Geographia Napocensis Anul IX, Nr. 1, 2015

QUANTITATIVE EVALUATION OF MULTI-VULNERABILITY TO HYDRO-GEOMORFOLOGICAL HAZARDS IN THE UPPER SECTOR OF NIRAJ CATCHMENT

1 SANDA ROȘCA

Abstract. - Quantitative Evaluation Of Multi-Vulnerability To Hydro-Geomorfological Hazards In The High Sector Of Niraj Catchment. A study of the natural hazards indicates that floods, landslides, fluvial erosion and soil erosion have the highest spatial-temporal occurrence and lead to the highest material losses in the study area of the Niraj Basin. The present study focuses on the upper section of1/2015 the Niraj basin, one that still evolving from a hydrological and geomorphological point of view, without any major anthropic interference. Due to its favourability for the establishing of settlements (a consequencenr, of favourable slopes, fertile lands and water resources), the most of the human settlements are situated in the floodplain area, hence in the most flood-prone area during spring and autumn. The rest of the settlements lie on the inferior sectors of the hillslopes, as well as on the valleys of the main tributaryIX, rivers of the Niraj, hence being exposed to the reactivated landslides- a consequence of the abundant rainfall events usually leading to floods. A cumulated approach of a multi-vulnerability type has beenAN chosen, one that allows the classifying of the built-up area and roads into spatial classes exposed to the identified natural hazards. Spatial analysis led to the obtaining of quantitative information concerning the number of constructions and the length of roads that can be exposed once the hydro-geomorphological processes have reactivated.

Key-words: vulnerability, flood-prone area, landslide, risk exposure, Niraj basin

