Kyriacos Themistocleous

Integrated use of GIS and remote sensing for monitoring landslides in transportation pavements: the case study of Paphos area in Cyprus

This study considers the impact of landslides on transportation pavements in rural road network of Cyprus using remote sensing and geographical information system (GIS) techniques. Landslides are considered to be one of the most extreme natural hazards worldwide, causing both human losses and severe damages to the transportation network. Risk assessment for monitoring a road network is based on the combination of the probability of landslides occurrence and the extent and severity of the resultant consequences should the disasters (landslides) occur. Factors that can trigger landslide episodes include proximity to active faults, geological formations, fracture zones, degree and high curvature of slopes, water conditions, etc. In this study, the reliability and vulnerability of a rural network are examined. Initially, landslide locations were identified from the interpretation of satellite images. Different geomorphological factors such as aspect, slope, distance from the watershed, lithology, distance from lineaments, topographic curvature, land use and vegetation regime derived from satellite images were selected and incorporated in GIS environment in order to develop a decision support and continuous landslide monitoring system of the area. These parameters were then used in the final landslide hazard assessment model based on the analytic hierarchy process method. The results indicated good correlation between classified high-hazard areas and field-confirmed slope failures. The CA Markov model was also used to predict the landslide hazard zonation map for 2020 and the possible future hazards for transportation pavements. The proposed methodology can be used for areas with similar physiographic conditions all over the Eastern Mediterranean region.

Monitoring urban land cover using satellite remote sensing techniques and field spectroradiometric measurements: case study of “Yialias” catchment area in Cyprus

Abstract. This study highlights the need for digital mapping of urban sprawl phenomenon in catchment areas with the use of both satellite and ground remote-sensing techniques. The Yialias River, located in the central part of Cyprus, was selected as a case study area. In this catchment, devastating flash flood events took place in both 2003 and 2009, with catastrophic results. Initially, ground spectroradiometric measurements were applied to investigate the spectral similarity of different classes such as those of “urban fabric” and “marl/chalk origin formations” within the watershed. Temporal land cover changes were analyzed by using multitemporal satellite imagery (ASTER) and by incorporating both pixel- and object-oriented classification techniques. To create effective land use and land cover maps, a classification model was proposed based on spectral, texture, and shape characteristics. The pixel-based classification results were compared and evaluated with the object-based classification products. The optimum classification products were imported to geographical information systems and FRAGSTATS software and were used to visually and statistically detect landscape identifying trends based on spatial landscape metrics. The final results indicated considerable urban expansion within the study area during the last 10 years.

The identification of pseudo-invariant targets using ground field spectroscopy measurements intended for the removal of atmospheric effects from satellite imagery: a case study of the Limassol area in Cyprus

This study proposes five types of commonly located surfaces that were evaluated to be determined for use as pseudo-invariant targets (PITs) in order to apply the so-called ‘empirical-line’ atmospheric correction method. Spectroradiometric measurements were taken over wet and dry conditions to obtain the spectral signatures of the targets. From the acquired in situ spectroradiometric campaign, it was found that the proposed commonly found PITs (sandy, concrete and asphalt) are suitable non-variant targets. An accuracy assessment of the empirical-line atmospheric correction method using the five PITs was performed using other calibration targets and aerosol optical thickness (AOT) values from MICROTOPS hand-held sun photometers acquired simultaneously with the satellite overpass. The radiative transfer equation was used to determine AOT levels, using the reflectance values derived from the empirical-line method, in order to conduct an accuracy assessment with in situ AOT measurements. It was also shown that precipitation conditions should be considered when using non-variant targets in atmospheric correction methods.

Development of a new image based atmospheric correction algorithm for aerosol optical thickness retrieval using the darkest pixel method

The problem of atmospheric intervention has received considerable attention from researchers in remote sensing who have developed a range of methods, either simple or sophisticated. The sophisticated methods require auxiliary information about the state of the atmosphere which is obtained either from standard databases or from simultaneous in-situ field measurements or by iterative techniques. It has been found that the darkest pixel atmospheric correction (DP) is one of the most effective atmospheric correction methods especially for visible spectral bands. The DP is the simplest and fully image-based correction method. The integrated use of the DP basic theory and the radiative transfer equation is implemented in this study. Indeed, this leads to the development of the proposed ‘image-based atmospheric correction algorithm.’ The proposed algorithm retrieves the aerosol optical thickness (AOT) only for areas with urban and maritime aerosols. The effectiveness of this algorithm is assessed by comparing the AOT values retrieved from the proposed ‘image-based atmospheric correction algorithm’ after applied to Landsat TM / ETM + images with those measured in-situ both from MICROTOPS II hand-held sun photometer and the CIMEL sun photometer (AERONET). It has been found that the AOT values retrieved from the proposed algorithm were very close with those measured from the CIMEL sun photometer for the Limassol area in Cyprus.

Water leakage detection using remote sensing, field spectroscopy and GIS in semiarid areas of Cyprus

Water pipelines need to be systematically monitored in order to minimize losses from possible leakages. In this paper, remote sensing techniques have been exploited in semiarid areas of Cyprus. In addition, ground spectroradiometer has been used to define the leakages threshold values. The data were analysed in a GIS environment. Two known leakage problems have been examined. In the first case study, a high resolution QuickBird image was used for the detection of the exact point of leakage. In the second case study a multi-temporal analysis was performed using SPOT images. This methodology was able to record 10 possible leakage points along the pipeline. Throughout the 25 km length of the pipeline, the in-situ observations were minimized to only 0.4%. In both studies the Normalised Difference Vegetation Index (NDVI) was applied. The final outcomes highlight the contribution of remote sensing to the early detection of leakages especially in difficult and near inaccessible areas.

