Project Description

In the German-Vietnamese research project ScaLa, scientists from the Karlsruhe Institute of Technology (KIT), the University of Potsdam, and Vietnamese partner institutions are investigating the causes and effects of land subsidence resulting from water scarcity and intensive groundwater use. The focus is on the Mekong Delta in southern Vietnam and selected peatland areas in Brandenburg, Germany. By combining innovative monitoring technologies, satellite-based remote sensing, and computer-aided modeling methods, the project aims to better understand the underlying processes and develop effective strategies to mitigate land subsidence.

Background and Motivation

Land subsidence poses a growing challenge worldwide, one that is further exacerbated by climate change and the intensive use of water resources. Particularly in densely populated coastal regions, sinking land surfaces can have far-reaching consequences for the population, infrastructure, and the availability of freshwater.

The Vietnamese Mekong Delta, one of Southeast Asia’s most economically and agriculturally significant regions, is particularly affected. With an average elevation of only about 0.8 meters above sea level, the region is especially vulnerable to land subsidence and rising sea levels. In recent years, land subsidence rates of up to three centimeters per year have been observed. The primary cause is considered to be intensive groundwater extraction, which leads to falling groundwater levels and progressive compaction of the sediment layers in the subsurface. Other contributing factors include natural sediment compaction, a lack of sediment deposition, and climate-related dry spells.

In Germany, too, water scarcity and falling groundwater levels are causing changes to the land surface. Particularly affected are drained peatlands in Brandenburg, whose water balance is increasingly being disrupted by longer and more intense droughts. Due to desiccation and the breakdown of organic soil matter, peatland soils lose volume, leading to progressive land subsidence. At the same time, carbon stored over long periods is released, causing degraded peatlands to contribute further to climate change.

Although the effects of these processes are becoming increasingly visible, the individual causes and their respective contributions to land subsidence have so far been inadequately quantified. In particular, there is a lack of detailed information on the depths at which these deformations occur and how they are related to changes in the water balance.

Research Objectives and Methodological Approach

The overarching target of ScaLa is to identify, characterize, and quantify the physical processes underlying land subsidence in both study regions. Based on these findings, models will be developed to predict future ground movements under various climate and groundwater use scenarios and to evaluate potential countermeasures.

A central component of the project is the use of innovative fiber-optic-based measurement systems that enable high-resolution, depth-resolved monitoring of subsurface deformations. Unlike conventional methods, which primarily detect changes at the ground surface, these measurement systems allow for the direct observation of compaction, swelling, and shrinkage processes at various soil depths. To this end, new monitoring stations are being established in the Mekong Delta and in selected peatland areas of Brandenburg.

In addition, satellite-based radar interferometry (InSAR), satellite-based positioning measurements (GNSS), and hydrological and pedological investigations are being employed. The combination of local measurement data and large-scale satellite observations makes it possible to characterize land subsidence both spatially and temporally and to identify its key influencing factors.

Another research focus is on the development of physically based and data-driven prediction models. Geomechanical simulations will be used, in particular, to investigate the effects of different groundwater abstractions and potential mitigation measures, such as artificial groundwater recharge. In addition, forecasts of future land subsidence trends under various climate scenarios are generated using satellite time series and machine learning methods.

In Brandenburg, the research also focuses on the state of degradation of carbon-rich soils and their swelling and shrinkage behavior. The results are intended to contribute to the improvement of existing peatland soil maps as well as to the assessment of the potential for the conservation and restoration of degraded peatland sites.

Development of an AI-Based Decision Support System

The data and findings obtained in the project form the basis for the development of an AI-based decision support system (DSS), which is being developed in collaboration with Vietnamese partners.

This system is designed to link measurement data, satellite observations, and modeling results, thereby enabling improved risk management. The target is to identify particularly vulnerable areas, assess future developments, and evaluate the effectiveness of potential measures to reduce land subsidence. The system, initially developed for the Mekong Delta, will also be tested using study areas in Brandenburg to examine its applicability to different geological and climatic conditions.

International Collaboration and Knowledge Transfer

ScaLa builds on the long-standing successful collaboration between German and Vietnamese research institutions within the framework of the predecessor projects ViWaT-Mekong-GO and ViWaT-Engineering. The monitoring infrastructure established there, as well as the data and scientific findings obtained, form an essential foundation for the ongoing investigations.

On the German side, the collaborative project is coordinated by the Institute of Applied Geosciences (AGW) at KIT. Other project partners include the Institute of Photogrammetry and Remote Sensing (IPF) at KIT and the Soil Science and Geoecology Research Group at the University of Potsdam. On the Vietnamese side, collaboration is taking place primarily with the National Center for Water Resources Planning and Investigation (NAWAPI).

Joint measurement campaigns, scientific workshops, and the continuous exchange of data, methods, and experiences are intended to ensure sustainability in the transfer of knowledge between the participating institutions.

With its interdisciplinary and international research approach, ScaLa contributes to a better understanding of the impacts of water scarcity and climate change on land and water resources. The monitoring and modeling approaches developed are intended to contribute, in the long term, to providing a sound basis for decision-making regarding sustainability in water resource management, the protection of vulnerable regions, and adaptation to climate-induced environmental changes.