Abstrak Sand spit (lidah pasir) adalah salah satu contoh bentuk sedimen yang sering dijumpai di kawasan daerah pantai. Lidah pasir yang terbentuk biasanya dihasilkan dari pergerakan sedimen transpor yang terjadi di laut. Proses lidah pasir yang terbentuk dalam kurun waktu yang lama menyebabkan terbentuknya daratan baru di sekitar pantai. Oleh karenanya untuk mengurangi pendangkalan di daerah alur pelayaran yang digunakan nelayan, diperlukan analisa terhadap pergerakan lidah pasir yang terjadi. Dalam penelitian ini analisa yang digunakan yaitu analisa spatio-temporal, yaitu pengamatan perubahan data spasial secara temporal atau dari waktu ke waktu. Dalam penelitian ini menggunakan alat UAV (Unmannde Aerial Vehicle) DJI Phantom 4 Pro untuk membantuu observasi spatio-temporal dari lidah pasir yang terbentuk di sekitar laguna. Metode yang digunakan adalah metode survey fotogrametri. Analisis yang digunakan dalam penelitian ini yaitu dengan bantuan software Agisoft dalam permodelan, dan QGIS (Quantum Geographic Information System) untuk menghitung data spasial yang mengalami perubahan. Berdasarkan dari hasil analisis regresi, koefisien korelasi antara hubungan laju angkutan sedimen sejajar pantai dengan volume adalah 0.85 dan korelasi dengan luasan adalah 0.89. Hal ini menunjukkan penggunaan drone untu observasi spatio-temporal memiliki tingkat validitas yang baik dibandingkan dengan penggunaan rumus empiris transpor sedimen. Akurasi hasil pengukuran fotogrametri dibandingkan dengan hasil pengukuran RTK GPS (Real Time Kinematic Global Positioning System) adalah 98% sama. Simpulan dari penelitian ini adalah penggunanan UAV mempunya nilai validitas yang baik untuk observasi jangka panjang pembbentukan lidah pasir disekitar laguna. Kata-kata Kunci: Lidah pasir, sedimentasi, pantai, fotogrametri, spatio-temporal, alur pelayaran, gelombang. Abstract Sand spit is one example of sedimentary forms that are often found in coastal areas. The sand spit formed usually are results from the movement of longshore sediment transport around littoral zone. The process of sand spit requires a long period of time of coastal processes. At some cases, the sand spits block navigation channels, inlets, and river mouths. Therefore, to understand the siltation process in the navigation channel used by fishermen, it is necessary to analyze the movement of the sand spit in the modes of spatio-temporal observations.  This study is aimed at utilizing aerial unmanned vehicle DJI Phantom 4 Pro to assist spatio-temporal observations of sand spits formation around inlet of a coastal lagoon. This research applied a photogrammetric survey method to analyze a series of aerial images taken around an inlet of coastal lagoon. The analysis used in this research was performed with the help of Agisoft software in the modeling and QGIS (Quantum Geographic Information System) to calculate the spatial data. Based on the results of the regression analysis, the correlation coefficient between the longshore sediment transport rate and the volume is 0.85 and the correlation coefficient between the longshore sediment transport rate and the area is 0.89. These show that the use of the drone for spatio-temporal observations has a reasonable rate of validity compared to empirical sediment budget formulas. The accuracy of the photogrammetric measurement results compared to the RTK GPS (Real Time Kinematic Global Positioning System) measurement results is 98%. This study concludes that the use of UAV has an acceptable validity value for long-term observations of sand spit formation around a coastal lagoon. Keywords: Sand spit, sedimentation, coastal, photogrammetry, spatio-temporal, groove sailing, waves.

Canopy characteristics have a significant influence on the process of canopy surface wetting and water canalization into the canopy reservoir. Canopy surfaces that have increased wetting until the canopy is saturated will describe the process of rainfall redistribution that occurs throughout the canopy. Canopy wetting until saturated or the canopy wetting index (β) is an indicator of rainfall redistribution by a canopy. Canopy reservoir filling can occur after the canopy surface per unit area has been completely saturated. This research was conducted with changes in rainfall intensity (R), leaf slope (α), canopy porosity, and canopy flow distribution (Tf) on Artocarpus heterophyllus. This study found that the rainfall redistribution process was strongly influenced by leaf characteristics, depth, and rainfall duration. Leaf characteristics, especially leaf inclination, will create a pattern of water canal from the canopy surface to the canopy reservoir. The leaf inclination characteristic will increase canopy wetting across the canopy surface simultaneously, but will not make water flow uniformly to the canopy reservoir.

The tree canopy around Merapi Volcano, Yogyakarta, Indonesia, has a unique structure. The frequency of volcanic eruptions influences the uniqueness of the structure, as it is a response to volcanic ash and rainfall characteristics. This research was conducted on eight species that have different canopy structures. In contrast to the trees canopy that was not affected by eruptions, the tree canopy around the Volcano has more dynamic canopy surface characteristics during the recovery period. The redistribution of rainfall in the tree canopy was traced by calculating unit area discharge and droplets' probability in each canopy structure segment. The results of empirical throughfall calculation and throughfall direct observation were tested using ANOVA. Most of the throughfall occurs simultaneously under the canopy during rain with a depth of 3.5 -72.5 mm or intensity of 10 -20 mm/hour (observed = 58% and empirical = 57%). The existing range of rainfall intensity or rainfall depth shows that the process of redistribution of rainfall in the canopy has time constraints and canopy storage capacity constrain. The canopy surface characteristics have a more significant effect than the canopy structure on the redistribution of rainfall. The canopy surface serves as a sheet of rainfall concentration to the next section. The important canopy surface structure parameters to rainfall concentration are leaves characteristics, branches stiffness, and crown density. Knowledge of the tree canopy's rainfall flow distribution process will help manage conservation-based rehabilitation activities in areas prone to volcanic disasters.