A frequency-modulated continuous-wave (FMCW) radar, operated at the central frequency of 27.75 MHz and the bandwidth of 300 kHz has been established on the seashore near the Taichung harbor (24°18.591′ N, 120°31.389′ E), Taiwan. Sixteen vertical dipole antennas were located linearly and attached with 16 receiving channels. One purpose of the radar is to monitor the ships that navigate toward, away, and around the harbor. In this article, we applied the radar beamforming methods that transform the temporal radar signals as brightness on the 2-D range-azimuthal domain, making the ship echoes visible directly on the spatial domain. Three beamformers, linear Fourier, directionally constrained minimum power (DCMP), and norm-constrained DCMP (NC-DCMP) algorithms, were employed to produce range-angle (RA) brightness distribution that is different from the conventionally used range-Doppler (RD) spectra in ship detection. Both DCMP and NC-DCMP are adaptive beamforming methods. With the auxiliary of a band-stop filter to suppress the sea echoes, the NC-DCMP beamformer was demonstrated to surpass the other two beamformers and could provide more visible ship echoes in the RA brightness distribution. Automatic Identification System (AIS) information was also used to validate the radar-determined ship locations from the RA brightness distribution. Although some ships having the AIS information were not observed clearly by the radar, the radar detected some targets without AIS information.

Real-time, continuous, and long-term marine monitoring data benefits ocean research. This study developed a low-cost, multi-parameter, miniature wave buoy. High spatial and temporal resolution of sea surface parameters, including wind, waves, and current, can be obtained at low cost through the deployment of numerous buoys, thus forming an observation array. Tested in the laboratory water tank, the relative error of water surface slope measurement of the buoy was approximately 5.6% when the slope angle was less than 15°. For frequencies between 0.1 and 1.0 Hz, the measurement of slope spectrum was almost identical to that of the wave gauge. The buoy underestimated the slope spectrum between 1.0–1.56 Hz. A good relationship (r² = 0.75) was obtained between wind speed at 10 m above sea surface (U10) and the low-pass-filtered mean square slope (LPMSS). After incorporating the wave age into the U10 inversion process, the root mean square error (RMSE) and BIAS were reduced to 1.15 m/s and 0.02 m/s, respectively. The 2D distribution of buoy-measured slope components was used to detect the wind direction, with an RMSE of 23.7°. The spectral tail slope steepened with increasing wind speed at low wind speeds (<7 m/s). A technical flow chart of the miniature wave buoy is proposed to observe the sea surface parameters. This miniature buoy will play an essential complementary role in the growing demand for sea state monitoring, especially in nearshore oceans.

The Taiwan Banks (Formosa Shoals), a large NE-SW oriented bathymetric feature near the southern end (23°N, 118 - 119°E) of the Taiwan Strait, is a region of extremely shallow water that exerts a profound effect on the propagation of tidal waves. As such waves propagate over the Taiwan Banks, they become distorted and asymmetric due to bottom friction and contribute to the generation of shallow water tides. The POM model was used in present study to simulate the tides in the Taiwan Strait region. Shallow water tidal dynamics in the area of Taiwan Banks are focused. The numerical model was validated against sea level observations from 34 tidal stations located on the coast of Mainland China and Taiwan. Trajectory records from two SVP drifters are used to be compared with the simulations using wavelet-based rotary spectral analysis

The physical processes governing coastal exchange between the surf zone, the inner shelf, and the open ocean is critical for estimating mass exchange and its impact on ecological processes. The present study combined field measurements and theoretical approaches to explore the hydrodynamics in the coastal boundary layer (CBL) in which both bottom drag and shore friction affect the transport and mixing processes. Observed drifter-cluster trajectories in a nearly alongshore-uniform coastal area showed that the occurrence of current reversal varies with cross-shore distance, which confirmed the tidal phase difference between different cross-shore distances predicted by the proposed CBL model. According to the CBL model, tidal phase difference is affected by the bottom drag coefficient and horizontal eddy viscosity coefficient. With the results of three experiments under different wave conditions, this study also discusses the effects of waves on the CBL. Data analysis based on observations indicates that the bottom drag term is closely related to the bottom shear stress induced by the interactions of waves and currents. The bottom drag coefficient under the more energetic wave condition was much greater than that under milder wave conditions during the experiment. The study also suggests that in addition to pressure gradient and bottom drag, flow structure is subject to lateral stress, which reflects the impact of shoreline roughness in the nearshore region and that the estimated eddy viscosity coefficient decreases linearly with distance from the shoreline.

Changes in the global climate have induced densified rainfall and caused natural hazards across the world in recent years. Formed by a central mountain range and a corridor of alluvial plains to the west, Taiwan is at risk of flood hazards owing to its low-lying lands as well as the distinct seasonality of rainfall patterns. The rapid discharge of surface runoff and a growing number of impervious surfaces have also increased flood hazards during recent typhoon landfalls. A century ago, ancestors in Taoyuan City constructed a system of water channels composed of thousands of ponds to fulfill the needs of agriculture and aquaculture. During the expansion of urban areas, land reformation replaced a majority of earlier ponds with residential and industrial zones. However, the remaining ponds could potentially serve as on-site water detention facilities under the increasing risk of floods. In this research, we first renewed an outdated pond database by deploying a novel unmanned aerial vehicle (UAV) system with a micro-sonar to map the bathymetry of 80 ponds. Next, a simplified inundation model (SPM) was used to simulate the flood extent caused by different scenarios of rainfall in Bade District of Taoyuan City. Assuming that extremely that heavy rainfalls at 25, 50, 75, and 100 mm occurred in a very short period, the flood area would decrease by 96%, 75%, 52%, and 37%, respectively, when the ponds were preparatorily emptied.