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    Gesündere Böden durch schaumbasierte Düngung
    Fertilizers play a critical role in supporting the agricultural activities worldwide. The conventional fertilizer application methods often utilize the fertilizer granules or liquids over the agricultural land. The fertilizer is transported into the soil with percolating irrigation water. However, the presence of preferential flow pathways in the soil affects the transport of the fertilizer into deeper layers of soil below the root zone and leaching into the groundwater resources. Hence, the application does not serve the intended purpose of supplying nutrients to the plants resulting in less healthy soils and higher possibility of surface and groundwater pollution. Different agronomic practices have been proposed to improve the efficiency of fertilizer application and reduce leaching to the environment. In this project, the application of a novel method for improving the efficiency of liquid fertilizer delivery using foam as a carrier was investigated. We experimentally addressed the impact of soil and foam characteristics on the retention of nutrients in soil. The experiments were conducted on fine, medium, and coarse-textured sand samples with particle size ranging from 0.1-0.4 mm, 0.4-0.8 mm, and 0.7-1.2 mm, respectively. Our preliminary results were promising showing the improvement of fertilizer retention in sand samples, particularly in medium-textured sand. The project provides insights into the application of foam fertilizers in agricultural practices; however, certain aspects such as the impact of different type of fertilizers, the interaction of plant roots with foam fertilizers, and the uptake of nutrients by plants need additional investigations.
      32
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    How does dyring-driven crystalized salt influences the dynamics of water evaporation from porous media
    Soil salinization, referring to excess accumulation of soluble salts in soil, has detrimental impacts on crops, animal and human health. It is one of the main land-degrading threats influencing soil fertility, stability, and bio-diversity leading to undesirable changes in the physical, chemical, and biological functions of the soil. Beyond soil, it has significant impacts on other processes such as the durability of building materials, preservation of pavements, and CO2 sequestration. Saline water evaporation is influenced by transport properties of the porous media, external conditions (e.g. wind, ambient temperature, and relative humidity), properties of the evaporating solution, and salt crystallization. During water evaporation from soil, solute is transported via capillary induced liquid flow, from the wet zone at the bottom to the evaporation surface. Simultaneously, diffusion tends to spread the solute homogeneously across the entire domain. The competition between upward advection and diffusion transport determines solute distribution throughout the soil. When advection dominates diffusion, solute in preferentially deposited close to the surface leading to gradual increase of its concentration. When salt concentration substantially exceeds the solubility limit, crystals will precipitate at soil surface. The crystals formed at the surface create complex, branching structures, which can substantially increase the surface area available for evaporation. How exactly the presence of the evolving evaporation-driven porous crystallized salt at the surface influences the evaporative water losses from soil under different boundary conditions is poorly understood. Detailed information about the complex coupling between flow and transport processes within porous media and the evolving crystallized salt at the surface is required for accurate prediction of water evaporation from soil otherwise our description of this process would reply on adjusting parameters. Without such knowledge, one may notably underestimate or overestimate water availability and evaporation from land surface which will influence several hydrologic processes. In this project, we plan to conduct a comprehensive multiscale numerical and experimental investigations to quantify the effects of the evolving evaporation-driven crystallized salt at the surface on the evaporative water loses from porous media. Within this context, we will utilize the state-of-art numerical and experimental tools such as molecular dynamics simulation, pore-network and continuum-scale modelling, synchrotron X-ray micro-tomography and customized laboratory experiments to achieve the objectives of this project. Such efforts will enable us to provide an accurate description of saline water evaporation which will place us in a stronger position to quantify soil water evaporation and land-atmosphere interactions.
      80
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    Land Cover Change and Climate Variability on a Global Scale
    According to the Sixth Assessment Report (AR6) of Intergovernmental Panel On Climate Change (IPCC, 2021, www.ipcc.ch/report/ar6/wg1/), an increase in the occurrence of extreme climate events such as droughts, heavy rainfalls and heat waves has been observed in recent years. This has devastating environmental and socio-economic effects. One of the possible contributors to this increase in occurrence of extreme events is the change of land cover, which influences the exchange of energy, water and CO2 between the terrestrial biosphere system and the atmosphere. Recent analysis (e.g. Scientific Reports (2021), 11, 12814) suggests that between 1992 and 2018, around 5% of the continental ice-free surface area has undergone a change in land cover. This change in land surface characteristics has been shown to affect temperature, humidity and precipitation. However, most of the existing studies focus on deforestation and its effect on mean climate parameters. Therefore, relatively little is known on the effect of different types of land cover change on the climate variability on a global scale. Hence, this research aims at deepening the understanding of these complex interactions on a global scale using a comprehensive set of climatic, soil and remote sensing data.
