Digital terrain models are key tools in land analysis and management as they are directly employable in GIS systems and other specific applications like hydraulic modelling, geotechnical analyses, road planning, telecommunication, and many others. TIN generation, from different kind of measurement techniques, is ruled by specific regulations. Interpolation techniques to compute a regular grid from a TIN, are, instead, still lacking in specific regulations: a unitary and shared methodology has not already been made compulsory in order to be used in cartographic production while generating digital models. Such ambiguity obviously involves non univocal results and can affect precision, which can lead to divergent analyses on the same territory. In the present study different algorithms will be analysed in order to spot an optimal interpolation methodology. The availability of the recent digital model produced by the Regione Piemonte with airborne LIDAR and the presence of sections of testing realized with higher resolutions and the presence of independent digital models on the same territory allow to set a series of analysis with consequent determination of the best methodologies of interpolation. The analysis of the residuals on the test sites allows to calculate the descriptive statistics of the computed values: all the algorithms have furnished interesting results; all the more interesting, notably for dense models, the IDW (Inverse Distance Weighing) algorithm results to give best results in this study case. Moreover, a comparative analysis was carried out by interpolating data at different input point density, with the purpose of highlighting thresholds in input density that may influence the quality reduction of the final output in the interpolation phase.
Abstract:Mapping ecosystem services (ES) increases the awareness of natural capital value, leading to building sustainability into decision-making processes. Recently, many techniques to assess the value of ES delivered by different scenarios of land use/land cover (LULC) are available, thus becoming important practices in mapping to support the land use planning process. The spatial analysis of the biophysical ES distribution allows a better comprehension of the environmental and social implications of planning, especially when ES concerns the management of risk (e.g., erosion, pollution). This paper investigates the nutrient retention model of InVEST software through its spatial distribution and its quantitative value. The model was analyzed by testing its response to changes in input parameters: (1) the digital terrain elevation model (DEM); and (2) different LULC attribute configurations. The paper increases the level of attention to specific ES models that use water runoff as a proxy of nutrient delivery. It shows that the spatial distribution of biophysical values is highly influenced by many factors, among which the characteristics of the DEM and its interaction with LULC are included. The results seem to confirm that the biophysical value of ES is still affected by a high degree of uncertainty and encourage an expert field campaign as the only solution to use ES mapping for a regulative land use framework.
In the present study different algorithms, usually available in GIS environment, are analyzed in order to spot an optimal interpolation methodology and to define, by classification techniques, which morphological variable affects the interpolation quality. The investigated dataset is a helicopter-borne laser scanner survey carried out on a mountain slope. It has been interpolated at various resolutions, and a percentage of the entire set has been employed to evaluate the interpolation accuracy. The analysis has highlighted, among the tested interpolators, the Natural Neighbour as the best one. The classification has drawn the attention to the total curvature and slope as the main factors affecting interpolation accuracy. The next goal is the mapping of such classification results.
4Land use change is strongly modifying the traditional landscape of hilly productive Mediterranean 5sites. An example of this situation is the Langhe region (Piemonte, NW Italy), where woody 6 plantations such as vineyards and orchards have been cultivated on hillslopes for centuries. In this 7paper we assess the landscape changes occurred in the Diano study area (2651 ha
In this paper a method for the estimation of the visual impact of buildings with symbolic relevance, such as skyscrapers that are out of scale with their surrounding urban space, is discussed and applied. It is based on the viewshed analysis as developed in rural landscape studies, but it also takes into account the peculiarity emerging from the urban studies. In order to go beyond the sole information of whether a cell is, or is not, visible, which is typical of viewshed analyses, in this work the various factors that cause the visual attenuation with the distance are discussed and quantitatively assessed by determining various limit-of-visibility distances that may also be time variable. These factors are the visual acuity, the contrast between the target and its surroundings, the atmospheric visibility, and the recognition process of the subject. An application of this methodology is carried out on various case study buildings in the city of Turin, Italy (an ancient building, an urban landmark, the Mole, and a skyscraper under construction). From the visibility maps, under various conditions, it can be seen that the new skyscraper will be a major landmark not only for the entire city, but also for the surrounding municipalities.
Ecosystem Service assessment requires better integration of the information that supports land use decisions. Nevertheless, the interpretation of maps and their utilisation to address sustainability during the land use planning process remains critical, especially at a local scale. In this study, a Geographic Information System-Based approach is presented to transform an Ecosystem Service biophysical multipart analysis into a composite parcel-scale indicator, mainly using Esri ArcGIS (version 10.5) functions, and particularly: (i) the Weighted Overlay, (ii) Hotspot Analysis and (iii) Aggregation of Polygons. This methodology has been used experimentally in three municipalities of the metropolitan city of Turin (Italy) during the LIFE SAM4CP project. The study aims to demonstrate how the operationalisation of Ecosystem Service assessment in planning aided Local Administrations in defining land use planning priorities, such as the identification of land take control strategies and the definition of Urban Growth Boundaries.
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