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Historic amphibian settlements in the northwestern Nile delta - a geoarchaeological perspective
(2020)
No concise picture of the archaeological and palaeoecological evolution can be drawn for the northwestern Nile delta, and archaeological records show significant population dynamics that still need explanation and spur the need for further palaeoenvironmental research. This study delivers a set of new methods especially in the fields of remote sensing and data analytics that can be regarded as important milestones and foundations for further palaeoenvironmental research in the area. Additionally, it shows new insights for individual time slices.
This geoarchaeological project is a cooperation with the archaeological excavations of the German Archaeological Institute (DAI) in Buto and Kom el’Gir. It expands the work of Wunderlich (1989) which laid important foundations in understanding the origin of the initial landscape that was later colonized in different cultural stages showing different dynamics, settlement intensities and even long phases of abandonment or breaks in between. This forms the starting point for relating the population dynamics of the different cultural phases reaching from Predynastic (prior to 3150 before Christ) up to the Greco-Roman era (~anno Domini 650) to the environmental history and events that occurred in the area. It is very likely that environmental changes such as the shifting of major water routes, inundation or paludification of larger areas or other environmental events affected settlements and human life in the area.
In the fields of remote sensing new methods are presented to complete information on the location of ancient settlements, and complex workflows are developed that allow the tracing of subsurface structures via indirect analysis of vegetation growth in larger time series data. It was verified that a relationship exists between vegetation performance, the appearance of archaeologic material in the topsoil, and the location of former Nile river branches.
Together with a new high resolution digital elevation model (DEM) based on TanDEM-X data, new interpretations with a high spatial significance are possible. For individual time slices, namely the Late Dynastic and Greco-Roman era, this work delivers a detailed landscape description suggesting a finely ramified subdelta, with all settlements placed on alluvial levees. This explains the massive increase in settlements in the Ptolemaic, Roman and in particular late Roman periods (4th century before Christ – anno Domini 7th century).
We sampled the Nile delta clays together with the channels and the material of the archaeologic excavations in vibracores and profile walls. This geologic inspection of the subsurface together with geochemical results from a handheld portable X-ray fluorescence device (pXRF) allowed new interpretations of the landscape and environmental history. For example, we used geochemical data to distinguish between artificial and natural channels as a measure for the anthropogenic influence, a proxy for past environmental characteristics and lastly as a basis for a new dating method. Many of the channels, for instance, were dated by our own 14C datings, comparisons with the previous work ofWunderlich (1989) and application of new dating approach based on machine learning with artificial neural networks. Additionally, we run a full methodological approach, and examine the applicability of pXRF methods in general, and test the quality of the data to detect distinct geochemical differences between the main settlement phases with advanced methods in data analytics. The dating is based, for example, on the training of artificial neural networks with pXRF data from archaeological material of well-dated context to date test data of cultural layers within the vibracores. With this method the homogeneous Nile alluvium, cultural layers and channels can be dated roughly and, as a result, fundamental changes in the landscape can be linked with the settlement history of Buto and neighboring tells.
