Modelling of solute transport in rivers under different flow rates: A case study without transient storage

A methodology to derive solute transport models at any flow rate is presented. The novelty of the proposed approach lies in the assessment of uncertainty of predictions that incorporate parameterisation based on flow rate. A simple treatment of uncertainty takes into account heteroscedastic modelling errors related to tracer experiments performed over a range of flow rates, as well as the uncertainty of the observed flow rates themselves. The proposed approach is illustrated using two models for the transport of a conservative solute: a physically based, deterministic, advection-dispersion model (ADE), and a stochastic, transfer function based, active mixing volume model (AMV). For both models the uncertainty of any parameter increases with increasing flow rate (reflecting the heteroscedastic treatment of modelling errors at different observed flow rates), but in contrast the uncertainty of travel time, computed from the predicted model parameters, was found to decrease with increasing flow rate.     

On the choice of calibration periods and objective functions: A practical guide to model parameter identification

Despite the development of new measuring techniques, monitoring systems and advances in computer technology, rainfall-flow modelling is still a challenge. The reasons are multiple and fairly well known. They include the distributed, heterogeneous nature of the environmental variables affecting flow from the catchment. These are precipitation, evapotranspiration and in some seasons and catchments in Poland, snow melt also. This paper presents a review of work done on the calibration and validation of rainfall-runoff modelling, with a focus on the conceptual HBV model. We give a synthesis of the problems and propose a practical guide to the calibration and validation of rainfall-runoff models.     

On the rheological characterisation of liquefied sands through the dam-breaking test

This paper concerns the rheological characterisation of liquefied sands as non-Newtonian Bingham fluids. For this purpose, dam-breaking laboratory tests are often executed and interpreted, offering a viable option to identify the properties of fluidised water-soil mixtures. However, limited attention has been devoted so far to clarify what variables and measurements would allow unambiguous calibration of Bingham parameters, namely, the viscosity η and the yield stress τ_y. The numerical results of parametric studies based on the particle finite element method (PFEM) are critically inspected to gain deeper insight into the problem. First, it is confirmed that multiple η − τ_y pairs may reproduce the same experimental evidence when formed by only one measurement—usually, the post–dam-breaking displacement of the bottom toe (tip) of the liquefied mass. Then, two alternative procedures are proposed for unambiguous identification of both η and τ_y: one is based on monitoring the evolving aspect ratio of the fluid mass during free, gravity-driven flow; the other relies on a slightly different dam-breaking test, also including impact against a rigid obstacle. In particular, the latter approach reduces the relevant duration of the test, reducing the possible influence of reconsolidation effects on the calibration of rheological parameters.     

Multi-stage metamorphism by progressive accretion of continental blocks,example from the Western Hindu Kush

Basement rocks from the Western Hindu Kush preserve evidence of multiple metamorphic and magmatic events that occurred along the boundary between the Archean–Proterozoic Afghan Central and Afghan–Tajik Blocks. To verify the different metamorphic stages or events, mineral textures and phase equilibria in metamorphic basement rocks and their age relations to magmatic episodes have been investigated. Quartzofeldspathic gneiss and migmatite with lenses of amphibolite (with assumed Proterozoic age for their metamorphism) are intruded by the Triassic Hindu Kush granitoid batholith and small Cretaceous and Oligocene granite intrusions. The age of thermal overprint (210–170 Ma) by the Triassic batholith is confirmed by new monazite data. Both Triassic and Cretaceous granitoids and surrounding basement rocks underwent subsequent metamorphism up to epidote–amphibolite facies. The degree of this metamorphism increases southward at the contact to the Kabul Block, which under-plates the Western Hindu Kush from the south. An early Miocene age was obtained by Pb–Th analyses in thorite and huttonite, which are close or slightly younger than the Oligocene granite in this area. The Cretaceous meta-granodiorite near the border with the Kabul Block contains xenoliths of granulite facies rocks that could come from the Neoarchean granulite facies basement of the Kabul Block. The multi-stage metamorphic and magmatic evolution classifies the Hindu Kush mountain belt as a long-lived suture zone that was active since the early Palaeozoic. The results of this study support the interpretation about possible relations of the Afghan Central Blocks to the southern margin of Eurasia during the evolution of Para- and Neotethys.     

Analysis of macroseismic fields using statistical data depth functions: considerations leading to attenuation probabilistic modelling

Modelling seismic attenuation is one of the most critical points in the hazard assessment process. In this article we consider the spatial distribution of the effects caused by an earthquake as expressed by the values of the macroseismic intensity recorded at various locations surrounding the epicentre. Considering the ordinal nature of the intensity, a way to show its decay with distance is to draw curves—isoseismal lines—on maps, which bound points of intensity not smaller than a fixed value. These lines usually take the form of closed and nested curves around the epicentre, with highly different shapes because of the effects of ground conditions and of complexities in rupture propagation. Forecasting seismic attenuation of future earthquakes requires stochastic modelling of the decay on the basis of a common spatial pattern. The aim of this study is to consider a statistical methodology that identifies a general shape, if it exists, for isoseismal lines of a set of macroseismic fields. Data depth is a general nonparametric method for analysis of probability distributions and datasets. It has arisen as a statistical method to order points of a multivariate space, e.g., Euclidean space \({\mathbb {R}}^{p}\), \(p \ge 1\), according to the centrality with respect to a distribution or a given data cloud. Recently, this method has been extended to the ordering of functions and trajectories. In our case, for a fixed intensity decay \(\varDelta I\), we build a set of convex hulls that enclose the sites of felt intensity \(I_s \ge I_0 -\varDelta I\), one for each macroseismic field of a set of earthquakes that are considered as similar from the attenuation point of view. By applying data depth functions to this functional dataset, it is possible to identify the most central curve, i.e., the attenuation pattern, and to consider other properties like variability, outlyingness, and possible clustering of such curves. Results are shown for earthquakes that occurred on the Central Po Plain in May 2012, and on the eastern flank of Mt. Etna since 1865.     

