Application of Satellite Imagery and Water Indices to the Hydrography of the Cetina River Basin (Middle Adriatic)

The paper gives a brief description of the remote sensing method used for the identification and extraction of water surfaces. Landsat 8 and Sentinel 2 satellite imagery was used to separate land from bodies of water in the complex karst area surrounding the Croatian Cetina River, flowing into the Adriatic Sea. Water indexing methods are presented in detail. The most frequently used water indices were selected: NDWI, MNDWI, AWEI_nsh, AWEI_sh, WRI and LSWI, and their results compared. The combination of satellite imagery and calculated water indices is concluded to be very useful for the identification and mapping of the area and banks of lakes, riverine zones, river mouths and the coastline in the coastal zone. Landsat 8 satellite imagery is slightly inferior to Sentinel 2 due to lower image resolution. The best results were obtained with the NDWI water index and the worst with LSWI

Vergleich von Algorithmen zur Kartierung der Küstenlinie mittels Satellitenmethoden

U radu su prikazane metode određivanja obalne crte, a detaljnije je prikazana metoda korištenja algoritama daljinske detekcije. Analizirani su rezultati najčešće korištenih algoritama vodenih indeksa: NDWI, MNDWI, AWEI_nsh, AWEI_sh i WRI, koji se koriste za potrebe određivanja obalne crte ili općenito vodenih površina. Algoritmi su primijenjeni na Landsat 8 i Sentinel 2 satelitskim scenama, a kao testno područje je odabrana srednja Dalmacija. Nakon izračuna vodenih indeksa, na područjima je provedena nenadzirana klasifikacija, zatim reklasifikacija i na kraju je prikazana ocjena točnosti klasifikacije pojedinog indeksa. Rezultati su u krupnijem mjerilu prikazani na dva područja: ušće rijeke Jadro u Solinu i ušće rijeke Cetine u Omišu. Analiza rezultata je pokazala da najbolje rezultate daje NDWI, a najlošije AWEI_nsh vodeni indeks.The paper presents the methods of coastline determination and describes the method using remote sensing algorithms in more detail. It further analyses the results of the most widely used algorithms of the water indices NDWI, MNDWI, AWEI_nsh, AWEI_sh and WRI, which are used for determining coastlines and water surfaces in general. The algorithms were applied to the Landsat 8 and Sentinel 2 satellite imagery, with central Dalmatia selected as the test area. After the calculation of water indices, unsupervised classification and reclassification were conducted in these areas and, finally, the evaluation of the classification accuracy for each individual index was presented. The results were shown at larger scale for two areas – the Jadro river mouth in Solin and the Cetina river mouth in Omiš. The result analysis revealed that the best results were obtained using the NDWI water index and the poorest results using the AWEI_nsh water index.Im Beitrag werden die Methoden zur Bestimmung der Küstenlinie und insbesondere die Anwendung von Algorithmen zur Fernerkundung dargestellt. Die Ergebnisse von am meisten genutzten Algorithmen zur Berechnung der für die Bestimmung von Küstenlinien oder allgemein von offenen Gewässern genutzten Wasserindices, d.h. NDWI, MNDWI, AWEI_nsh, AWEI_sh und WRI, werden analysiert. Die Algorithmen wurden auf die Landsat 8 und Sentinel 2 Satellitenszenen von in Mitteldalmatien befindlichen Testgebieten angewendet. Nach der Berechnung der Wasserindices wurden für die Testgebiete erstens unüberwachte Klassifizierung und zweitens Reklassifizierung durchgeführt, und schließlich wurde die Richtigkeit der Klassifikation einzelner Indices beurteilt. Die Ergebnisse werden für zwei Gebiete – die Mündung des Flusses Jadro in der Stadt Solin und die Mündung des Flusses Cetina in Omiš – in größerem Maßstab gezeigt. Die Analyse der Ergebnisse zeigte, dass die besten Ergebnisse mit NDWI und die schlechtesten mit AWEI_nsh erzielt wurden

