Glacial and periglacial data integration in a GIS: methodology used in the Serra da Estrela, Portugal

Geological Quarterly, 2000,44 (1): 27-3 1 Glacial and periglaeial data integration in a GIs: methodology used in the Serra da Estrcla, Portugal Gonqalo Teles WEE4 Vieira 0. T. (2000) - Crlaciaf and pcriglaciol data integration in a GIS: mcthodalogy used in the Serra da Estreta, Portugd. Geol. Quart., 44 (1): 27-3 1. The methodology applied in the research in Serra da Estrela (Potttlgal} is to integrate glacial and pcriglacial gcomorphological data in a Geographical Information System and a Database Management System. The main objective of thc procedure is to make use of low cost software for geospatial data integration, statistical analysis and production of geomorphoEogicd mag. The digital storage format provides the means for fast access and easy tmnsportation of Ule data during field cnmpaigns. It is also a very useful way to store the geomorphologicui data, so it can be used in the future by other researchers working in the area GonpIa Teles Yreim, Centm de Estrrdas Geogr&cm, Unhvrsidade de Lisboa, Faculdade & Lem, CiAde Universitnriu, 160IF214 L~sboa, Por~ugol; e-maib [email protected] (received: August 12, 1999; accepted: September 27,1999). Key words: PortugaI, Serra dn Esttela, glacinl geomorpholagy, GIs, DBMS. MTRODUCTION mapping, sedimenhlogical study ofthe d~posits and dating, led to a new lihe of research conducted by investigators from the Physical Geography and Environmental Research Group ofthe The Serra da Estrela (1,993 m as.1.) is a granitic mountain Centro de Estudos Geogdficos (University of Lisbon), whicli located in the Iberian Cordillera Central (Fig. I). It is a started in 1995. significant ma in the framework of Quaternary science, as it It became clear very early that the data collection generated presents the best preserved glacial and periglacial landscape of signscant amounts of information that would rapidly become Portugal. ne geographical position of the mountain at 40"20'N difficult to manage. It was decided to store the data in digital md 15, and low altihlde make it an important format in order to promote an easy access to information, site for palaeogeographical reconsmction in the western availability for statistical analysis, visualisation, printing, etc, European framework. Despite the absence of direct absolute Furthermore, the use of CD-ROM for data storage should allow datings, glacial deposits and landfms are attributed to the Last high mobility for the whole database (e,g, during fieldwork Glacial Maximum (Daveaq 1 97 1 ; Ferreira, I 998; Vieira and campaigns)- Ferreira, 1998). 'I%e more significant periglacial evidences are Taking into account the financial limitations for the research attributed to the same period, but mom recent periglacial events and the lack of personnel it was decided that the software should seem to have occurred (Vieira, 1 998). Above ca. 1,750 m a.s.l., be affordable and relatively simple to use. Therefore, for the marginal cryogenic processes are active today and play a role in construction and analysis of the cartographic database we use the morphogenesis. the raster Geographical Information System IL WlS CJntegmted General aspects ofthe glaciation of he Serra da Estrcla were Land and Water Infomation System) and for the final outputs fmt pointed out by Lautensach in 1932. In the late 60"s S. the design package Microstation 95 is employed. The alphanuDaveau defined with a good accuracy the glaciation limits and meric data are stored in a relationaI data basr: management systheir chamcteristics (see Daveau, 1971). But until the mid-90's tern (cf. IAEA, 1993). The data transfer between the three packresearch on glacial and perigIacia1 problems of the Serra da ages is relatively simple but not direct. In the future we intend to Estrela had almost: stopped The need for better knowledge of compile the data in CD-ROM using a current Internet bmwser glaciation, especially rearding detailed geomorphological as a viewer (Fig. 2). 28 Gonqalo Teles Vieira I The examples presented in this paper relate to the geomorphoIogical research carried out in the ZGzere catchment (ca. 62 km2), chosen as the first area to be studied in the Serra da ' Eslxela. CARTOGRAPHIC DATABASE The cartographic database incorporates the spatiaI information and includes point, line and area (polygon and raster) data and attribute tables (Fig. 33, The GI5 software that is used allows the djrect digitising (via digitising tablet or on-screen, using a pointing device) of cartographic data (Budde e& al., 1997; Van Wesren and Parifteh, 1997; Van Westen et a/., 1997). The data sources are published maps, aerial photographs, orthophotographic maps and field maps. Georeferenced points also can be entered into the database (e.g. txpostrres of deposits or GPS reference marks), Point, line and polygon data are linked to attribute tables. 11ese types of layers can only be used directly for visualisation purposes; for analytical purposes a raster transformation needs to be performed. The geomorphoIogica1 data layers constructed in the GIs are to be exported to Microstation 95 and will be used For the production of detaiIed geornorphological maps of the study areas. THE DlGFTAL ELEVATlON MODEL AND DERIVATIVE LAYERS I The Zkere catchment Digital Elevation Model (DEM) was constructed from a 10 rn contour interval topographic map rasterized using 10 rn pixels. This size allows the detailed location of the fentures in the field and a good spatial resolution for the DEM. Fig. 1. Location of the Serrn da Estrcja in Pottug~l Databe Managmt Information System System - Ribliographical rcse=mh - Colle~tiog pre-cxisting map - Awinl photo inlerpmtion - Sedimentologicol analysis I Dnta adysis I I StmgdArehi~iy I I Compufer Aidcd Drawing I - Reeonaissancc ofthe terrain - Dcbiled geommpholog~cal mopping -1dentificalion and sludy dthe m&e s%psurcs -Photos ond obaemtions - Dmriptivc I Visualfsation based - Duailtd gmmorpholo~igicol - Quantilieatian I Morphamerrienl -Statistical Fig. 2. Methodology used in thc Serra da Estrela Glacial and perigIacial data integration in a GIs 29 Digital Elovation Modd - TopoPPfic MP - D~ne~OTk IL.LCssnd&+. .m Geologid map -w . . GeoIom-.r'- -- brn Field survey .