74 research outputs found
Impact of urban sprawl to cultural heritage monuments: The case study of Paphos area in Cyprus
No full textUrbanisation processes as a result of population growth, migration and infrastructure initiatives have a direct impact to cultural heritage sites. This paper aims to monitor growth dynamics of the urbanisation process that took place in the Paphos district, southwest Cyprus during the last decades, and evaluate its impact to monuments and archaeological sites. In this extensive area, several important archaeological sites and monuments are found, while some of them are also listed in the UNESCO catalogue of World Cultural Heritage sites. GIS and remote sensing techniques have been used in order to map the listed monuments in the Paphos District, as well as to record spatial and temporal land use changes since the 1980s. The spatial patterns of urban sprawl are studied and analysed using archive time series medium resolution Landsat ETM+ and TM satellite imagery. In addition, a DMSP-OLS night-ime image was also used. Several supervised and unsupervised classification algorithms have been evaluated and examined for this purpose. Additionally, Markov equation were applied in an attempt to predict future urban expansion The final outcomes revealed that a dramatic increase of the urban areas took place in the last years in Paphos district, and as a result significant pressure is expected on archaeological sites found in the peri-urban areas
Integrated method for tracking changes in archeolandscapes using remote and close-range technologies: Monitoring of change and risk assessment methodologies
No full textThe importance of visible built heritage and archeolandscapes for preservation of collective memory and identity is widely acknowledged across disciplines regarding heritage protection and valorisation. The complex analysis of archaeolandscape transformations through time needs multilevel geospatial information. To this purpose, it is necessary to consider different domains of technological tools but also an appropriate geospatial framework, applying a multi-scale, multitemporal and multi-sensor approach. In this way, the capabilities of new technologies can be further expanded aiming towards to an effective integration and improvement of preservation strategies and protection methodologies for cultural heritage sites. This paper illustrates the integration of in situ surveying campaigns, close range photogrammetry, aerial and satellite remote sensing imagery for identify change detection at the “Nea Paphos”, a UNESCO protected archaeological site of Cyprus. In particular, this paper examines the evolution of a buried archaeological feature (amphitheatre?) which is already known to experts but has not yet been excavated. Changes of shape and size have been documented, interpreted and mapped using resources covering a temporal arch of circa last 50 years. While soil and vegetation marks of the buried feature are very clear in the historic aerial imagery, these traces are disturbed on the recent images. An integrated method of detecting natural and physical consequences for evolving landscapes, using remote sensing techniques, airborne, and 3D photogrammetric models developed using open-source tools has been applied. Such integration is envisaged to (1) provide new kind of information and possible scenarios for retrieving geospatial knowledge of evolving archeolandscapes and their multiple layers of history and to (2) enable archaeologists, public administration and conservation professionals to pursue specific tailored-made preservation strategies of- specific archaeological sites and to support them in more informed decision making
Comparison of Different Rainfall Erosion Estimation Methods for the Island of Crete
No full textInteractions between soil and rainfall plays a vital role in ecological, hydrological and biogeochemical cycles of land. Among those interactions, the phenomenon of rainfall induced soil erosion is crucial to the soil functions, as it affects the soil structure and organic matter content that subsequently affects soil ability to hold moisture and nutrients. The erosive power of a specific rainfall event is regulated by its intensity and total duration. Various methodologies have been developed and tested to estimate the rainfall erosivity in different hydroclimatic regions and using different rainfall measuring timescales. Studies have shown that high temporal resolution measurements provide a more robust erosivity estimation. Nonetheless the sparsity and scarcity of such high temporal resolution data make the accurate estimation of rainfall erosivity difficult. Here, we compare different erosion power estimation methods based on different rainfall timescales for the island of Crete. Sub-daily (30-min) rainfall data based estimation is used as the basis for the assessment of a daily data based estimation methodology and two different methods that use monthly rainfall data. Modified Fournier Index (MFI) is incorporated in the study through different literature approaches and a regression equation is developed between rainfall erosivity power and MFI index for Crete. Results indicate that the use of daily data in the rainfall erosive power estimation is a good approximation of the sub-daily estimation, while formulas based on monthly rainfall data tend to exhibit larger deviations