1. Introduction of the statistical analysis of data series obtained The quantifying of vulnerability and risk from previous measurements (Roșca et al., 2014). generated by floods and landslidesNAPOCENSIS is necessary Concerning landslides, the identification of to be expressed in qualitative terms, but even cumulated rainfall values considered as thresholds more so in quantitative ones, for the sake of good in the analysed territory is mandatory (Crozier management in the process of establishing the 1997, Schmidt and Dikau 2004, Polemio and priorities for the possible emergencies, as the EU Petrucci 2010). Offices dedicated to the directive (EPA, 2003) recommends, directive in identifying of the risk exposed elements have been which the principles of thegeographianapocensis.acad-cluj.ro multi-risk study are set in Europe, in countries such as Belgium, enumerated (Marzocchi et al., 2009). The authors France, Germany, the Netherlands, Bulgaria, mention that this method allows a comparison Hungary, Romania, Poland and Slovakia and hierarchyGEOGRAPHIA of the natural hazards and their (www.eurosense.com). Urban planning authorities derived effects. Applying a common and risk strategists can obtain valuable methodology implies a probabilistic analysis of information from the hazard analyses individual risk, namely that of terrain accomplished at a local, regional or national scale vulnerability when it comes to the risk generating (Cascini et al., 2005, Fell et al., 2008). processes in the territorial equation. The vulnerability concept reffers to the The spatial identification of the flood and exposure and capacity characterising the risk landslides associated risk, in hydrology, is elements to resist to the hazardous determined by the establishing of floodplain areas conditions/the occured damages. For damage for different probabilities, computed on the basis identification, the authors take into account the 1 Babeş-Bolyai University, Faculty of Geography, 400006, Cluj-Napoca, Romania, e-mail: [email protected] 67 Sanda Roşca spatial-temporal probability of floods and taken place in 12. 07. 2009 when 5 houses and 7 landslides as well as the vulnerability of the households were damaged, 7 small bridges were people in the area and of the exposed elements destroyed and traffic was disrupted on 0,1 km of (Corominas, 2008). From a conceptual and road as well as 1, 2 ha of agricultural terrain were methodological point of view, the identifying of flooded (according to the data of the Inspectorate exposed elements and their vulnerability is for Emergency Situations, Mureș). necessary in the multi-risk studies allowing the The morphometric characteristics of the relief identification and analysis of individual risk and play an important role on the production and of the cumulated risk (Cutter, 2001). evolution of hydrological phenomena; hence it is Hence it is important that a vulnerability and important to take into account the shape of the risk class be assigned to each unit of the hydrographic basin, given by the direction and administrative territory. Risk zoning consists in orientation of the water divide, which determines the division of the analysed territory in the runoff characteristics. Secondly, the river homogenous areas according to their present or length and the water discharge1/2015 of the tributary presumed susceptibility degree, hazard, flood rivers, closely connected with the altitude of a and landslide risk (Corominas, 2008). An open basin (Zăvoianu, 2006)nr, need to be considered as subject stays, nonetheless, the establishment of well. The hydrographic basin was divided in the acceptable risk (tolerated risk) concerning subwatersheds withIX, the help of the ArcHydro9 damages when it comes to the authorities‟ point extension of the ArcG.I.S software. ArcHydro of view, their opinion being different from one offers the possibility of determining watersheds, country to another (Dai et al., 2002). It is a subwatershedsAN and catchments automatically, as known fact that the scales and quality of the well as it allows the intervention of the user via input data in the analysis and risk evaluation its batch watershed delineation function. For the models will determine the amount of details and upper river basin of the Niraj River a number of the practical application of results. 11 hydrographic subwatersheds has been determined, their surfaces ranging between 9 şi 2. Hydro-geomorfological hazards in the 39 km2 (table 1). GIS allowed the computation of study area different morphometric elements such as the The Niraj hydrographic basin is situated in surface of a hydrographic basin and its perimeter the Central-Eastern part of the TransylvanianNAPOCENSIS (necessary for the computing of the circularity Depression. It is a geographically complex coefficient), the length of several sectors of the territory (from a geological, geomorfological and hydrographic network etc. climatic point of view), displaying favourability For the present study area, the values close towards being inhabited (Roșca, 2011) due to its to 1, indicating an almost circular shape, are morphometric and morphographic characteristic only for the Diceal subwatershed characteristics. Hence there exist 14 localities (C=1,01), the rest of the subbasins being (Fig. 1) only in the uppergeographianapocensis.acad-cluj.ro basin, comprising the characterised by values that indicate their mountainous and piedmountainous sector of the prolonged shape (Nirajul Mic, Nirajul Mare, Gurghiului Mountains. Hodoșa, etc.) which determine a delay in the GEOGRAPHIA registering of peak discharges and a decrease of 2.1. Hydrological hazards the flash-floods amplitudes. These subbasins Amongst the types of hydrological hazards regulate river flow as the abundant rainfall existing in the analysed sector, floods are certainly events from the upstream part and the sudden noticeable, being caused by the spring flash-floods snowmelt in the mountainous area have a latter of mixed origin (rainfall and snow) which impact, due to the different situations existing at represent 52% and followed by the pluvial origin a subbasin level, these situations resulting from summer flash-floods representing 32% (Roșca, the geologic diversity and the different levels of 2011, 2014). These events are accompanied by resistance to erosion which are conditioned by negative effects, the last event of such kind having the local topographic level.

68 Quantitative evaluation of multi-vulnerability to hydro-geomorfological hazards in the upper sector of Niraj Catchment

1/2015 nr,

IX, Fig. 1. Geographical position of Niraj subwatershed (where: 1 – subwatershed Nirajul Mare, 2 – Nirajul Mic, 3 – Pârâul Cald, 4 – Diceal, 5 – Săcădad, 6 – Aluniș, 7 – Pârâul Litigios, 8 - Ciadon, 9- Hodoșa și 10 – Zambo)AN

Tabelul 1. Morphometric characteristics of subwatersheds

ORDER Watershed F P C Rc f Dd T N1 N2 N3 N4 23 4 1 - Nirajul Mic 25 36,9 2,08 4,87 1.12 1,31 1,17 18,04 6,33 8,59 - 25 7 1 - Nirajul Mare 39 38,5 1,74 5,28 0.85 1,07 1,26 NAPOCENSIS20,06 13,98 7,88 - 5 2 1 - basin Mountainous Pârâul Cald 10 14 1,25 2,25 0.80 1,29 1,61 9,26 2,76 0,97 - 6 3 2 - Diceal 13 12,9 1,01 1,83 0.92 0,93 1,01 5,8 2,69 3,69 - 5 1 - - Săcădad 10 15,5 1,38 5 0.60 1,1 1,83 7,79 3,4 - -

