Scaling the Baltic Sea environment

The Baltic Sea environment has since the early 1970s passed through several phases of spatial objectification in which the ostensibly well-defined semi-enclosed sea has been framed and reframed as a geographical object for intergovernmental environmental politics. Based on a historical analysis of this development, this article suggests that environmental politics critically depend on the delineation of relatively bounded spaces that identify and situate particular environmental concerns as spatial objects for politics. These spaces are not simply determined by ‘nature’ or some environmental-scientific logic, but should rather be seen as temporal outcomes of scale framing processes, processes that are accentuated by contemporary conceptions of the environment (or nature) in terms of multi-scalar ecosystems. This has implications for how an environmental concern is perceived and politically addressed.     

Initial design of urban drainage systems for extreme rainfall events using intensity–duration–area (IDA) curves and Chicago design storms (CDS)

ABSTRACT

Due to more frequent extreme rainfall incidents in recent years, many large cities are considering the construction of new drainage systems to cope with rainfall in the order of 100-year events. In such cases, T-year point rainfall events should be supplemented with areal reduction factors (ARF) to avoid overdesign. To facilitate an initial design, a procedure based on using Chicago Design Storms (CDS) in combination with intensity–duration–area (IDA) curves was developed to produce CDS-ARF input rainfall. By means of the time of concentration, a specific instantaneous unit hydrograph (IUH) was obtained for each subcatchment. Combination of CDS-ARF rains and the subcatchment IUHs using convolution integrals was used to produce inflow hydrographs to the drainage system. A sequential design procedure that successively includes subcatchments for the entire drainage system in the downstream direction is implemented and exemplified ensuring a consistent initial design.     

Geological evolution,regional perspectives and hydrocarbon potential of the northwest Phu Khanh Basin,offshore Central Vietnam

Seismic stratigraphic and structural analyses of the northwest Phu Khanh Basin, offshore Central Vietnam, based on 2-D seismic data, indicate that the initial rifting began during the latest Cretaceous? or Palaeogene controlled by left-lateral transtension along the East Vietnam Boundary Fault Zone (EVBFZ) and northwest–southeast directed extension east of the EVBFZ. Rifting stopped due to transpression during middle Oligocene times but resumed by left-lateral transtension during the Late Oligocene. Thick sequences of lacustrine and alluvial sediments were deposited during the Palaeogene rift periods. The Late Oligocene rifting ended due to inversion, triggered by right-lateral wrenching near the Palaeogene–Neogene boundary. Following the onset of this inversion regional uplift and volcanism took place in the southern half of the study area and contemporaneous subsidence and transgression took place farther north, leading to widespread carbonate deposition. As the right-lateral wrenching decreased during the early Neogene, thermal subsidence and siliciclastic sedimentation became dominant, resulting in the buildup and southward propagation of the shelf slope. Sediment accumulation and subsidence rates increased after the Middle Miocene times due to eastward tilting of Central Vietnam and the adjacent offshore area.     

Luminescence and tenebrescence of natural sodalites: a chemical and structural study

Sodalite (Na₈Al₆Si₆O₂₄Cl₂) shows a wide range of colours and may exhibit a variety of optical properties including cathodoluminescence, photoluminescence and tenebrescence. These optical peculiarities are not yet fully understood but are of key interest for industry. We provide a detailed study on the photochromic properties of natural sodalite, and we show that S is crucially influencing luminescence of sodalites. A reduced intensity in cathodoluminescence was observed at high S contents for some samples, showing that S can act as cathodoluminescence quencher. Photoluminescent sodalites are generally enriched in S compared to non-photoluminescent samples, although few samples being very low in S still show photoluminescence. Additionally, S was found to enlarge the unit cell in natural sodalites which might have a crucial impact on their photochromic properties. The most efficient tenebrescent samples were found to be low in Fe, Mn and S. They showed the smallest unit-cell dimensions, and a strong link between the atomic structure and the formation of F-centres is proposed. Tenebrescence in natural sodalites appears to be enhanced (1) by S but saturated at too high S concentrations and (2) by a stoichiometry and structure close to the ideal sodalite composition. In contrast to the term self-quenching for luminescence, we propose a saturation of F-centres to explain tenebrescence at different S contents.     