Ekstremne vrijednosti visina valova za područje sjevernog Jadrana

Extreme return values of significant wave heights were calculated using the data of wave heights measured in the open part of the northern Adriatic (platforms PANON and LABIN, lighthouse Sv. Ivan na pučini), by approximating the distribution of monthly extremes by Fisher-Tippet curve (F-T I). Parameters of F-T I distribution of extremes were estimated using three methods: graphic method, method of moments, and maximum likelihood method. Comparison of the results obtained from each method has shown that extreme return values of significant wave heights obtained using the maximum likelihood method best agree with the data of direct instrumental measurements. The greatest significant wave heights are to be expected in the winter period, from December to February. Absolute calculated monthly maximum of a significant wave height occurs in February, being 7.54 m for the return period of 100 years. Major deviations are evident in the summer period (overestimated values), due to a small number of measured data and their dispersion. Extreme expected value of significant wave height in the northern Adriatic for the return period of 100 years is 8.57 m, from which a maximum wave height of about 14 m is estimated, being considered real as regards the maximum measured value of 10.8 m.Koristeći podatke valnih visina mjerenih u otvorenom dijelu sjevernog Jadrana (platforme PANON i LABIN, svjetionik Sv. Ivan na pučini) izračunate su ekstremne povratne vrijednosti značajnih visina, na način da je razdioba mjesečnih ekstrema aproksimirana Fisher-Tippett krivuljom prvog tipa (F-T I). Parametri F-T I razdiobe ekstrema procijenjeni su pomoću tri metode: grafičkom metodom, metodom momenata, te metodom maksimalne vjerojatnosti (maximum likelihood). Usporedba rezultata pojedinih metoda pokazala je da se povratne ekstremne vrijednosti značajnih valnih visina dobivene metodom maksimalne vjerojatnosti ponajbolje podudaraju s podacima direktnih instrumentalnih mjerenja. Najveće značajne visine vala treba očekivati u zimskom razdoblju, od prosinca do veljače. Apsolutni izračunati mjesečni maksimum značajne valne visine je u veljači i iznosi 7.54 m za povratni period od 100 godina. Značajnija odstupanja zapažaju se u ljetnim mjesecima (precijenjene vrijednosti) zbog malog broja i velikog raspršenja mjerenih podataka. Ekstremna očekivana vrijednost značajne visine vala u sjevernom Jadranu za povratni period od 100 godina iznosi 8.57 m, iz čega se može procijeniti maksimalna visina vala od oko 14 m, što se smatra realnim s obzirom na maksimalnu izmjerenu vrijednost od 10.8 m

Vergleich von Algorithmen zur Kartierung der Küstenlinie mittels Satellitenmethoden

U radu su prikazane metode određivanja obalne crte, a detaljnije je prikazana metoda korištenja algoritama daljinske detekcije. Analizirani su rezultati najčešće korištenih algoritama vodenih indeksa: NDWI, MNDWI, AWEI_nsh, AWEI_sh i WRI, koji se koriste za potrebe određivanja obalne crte ili općenito vodenih površina. Algoritmi su primijenjeni na Landsat 8 i Sentinel 2 satelitskim scenama, a kao testno područje je odabrana srednja Dalmacija. Nakon izračuna vodenih indeksa, na područjima je provedena nenadzirana klasifikacija, zatim reklasifikacija i na kraju je prikazana ocjena točnosti klasifikacije pojedinog indeksa. Rezultati su u krupnijem mjerilu prikazani na dva područja: ušće rijeke Jadro u Solinu i ušće rijeke Cetine u Omišu. Analiza rezultata je pokazala da najbolje rezultate daje NDWI, a najlošije AWEI_nsh vodeni indeks.The paper presents the methods of coastline determination and describes the method using remote sensing algorithms in more detail. It further analyses the results of the most widely used algorithms of the water indices NDWI, MNDWI, AWEI_nsh, AWEI_sh and WRI, which are used for determining coastlines and water surfaces in general. The algorithms were applied to the Landsat 8 and Sentinel 2 satellite imagery, with central Dalmatia selected as the test area. After the calculation of water indices, unsupervised classification and reclassification were conducted in these areas and, finally, the evaluation of the classification accuracy for each individual index was presented. The results were shown at larger scale for two areas – the Jadro river mouth in Solin and the Cetina river mouth in Omiš. The result analysis revealed that the best results were obtained using the NDWI water index and the poorest results using the AWEI_nsh water index.Im Beitrag werden die Methoden zur Bestimmung der Küstenlinie und insbesondere die Anwendung von Algorithmen zur Fernerkundung dargestellt. Die Ergebnisse von am meisten genutzten Algorithmen zur Berechnung der für die Bestimmung von Küstenlinien oder allgemein von offenen Gewässern genutzten Wasserindices, d.h. NDWI, MNDWI, AWEI_nsh, AWEI_sh und WRI, werden analysiert. Die Algorithmen wurden auf die Landsat 8 und Sentinel 2 Satellitenszenen von in Mitteldalmatien befindlichen Testgebieten angewendet. Nach der Berechnung der Wasserindices wurden für die Testgebiete erstens unüberwachte Klassifizierung und zweitens Reklassifizierung durchgeführt, und schließlich wurde die Richtigkeit der Klassifikation einzelner Indices beurteilt. Die Ergebnisse werden für zwei Gebiete – die Mündung des Flusses Jadro in der Stadt Solin und die Mündung des Flusses Cetina in Omiš – in größerem Maßstab gezeigt. Die Analyse der Ergebnisse zeigte, dass die besten Ergebnisse mit NDWI und die schlechtesten mit AWEI_nsh erzielt wurden

