Spatial Variability of Surface Waves and Nearshore Currents Induced by Hurricane Harvey along the Southern Texas Coast

Abstract

Extreme weather events such as hurricanes are expected to become more severe with the human-induced increase in average global temperatures, exacerbating the risk of major damage. Efforts to predict these events typically require detailed hydrodynamic data that are difficult to collect in the field. Here, nearshore data collected with three ADCP moorings were used to describe the hydrodynamics induced by Hurricane Harvey along the southern Texas coast. Wave spectra and nearshore current variations were analyzed along the hurricane’s trajectory and compared to other offshore locations. The results indicate that winds intensified along the coast as Harvey approached the Port Aransas coastline. Southerly wind stresses of ~−0.9 Nm−2 generated ~2 ms−1 depth-averaged flows towards the southwest close to landfall in the north, while flows of ~1 ms−1 and <1 ms−1 were measured in the center and the south of the study site, respectively. The hydrodynamics induced by the hurricane were compared to those induced by an intense synoptic-scale cold front (CF). Both events generated southward-directed alongshore wind stresses of similar magnitudes (τy ~−0.4 Nm−2) that caused similar depth-averaged flows (0.5 to 0.7 ms−1) and wave energy conditions (Hs of ~4 m) in the south. Harvey caused extremely energetic conditions close to landfall in the north compared to the CF; depth-averaged flows and Hs of 2 ms−1 and 10 m were induced by Harvey, as opposed to 0.6 ms−1 and 4 m by the CF, respectively. While intense currents (>1 ms−1) and waves (Hs > 4 m) lasted for less than a day during Harvey, these persisted a few days longer during the CF. This study highlights the relevant role of synoptic-scale cold fronts in modulating the nearshore hydrodynamics, which occur more frequently than tropical cyclones in the northwestern Gulf of Mexico.