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| Titel |
Satellite radar altimetry for monitoring small rivers and lakes in Indonesia |
| VerfasserIn |
Y. B. Sulistioadi, K.-H. Tseng, C. K. Shum, H. Hidayat, M. Sumaryono, A. Suhardiman, F. Setiawan, S. Sunarso |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 1 ; Nr. 19, no. 1 (2015-01-19), S.341-359 |
| Datensatznummer |
250120596
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| Publikation (Nr.) |
 copernicus.org/hess-19-341-2015.pdf |
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| Zusammenfassung |
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. |
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