A new GA-IDW approach for interpolating the precipitation

This article presents a new algorithm for detecting the Inverse Distance Weighting Algorithm parameter (IDW) using an evolutionary technique. The algorithm was applied to interpolate 51 series of maximum annual precipitation series. Comparisons of its results with those of IDW and the optimized OIDW (a version of IDW optimized with PSO) are provided. The best performances are those of the actual approach.

DISTRIBUSI SUHU DAN SALINITAS PERMUKAAN DI PERAIRAN RANOOHA RAYA KECAMATAN MORAMO SULAWESI TENGGARA

Suhu permukaan laut dan salinitas merupakan parameter kunci oseanografi yang berperan untuk menilai kondisi ekologi lingkungan perairan, terutama di daerah perairan dangkal. Penelitian ini bertujuan untuk mengetahui distribusi spasial suhu dan salinitas permukaan di perairan Ranooha Raya. Metode penelitian menggunakan Hand Refraktometer dan Termometer untuk pengukuran langsung sampel air pada kedalaman 0-2 m. Analisis spasial distribusi suhu dan salinitas permukaan laut menggunakan teknik interpolasi Inverse Distance Weighting (IDW). Hasil penelitian menunjukkan bahwa nilai suhu permukaan laut cenderung homogen berkisar antara 28-30 0C pada saat pasang dan 29-32 0C pada saat surut. Nilai variasi salinitas permukaan laut cukup lebar berkisar antara 22-30 ppt yang diperoleh pada saat pasang dan berkisar antara 15-31 ppt pada saat surut. Distribusi nilai suhu dan salinitas permukaan laut menunjukkan bahwa semakin menjauhi garis pantai nilainya semakin tinggi. Faktor-faktor lingkungan, seperti presipitasi, evaporasi dan masukkan air tawar dari beberapa aliran sungai mempengaruhi perubahan nilai suhu dan salinitas perairan. Kata kunci: Analisis Spasial, Distribusi Spasial, Ranooha Raya, Salinitas Permukaan Laut, Suhu Permukaan Laut

Aiming for the Optimum: Examining Complex Relationships Between Sampling Regime, Sampling Density and Landscape Complexity to Accurately Model Resource Availability

Context Obtaining accurate maps of landscape features often requires intensive spatial sampling and interpolation. The data required to generate reliable interpolated maps varies with spatial scale and landscape heterogeneity. However, there has been no rigorous examination of sampling density relative to landscape characteristics and interpolation methods.ObjectivesOur objective was to characterize the 3-way relationship among sampling density, interpolation method, and landscape heterogeneity on interpolation accuracy in simulated and in situ landscapes. MethodsWe simulated landscapes of variable heterogeneity and sampled at increasing densities using both systematic and random strategies. We applied each of three local interpolation methods: Inverse Distance Weighting, Universal Kriging, and Nearest Neighbor — to the sampled data and estimated accuracy (R2) between interpolated surfaces and the original surface. Finally, we applied these analyses to in situ data, using a normalized difference vegetation index raster collected from pasture with various resolutions.Results All interpolation methods and sampling strategies resulted in similar accuracy; however, low heterogeneity yielded the highest R2 values at high sampling densities. In situ results showed that Universal Kriging performed best with systematic sampling, and inverse distance weighting with random sampling. Heterogeneity decreased with resolution, which increased accuracy of all interpolation methods. Landscape heterogeneity had the greatest effect on accuracy.ConclusionsHeterogeneity of the original landscape is the most significant factor in determining the accuracy of interpolated maps. There is a need to create structured tools to aid in determining sampling design most appropriate for interpolation methods across landscapes of various heterogeneity.

Pemetaan Kesesuaian Lahan Budidaya Rumput Laut Di Kecamatan Banyuputih, Situbondo Berdasarkan Indikator Kimia Air