Monitoring Short-Term Morphobathymetric Change of Nearshore Seafloor Using Drone-Based Multispectral Imagery
No full textShort-term changes in shallow bathymetry affect the coastal zone, and therefore their monitoring is an essential task in coastal planning projects. This study provides a novel approach for monitoring shallow bathymetry changes based on drone multispectral imagery. Particularly, we apply a shallow water inversion algorithm on two composite multispectral datasets, being acquired five months apart in a small Mediterranean sandy embayment (Chania, Greece). Initially, we perform radiometric corrections using proprietary software, and following that we combine the bands from standard and multispectral cameras, resulting in a six-band composite image suitable for applying the shallow water inversion algorithm. Bathymetry inversion results showed good correlation and low errors (<0.3 m) with sonar measurements collected with an uncrewed surface vehicle (USV). Bathymetry maps and true-color orthomosaics assist in identifying morphobathymetric features representing crescentic bars with rip channel systems. The temporal bathymetry and true-color data reveal important erosional and depositional patterns, which were developed under the impact of winter storms. Furthermore, bathymetric profiles show that the crescentic bar appears to migrate across and along-shore over the 5-months period. Drone-based multispectral imagery proves to be an important and cost-effective tool for shallow seafloor mapping and monitoring when it is combined with shallow water analytical models
Studying Land Use and Land Cover Spatial Patterns Distribution in Crete, Greece with Means of Satellite Remote Sensing
No full textMulti-temporal Land use and Land cover (LULC) monitoring is a crucial parameter for assessing an area’s landscape ecology regime. LULC changes can be effectively used to describe dynamics of both urban or rural environments and vegetation patterns as an important indicator of ecological environments. In this context, spatial land use properties can be quantified by using a set of landscape metrics. Landscape metrics capture inherent spatial structure of the environment and are used to enhance interpretation of spatial pattern of the landscape. This study aims to monitor diachronically the LULC regime of the island of Crete, Greece with the use of Landsat satellite imageries (Landsat 5, Landsat-7 and Landsat-8) in terms of soil erosion. For this reason, radiometric and atmospheric corrections are applied to all satellite products and unsupervised classification algorithms are used to develop detail LULC maps of the island. The LULC classes are developed by generalizing basic CORINE classes. Following, various landscape metrics are applied to estimate the temporal changes in LULC patterns of the island. The results denote that the diachronic research of spatial patterns evolution can effectively assist to the investigation of the structure, function and landscape pattern changes
Linear 3-D transformations of Landsat 5 TM satellite images for the enhancement of archaeological signatures during the phenological cycle of crops
No full textA linear 3-D transformation that can be used for the enhancement of crop marks
related to buried archaeological features is developed and presented in this article. The
methodology is based on three steps: (1) recalculation of the ground narrowband
spectroradiometric measurements to the multispectral Landsat 5 Thematic Mapper
(TM) sensor, based on the relative response filter of the sensor, (2) application of
principal component analysis (PCA) transformation in order to determine the initial
axes used for the orthogonal transformation, followed by (3) a 3-D rotation of the PCA
axes. The linear coefficients of the transformation were retrieved and adjusted to
different phenological stages of the crops. The transformation was successfully evaluated
using both in situ measurements and Landsat 5 TM images in two different
archaeological case studies. The proposed transformation tends to enhance archaeological
signatures better than other established vegetation indices or algorithms, while
the methodology can be expanded to any other multispectral satellite images using
only the visible and very near-infrared part of the spectrum
Evaluation of Broadband and Narrowband Vegetation Indices for the Identification of Archaeological Crop Marks
No full textSeveral studies in the past have examined the spectral capability of multispectral and hyperspectral imagery for the identification of crop marks, while recent studies have applied different vegetation indices in order to support remote sensing archaeological applications. However, the use of vegetation indices for the detection of crop marks lacks in accuracy assessment and critical evaluation. In this study, 71 vegetation indices were indexed, from the relevant bibliography, and evaluated for their potential to detect such crop marks. During this study, several ground spectroradiometric campaigns took place, in a controlled archaeological environment in Cyprus, cultivated with barley crops, during a complete phenological cycle (2011&#8211;2012). All vegetation indices, both broadband and narrowband, were evaluated for their separability performance, and the results were presented through tables and diagrams. In the end, the use of more than one vegetation index is suggested in order to enhance the final results. In fact, several not widely used vegetation indices are suggested and evaluated using both Landsat TM and EO-1 Hyperion images
