Abstract. The bathymetric survey of Lake Vrana included a wide range of activities that were performed in several different stages, in accordance with the standards set by the International Hydrographic Organization. The survey was conducted using an integrated measuring system which consisted of three main parts: a single-beam sonar HydroStar 4300 and GPS devices; a Ashtech ProMark 500 base, and a Thales Z-Max ® rover. A total of 12 851 points were gathered.In order to find continuous surfaces necessary for analysing the morphology of the bed of Lake Vrana, it was necessary to approximate values in certain areas that were not directly measured, by using an appropriate interpolation method. The main aims of this research were as follows: (a) to compare the efficiency of 14 different interpolation methods and discover the most appropriate interpolators for the development of a raster model; (b) to calculate the surface area and volume of Lake Vrana, and (c) to compare the differences in calculations between separate raster models. The best deterministic method of interpolation was multiquadric RBF (radio basis function), and the best geostatistical method was ordinary cokriging. The root mean square error in both methods measured less than 0.3 m.The quality of the interpolation methods was analysed in two phases. The first phase used only points gathered by bathymetric measurement, while the second phase also included points gathered by photogrammetric restitution.The first bathymetric map of Lake Vrana in Croatia was produced, as well as scenarios of minimum and maximum water levels. The calculation also included the percentage of flooded areas and cadastre plots in the case of a 2 m increase in the water level. The research presented new scientific and methodological data related to the bathymetric features, surface area and volume of Lake Vrana.
Abstract. The bathymetric survey of Lake Vrana included a wide range of activities that were performed in several different stages, in accordance with the standards set by the International Hydrographic Organization. The survey was conducted using an integrated measuring system which consisted of three main parts: a single-beam sonar Hydrostar 4300, GPS devices Ashtech Promark 500 – base, and a Thales Z-Max – rover. A total of 12 851 points were gathered. In order to find continuous surfaces necessary for analysing the morphology of the bed of Lake Vrana, it was necessary to approximate values in certain areas that were not directly measured, by using an appropriate interpolation method. The main aims of this research were as follows: to compare the efficiency of 16 different interpolation methods, to discover the most appropriate interpolators for the development of a raster model, to calculate the surface area and volume of Lake Vrana, and to compare the differences in calculations between separate raster models. The best deterministic method of interpolation was ROF multi-quadratic, and the best geostatistical, ordinary cokriging. The mean quadratic error in both methods measured less than 0.3 m. The quality of the interpolation methods was analysed in 2 phases. The first phase used only points gathered by bathymetric measurement, while the second phase also included points gathered by photogrammetric restitution. The first bathymetric map of Lake Vrana in Croatia was produced, as well as scenarios of minimum and maximum water levels. The calculation also included the percentage of flooded areas and cadastre plots in the case of a 2 m increase in the water level. The research presented new scientific and methodological data related to the bathymetric features, surface area and volume of Lake Vrana.
The main objective of this paper was to discuss applications of GIS based multi-criteria decision analysis (GIS MCDA) and Analytical Hierarchy Process (AHP). These two techniques were applied in order to assist preparation of the Tourism Management Plan, depicting the most suitable zones for ecotourism development in Dikgathlong Dam Lease Area (DDLA) as one of the largest resources of potable water in Botswana. The MCDA was based on geo-morphometric, hydrologic, landscape and community indicators and criteria which emanated from expert's opinions, intensive field survey and literature review. In addition the AHP has helped to calculate individual criteria weights and to point the degree of suitability zones classified as highly suitable, moderately suitable, marginally suitable and not suitable for ecotourism. After performing both processes and establishing broad management zones it has been found that the Sustainable Development Scenario is the most appropriate option as the future ecotourism development proposal. This research provides new methodology that can be incorporated into future tourism policies and management strategies.