Budidaya rumput laut adalah salah satu sub-kegiatan akuakultur yang sangat potensial untuk dikembangkan di Kecamatan Banyuputih, Situbondo. Tujuan dari penelitian ini adalah untuk memetakan kesesuaian lahan budidaya di Kecamatan Banyuputih Situbondo guna dapat digunakan sebagai area budidaya rumput laut berdasarkan nilai indikator parameter kimia air yang ada. Penelitian ini dilaksanakan di perairan pesisir Kecamatan Banyuputih, Situbondo selama bulan januari-maret 2019 dengan konsep penelitian lapang dan analisa spasial dari pengambilan data kimia air (oksigen terlarut, fosfat, dan nitrat) yang kemudian dianalisis menggunakan metode Inverse Distance Weighting (IDW) dan overlay pada aplikasi GIS (Geographic Information System) guna mendapatkan model visualisasi peta tematik kesesuaian lahan. Hasil penelitian menunjukan parameter oksigen terlarut, fosfat, serta nitrat berfluktuasi secara variatif dan dinamis selama masa penelitian berlangsung, dengan kisaran konsentrasi 5.4-6.1 mg/L (DO), 0.8-1.6 mg/L (PO4), dan 2.1-3.7 mg/L (NO3). Kondisi tersebut, menandakan bahwa perairan pesisir Kecamatan Banyuputih cenderung subur dan layak untuk digunakan sebagai lahan budidaya akuakultur. Pernyataan tersebut juga bisa dilihat dari hasil visualisasi warna pada gambar kesesuaian lahan di peta tematik peneltian. Nilai konsentrasi dari parameter DO (5.4-6.1 mg/L), fosfat (0.8-1.6 mg/L), dan nitrat (2.1-3.7 mg/L) di perairan Kecamatan Banyuputih juga masih sesuai dengan ambang batas baku mutu kualitas air yang diperuntukan untuk budidaya rumput laut. Sehingga dari penelitian ini dapat disimpulkan, dari berbagai gambar peta tematik hasil analisis spasial berdasarkan indeks parameter kimia air yang ada, lokasi perairan Kecamatan Banyuputih sangat layak dan potensial untuk dikembangkan sebagai area budidaya rumput laut yang produktif.

Static Reservoir Modeling Comparing Inverse Distance Weighting to Kriging Interpolation Algorithm in Volumetric Estimation. Case Study: Gullfaks Field

Understanding and characterizing the behaviour of the subsurface by combining it with a suitable statistical method gives a higher level of confidence in the reservoir model produced. Interpolation of porosity and permeability data with minimum error and high accuracy is, therefore, essential in reservoir modeling. The most widely used interpolation algorithm, kriging, with enough well data is the best linear unbiased estimator. This research sought to compare the applicability and competitiveness of inverse distance weighting (IDW) method using power index of 1, 2 and 4 to kriging when there is sparse data, due to time and budget constraints, to calculate hydrocarbon volumes in a fluvial-deltaic reservoir. Interpolation results, estimated from descriptive statistics, were insignificant and showed similar prediction accuracy and consistency but IDW with power index of 1 indicated the least error estimation and higher accuracy. The assessment of hydrocarbon volume calculations also showed a marginal difference below 0.08 between IDW power index of 1 and kriging in the reservoir zones. Reservoir segments cross-validation and correlation analysis results indicate IDW to have no significant difference to kriging with absolute errors of 3% for recoverable oil and 0.7% for recoverable gas. Grid upscaling, which usually causes a loss of geological features and extreme porosity values, did not impact the results but rather complemented the robustness of IDW in both fine and coarse grid upscale. With IDW exhibiting least errors and higher accuracy, the volumetric and statistical results confirm that when there are fewer well data in a fluvial-deltaic reservoir, the suitable spatial interpolation choice should be IDW method with a power index of 1.

Applied Research on InSAR and GPS Data Fusion in Deformation Monitoring

With the enrichment of land subsidence monitoring means, data fusion of multisource land subsidence data has gradually become a research hotspot. The Interferometry Synthetic Aperture Radar (InSAR) is a potential Earth observation approach, and it has been verified to have a variety of applications in measuring ground movement, urban subsidence, and landslides but similar to Global Positioning System (GPS). The InSAR observation accuracy and measurements are affected by the tropospheric delay error as well as by the Earth’s ionospheric and tropospheric layers. In order to rectify the InSAR result, there is a need to interpolate the GPS-derived tropospheric delay. Keeping in view of the above, this research study has presented an improved Inverse Distance Weighting (IIDW) interpolation method based on Inverse Distance Weighting (IDW) interpolation by using Sentinel-1 radar satellite image provided by European Space Agency (ESA) and the measured data from the Continuously Operating Reference Stations (CORS) provided by the Survey and Mapping Office of the Lands Department of Hong Kong. Furthermore, the corrected differential tropospheric delay correction is used to correct the InSAR image. The experimental results show that the correction of tropospheric delay by IIDW interpolation not only improves the accuracy of Differential Interferometry Synthetic Aperture Radar (D-InSAR) but also provides a new idea for the solution of InSAR and GPS data fusion.

