ALBERT

Description: Chloride-induced corrosion of steel rebars is a key problem for the durability and safety of reinforced concrete buildings such as bridges. Penetrating rainwater transports the chlorides into exposed parts of these buildings. Hence, the characterization of moisture conditions and their tempospatial variability is a fundamental part of an on-site practical investigation. Ground-penetrating radar (GPR) is a common tool for efficient non-destructive imaging of small-scale structural defects in concrete. When evaluating constant-offset GPR data, the analysis of diffraction hyperbolas yields quantitative information on GPR velocity, and thereby on the water content of the medium. However, when performing a thorough velocity analysis to estimate moisture content, precise information on time zero is a key problem. In this study, a GPR monitoring experiment has been performed under laboratory-like conditions across a reinforced concrete specimen. We show the results of a typical processing flow providing a highly-resolved structural image. Furthermore, we develop and apply a migration-based velocity and time-zero analysis and calculate changes in moisture content. We compare our results to independent measurements of concrete moisture to evaluate the potential and limitations of GPR for estimating tempo-spatial changes in concrete moisture content.

Description: Geo.X

Description: DFG

Description: poster

Description: Poster describing the general and current work of the FID GEO.

Description: DFG

Description: poster

Description: Earthquake Database of Germany Diethelm Kaiser, Gernot Hartmann Federal Institute for Geosciences and Natural Resources, Hannover, Germany The earthquake catalogue for Germany (Leydecker 2011) was integrated in the earthquake database GERSEIS of BGR. For this purpose, the database was extended and a browser based application was developed to improve the database access (Kaiser et al. 2014). The following requirements in terms of structure and functionality were considered: tracking of event parameter changes, archive of erroneously inserted events (fakes, misinterpretations), schemes of relationships among the references and sources for an event, macroseismic data points, prioritization of epicentres, magnitudes and intensities, synchronization with catalogues from other institutions. The parameters of 12,667 seismic events for the years 800 to 2008 have been integrated. 6,861 of these events could be associated to events already existing in GERSEIS. In the course of integration seismological parameters have been reviewed, they have been corrected or complemented for 68 earthquakes. The database GERSEIS now contains instrumental and macroseismic parameters of more than 43,000 earthquakes since the year 800 until today. For approximately 38,000 events at least one instrumental magnitude is available, mostly local magnitude ML. Homogenously determined ML (BGR/SZGRF) are available since 1995 for 11,000 earthquakes. For 6,700 earthquakes macroseismic parameters are available, mostly epicentral intensity which is the most common parameter for earthquakes older than 1970. The database contains isoseismal radii for 1100 earthquakes, 150 of these have isoseismal radii of intensity 5 and larger. The database GERSEIS is accessible as web map service (WMS) through the BGR Product-center https://produktcenter.bgr.de and by interactive query, map display, and data download through the BGR Geoviewer https://geoviewer.bgr.de. We plan to improve the earthquake database by re-evaluating important historical earthquakes, building a macroseismic database, and determining moment magnitudes from instrumental and macroseismic data. References Kaiser, D., Bürk, D., Hartmann, G., Stelling, U. & Schlote, H. (2014): Integration of catalogues of historical and instrumentally recorded earthquakes in Germany in a common database – Concepts, uses, and products. Second European Conference on Earthquake Engineering and Seismology (2ECEES); Istanbul, http://www.eaee.org/Media/Default/2ECCES/2ecces_esc/3202.pdf. Leydecker, G. (2011): Erdbebenkatalog für Deutschland mit Randgebieten für die Jahre 800 bis 2008. Geologisches Jahrbuch, E 59, 1-198.

Description: https://www.bgr.bund.de/DE/Themen/Erdbeben-Gefaehrdungsanalysen/Veranstaltungen/HistEarth_Paleoseis_Okt2017/histEarth_paleoseis_2017_node.html

Description: presentation

Description: Magmatic settings involving active volcanism are potential locations for economic geothermal systems due to the occurrence of high temperature and steam pressures. Indonesia, located along active plate margins, hosts more than 100 volcanoes and, therefore, belongs to the regions with the greatest geothermal potential worldwide. However, tropical conditions and steep terrain reduce the spectrum of applicable exploration methods, in particular in remote areas. In a case study from the Lamongan volcanic field in East Java, we combine field-based data on the regional structural geology, elemental and isotopic composition of thermal waters, and the mineralogical and geochemical signatures of volcanic rocks in exploring hidden geothermal systems. Results suggest infiltration of groundwater at the volcanoes and faults. After infiltration, water is heated and reacts with rocks before rising to the surface. The existence of a potential heat source is petrologically and geophysically constrained to be an active shallow mafic-magma chamber, but its occurrence is not properly reflected in the composition of the collected warmed spring waters that are predominantly meteoric in origin. In conclusion, spring temperature and hydrochemistry alone may not always correctly reflect the deep geothermal potential of an area.

