ANALYSIS OF TIDAL OBSERVATION DATA LENGTH ON TIDAL DATUM VALUE IN INDONESIA

• Main Author: Oktaviani, Nadya
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/65788
• Institution: Institut Teknologi Bandung

Tide measurements are carried out to support scientific and practical needs. Tides is dominant caused by the gradient of the gravitational field of the moon and sun to the water masses on earth, resulting in periodic vertical movements on the sea surface. Although very dynamic, sea tides are one of the vertical parameters on the earth's surface besides the geoid. To make the dynamic sea level conditions can be used as a reference, mathematical calculations are needed to produce a fixed value. This fixed value is then referred to as the tidal datum. The tidal datum value can be obtained from calculations or forecasts using tidal observation data for a certain period. The tidal datum value is different for each observation location. This condition is determined by the position of the location at a certain latitude and the characteristics of the waters on the earth's surface. The length of observation also affects the resulting tidal value. Therefore, the purpose of this study is to analyze the effect of the length of time of the tidal observation at certain locations in Indonesian waters. This study uses data from 31 tidal stations belonging to the Geospatial Information Agency which are scattered and represent the types of waters in Indonesia. The tidal datum analyzed is the tidal datum based on Mean High Water Spring (MHWS), Mean Sea Level (MSL), and Mean Low Water Spring (MLWS). Observational data at each tidal station are grouped based on different lengths of observational data, namely calculating the tidal datum every 15 days, one month, six months, and one year. The result is that generally the datum calculated from one year's data has lower value fluctuations. The lowest value fluctuations on every tidal day with tidal observations for one year are in the range of 0 - 0.007 meters. By observing six months of data, the lowest value fluctuation is in the range of 0.034 - 0.040 meters. Meanwhile, by observing one month's data, the lowest value fluctuation of the tidal datum is in the range of 0.042 - 0.064 meters and with 15 days of data the lowest value fluctuation is in the range of 0.054 - 0.068 meters. The differences in waters does not affect the pattern of variation in the value of the tidal datum, namely the observation of data for at least 15 days, can calculate the tidal datum which is close to the calculation results with one month's data. While the minimum observation data is six months, it can calculate the tidal datum whose value is close to the calculation results with one year's data. However, differences in water characteristics affect the level of precision of the tidal datum value. If grouped based on the type of oceanic, sea and strait waters, and compared with the variation of values from calculations with one year's data, the tidal stations located in oceanic waters produce a small tidal datum value. On the other hand, differences in water characteristics can affect the type of tide at the location of the tidal station.