POLA ARUS LAUT PERMUKAAN DI PERAIRAN TANJUNG TIRAM KONAWE SELATAN

Arus laut permukaan merupakan arus laut yang bergerak pada lapisan massa air permukaan. Beberapa faktor yang membangkitkan arus permukaan pada perairan sekitar pantai umumnya bersumber dari gerakan angin dan pasang surut. Penelitian ini bertujuan untuk mengetahui kecepatan dan arah arus laut permukaan dan memetakan pola arus permukaan secara spasial. Metode penelitian untuk mengukur kecepatan arus permukaan menggunakan metode Euler. Metode untuk memperhitungkan gerak osilasi pasang surut secara periodik menggunakan Metode Admiralty. Metode untuk memperhitungkan nilai dan arah kecepatan angin menggunakan metode Wind Rose. Pola arus permukaan dianalisis menggunakan metode analisis spasial dengan teknik interpolasi Inverse Distance Weighting (IDW). Hasil penelitian menunjukkan bahwa kecepatan arus laut permukaan pada kondisi pasang berkisar antara 0,023-0,183 m/s. Kecepatan arus permukaan tertinggi terjadi di sisi kanan tanjung dengan arah pergerakan menuju ke Timur Laut. Kecepatan arus permukaan terendah terjadi di sebelah kiri tanjung dengan arah pergerakan menuju ke Barat Laut. Pada kondisi surut, kecepatan arus laut permukaan berkisar antara 0,02-0,094 m/s. Kecepatan arus permukaan tertinggi terjadi di depan tanjung dengan arah menuju ke Barat Laut. Kecepatan arus permukaan terendah berada di sebelah kiri tanjung dengan arah ke Timur Laut. Kedalaman perairan area studi relatif dangkal mencapai 31 m. Kecepatan angin yang tenang tidak berpengaruh terhadap kecepatan arus permukaan. Hasil analisis spasial menunjukkan bahwa pola arus laut permukaan di perairan Tanjung Tiram mengikuti pola pergerakan pasang surut. Pada saat pasang arus permukaan bergerak dari Timur ke Barat sedangkan saat surut arus permukaan bergerak dari Barat ke Timur. Kata Kunci: Arus, Angin, Pasang Surut, Perairan Tanjung Tiram

Διαχρονική παρακολούθηση των αλλαγών κάλυψης/χρήσης γης, βροχόπτωσης και του κινδύνου διάβρωσης στο Δήμο Νάουσας με τη χρήση πολυφασματικών δορυφορικών εικόνων και Γεωγραφικών Συστημάτων Πληροφοριών

Σκοπός αυτής της διατριβής είναι η μελέτη και η εκτίμηση των διαχρονικών αλλαγών της βροχόπτωσης, της διάβρωσης και της κάλυψης γης του Δήμου Νάουσας, καθώς επίσης και ο υπολογισμός των καμένων εκτάσεων της πόλης διαχρονικά. Για την υλοποίηση αυτού του σκοπού έπρεπε πρώτα να παραχθούν διαχρονικοί χάρτες της βροχόπτωσης, της κάλυψης γης και της διάβρωσης, χρησιμοποιώντας τρεις δορυφορικές εικόνες του Δήμου Ηρωικής Πόλης Νάουσας, διαφορετικών χρονολογιών 2018, 2019 και 2020. Χρησιμοποιώντας μεταδεδομένα των εικόνων, πραγματοποιήθηκε η ατμοσφαιρική και τοπογραφική διόρθωση των εικόνων. Έπειτα έχοντας στοιχεία από δύο βροχομετρικούς σταθμούς του Δήμου (βροχομετρικός σταθμός Αγίου Παύλου και βροχομετρικός σταθμός Δημαρχείου Νάουσας), δημιουργήθηκαν χάρτες βροχόπτωσης για τα τρία έτη (2018, 2019, 2020) καθώς και για τις τέσσερεις περιόδους (εποχές) του έτους, χρησιμοποιώντας τη μέθοδο Inverse Distance Weighting (IDW), διότι υπήρχαν δεδομένα από δύο σταθμούς. Στη συνέχεια έγινε ταξινόμηση των διαχρονικών δορυφορικών εικόνων (διαχρονικοί χάρτες χρήσης και κάλυψης γης) με τη χρήση του αλγόριθμου της μέγιστης πιθανοφάνειας (maximum likelihood). Με την ολοκλήρωση του σταδίου της ταξινόμησης δημιουργήθηκαν οι διαχρονικοί χάρτες διάβρωσης χρησιμοποιώντας το μοντέλο διάβρωσης Universal Soil Loss Equation (USLE).Τα αποτελέσματα της διατριβής μπορούν να χρησιμοποιηθούν από τις αρμόδιες υπηρεσίες για το σχεδιασμό και υλοποίηση αντιδιαβρωτικών καθώς και αντιπλημμυρικών έργων προστασίας του Δήμου, έτσι ώστε να περιορίσουν τη μελλοντική αύξηση των προβλημάτων αυτών ή ακόμα και να προχωρήσουν στη μελλοντική μείωση αυτών, καταβάλλοντας και προγραμματίζοντας τις απαραίτητες ενέργειες.Τέλος η διδακτορική διατριβή θα αποτελέσει ένα σημαντικό αναπτυξιακό εργαλείο λήψης αποφάσεων αναφορικά με το μελλοντικό έλεγχο των καλλιεργειών, την κατασκευή έργων, την προτεινόμενη μελλοντική αλλαγή των χρήσεων γης, την ποιότητα των καλλιεργειών, τη μελλοντική εκτίμηση του κινδύνου διάβρωσης και στερεοαπορροής συνδυαστικά με την εν δυνάμει ποιοτική και ποσοτική υποβάθμιση των παραγωγικών εδαφών.