5 3 1 - Aluniş 8 14,5 geographianapocensis.acad-cluj.ro1,45 2,33 1.13 1,23 1,09 7,71 0,66 1,49 - Pârâul 6 1 - - 13 17,3 1,35 6 0,54 1,36 2,52 Litigios 13,98 3,81 - - 5 1 - - CiadonGEOGRAPHIA 9 16,3 1,53 5 0,67 1,15 1,72 5,69 4,68 - - Hillside basin 13 1 - - Hodoşa 38 33,2 1,52 13 0.37 1,23 3,32 34,22 12.51 - - 9 2 1 - Zambo 19 23 1,49 3,25 0,63 1,48 2,35 20,64 4,92 2,59 - 102 25 7 1 Niraj 184 4,88 1,80 1,36 0,75 143,1 55,7 22,6 29 F (km²)-Area of watershed, P – watershed perimeter (km), C – circularity coefficient (km), Alt. max – maximum st altitude (m), N1,2,3,4,5 – river‟s order, Rc = Nx/Nx+1 – confluence report, f – frecvency of 1 order segments (f=N/F), Dd – Drainage density (Dd=ΣL/F, km/km2), T – Torentiality (T = Dd/f)

69 Sanda Roşca

As it can be seen in figure 1 the river courses the drainage density and the frequency of display an arborescent hierarchy. So as to create elementary thalwegs, offers supplementary the morpho-hydrographic hierarchy, the authors information. Hence the Hodoșa, Pârâul Litigios, use Horton‟s, R.E., (1945) and Strahler‟s, A.N, Zambo display high values due to rocks that are (1957) method. The hydrographic network soft and due to low forested areas. Having the systematization was followed by the assignment complete database describing the geological, of river segment numbers according to order geomorphological, meteorological and number as stipulated by Horton‟s laws and their pedological features, as well as the land use and length (table 1). The upper basin of the Niraj hydrometric data series (discharges and maximum counts 102 river segments of 1st order, 25 of the flash-flood levels registered on the Niraj River 2nd order, 7 of the 3rd order and 1 corresponding between 1970-2013) the floodplain area for the to the 4th order. The large number of elementary 1% return period flash-floods has been determined thalwegs is noticeable, being characterised by (Roșca et al., 2014) representing1/2015 from a spatial small lengths favouring the downwards runoff on and temporal point of view those areas exposed to hillslopes, their presence being connected to the flooding along the main nr,river (Fig. 2). different resistance to erosion, one of the superficial landslides causal factors in the study 2.1. Geomorphological hazards area. Concerning the hydrographic basin of Niraj, From the categoryIX, of geomorphological the diversity determined by the region‟s hazards causing material losses in the sector of evolution, geology and external factors leaves a the built-upAN area, transport infrastructure and mark on the morphometric characteristics as the agricultural terrain, the authors have to mention previous morphometric studies have concluded the landslides, soil erosion and river erosion as (Zăvoianu, 1978, Grecu, Florina, 1992, Armaş, occurring in the study area. The estimation of Iuliana, 1999). The frequency of elementary soil erosion in the upper sector of the Niraj thalwegs shows the influence the lithology has, River, has been previously determined via the as well as the existing resistance to erosion and R.U.S.L.E. model (Roșca, 2014), the highest the vegetation protection cover given by the mean values being registered in the Pârâul Cald wooden vegetation. subbasin (0,110 t/ha/yr), Săcădad (0.119 t/ha/yr) The torrential level calculated asNAPOCENSIS a product of and Pârâul Litigios (0,239 t/ha/yr).

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Fig. 2. Landslide occurrence probability map and the 1% flood stripes area