Original scientific paper The aim of this research is to choose the most appropriate interpolators for the purpose of geomorphologic research, by comparing 7 deterministic methods. For the purpose of developing a model and comparing interpolators, the research used a set of elevation data gathered by aero-photogrammetry and stereo-restitution. The accuracy of interpolation methods was tested by analysing 8 statistic parameters, which were obtained by methods of crossvalidation, split sampling and jackknifing. Apart from analysing the parameters, the research also compared the interpolation methods by visual means, through graphic representation of data (two-dimensional and three-dimensional) on the basis of credible graphic representations of sets of data. The research also tested the effect of power, number of neighbours, distance and sectors on the quality of output data. The multiquadratic radial basis function (MQ-RBF) proved to be the best deterministic method of interpolation by all the relevant parameters.Keywords: digital terrain model; deterministic interpolation methods; methods of comparison of interpolation methods; root mean square error; Vrana Lake Nature Park Točnost determinističkih metoda interpolacije u generiranju digitalnog modela reljefa -primjer PP Vransko jezeroIzvorni znanstveni članak Cilj istraživanja je, usporedbom 7 determinističkih metoda interpolacije, odabrati najprikladnije interpolatore za potrebe geomorfoloških istraživanja. Za izradu modela i usporedbu metoda interpolacije korišten je skup visinskih podataka prikupljenih aerofotogrametrijskom izmjerom i stereorestitucijskom obradom. Točnost metoda interpolacije ispitana je analizom 8 statističkih parametara koji su dobiveni metodama unakrsnog vrednovanja, podijeljenih uzoraka i ponovno uzorkovanje (jackknifing). Osim analize parametara, interpolacijske metode su uspoređene i vizualno, kroz grafički prikaz podataka (dvodimenzionalno i trodimenzionalno) na osnovi vjerodostojnih grafičkih prikaza skupa podataka. Ispitan je utjecaj eksponenta udaljenosti, broja susjeda, udaljenosti i sektora na izlazne rezultate. Utvrđeno je da je multikvadratna radijalna osnovna funkcija (MK-ROF) po svim parametrima najbolja deterministička metoda interpolacije.Ključne riječi: digitalni model reljefa; determinističke metode interpolacije; metode usporedbe metoda interpolacije; PP Vransko jezero; srednja kvadratna pogreška
Dostupnost urbanih zelenih površina (UZP) sastavni je element zadovoljavajuće kvalitete života. Zbog nagle urbanizacije proučavanje zelenih površina postaje jedan od ključnih elemenata urbanističkog planiranja. Funkcionalna mreža prometnog sustava i optimalan prostorni raspored UZP-a preduvjeti su za održavanje ekološke ravnoteže urbanog krajolika. Analiza dostupnosti UZP-a u naselju Zadar izvršena je u sklopu projekta Urban Green Belts Project (UGB). Analizi je prethodila izrada prostorno-orijentirane baze UZP-a. Podaci su prikupljeni metodom nadzirane klasifikacije multispektralnih LANDSAT snimaka i metodom ručne vektorizacije DOF snimaka. U prvoj fazi istraživanja izvršena je analiza dostupnosti UZP-a prema ANG standardu. Indikator dostupnosti generiran je na temelju sedam objektivnih mjera koji uključuju površinu UZP-a po stanovniku te dostupnost šest funkcionalnih razina UZP-a. Izvedeni indikator dostupnosti uspoređen je sa subjektivnim mjerama koje su izvedene anketnim ispitivanjem 718 ispitanika unutar 41 statističkog kruga. Prikupljeni podaci reflektiraju individualnu procjenu te zadovoljstvo dostupnošću UZP-om. Ovo istraživanje istaknulo je važnost korištenja objektivnih i subjektivnih mjera u procesu razumijevanja dostupnosti UZP-a. Rezultati su pokazali da prilikom vrednovanja dostupnosti stanovnici naglasak stavljaju na uže stambeno okruženje, zanemarujući time više funkcionalne razine UZP-a. Nadalje, velike količine UZP-a unutar grada (114 m² po stanovniku) ne moraju generirati slično zadovoljstvo njihovom dostupnošću. Izlazni rezultati mogu služiti kao smjernice za daljnji razvoj grada u kontekstu planiranja funkcionalne mreže UZP-a.
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