The analysis of the global stratospheric meridional circulation, known as the Brewer-Dobson circulation, is an essential part of both experimental and theoretical atmospheric sciences. This large-scale circulation has a crucial influence on the global burden of greenhouse gases and ozone depleting substances throughout the complete atmosphere. This makes it an important factor for the Earth’s radiative budget, which is perceptible at the Earth’s surface despite the remote location of the stratosphere. In the course of climate change it is generally expected that also the Brewer-Dobson circulation undergoes significant changes in structure and strength, although the exact repercussions are still uncertain and thus remain an open scientific question. A general problem for the observational investigation of the dynamical processes in the stratosphere is that residual mean transport cannot be measured directly and hence requires the use of sophisticated proxies. Many studies in the past consider the so-called mean age of air, which is a measure of the average time an air parcel has spent in the stratosphere since passing a certain reference point. While changes in the strength and structure can be detected and visualized using mean age of air, a more thorough distinction between the different involved transport mechanisms of the circulation (residual circulation, mixing) cannot be made. For that, consideration of a full distribution of all relevant transit times through the stratosphere, an age spectrum, is favorable and a powerful tool to analyze the spatial structure as well as possible future changes in detail. Mean age of air and age spectra can be readily derived in atmospheric modeling studies, but an observationally based retrieval is challenging. Mean age of air is usually approximated from measurements of very long-lived trace gas species that act as a dynamical tracer for the stratosphere. The retrieval of age spectra from observations, however, remains an open task for which different methods have been proposed in the past, that often require a combination of strong assumptions and model data explicitly. This is a major issue for a precise and independent investigation of stratospheric dynamics based on measurements. The focus of this cumulative dissertation is on the development process and application of an inversion method to derive stratospheric age spectra from mixing ratios of chemically active substances that combines an applicable and precise ansatz with a minimized amount of necessary model data. Chemically active species have the important benefit that chemistry and transport in the stratosphere are strongly correlated so that the state of depletion of a trace gas can give some information on certain parts of the age spectrum. Considering a sufficient number of distinct trace gases simultaneously, a full approximation of the age spectrum should be possible. The main section of this thesis is split into three parts, which follow the main aspects and key results of the three publications involved (Hauck et al., 2019, 2020; Keber et al., 2020). The newly developed inverse method is based upon the previously established ansatz by Schoeberl et al. (2005), but constrains the shape of the age spectrum by a single parameter inverse Gaussian function. This keeps the balance between applicability and accuracy with a limited amount of measurement data. Additionally, the method introduces a seasonal scaling factor that imposes higher order maxima and minima onto the intrinsically monomodal spectrum based on the seasonal cycle of the tropical upward mass flux to incorporate phases of weaker and stronger transport. A proof of concept of the inverse method is provided using an idealized simulation of the ECHAM/MESSy Atmospheric Chemistry (EMAC) model, where the method is applied to a set of artificial radioactive trace gases with known chemical lifetime. The results imply that the method works properly and retrieves age spectra that match the EMAC reference spectra significantly well on the global and seasonal scale. Only in the lower stratosphere, the performance of the inverse method on the seasonal scale decreases as entrainment into the stratosphere is considered only across the tropical tropopause. Transport across the local extratropical tropopause, however, is a key feature for trace gases in the extratropical lowermost stratosphere so that this entrainment must be included explicitly.
In the second part, the discovered problems are approached to make the inverse method applicable to observations. The formulation of the method is extended to incorporate transport explicitly across the tropical (30° S – 30° N), northern extratropical (30° N – 90° N), and southern extratropical tropopause (30° S – 90° S) each with a single age spectrum that can be inverted independently.
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Vor dem Hintergrund der zunehmenden Veränderung des städtischen Lebensumfeldes durch Gentrifizierung, investorenfreundliche Stadtpolitik, Privatisierung öffentlicher Räume, Einsparung öffentlicher Investitionen und den Abbau demokratischer Beteiligungsinstrumente haben wir uns gefragt: Wie könnte eine solidarische Stadt der Zukunft aussehen? Welche Gegenentwürfe zu aktuell herrschenden Paradigmen in der Stadtentwicklung zeigen uns Wege aus der Alternativlosigkeit hin zu einer solidarischen Praxis auf Quartiersebene? Im Rahmen einer angewandten kritischen Geografie möchten wir zeigen, dass es eine Vielzahl an Projekten und Initiativen gibt, die die Kreativlosigkeit, zu der uns der Neoliberalismus erzogen hat, durchbrechen und an konkreten Ideen und deren praktischer Umsetzung arbeiten. Als theoretische Annäherung dafür setzen wir uns mit Utopien und deren Potenzialen für eine politische Praxis auseinander. Da wir selbst im Kontext stadtpolitischer Gruppen engagiert sind, nutzen wir die aktivistische Stadtforschung als methodischen Rahmen unserer Forschung. Daraus entstanden ist ein Faltblatt, der „Kompass für ein solidarisches Quartier“, welcher als aktivistisches Werkzeug und Ideengeber für die konkrete Umsetzung transformativer Stadtpolitik dienen soll.
IFLS-Journal. Nr. 25, 2020
(2020)