70 Geographia Napocensis Anul IX, Nr. 1, 2015

The active landslides charting process has scale as large as possible. Hence recent satellite been made on the basis of recent satellite images images and field work in the study area. The administrative units of Vărgata, Hodoșa and results can be seen in Figure 2, namely the 12 Eremitu. The administrative borders of the areas where active landslides exist. The Chiheru de Jos locality have not been a subject probability map of landslide occurrence (Fig. 2) of the detailed analysis on the account of a very could be drawn once the susceptible areas to low probability of flooding and landslide landslides have been identified on the basis of occurrence, since the settlement is located in a the legally reglemented Romanian method relatively stable area in the Gurghiului through the Governmental Decision 447 in Mountains. 2003- The Methodological Norms Concerning By analysing the geographical position of the Elaboration and the Contents of Natural the buildings within the 5 localities in the Risk with Respect to Landslides. In order for it Eremitu commune, their preponderant to be achieved, a database containing the most localization in the Niraj River1/2015 floodplain is important factors conditioning and triggering noticeable, the majority of the buildings being landslides in Romania was used. These factors situated within the 1%nr, floodplain area (Fig. 3), include the following: lithology, an exception from this rule constitutes geomorphologic and structural characteristics, nonetheless terrainsIX, exposed to the analysed hydro-climatic ones, hydrogeological, seismic hazards. and anthropic intervention. AN The occurrence probability of landslides 3. Multi-vulnerability assessments varies between the values of 0,078 and 0,1 For determining the vulnerability degree a values characterising the lower class (for 13,1 database had to be gathered, comprising the risk km2 - 5,59 % of the area), the mean probability receptors, namely: the dating from 2013 and class characterizing the widest surface in the several 2010 othophotos have been used, images study area (137 km2 - 58,2%), followed by the on which land use, roads and the built-up areas mean-towards-high class for the 85,2 km2 - have been digitised. 36,1% of the territory, and the high values such For an increase in the application of the as 0,606 situating the territoriesNAPOCENSIS in the high results, the analysis will be done at the level of probability class (values existing on small areas the territorial the constructions situated on the of 0,001 km2 representing only 0,04% out of Ineului alluvial fan (88 buildings) as well as the Niraj upper basin). those in Săcădad (161 buildings), or those in the The hazard flood map is created on the basis Pârâului Litigios River (141 buildings) as well of the 1% floodplain area map and the landslide as on the ones on the 10 m length of the terrace hazard map. It was drawn on the basis of the tread in the Dămieni locality (32 constructions). occurrence probability geographianapocensis.acad-cluj.ro of landslides as In the Hodoșa commune, a high number of stipulated by the Governmental Decision H.G. buildings is evident, buildings that are situated 447/2013. The hazard flood map is part of the on areas characterised by a medium probability territorialGEOGRAPHIA planning documentation along with (126 buildings in the Isla locality, 156 in Ihod, the existing recommendation that the map be 145 in Hodoșa, 329 in Sâmbriași) and by a obtained at a scales of 1:25000 and larger scales medium-high probability of landslide be used for the territories with a high probability occurrence (262 constructions in the Sâmbriași of landslide or flooding occurrence (Art. 28). locality, 73 in Isla, 54 in Hodoșa and only 17 in The authors will analyse further the built-up Ihod). Steep slopes as well as the predominant area, the infrastructure elements and the clayey-marl lithology, leads to the occurrence of human settlements, population statistics, social- active landslide areas affecting 3 buildings in economic units, the infrastructure elements as the Sâmbriași locality (Fig. 4). well as agricultural fields and forested areas at a

71 Sanda Roşca

Fig. 3. Classification of the built-up area and roads according to the various forms of relief they are situated on and to their exposure to the hydro- geomorphological hazards within the Eremitu administrative territorial border (where: 1- floodplain, 2-hillslopes and connecting1/2015 surfaces, 3- hillslopes displaying nr, complex modelling, 4- active landslides, 5- IX, interfluvial surfaces, 6- the risers of the terraces, 7-the tread of the terraces 8- alluvial fan, 9- the administrative territorial border, 10-localities, 11- floodplain area for 1% return period events, 12-the class of landslideAN occurrence probability: P1-low, P2- medium, P3-medium-high, P4-high, 13-roads, 14- the built-up area).

NAPOCENSIS

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Fig. 4. Classification of the built-up area and roads according to the various forms of relief they are situated on and to their exposure to the hydro-geomorphological hazards within the Hodoșa administrative territorial border

72 Quantitative evaluation of multi-vulnerability to hydro-geomorfological hazards in the upper sector of Niraj Catchment

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Fig. 5. Classification of the built-up area and roads according to the various forms of relief they are situated on and to their exposure to the hydro-geomorphological hazards within the Vargata administrative territorial border NAPOCENSIS

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Fig. 6. The percentual distribution of the road network and the buildings according to the hydro- geomorfhologic probability classes

