Ohio State University. Division of Geodetic Science
Abstract
This report was prepared for and submitted to the Graduate School of the Ohio State University as a dissertation for partial fulfillment of the requirements for the Doctor of Philosophy (PhD) degree.This research was carried out under supervision of Professor C.K. Shum, Division of Geodetic Science, School of Earth Sciences, The Ohio State University. Hidayat at Hydrology and Quantitative Water Management Department of Wageningen University and Limnology Research Agency of Indonesian Institute of Sciences (LIPI) are especially acknowledged for providing in-situ discharge, rating curve and precipitation data for the Upper Mahakam Sub-watershed study region.This research is primarily supported by the Fulbright PhD Presidential Scholarship administered by American Indonesian Exchange Foundation (AMINEF) and the Institute for International Education (IIE). In addition, this study is partially funded by grants from NASA's Ocean Surface Topography Science Team project (Univ. of Colorado, 154-5322), NASA's Geodetic Imaging project (NNX12AQ07G), NASA's Application Science Program under the SERVIR project (NNX12AM85G), and The Ohio State University's Climate, Water, and Carbon (http://cwc.osu.edu/) program.Fresh water resources are critical for daily human consumption. Therefore, a
continuous monitoring effort over their quantity and quality is instrumental. One
important model for water quantity monitoring is the rainfall-runoff model, which
represents the response of a watershed to the variability of precipitation, thus estimating
the discharge of a channel (Bedient and Huber, 2002, Beven, 2012). Remote sensing and
satellite geodetic observations are capable to provide critical hydrological parameters,
which can be used to support hydrologic modeling. For the case of satellite radar
altimetry, limited temporal resolutions (e.g., satellite revisit period) prohibit the use of
this method for a short (<weekly) interval monitoring of water level or discharge. On the
other hand, the current satellite radar altimeter footprints limit the water level
measurement for rivers wider than 1 km (Birkett, 1998, Birkett et al., 2002). Some
studies indeed reported successful retrieval of water level for small-size rivers as narrow
as 80 m (Kuo and Kao, 2011, Michailovsky et al., 2012); however, the processing of
current satellite altimetry signals for small water bodies to retrieve accurate water levels,
remains challenging.
To address this scientific challenge, this study poses two main objectives: (1) to
monitor small (40–200 m width) and medium-sized (200–800 m width) rivers and lakes
using satellite altimetry through identification and choice of the over-water radar
waveforms corresponding to the appropriately waveform-retracked water level; and (2) to
develop a rainfall-runoff hydrological model to represent the response of mesoscale
watershed to the variability of precipitation. Both studies address the humid tropics of
Southeast Asia, specifically in Indonesia, where similar studies do not yet exist. This
study uses the Level 2 radar altimeter measurements generated by European Space
Agency’s (ESA’s) Envisat (Environmental Satellite) mission.
The first study proves that satellite altimetry provides a good alternative or the
only means in some regions to measure the water level of medium-sized river (200–800
m width) and small lake (extent <1000 km2) in Southeast Asia humid tropic with
reasonable accuracy. In addition, the procedure to choose retracked Envisat altimetry
water level heights via identification or selection of over water waveform shapes is
reliable; therefore this study concluded that the use of waveform shape selection
procedure should be a standard measure in determining qualified range measurements
especially over small rivers and lakes. This study also found that Ice-1 is not necessarily
the best retracker as reported by previous studies, among the four standard waveform
retracking algorithms for Envisat altimetry observing hydrologic bodies.
The second study modeled the response of the poorly-gauged watershed in the
Southeast Asia’s humid tropic through the application of Hydrologic Engineering Center
– Hydrologic Modeling System (HEC-HMS). The performance evaluation of HEC-HMS
discharge estimation confirms a good match between the simulated discharges with the
observed ones. As the result of precipitation data analysis, this study found that Tropical
Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) is
the preferred input forcing for the model, given the thorough evaluation of its relationship
with field-measured precipitation data prior to its use as primary climatic forcing. This
iii
research also proposes a novel approach to process the TRMM precipitation estimation
spatially through Thiessen polygon and area average hybrid method, which model the
spatial distribution of TRMM data to match the spatial location of field meteorological
stations.
Through a simultaneous validation that compares the water level anomaly
transformed from HEC-HMS simulated discharge and satellite altimetry measurement,
this study found that satellite altimetry measures water level anomaly closer to the true
water level anomaly than the water level anomaly converted from HEC-HMS simulated
discharge.
Some critical recommendations for future studies include the use of waveform
shape selection procedure in the satellite altimetry based water level measurement of
small and medium-sized rivers and small lakes, as well as the exploration to implement
data assimilation between satellite altimetry and the hydrologic model for better
discharge and water level estimations