Description: Specialization in agricultural systems can lead to trade-offs between economic gains and ecosystem functions. We suggest and explore a conceptual framework in which economic gains can be maximized when production activities are specialized at increasingly broader scales (from the household to the village, region or above), particularly when markets for outputs and inputs function well. Conversely,more specialization likely reduces biodiversity and significantly limits ecosystem functions. When agricultural specialization increases and moves to broader scales as a result of improved infrastructure and markets or other drivers, ecosystem functions can also be endangered at broader spatial scales. Policies to improve agricultural incomes may influence the level of specialization at different scales and thus affect the severity of the trade-offs. This paper takes Jambi province in Indonesia, a current hotspot of rubber and oil palm monoculture, as a case study to illustrate these issues.We empirically show that the level of specialization differs across scales with higher specialization at household and village levels and higher diversification towards the province level. We discuss ways to resolve trade-offs between economic gains and ecological costs, including landscape design, targeted policies, and adoption of longterm perspectives.

Description: Conversions of natural ecosystems, e.g., from rain forests to managed plantations, result in significant changes in the hydrological cycle including periodic water scarcity. In Indonesia, large areas of forest were lost and extensive oil palm plantations were established over the last decades. We conducted a combined social and environmental study in a region of recent land-use change, the Jambi Province on Sumatra. The objective was to derive complementary lines of arguments to provide balanced insights into environmental perceptions and eco-hydrological processes accompanying land-use change. Interviews with villagers highlighted concerns regarding decreasing water levels in wells during dry periods and increasing fluctuations in stream flow between rainy and dry periods. Periodic water scarcity was found to severely impact livelihoods, which increased social polarization. Sap flux measurements on forest trees and oil palms indicate that oil palm plantations use as much water as forests for transpiration. Eddy covariance analyses of evapotranspiration over oil palm point to substantial additional sources of evaporation in oil palm plantations such as the soil and epiphytes. Stream base flow from a catchment dominated by oil palms was lower than from a catchment dominated by rubber plantations; both showed high peaks after rainfall. An estimate of erosion indicated approximately 30 cm of topsoil loss after forest conversion to both oil palm and rubber plantations. Analyses of climatic variables over the last 20 years and of a standardized precipitation evapotranspiration index for the last century suggested that droughts are recurrent in the area, but have not increased in frequency or intensity. Consequently, we assume that conversions of rain forest ecosystems to oil palm plantations lead to a redistribution of precipitated water by runoff, which leads to the reported periodic water scarcity. Our combined social and environmental approach points to significant and thus far neglected eco-hydrological consequences of oil palm expansion.

Description: Open-Access-Publikationsfonds 2016

Description: Oil palm plantations have expanded rapidly in recent decades. This large-scale land-use change has had great ecological, economic, and social impacts on both the areas converted to oil palm and their surroundings. However, research on the impacts of oil palm cultivation is scattered and patchy, and no clear overview exists. We address this gap through a systematic and comprehensive literature review of all ecosystem functions in oil palm plantations, including several (genetic, medicinal and ornamental resources, information functions) not included in previous systematic reviews. We compare ecosystem functions in oil palm plantations to those in forests, as the conversion of forest to oil palm is prevalent in the tropics. We find that oil palm plantations generally have reduced ecosystem functioning compared to forests: 11 out of 14 ecosystem functions show a net decrease in level of function. Some functions show decreases with potentially irreversible global impacts (e.g. reductions in gas and climate regulation, habitat and nursery functions, genetic resources, medicinal resources, and information functions). The most serious impacts occur when forest is cleared to establish new plantations, and immediately afterwards, especially on peat soils. To variable degrees, specific plantation management measures can prevent or reduce losses of some ecosystem functions (e.g. avoid illegal land clearing via fire, avoid draining of peat, use of integrated pest management, use of cover crops, mulch, and compost) and we highlight synergistic mitigation measures that can improve multiple ecosystem functions simultaneously. The only ecosystem function which increases in oil palm plantations is, unsurprisingly, the production of marketable goods. Our review highlights numerous research gaps. In particular, there are significant gaps with respect to socio-cultural information functions. Further, there is a need for more empirical data on the importance of spatial and temporal scales, such as differences among plantations in different environments, of different sizes, and of different ages, as our review has identified examples where ecosystem functions vary spatially and temporally. Finally, more research is needed on developing management practices that can offset the losses of ecosystem functions. Our findings should stimulate research to address the identified gaps, and provide a foundation for more systematic research and discussion on ways to minimize the negative impacts and maximize the positive impacts of oil palm cultivation.