73 Geographia Napocensis Anul IX, Nr. 1, 2015

The predominant buildings position from the The present study consists in an analysis Vărgata commune in the 1% floodplain area, concerning the built-up area and main road hence in the floodplain and the inferior terrace exposure to the hydro-geomorphological of the Niraj River, constitutes a flooding processes from the upper sector of the Nirajului exposure when it comes to the built-up area and hydrographic basin. Their localization within roads. However on the account of the relative territories characterised by different return stability imposed by the mild slopes, the periods of the processes mentioned has also occurrence probability of landslides is low (Fig. been taken into account. As a consequence 5). An exception to the rule is the Vad locality qualitative and georeferenced data indicating the that displays a medium-high probability for 44 spatial susceptibility classes have been obtained of its buildings and for the remainder of 228, a as specified by the recommended methodology medium probability, due to morphometric at a national level via the Governmental conditions favouring the occurrence of hillslope decision 447/2003. Qualitative data- referring processes. to the number of buildings and1/2015 the road length, The analysis of the road network distribution classified according to the susceptibility classes in the analysed communes for determining their they belong to, has alsonr, been obtained- data that vulnerability to the hydro-climatic hazards can easily and successfully be used in reveal road sectors displaying a high quantitative studiesIX, for identification of risk probability, Eremitu, Mătrici, Isla and Vad related to the hydro-geomorphological hazards. representing road sectors under the incidence of AN mass movement processes. Acknowledgments This paper is made and published under the 4. Conclusions aegis of the Research Institute for Quality of The geomorphological applicative analysis Life, Romanian Academy as a part of due to its functions, offers useful data for the programme co-funded by the European Union identifying of the relief evolutionary tendencies within the Operational Sectorial Programme for that have proven so many times their usefulness Human Resources Development through the when it comes to regional studies. The functions project for Pluri and interdisciplinary in doctoral of the geomorphological applicativeNAPOCENSIS analysis and post-doctoral programmes Project Code: consist of: risk identification of the generating POSDRU/159/1.5/S/141086. processes comprised within the territorial equation; the system functioning diagnosis, a system within a relief unit that was previously REFERENCES outlined on the basis of natural criteria (in the present study according to the hydrographic [1] ARMAŞ IULIANA, (1999), Bazinul subwatersheds) or on the geographianapocensis.acad-cluj.robasis of administrative hidrografic Doftana: studiu de geomorfologie, criteria (territorial administrative units, Editura Enciclopedică, Bucureşti; administrative borders of the component [2] CASCINI L, BONNARD CH, COROMINAS J, JIBSON R, MONTERO-OLARTE J., (2005) localities etc.) GEOGRAPHIA Landslide hazard and risk zoning for urban Concerning vulnerability as seen through the planning and development, în: Hungr O, Fell R, degree of the possible losses due to the risk- Couture R, Eberhardt E (coord.), Landslide generating natural phenomenon, characterised Risk Management, Proceeding of the by frequency and magnitude, most frequently International Conference on Landslide Risk the quantification and integration of the risk Management, Vancouver, Canada. A.A. elements is done. It is achieved via their Balkema Publishers, Taylor & Francis Group, classifying within the corresponding Londra, p. 199-235; susceptibility classes (for which a spatial [3] COROMINAS, J., (2008), Framework for analysis related to their return period had been Landslide Quantitative Risk Assessment – done). Intensive Course, Barcelona; 74 Quantitative evaluation of multi-vulnerability to hydro-geomorfological hazards in the upper sector of Niraj Catchment