      57
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    Sea-Level Rise and Coastal Wetland Dynamics
    Sea level rise (SLR) is a well-documented aspect of anthropogenic climate change which is primary due to the thermal expansion of seawater and melting of ice caps and glaciers. Climate change is expected to exacerbate sea-level rise within the next century, much larger than the observations since the beginning of the recordings. Wetlands are ecosystems characterized by either permanent or seasonal flooding. They provide a number of important functions including coastal protection, improvement in water quality and carbon sequestration. SLR has been shown to move coastlines, including wetlands. If no accommodation space is available, the wetlands along the coastlines could be permanently lost due to this movement. In this project, our objective is to delineate the impacts of SLR on wetland dynamics under changing climate on a global scale where particular focus is given to the consequences of manmade structures along coastlines.
      63
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    Global Soil Salinization
    Soil salinization refers to the excessive accumulation of soluble salts in soil to a degree that adversely influences vegetation and environmental health. Soil salinization poses an existential threat to ecosystem functioning, socioeconomic structure and food security. The excess accumulation of salt in soil is a global problem and is one of the main land-degrading threats influencing soil fertility and biodiversity. High salinity in the root zone severely impedes plant growth resulting in reduced crop productivity. Moreover, salt stress in salt-affected soils may cause a drastic reduction of plant transpiration influencing soil water budget and hydrologic cycle. Soil salinity also imposes nutritious imbalances in plants that may induce significant alterations in Earth’s organisms and ecosystems. Salt storms from saline soils, desertification, modification of soil organic carbon cycle and worsening of economic opportunity which may lead to human migration are other detrimental consequences of soil salinization. All this created an urgent need to understand the processes affecting soil salinization. We employ a broad array of cutting-edge experimental and computational tools including artificial intelligence, pore- and continuum-scale numerical simulation, high resolution thermal imaging, and customized laboratory experiments to investigate the parameters and mechanisms controlling soil salinization at different scales (ranging from a pore with the size of a few microns to the global scale). One of our key objectives is to develop predictive models capable of describing soil salinization on a global scale under different climate scenarios. We employ a comprehensive set of climatic, topographic, soil, agroeconomic and remote sensing data to develop models trained by machine learning algorithms to predict past, present and future dynamics of soil salinization on a global scale (typical examples of our results are presented below). Additionally, we are interested in establishing the link between the physical mechanisms identified using small‐scale experimental and numerical analyses and the responses observed at the field-scale. Such efforts will contribute toward addressing the long-standing upscaling issue present in soil physics and hydrology community.
      63
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    Klima, Klimawandel und Gesellschaft
    By accepting that the world is warming and humans are largely responsible, the Paris climate agreement from December 2015 has provided a powerful impetus not only for climate policy but also for climate research. To address the resulting new challenges, the Cluster of Excellence "Climate, Climatic Change, and Society (CliCCS)" will establish a long-term program spanning the range from basic research on climate dynamics and climate-related social dynamics to the transdisciplinary exploration of human–environment interactions. CliCCS will explore climate change with a broader expertise than at any other center in Germany and worldwide. CliCCS will investigate how the climate changes and how society changes with it, thereby feeding back on climate. Understanding these changes, including how societies adapt, will enable us to assess with far greater confidence than before the range of imaginable climate futures. In taking on this challenge, CliCCS is guided by the overarching question:Which climate futures are possible and which are plausible?CliCCS will identify those climate futures that are possible, meaning that they are consistent with our joint understanding of both climate and social dynamics, and those that are plausible, meaning that we expect them to unfold with appreciable probability. CliCCS will boost the understanding of the crucial natural processes that either enhance or reduce anthropogenic climate change, allowing us to rein in more tightly our estimates of possible climate futures. CliCCS will identify which social dynamics support or prevent the deep decarbonization required to meet the climate targets of the Paris agreement; this will enable an assessment of which greenhouse-gas emissions pathways are more probable than others. CliCCS will comprehensively characterize magnitude and mechanisms of chaotic variability in a warming climate, recently found to be much larger than expected, and will explore how the resulting irreducible (aleatoric) uncertainty can be accounted for in climate-socioeconomic interactions and in decision-making processes. CliCCS will establish an understanding of the competition between climate targets and other societal goals in concrete case studies of sustainable adaption to climate change, by combining possibly unstable social dynamics with the impulses arriving from the physical system marked by unpredictable variability and extreme events.CliCCS will use observations and models of the natural, coupled human–environment, and social systems to understand the processes that govern these systems. The new ICON-based Earth system model, arguably the most modern of its kind worldwide, will provide a powerful and flexible numerical laboratory of the natural Earth system and will allow efficient use of high-performance computing systems at the German Climate Computing Centre. A central CliCCS synthesis will be provided through an expert assessment published annually in a Hamburg Climate Futures Outlook.
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