Complexity as a streamflow metric of hydrologic alteration

We explore the potential of using a complexity measure from statistical physics as a streamflow metric of basin-scale hydrologic alteration. The complexity measure that we employ is a non-trivial function of entropy. To determine entropy, we use the so-called permutation entropy (PE) approach. The PE approach is desirable in this case since it accounts for temporal streamflow information and it only requires a weak form of stationarity to be satisfied. To compute the complexity measure and assess hydrologic alteration, we employ daily streamflow records from 22 urban basins, located in the metropolitan areas of the cities of Baltimore, Philadelphia, and Washington DC, in the United States. We use urbanization to represent hydrologic alteration since urban basins are characterized by varied and often pronounced human impacts. Based on our application of the complexity measure to urban basins, we find that complexity tends to decline with increasing hydrologic alteration while entropy rises. According to this evidence, heavily urbanized basins tend to be temporally less complex (less ordered or structured) and more random than basins with low urbanization. This complexity loss may have important implications for stream ecosystems whose ability to provide ecosystem services depend on the flow regime. We also find that the complexity measure performs better in detecting alteration to the streamflow than more conventional metrics (e.g., variance and median of streamflow). We conclude that complexity is a useful streamflow metric for assessing basin-scale hydrologic alteration.     

The pionic contribution to diffuse γ-rays: upper limits

Diffuse γ-rays probe the highest-energy processes at the largest scales. Here we derive model-independent constraints on the hadronic contribution to the Galactic and extragalactic γ-ray spectra at in the energy range 50 MeVE_γ10 GeV. The hadronic component is dominated by emission from neutral pions, with a characteristic spectrum symmetric about m_π⁰/2. We exploit the well-defined properties of the pion decay spectrum to quantify the maximum pionic fraction of the observed γ-ray intensity. We find that the Galactic spectrum above 30 MeV can be atmost about 50% pionic. The maximum pionic contribution to the extragalactic spectrum is energy dependent; it also depends on the redshift range over which the sources are distributed, ranging from as low as about 20% for pions generated very recently, to as much as 90% if the pions are generated around redshift 10. The implications of these constraints for models of γ-ray and neutrino emission are briefly discussed.     

Land use optimization for sustainable development of mountain regions of western Serbia

This study analyses the possibilities for optimal land use structure in mountainous areas of rural Serbia, which is faced with problems such as unfavorable terrain characteristics and inadequate land use patterns causing economic underdevelopment and increasing population migration. In the case of a small privately owned farm in Western Serbia, optimal land use pattern is determined using the linear programming model. The objective function-cost-effectiveness or soil erosion reduction, as well as constraints, are formulated using the benefit-cost ratio (BCR) for a 15-year production period and soil losses data calculated using the Universal Soil Loss Equation (USLE). The best results are achieved using the scenario with the aim to minimize soil erosion, considering the BCR in the constraints. This scenario is proposed since it was registered that the benefit for landowners would increase by five times, while the losses of land would decline about 80%. The sensitivity analysis of investments is performed to check whether the price variation affects the cost-effectiveness of proposed land use. Results show that market changes (nine cases are considered) do not lead to significant changes in land use allocation. Proposed land use pattern improves the environmental condition, strengthens the rural economy and thus offers the greatest potential for sustainable development of mountainous rural areas.     

The development of transport infrastructure and attitudes of the local population: a case study from the Republic of Serbia

In the last decades, the development of transport infrastructure has been necessary because of the population increase and expansion of urban centres. Infrastructure development leads to modification and changes in areas characterized by high human population density. The lack of adequate transport infrastructure inhibits local economic and social performance. In the period of economic stability (from 1970 to 1990), important roads that increased the connectedness of the Kolubara District (Western Serbia) with other parts of the country and the surrounding countries were built, but there is still a need for the construction of new roads. In order to examine the attitude of the local population in regard to transport infrastructure, a survey was conducted using a questionnaire consisting of closed questions. This topic is one that has not previously been examined. The data obtained were analyzed statistically and showed that local people have a positive attitude towards the existing infrastructure and towards the construction of new roads. There are statistically significant differences between the attitudes of the local population in different municipalities. The results from this research offer an opportunity to develop guidelines which can influence traffic development in these and similar areas.     

Understanding the influence of climate elements on traffic: the wind impact approach

Theoretical and Applied Climatology - Due to intense highway congestion in Europe, increased percentage of highway accidents, as well as mortality rate, safety is an imperative in highway planning...     

Spectral distributions of the pressure gradient force errors in σ-coordinate spectral and grid-point models in an idealized case

Summary The spectral distributions of the pressure gradient force errors of the spectral and the finite-difference techniques used in combination with the vertical coordinate were examined in an idealized case of an atmosphere at rest and in hydrostatic equilibrium. The vertical temperature profile was piece-wise linear in lnp, with an inversion at the bottom. Trapezoidal mountains of different widths were used. The same amounts of input information were given to both the spectral and the finite-difference methods. In the rms sense, the spectral errors were generally much larger than those of the finite-difference method. However, on the larger and medium scales, a remarkable similarity of the error spectra of the two methods was found. The build up of the error of the spectral method occurs at the smallest scales. This may explain difficulties in documenting the error in higher resolution spectral models where the contribution to the total error in this part of the spectrum may be removed as the small-scale noise by the horizontal smoothing and/or filtering. In order to reduce the small-scale noise generation, the finite-difference pressure gradient force may be used in spectral models.With 6 Figures