Abstract. Remote sensing and satellite geodetic observations are capable of hydrologic monitoring of freshwater resources. Although satellite radar altimetry has been used in monitoring water level or discharge, its use is often limited to monitoring large rivers (>1 km) with longer interval periods (>1 week) because of its low temporal and spatial resolutions (i.e., satellite revisit period). Several studies have reported successful retrieval of water levels for small rivers as narrow as 40 m. However, processing current satellite altimetry signals for such small water bodies to retrieve water levels accurately remains challenging. Physically, the radar signal returned by water bodies smaller than the satellite footprint is most likely contaminated by non-water surfaces, which may degrade the measurement quality. In order to address this scientific challenge, we carefully selected the waveform shapes corresponding to the range measurement resulting from standard retrackers for the European Space Agency's (ESA's) Envisat (Environmental Satellite) radar altimetry. We applied this approach to small (40–200 m in width) and medium-sized (200–800 m in width) rivers and small lakes (extent <1000 km2) in the humid tropics of Southeast Asia, specifically in Indonesia. This is the first study that explored the ability of satellite altimetry to monitor small water bodies in Indonesia. The major challenges in this study include the size of the water bodies that are much smaller than the nominal extent of the Envisat satellite footprint (e.g., ~250 m compared to ~1.7 km, respectively) and slightly smaller than the along-track distance (i.e., ~370 m). We addressed this challenge by optimally using geospatial information and optical remote sensing data to define the water bodies accurately, thus minimizing the probability of non-water contamination in the altimetry measurement. Considering that satellite altimetry processing may vary with different geographical regions, meteorological conditions, or hydrologic dynamic, we further evaluated the performance of all four Envisat standard retracking procedures. We found that satellite altimetry provided a good alternative or the only means in some regions of measuring the water level of medium-sized rivers and small lakes with high accuracy (root mean square error (RMSE) of 0.21–0.69 m and a correlation coefficient of 0.94–0.97). In contrast to previous studies, we found that the commonly used Ice-1 retracking algorithm was not necessarily the best retracker among the four standard waveform retracking algorithms for Envisat radar altimetry observing inland water bodies. As a recommendation, we propose to include the identification and selection of standard waveform shapes to complete the use of standard waveform retracking algorithms for Envisat radar altimetry data over small and medium-sized rivers and small lakes.
As part of operational guidance of mangrove forest rehabilitation in the Mahakam delta, Indonesia, site suitability mapping for 14 species of mangrove was modelled by combining 4 underlying factors-clay, sand, salinity and tidal inundation. Semivariogram analysis and a geographic information system (GIS) were used to apply a site-suitability model, while kriging interpolation generated surface layers, based on sample point data collection. The tidal inundation map was derived from a tide table and a digital elevation model from topographic maps. The final site-suitability maps were produced using spatial analysis technique, by overlaying all surface layers. We used a Gaussian model to adjust a semivariogram graph in order to help to understand the variation of sample data values, and create a natural surface layer of data distribution over the area of study. By examining the statistical value and the visual inspection of surface layers, we saw that the models were consistent with the expected data behavior; therefore, we assumed that interpolation has been carried out appropriately. Our site-suitability map showed that Avicennia species was the most suitable species and matched with 50% of the study area, followed by Nypa fruticans, which occupied about 42%. These results were actually consistent with the mangrove zoning pattern in the region prior to deforestation and conversion.
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Dalam rangka mengurangi laju degradasi keanekaragaman tumbuhan dibutuhkan suatu kawasan konservasi tumbuhan secara ex-situ yang memiliki koleksi tumbuhan terdokumentasi dan ditata berdasarkan pola klasifikasi taksonomi, bioregion, tematik atau kombinasi dari pola-pola tersebut untuk tujuan kegiatan konservasi, penelitian, pendidikan, wisata dan jasa lingkungan, maka perlu dibangun KHDTK Hutan Pendidikan Dan Pelatihan. Untuk menunjang kegiatan dimaksud maka perlu adanya pengelolaan kawasan yang salah satunya adalah dalam bentuk penataan zonasi. Penelitian ini bertujuan mengaplikasi pemanfaatan data keruangan yang terkini di areal KHDTK Hutdik Loa Haur di Kabupaten Kutai Kartanegara dengan penerapan teknologi sistem informasi geografis dan penginderaan jauh, mengetahui kondisi biofisik, pemanfaatan ruang secara aktual dan peruntukan KHDTK Hutan Pendidikan Dan Pelatihan sebagai dasar penataan zonasi secara mikro, menghasilkan peta zonasi terbaru dalam rangka mendukung pengelolaan KHDTK Hutan Pendidikan Dan Pelatihan. Penelitian ini dilaksanakan di KHDTK Hutan Pendidikan Dan Pelatihan di Kabupaten Kutai Kartanegara. Pengumpulan data berupa peta analog dan digital yang selanjutnya diproses melalui analisis data spasial dan interpretasi citra satelit. Dari semua peta yang diperoleh dari hasil tumpang susun, analisis data spasial dan interpretasi citra satelit, kemudian dilakukan pembuatan peta tutupan lahan dan peta arahan zonasi KHDTK Hutan Pendidikan Dan Pelatihan. Hasil yang diperoleh dari panelitian ini adalah terbentuk 4 (empat) zona di dalam KHDTK Hutan Pendidikan Dan Pelatihan, yaitu zona sarana dan prasarana, zona perlindungan dan pelestarian alam, zona wisata alam dan jasa lingkungan, serta zona Rehabilitasi dan Kelompok Tani Hutan
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