International Journal of Research In Vocational Studies (IJRVOCAS)
Vol. 2 No. 4 (2023): IJRVOCAS – Special Issues – INCOSTIG – PP. 67~70 Print ISSN 2777-0168| Online ISSN 2777-0141| DOI prefix: 10.53893 https://journal.gpp.or.id/index.php/ijrvocas/index
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Rainfall Mapping in Medan Selayang Sub-District using Geographic Information System
Dina Tri Septiningtiyas* & Rifka Ananda
Department of Civil Engineering, Politeknik Negeri Medan, Indonesia
ABSTRACT
Indonesia is a tropical country which has two seasons, namely the rainy season and the dry season. Rainfall that occurs will vary in each area depending on the altitude of the area, climate, season, and other factors.
Medan Selayang Subdistrict is the Subdistrict with the closest distance to the rain station. Where the closer the location of the study area to the rain station, the more accurate the rainfall data obtained will be. One way to make it easier to record and process data is to create a rainfall map by utilizing spatial analysis through a Geographic Information System (GIS). The data in this study are rainfall data and geographic coordinate data obtained from the Meteorology, Climatology and Geophysics Agency in the Medan City area.
After data collection, data processing was carried out using the QGIS 3.10 application. with the Inverse Distance Weighted (IDW) interpolation method.
From the results of processing rainfall maps in the Medan Selayang sub- district using Inverse Distance Weighted (IDW) interpolation, the rainfall values (rainfall) ranged from 3029.74 mm/year – 3164.20 mm/year.
Keywords:
Mapping Rainfall
Geographic Information System Quantum GIS
Medan Selayang Sub-district
Corresponding Author:
Dina Tri Septiningtiyas,
Department of Civil Engineering, Politeknik Negeri Medan,
Almamater Road No 1, Padang Bulan, Medan, North Sumatera, Indonesia.
Email: dinatriseptiningtiyas@polmed.ac.id
1. INTRODUCTION
Indonesia is a tropical country that has two seasons, the rainy season and the dry season. In the hydrological cycle, rain is an important factor in determining the water capacity in an area. Rain that falls in an area will enter the watershed, flow into the river, and finally into the sea. The rain that occurs will vary in each area, depending on the altitude of the area, climate, season, and other factors that cause it to fall. The intensity and duration of rain also determine the amount of water that falls in the area.[1]
All regions in Indonesia are equipped with rain stations, one of which is Medan City which has one rain station, namely the Meteorology, Climatology and Geophysics Agency area 1 which is located in the District of Medan Selayang. Medan Selayang Subdistrict is one of 21 sub-districts in the city of Medan with an area of 12.81 km2 or 4.83% of the entire area of Medan City[2]. Of all sub-districts in Medan City, Medan Selayang District is the district with the closest distance to the city of Medan. rain station. Where the closer the research area to the rain station, the more accurate the rainfall data obtained will be.
Rainfall data in an area must be recorded continuously. One way to make it easier to record and process data is to create a rainfall map by utilizing spatial analysis through a Geographic Information System
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(GIS). Making this map is intended for technical planning, especially water structures such as irrigation, dams, urban drainage, ports, docks, knowing flood-prone areas in an area, and can even be used to determine the potential damage of a highway.
2. RESEARCH METHOD a. Research Location
Research was conducted by taking objects in Medan Selayang District which is located between 3 ͦ 31' 46.33” North Latitude and 98 ͦ 36' 24.23” East Longitude - 3 ͦ 34' 38.31” North Latitude and 98 ͦ 39' 45.29” East Longitude, as shown in Figure 1.
Figure 1. Research Locations for b. Data Collection Techniques
Data were obtained from the Meteorology, Climatology and Geophysics Agency in Medan City and its surroundings. The data used are rainfall data and geographic coordinate data from rainfall stations.
c. Data Processing Techniques
Data processing techniques use geographic information systems in the form of Quantum GIS 3.10 applications.
Figure 2. Research Flowchart
3. RESULTS AND ANALYSIS
Rainfall data were obtained from the BMKG station (Meteorology, Climatology, and Geophysics Agency) in the city of Medan and its surroundings. The data obtained are rain station points (Table 1) and annual rainfall data in 2021 (Table 2). These data are used to input data into the QGIS application.
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Table 1. Rain Station in Medan City and Surrounding Areas
Source: Meteorology, Climatology and Geophysics Agency Online Data Table 2. Rainfall Data in Medan Selayang Subdistrict in 2021 (mm/Year)
Source: BMKG Online Data
The method used in making rainfall maps using the QGIS 3.10 application.interpolation method Inverse Distance Weighted (IDW)IDW interpolation is a method to determine the value of an unknown point using a combination of linear weights from a set of sample points. The sample points in question are points whose values are known and spatially located closest to the point to be determined.
This IDW Interpolation method produces regional rainfall by calculating the Isohyet method. The Isohyet method is used to determine the average rainfall at an uneven distribution of stations or observation posts.
Technically, the value of rain at each point of the rainfall station is plotted according to geographical position, then interpolation is carried out. Thus, the same rainfall value will be obtained from all rainfall stations so as to produce a rainfall map. From the results of the processing of the rainfall map in the Medan Selayang sub- district using Inverse Distance Weighted (IDW) interpolation, it was found that the rainfall value (rainfall) was in the range of 3029.74 mm/year – 3164.20 mm/year as shown in Figure 3.
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INCOSTIG International Conference on Science, Technology and Engineering February 2022 Figure 3. Sub-district Rainfall Map Medan Selayang
4. CONCLUSION
From the results of processing rainfall maps in the Medan Selayang sub-district using Inverse Distance Weighted (IDW) interpolation in QGIS 3.10. rainfall value is found in 3029.74mm/year – 3164.20 mm/year
ACKNOWLEDGEMENTS
Thank you to the Center for Research and Community (P3M) Medan State Polytechnic for funding this research.
REFERENCES
[1] Prawaka F, Zakaria A, Tugiono S. “Analisis Data Curah Hujan yang Hilang Dengan Menggunakan Metode Normal Ratio, Inversed Square Distance, dan Cara Rata-Rata Aljabar (Studi Kasus Curah Hujan Beberapa Stasiun Hujan Daerah Bandar Lampung),” Jurnal Rekayasa Sipil dan Desain, 2016 Jun 22;4(3):397-406.
[2] Statistik, Badan Pusat. "Badan pusat statistik." Badan Pusat Statistik (2022).
[3] Singal, R.Z. and Jumario, N., Pemetaan Curah Hujan Dalam Upaya Mengurangi Resiko Bencana Hidrometeorologi Dengan Sistem Informasi Geografis (SIG) Untuk Wilayah Kalimantan Utara. Borneo Engineering: Jurnal Teknik Sipil, 3(2),2019, pp.129-142.
How to Cite
Septiningtiyas, D. T., & Ananda, R. (2023). Rainfall Mapping in Medan Selayang Sub-District using Geographic Information System. International Journal of Research in Vocational Studies (IJRVOCAS), 2(4), 67–70.
https://doi.org/10.53893/ijrvocas.v2i4.164