[4] CROZIER, M.J., (1997), The climate–landslide [15] POLEMIO, M, PETRUCCI, O., (2010), couple: a Southern Hemisphere perspective. In: Occurrence of landslide events and the role of Matthews, J.A., Brunsden, D., Frenzel, B., climate in the twentieth century in Calabria, Gläser, B. &Weiß, M.M. (eds.), Rapid Mass southern Italy, în Quaterly Journal of Movement as a Source of Climatic Evidence for Engineering Geology and Hydrogeology, the Holocene. Gustav Fisher, Stuttgart, 43:403-415 DOI:10.1144/1470-9236/09-006; Palaeoclimate Research, 19: 333–354 ; [16] ROŞCA SANDA, (2011), The flash floods [5] Cutter, S., (2001), A research agenda for analysis, representative for Niraj river between vulnerability and environmental hazards. IHDP 1970-2008, în Air and Water components of the Newsletter Update 2, Article 3. Enviroment, Cluj Napoca; [6] DAI, F., C., LEE, C.F., NGAI, Y.Y., (2002), [17] ROȘCA, SANDA, PETREA, D., BILAŞCO, Landslide risk assessment and management: an ŞT., RUS, I., IRIMUŞ, I.-A., FODOREAN, I., overview. Engineering Geology, 64, 65-87; VESCAN, I., (2014), Assessment Of Flood [7] FELL R, COROMINAS J, BONNARD C, Hazard And Risk Using Gis And Historical CASCINI L, LEROI E, SAVAGE WZ, (2008) Data. Case-Study: The 1/2015 Niraj River Basin Guidelines for Landslide Susceptibility, (Transylvania Depression, Romania), in Hazard, and Risk Zoning for Land Use Informatics, Geoinformaticsnr, and Remote Planning, Engineering Geology 102: 85-98; Sensing, Conference Proceedings – [8] GARRELTS, H. & LANGE, H., (2011), Path Photogrametry and Remote Sensing, dependencies and path change in complex Cartography andIX, GIS, Volume III, pp. 497-504; fields of action: Climate adaptation policies in [18] ROȘCA SANDA, 2014, Application of soil loss Germany in the realm of flood risk scenarios using the ROMSEM model depending management. AMBIO, 40: 200–209; on maximumAN land use pretability classes. A [9] GRECU FLORINA, (1992), Bazinul case study, în Studia UBB Geographia, LIX, Hârtibaciului – Elemente de morfohidrografie, pp. 101-116; Edit Academiei, Bucureşti. [19] SCHMIDT J., DIKAU, R., (2004), Modelling [10] HORTON, R., E, (1945), Erosional historical climate variability and slope stability. developmets of streams and their drainage Geomorphology, 60, 433-447. basins: hydrophysical approch to quantitative doi:10.1016/j.geomorph.2003.11.001 ; morphology. în Geological Society of America, [20] STRAHLER, A., N., (1957), Quantitative Bulletin 56, 273-370; Analysis of Wathershed Geomorphology, in [11] JONKMAN, S. N., (2005), Global perspectives Transactions, American Geophysical Union, 38 on loss of human life caused by NAPOCENSISfloods. Natural (6), 913-920. Hazards, 34 (2), 151-175; [21] ZĂVOIANU, I, (1978), Morfometria bazinelor [12] LASDA, O, DIKOU, A. & PAPAPANAGIOTOU, hidrografice, Editura Academiei, București E., 2010. Flash flooding in Attika, Greece: [22] ZĂVOIANU, I., (2006), Hidrologie, Editura Climatic change or urbanization?. AMBIO, 39: Fundaţiei România de Mâine, Bucureşti; 608–611; [23] *** (2003), Government Order no. 447 since [13] MARZOCCHI, W., MASTELLONE, M., L., April, 10, 2003, concerning the approval of the DI RUOCCO, A., NOVELLI,geographianapocensis.acad-cluj.ro P., ROMEO, E., methodologycal rules related to the drafting and GASPARINI, P., (2009), Principle af multi-risk content of the natural hazards at floods and assessment, research performed in the frame of landslides maps, published in Monitorul Na.R.AsGEOGRAPHIA (Natural Risks Assessment) FP6 SSA Oficial, May, 7. 2013. (In Romanian); Project No. 511264,Napoli, Italia; [24] *** EPA, 2003, Framework for Cumulative Risk [14] PETREA, D., BILAŞCO, ŞT., ROŞCA, S., Assessment, US Environmental Protection VESCAN. I., FODOREAN, I., (2014), The Agency, Washington, DC 20460, disponibil determination of the Landslide occurence online: http://epa.gov/ncer/cra/ probability by spatial analysis of the Land [25] *** 2012. EEA Report, Climate change, Morphometric characteristics (case study: The impacts and vulnerability in Europe 2012, EEA Transylvanian Plateau), in Carpathian Journal Report, No.12/2012, ISSN 1725-9177, 300 pp; of Earth and Environmental Sciences., 9: 91- [26] www.eurosense.com. 110;

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