Stomach contents in Baltic fourhorn sculpin (Myoxocephalus quadricornis L.) with normal and deformed spinal vertebrae

In the northern part of the Baltic Sea, the Gulf of Bothnia, fourhorn sculpin (Myoxocephalus quadricornis) is one of the dominant fish species. A considerable proportion of the population (up to 54% of fish in gill net catches) have been reported to have spinal deformations, with a higher frequency in polluted than in clean areas. The stomach content of sculpins with normal and with severely deformed backbone were compared, but no statistically significant differences were revealed. The diet was generally dominated by the isopod Mesidotea entomon and three-spined stickleback (Gasterosteus aculeatus).     

Shoaling of sixth-order Stokes waves on a current

Jonsson and Arneborg (Jonsson, I.G., Arneborg, L., 1995. Energy properties and shoaling of higher-order Stokes waves on a current. Ocean Engng 22, 819-857.) combined energy flux and set-down to make shoaling predictions for fourth-order Stokes waves with and without a net volume flux. With basis in their expressions, sixth-order expressions are derived and combined to make shoaling predictions correct to sixth order with an arbitrary net volume flux. The new sixth-order results are compared with the fourth-order results and the practically exact results obtained by Sobey and Bando (Sobey R.J., Bando K., 1991. Variations on higher-order shoaling. J. Waterway, Port, Coastal Ocean Engng ASCE 117, 348-368) with a Fourier 18 model. The effects of introducing sixth-order theory rather than the fourth-order theory in shoaling calculations are in general found to be small. As expected the deviations increase with increasing wave-steepness, decreasing depth and opposing currents. Also as expected, the results obtained with the sixth-order expressions improve the results obtained with the fourth-order expressions when compared to the results of Sobey and Bando. As novelties, some considerations regarding the consistency of odd- and even-order shoaling calculations, and the magnitude of the bottom slope, are presented. Furthermore a comparison between the wave-induced current and the total current is given.     

Surface velocity fields of active rock glaciers and ice-debris complexes in the Central Andes of Argentina

Rock glaciers and transitional ice-debris complexes predominate the Central Andean landform assemblage, yet regional studies on their state of activity and their kinematics remain sparse. Here we utilize the national glacier inventory of Argentina to quantify surface velocity fields of 244 rock glaciers and 51 ice-debris complexes, located in the Cordón del Plata range, Argentina. Applying a feature-tracking approach to repeated RapidEye satellite imagery acquired between 2010 and 2017/18, we find mean displacement rates between 0.37 and 2.61 m year⁻¹ for 149 landforms, while for the remaining 146 features, surface movement remains below our level of detection. We compare our satellite-derived velocity fields with ground-truth data from two local field sites and find closely matching results in magnitude and spatial distribution. With average displacement of one-third of the active rock glaciers and ice-debris complexes exceeding 1 m year⁻¹, the region hosts an exceptional number of fast-flowing periglacial landforms, compared to other mountain belts. Using a random forest model, we test the predictive power of 25 morphometric and topoclimatic candidate predictors for modelling the state of activity of rock glaciers and ice-debris complexes on two different scales. For entire landforms and individual landform segments, constructed along displacement centrelines, we can predict the state of activity with overall accuracies of 70.08% (mean AUROC = 0.785) and 74.86% (mean AUROC = 0.753), respectively. While topoclimatic parameters such as solar radiation and elevation are most important for entire landforms, geometric parameters become more important at the scale of landform segments. Despite tentative correlations between local slope and surface kinematics, our results point to factors integrating slope and distance to the source to govern local deformation. We conclude that feature tracking in optical imagery is feasible for regional studies in remote regions and provides valuable insight into the current state of the Andean cryosphere. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd     

Assessing climate change impacts on the Iberian power system using a coupled water-power model

Climate change is expected to have a negative impact on the power system of the Iberian Peninsula; changes in river runoff are expected to reduce hydropower generation, while higher temperatures are expected to increase summer electricity demand, when water resources are already limited. However, these impacts have not yet been evaluated at the peninsular level. We coupled a hydrological model with a power market model to study three impacts of climate change on the current Iberian power system: changes in hydropower production caused by changes in precipitation and temperature, changes in temporal patterns of electricity demand caused by temperature changes, and changes in irrigation water use caused by temperature and precipitation changes. A stochastic dynamic programming approach was used to develop operating rules for the integrated system given hydrological uncertainty. We found that changes in precipitation will reduce runoff, decrease hydropower production (with accompanying increases in thermal generation), and increase irrigation water use, while higher temperatures will shift power demand from winter to summer months. The combined impact of these effects will generally make it more challenging to balance agricultural, power, and environmental objectives in the operation of Iberian reservoirs, though some impacts could be mitigated by better alignment between temporal patterns of irrigation and power demands.