Quantitative Landscape Analysis Using Earth-Observation Data: An Example from Chania, Crete, Greece
No full textPursuing sustainability in a challenging world and under the influence of numerous natural and anthropogenic drivers of change presents one of the major global concerns. The transition towards a more sustainable development requires a harmonious balance between human well-being and environmental management. The concept of landscape is at the core of such a process. Hence, evaluating the different aspects of the landscape and their components is crucial for policy making, planning and management. In fact, landscape quality assessment has become a special focus of interest, especially with the directives of the European Landscape Convention. This research work aims to analyze the rural landscape of the Chania prefecture, West Crete, Greece, taking into account its multifold dimensions. The analysis was carried out using a series of quantitative spatial indicators. Consecutively, structural (mean patch area, contagion index, edge density and percentage of landscape occupied by a class of the highest share), ecological (density of ecological barriers, Modified Shannon diversity index), visual (share of positive land-cover forms, share of negative land-cover forms, form and color disharmony index, shape disharmony index) and cultural indices (historical monuments index) were estimated and analyzed in a GIS environment. The overall methodology incorporated different land-use/land-cover data (multitemporal Corine data and land use derived from the classification of Earth-observation (EO) data). The historical and current analysis of the landscape within Chania revealed quite high structural and visual values. The ecological dimension is rather stable, with a potential decrease by the year 2045. Additionally, the structural dimension seemed to be sensitive to the spatial resolution of the data source. The spatial extent, at which the landscape is evaluated, seemed to impact the landscape’s ecological, visual and cultural values
Linking Soil Erosion Modeling to Landscape Patterns and Geomorphometry: An Application in Crete, Greece
No full textSoil erosion is a severe and continuous environmental problem caused mainly by natural factors, which can be enhanced by anthropogenic activities. The morphological relief with relatively steep slopes, the dense drainage network, and the Mediterranean climate are some of the factors that render the Paleochora region (South Chania, Crete, Greece) particularly prone to soil erosion in cases of intense rainfall events. In this study, we aimed to assess the correlation between soil erosion rates estimated from the Revised Universal Soil Loss Equation (RUSLE) and the landscape patterns and to detect the most erosion-prone sub-basins based on an analysis of morphometric parameters, using geographic information system (GIS) and remote sensing technologies. The assessment of soil erosion rates was conducted using the RUSLE model. The landscape metrics analysis was carried out to correlate soil erosion and landscape patterns. The morphometric analysis helped us to prioritize erosion-prone areas at the sub-basin level. The estimated soil erosion rates were mapped, showing the spatial distribution of the soil loss for the study area in 2020. For instance, the landscape patterns seemed to highly impact the soil erosion rates. The morphometric parameter analysis is considered as a useful tool for delineating areas that are highly vulnerable to soil erosion. The integration of three approaches showed that there is are robust relationships between soil erosion modeling, landscape patterns, and morphometry
Geomorphometric analysis of nearshore sedimentary bedforms from high-resolution multi-temporal satellite-derived bathymetry
No full textMonitoring sedimentary bedforms is crucial for coastal planning projects. Detailed shallow bathymetry is a fundamental tool for analyzing sedimentary bedforms, however it is often unavailable due to fieldwork limitations. This study utilizes high resolution satellite-derived bathymetry (SDB) for monitoring nearshore bedforms at the northern coast of Chania (Crete, Greece). A random forest technique is employed for training and predicting SDB using two types of multispectral satellite imagery along with ground-truth sonar data. SDB maps have an error of 0.5 meter and allowed for identifying nearshore crescentic bar systems which are the result of local hydrodynamic activity. Bedform metrics were extracted by applying geomorphological indices. Crescentic bars found to be changing shape on annual scale. Nearshore seafloor with soft substrate, changes rapidly and temporal SDB mapping is a fundamental approach for effective coastal monitoring. Multi-temporal SDB maps provide observational evidence about local hydrodynamics which is beneficial in coastal engineering applications
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