MOSTAR AREA LAND SURFACE TEMPERATURE DETERMINATION WITH SATELLITE METHODS

U članku su ukratko prikazani najkritičniji faktori koji utječu na temperaturu tla. Većina se tih čimbenika može naći na području grada Mostara. Najjednostavniji i najčešće korištena metoda određivanja površinske temperature tla je obrada termalnih kanala satelitskih scena. Landsat je najduža i najraširenija satelitska misija s slobodnim podacima. Za potrebe ovog istraživanja su korišteni Landsat 5, 7 i 8 satelitske scene i slobodni meteorološki podaci iz kojih su izračunate atmosferske korekcije, a zatim površinska temperatura tla (PTT) za područje Mostara. Korištene su četiri zimska scene (uzete u hladnijem dijelu godine), i četiri ljetne scene (uzete u najtoplijem dijelu godine). Iz obrađenih se podataka može zaključiti da se Mostar može smatrati jednim od najtoplijih gradova u Bosni i Hercegovini i šire.The article briefly presents the most critical factors that affect the soil temperature. Most of these factors can be found in city of Mostar area. The simplest and the most widely used method of land surface temperature determination is processing of thermal bands of satellite scenes. Landsat is the longest and most widely used satellite mission with open data. For the purposes of this study Landsat 5, 7 and 8 satellite scenes and open meteorological data were used, from which the atmospheric correction, and then land surface temperature (LST), were calculated for Mostar area. Four winter scenes (taken in the colder part of the year) and four summer scenes (taken in the warmest part of the year) were used. From all processed data, it can be concluded that Mostar can be considered as one of the warmest cities in Bosnia and Herzegovina and wider

Land Surface Temperature Determination in the Town of Mostar Area

The article presents the most critical factors that affect the soil temperature, such as the effects of the canyon, anthropogenic heat, greenhouse effect, effective reflectivity, evaporating reduction and turbulent transfer of heat. Most of these factors can be found in the town of Mostar area. The simplest and the most widely used method of land surface temperature determination is processing of thermal channels satellite scenes. Landsat is the longest and most widely used satellite mission with open data. For the purposes of this study Landsat 5, 7 and 8 satellite scenes were used and open meteorological data from which the atmospheric correction was calculated, and then land surface temperature (LST) for the Mostar area. Three winter scenes were used (occurred in the colder part of year) and three summer scenes (occurred in the warmest part of the year). From all processed data can be concluded that Mostar can be considered as one of the warmest towns in Bosnia and Herzegovina and wider

Satellite Derived Bathymetry Survey Method – Example of Hramina Bay

Satellite Derived Bathymetry (SDB) method uses satellite or other remote multispectral imagery for depth determination in very shallow coastal areas with clear waters. Commonly, SDB survey method can be used when planning hydrographic surveying of marine areas not surveyed or areas with old bathymetric data. This method has become widely used in the past few years. SDB is a survey method founded on analytical modelling of light penetration through the water column in visible and infrared bands. In this article, SDB method was applied by using free-of-charge Landsat 8 and Sentinel 2 satellite images to get the bathymetric data in the area of Hramina Bay in the Central Adriatic. SDB processing procedures and algorithms were described. Processed satellite data was uploaded on geodetic software and ENC S-57 format. The bathymetric map of Hramina Bay obtained by the SDB method was compared with the approach usage band Electronic Nautical Chart (ENC) HR400512 with satisfying positional and vertical accuracy

Oscilacije inercijalnog perioda u sjevernom Jadranu

Since 1978, Hydrographic Institute of the Yugoslav Navy has organised continous meteorological and oceanographic measurements at the oil-driling platform “Panon”. The existence of inertial-period oscillations was observed only in summer season when sub-tropical high pressure disappears and cyclonic disturbances travel towards the Adriatic Sea. Inertial oscillations are unbalanced motions in stratified sea. They are generated by the temporal variations of the wind and occur outside the coastal boundary layer during geostrophic adjustment process. In this paper inertial oscillations were examined in August, 1985, when the platform “Panon” was located in the North Adriatic. Current data were subjected to the rotary spectral analysis. The most prominent peaks are centred at the local inertial frequency in the clockwise part of the spectrum at three depths. The inertial peak in the surface layer was almost one order of magnitude larger than the peaks at 25 and 63 meters depth. The 180° phase-lag between the surface and deeper layers was observed. Zero-crossing was probably in the termocline. During the outset of the stormy wind, mean hourly current speed reached value of about 60 cm s-1