Modeling the photosynthetically active radiation in South West Amazonia under all sky conditions

Accurate estimates of photosynthetically active radiation (PAR) are critical for the development of realistic models of plant productivity. However, in many areas such as the vast Amazon region of South America, there have been few empirical studies of PAR. Here, we analyzed the relationship between PAR and broadband solar irradiance (R _s) and formulated models to estimate PAR in two experimental sites (pasture and forest) in the Brazilian Amazon. Three different models of increasing complexity were developed based on information from R _s (model 1), R _s and clearness index (k _t; model 2), and R _s, k _t, and water vapor pressure (model 3). Estimates of PAR were generated for each season and for the entire year. All models had very high determination coefficients and indices of agreement for both pasture and forest sites. This strongly supports the use of R _s and k _t to produce robust estimates of PAR. The results obtained by annual models were close than that found by seasonal models, demonstrating that a single annual model is able to estimate PAR, albeit with lower accuracy.     

Intermediate-term seismic precursors for some coupled subduction zones

The paper discusses model results and then reviews observational data concerning some aspects of the mechanics of mature seismic gaps in coupled subduction zones. The concern is with space-and time-varying stresses, as signalled by the presence and mechanisms of earthquakes in the outer-rise zones adjacent to main thrust areas of large subduction events, and down-dip from such areas, in the downgoing slab. Observations are shown to be consistent with the expectation that in mature seismic gaps, as a result of interplate boundary locking in presence of sustained gravitational driving forces, at least the deeper portions of the ocean plate in the outer-rise zones are under increased compression, and the downgoing slab is under increased tension. The observational data cover two cases of closed seismic gaps, namely the region of the Chilean Valparaiso earthquake of March 3, 1985, and the earthquake of October 4, 1983. Four other cases concern still to-be-closed gaps in northern Chile and along the coast of Guatemala, and also the Kurile Islands Trench gap and the northern New Hebrides gap. It is concluded that the intermediate-term precursor, consisting of a combination of compressional outer-rise earthquake(s) and tensional intermediate-depth, intra-plate events in the downgoing slab, which mechanically signals the latter part of the earthquake cycle, could be useful in evaluating the maturity, and hence great earthquake potential of a seismic gap.     

Gully erosion as a natural hazard: the educational role of geotourism

Gully erosion is one of the greatest natural hazards in the loess areas of E. (Eastern) Poland. At the same time, permanent gullies are a major tourist attraction and can provide a basis for the development of geotourism. The study objective was to assess the possibilities of using the loess gullies for educational purposes. Detailed studies were conducted within the municipality of Kazimierz Dolny, an area with an extremely high concentration of permanent gullies. The questionnaire survey of students and tourists (nearly 300 surveys were completed) showed that the respondents’ knowledge of geomorphology was limited, despite their familiarity with gullies. In most cases, they were unable to accurately identify the determinants of gully erosion, its negative effects and methods for preventing it. An assessment of the tourism and geotourism potential of the municipality made it possible to identify the sites (gullies) that can perform an educational function, with regard to gully erosion. The establishment of the Ma?opolska Vistula Gap Geopark, whose highlights will include numerous loess gullies, can pave the way for the development of geotourism.     

Assessing the Impact of a Heated Basement on Groundwater Temperatures in Bratislava,Slovakia

Groundwater temperature is a useful hydrogeological parameter that is easy to measure and can provide much insight into groundwater flow systems, but can be difficult to interpret. For measuring temperature directly in the ground, dedicated specifically designed monitoring wells are recommended since conventional groundwater wells are not optimal for temperature monitoring. Multilevel monitoring of groundwater temperature is required to identify contributions of different possible heat inputs (sources) on measured temperature signals. Interpreting temperature data as a cosine function, including period, average temperature, amplitude, and phase offset, is helpful. Amplitude dampening and increasing phase shift with distance from a boundary can be used for estimation of transport parameters. Temperature measurements at different depths can be used for evaluation of unknown parameters of analytical functions by optimization of regression fits in Python. These estimated parameters can be used to calculate temperatures at known water table depths which can be applied as a fixed transient boundary condition in MT3DMS to overcome the limitations of MT3DMS heat transport modeling in the unsaturated zone. In this study, temperature monitoring and modeling was used to evaluate the influence of a department store's heated basement foundation on groundwater temperature within a green space (city park), with the main outcome that 17 years after construction, the department store foundation has increased the mean groundwater temperature by 3.2 °C. Heat input evaluated by the MT3DMS model varied from 0.1 W/m² at a distance of 100 m up to 12 W/m² next to the building.