Description: Tropical lowland rainforests are increasingly threatened by the expansion of agriculture and the extraction of natural resources. In Jambi Province, Indonesia, the interdisciplinary EFForTS project focuses on the ecological and socio-economic dimensions of rainforest conversion to jungle rubber agroforests and monoculture plantations of rubber and oil palm. Our data confirm that rainforest transformation and land use intensification lead to substantial losses in biodiversity and related ecosystem functions, such as decreased above- and below-ground carbon stocks. Owing to rapid step-wise transformation from forests to agroforests to monoculture plantations and renewal of each plantation type every few decades, the converted land use systems are continuously dynamic, thus hampering the adaptation of animal and plant communities. On the other hand, agricultural rainforest transformation systems provide increased income and access to education, especially for migrant smallholders. Jungle rubber and rubber monocultures are associated with higher financial land productivity but lower financial labour productivity compared to oil palm, which influences crop choice: smallholders that are labour-scarce would prefer oil palm while land-scarce smallholders would prefer rubber. Collecting long-term data in an interdisciplinary context enables us to provide decision-makers and stakeholders with scientific insights to facilitate the reconciliation between economic interests and ecological sustainability in tropical agricultural landscapes.

Description: Weather prediction today is performed with numerical weather prediction (NWP) models. These are deterministic simulation models describing the dynamics of the atmosphere, and evolving the current conditions forward in time to obtain a prediction for future atmospheric states. To account for uncertainty in NWP models it has become common practice to employ ensembles of NWP forecasts. However, NWP ensembles often exhibit forecast biases and dispersion errors, thus require statistical postprocessing to improve reliability of the ensemble forecasts. This work proposes an extension of a recently developed postprocessing model utilizing autoregressive information present in the forecast error of the raw ensemble members. The original approach is modified to let the variance parameter depend on the ensemble spread, yielding a two-fold heteroscedastic model. Furthermore, an additional high-resolution forecast is included into the postprocessing model, yielding improved predictive performance. Finally, it is outlined how the autoregressive model can be utilized to postprocess ensemble forecasts with higher forecast horizons, without the necessity of making fundamental changes to the original model. We accompany the new methodology by an implementation within the R package ensAR to make our method available for other researchers working in this area. To illustrate the performance of the heteroscedastic extension of the autoregressive model, and its use for higher forecast horizons we present a case-study for a dataset containing 12 years of temperature forecasts and observations over Germany. The case-study indicates that the autoregressive model yields particularly strong improvements for forecast horizons beyond 24 h.

Description: The consequences of regularizing the Sawyer–Eliassen equation to calculate the stream function for the axisymmetric secondary circulation of a tropical cyclone are explored. Regularization is an ad hoc procedure in which the coefficients of the equation are suitably modified to replace negative values of the discriminant by small positive values, thereby ensuring that the equation is globally elliptic. The consequences of the procedure may be understood in terms of the analogue behaviour of a stretched membrane subject to a particular force distribution. Several regularization procedures are assessed by comparing the azimuthally averaged radial flow from a three-dimensional numerical simulation of a tropical cyclone with that from an axisymmetric balance calculation of the Sawyer–Eliassen equation, forced by diabatic and frictional terms diagnosed from the simulation. The comparison shows that the largest challenge for regularization occurs in regions of inertial instability, especially when the diagnosed forcing overlaps with such regions. In the example shown, the diagnosed balanced flow is sensitive to the particular regularization procedure and none of the procedures examined give a flow that is structurally and quantitatively close to that obtained from the numerical solution in and near the region of regularization. The flow in regions of large vertical shear that are common in the lower part of the boundary layer is less sensitive to the regularization procedure, even though such regions are ones in which there is (frictional) forcing. Nevertheless, there are comparatively large differences between the low-level inflow in the azimuthally averaged numerical solution and the axisymmetric balance solution. These differences can be attributed to the intrinsic lack of balance in the boundary layer. This finding, together with the issues associated with regularization, is further confirmation that balance dynamics is unable to adequately capture the flow in the boundary layer, contrary to recent claims.