Spectro-radiometric measurements of non-variant targets intended for the removal of atmospheric effects from satellite images: the case study of Lemesos area in Cyprus

It has been shown by Hadjimitsis et al. (2009) that the use of suitable non-variant targets in conjunction with the application of the empirical line method can remove atmospheric effects from satellite images effectively. The method is based on the selection of a number of suitable generic non-variant targets, on the basis that they are large, distinctive in shape, and occur in many geographical areas. The need to further test such method by suggesting more suitable nonvariant targets is one of the main aims of this study. Indeed, six targets have been already identified in the Lemesos District area in Cyprus, near the harbour and tested. In-situ spectro-radiometric measurements using the SVC HR-1024 field spectro-radiometer have been made on November 2009 and from February 2010 to April 2010. Some of the in-situ measurements were coincided with the Landsat TM/ETM+ overpass and the removal of atmospheric effects was very effective. The above targets have been scanned using a 3D terrestrial laser scanner (Leica ScanStation C10) so as to investigate the non-variability and uniformity of the proposed targets (through the laser scanner intensity values).

Damage assessment using advanced non-intrusive inspection methods: integration of space, UAV, GPR, and field spectroscopy

The predominant approach for conducting road condition surveys and analyses is still largely based on extensive field observations. However, visual assessment alone cannot identify the actual extent and severity of damage. New non-invasive and cost-effective non-destructive (NDT) remote sensing technologies can be used to monitor road pavements across their life cycle, including remotely sensed aerial and satellite visual and thermal image (AI) data, Unmanned Aerial Vehicles (UAVs), Spectroscopy and Ground Penetrating Radar (GRP). These non-contact techniques can be used to obtain surface and sub-surface information about damage in road pavements, including the crack depth, and in-depth structural failure. Thus, a smart and cost-effective methodology is required that integrates several of these non-destructive/ no-contact techniques for the damage assessment and monitoring at different levels. This paper presents an overview of how an integration of the above technologies can be used to conduct detailed road condition surveys. The proposed approach can also be used to predict the future needs for road maintenance; this information is proven to be valuable to a strategic decision making tools that optimizes maintenance based on resources and environmental issues.

Smart monitoring of water quality in Asprokremmos Dam in Paphos, Cyprus using satellite remote sensing and wireless sensor platform

The use of satellite remote sensing for water quality monitoring in inland waters has substantial advantages over the insitu sampling method since it provides the ability for overall area coverage and also for study and supervision of isolated locations. The development of algorithms for water quality monitoring using satellite data and surface measurements can be widely found in literature. Such algorithms require validation and one of the major problems faced during these attempts was the need for continuous surface measurements requiring numerous in-situ samplings that imply also very high costs due to the need of increased human labour. The development of an automatic and autonomous sensor system able to be remotely controlled, will cover this gap and will allow the real time combined analysis of satellite and surface data for the continuous monitoring of water quality in dams as well as the overall water resources management. Wireless Sensor Networks (WSN) can provide continuous measurements of parameters taken from the field by deploying a lot of wireless sensors to cover a specific geographical area. An innovative, energy-autonomous floating sensor platform (buoy) transferring data via wireless network to a remote central database has been developed for this study which can be applied on all dams in Cyprus. Indeed this project describes the results obtained by an existing running campaign in which in-situ spectroradiometric (GER1500 field spectroradiometer) measurements, water sampling measurements (turbidity), sensor measurements (turbidity) and Landsat TM/ETM+ data have been acquired at the Asprokremmos Dam in Paphos (Cyprus). By applying several regression analyses between reflectance against turbidity for all the spectral bands that correspond to Landsat TM/ETM+ 1-2-3-4, the highest correlation was found for TM band 3 (R2=0.83).

Integration of micro-sensor technology and remote sensing for monitoring coastal water quality in a municipal beach and other areas in Cyprus

The proposed project has as main objective the monitoring of coastal waters using satellite remote sensing and wireless sensor technology employed on a buoy with emphasis firstly in municipal beaches and further to areas that a systematic sampling is required. Satellite remote sensing has the advantage of using remote sensing data to assess the quality of water bodies has proven to be successful not only in inland waters but to coastal water areas as shown by several others conducted studies. Reflectance signature of municipal coastal water is monitored using a GER 1500 field spectroradiometer. Simultaneous measurements of turbidity, temperature have been acquired. Cross-validation of measurements of water quality both from micro-sensor and remote sensing are planned to be undertaken. An overall methodology that integrates both micro-sensor technology and satellite remote sensing is presented.

Monitoring ground deformation of cultural heritage sites using UAVs and geodetic techniques: the case study of Choirokoitia, JPI PROTHEGO project

This paper presents the integrated methods using UAVs and geodetic techniques to monitor ground deformation within the Choirokoitia UNESCO World Heritage Site in Cyprus. The Neolithic settlement of Choirokoitia, occupied from the 7th to the 4th millennium B.C., is one of the most important prehistoric sites in the eastern Mediterranean. The study is conducted under the PROTHEGO (PROTection of European Cultural HEritage from GeO-hazards) project, which is a collaborative research project funded in the framework of the Joint Programming Initiative on Cultural Heritage and Global Change (JPICH) – Heritage Plus in 2015–2018 (www.prothego.eu) and through the Cyprus Research Promotion Foundation. PROTHEGO aims to make an innovative contribution towards the analysis of geo-hazards in areas of cultural heritage, and uses novel space technology based on radar interferometry to retrieve information on ground stability and motion in the 400+ UNESCOs World Heritage List monuments and sites of Europe. The field measurements collected at the Choirokoitia site will be later compared with SAR data to verify micro-movements in the area to monitor potential geo-hazards. The site is located on a steep hill, which makes it vulnerable to rock falls and landslides.