~iold kvsy path8 , photDgnphs t+m Pig. 3. CMogmphic datab1~3c of he Zhere catEhmeot In gempatid analysis, theDEUis we ofthemast hpmt From the DEM it is pmsibIe h3genemte slope we and ' layers, as it is ibe ~FW for the ~~n of ofher topographic qact maps and with trigmmelrical formulae applied using derivative Iayers (e.g slope md wpe@ that are important iterations, to calculate ashmiow map for a chosen d& and hour whbh h a gemtatistical approach to geomorphologicaI (Vieira, 1999) and therefore potential radiation maps mdysis (Fig. 4). (Feficisimo, 1994; Meijerhk et d ,1994; Vie& 1999) pig. 4). Slope Angle Aspect 4 Digital Elevatiw Modd Potential Radiation (21 Dec) Potential Insolation (21 Dec) Pig. 4. Digital Elevation Mokl and some examples of den'yatiye faym cmtnrcted for them catEhment 30 Goado Teles Vieha Fig. 5. Display of the Dighi Elevation Model of the Ztzcrc valley with shaded rcticf as draw file Tfie Zeztre dcbrnent in markd in yellow, the main mil= ridges in red and !he dnts reprepent he exposum of Quaternary deposits These are especial& sigdlcant in tbe study of @ial and periglacial geommphoIogy. The DEM can also be used for generation of cross-sections and 3-D vhaIisaeion of lhe landscape, ifnecessary, using also raster drapes {e,g. geology or location ofthemoraines -Fig. 5). Hydrography. Layers with the hydrograpbicd Wmx include the drainage network and the Iakes and dams. They were Wtised from the 1:25,000 topogmphc map. The lakes in the Serra da Wa correspond to old glacier basins and are relict glacial forms. A unique identEcation was given to each of them, d they are linked to a table used for stmage of refated informdun. The &&age network layer sems for perfodng morphometrical analysis, and useful information can be retrieved from it enabling the bcof valley floors and calcuIations derived hm kt parameter. GeoIogy. The geology layerrwas digitised hm the 1:50,000 gwlogi~l map of the area qd represents the substratum. Surface deposits were digitised in a sepmte hyer and were mapped diredy in the field. The geology layer is originaUy a polygon layer connected to a table where the main chwacteristics of the geological formations are incIuded. Whenever an analysis is to be done, a raster layer with the chosen lifiological mute must be produced (e.g, texture, lithologid type). Geomorphology. The constnrction of the laye13 on the geomqhologicaI variables is one ofthe main objectives of the study that is being carried out in the ZEzere valley. The data are in fact a result of the research inthe area and therefore their integration proceeds as new Eeld data become available. The ~0morphoIogid layers include the swlicial deposits and the landforms layer. They were constructed using field obsmations and aerial photo hlqretation and their purpose is to serve both for visudisation and geostatistical analysis. Exposures of deposits are represented in a point map with unique identifiers for each deposit and linked to a table that allows logging their geographical and sedimentoIogica1 characteristics. The unique identifier allows fast access to fhe dphagumeric database of the deposits, which includes photographs and sketches of the exposum. ALPIMNUMERIC DATABASE The alphanumeric database incIwles the gem-efmnced point data repmentiug the exposures of deposits and pictures taken during field wmk It serves both for archive and analysis purposes and can be exported to the GIS package. The exposures database is an hustive record of the exposures in Quaternary deposits and holds photographs and other significant sedimentological and interpretative data (Fig. 6). The datq can be used for statistical analysis and cattographic representation. It is a vrtluable resource for future research in the area and aIso for landscape pImning issues in the hewok of the Sma da EstreIa MaturaI Park, as it allows for rapid Wcation of the more sideposits and of their &m&ristics. Glacial and pcriglacial data integration in a GIS 31 Deposit exposures data Iayer Deposit exposures data table D.id Location TL FA MT Coord. x Coord. y Alt (...) USI-t US 1 -esp (,..) -- ......... ... ......... ... C.S 3Ih3 ... ......... ... .,, ......... ... Photo database Ph.id D.id Datc Location Catchment Kcy-words Notcs (...I ......... ... 5km , Fig. 6. Organisntion of the dcposit exposum data in the GIS and DBMS (please note that the survey ofthe exposures in not yet cornplele) The photographs database includes all the pictures (and observations on their characteristics) made during field work. The digital fonnat of the data makes ie especialIy easy for bansportatioi~ and therefore to be carried in field campaigns. In this way, it is possible to visualise older photos and notes. CONCLUSIONS 7l1e integration of the glacial and periglacial data of the Serra da Estrela in a GTS constitutes an excellent way for storage of the data captured and produced during research projects in the area. This data is easy to retrieve and use, both for visualisation and analytical procedures. Expected uses for the database include the support for research conducted by investigators of the Centre de Estudos Geogr3icos and by students ofthe Deparhncnt of Geography of tlie University oflisbon. A project with thc Natural Park of the Serm da EstreIa is expected in order to promote the use of the database as a tool for planning purposes, especially in what concerns to the conservation of the geomoiphological assets of glacial and periglacial origin. 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