• prof. dr. Maarten Kleinhans
• drs. Marjolein Gouw-Bouman
• dr. Ad van der Spek
• dr. Marcel van der Perk
• Bas Knaake MSc
• J.I.M. (Jelle) Moree MSc

• Deltares
• TNO Geologische Dienst Nederland
• Rijksdienst Cultureel Erfgoed
• VU Amsterdam