Envisat/ASAR Images for the Calibration of Wind Drag Action in the Doñana Wetlands 2D Hydrodynamic Model

Anaïs Ramos-Fuertes,Ernest Bladé,Josep Dolz,Belen Marti-Cardona

doi:10.3390/rs6010379

Anaïs Ramos-Fuertes, Ernest Bladé + Show 2 more

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https://doi.org/10.3390/rs6010379

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Abstract

Doñana National Park wetlands are located in southwest Spain, on the right bank of the Guadalquivir River, near the Atlantic Ocean coast. The wetlands dry out completely every summer and progressively flood again throughout the fall and winter seasons. Given the flatness of Doñana’s topography, the wind drag action can induce the flooding or emergence of extensive areas, detectable in remote sensing images. Envisat/ASAR scenes acquired before and during strong and persistent wind episodes enabled the spatial delineation of the wind-induced water displacement. A two-dimensional hydrodynamic model of Doñana wetlands was built in 2006 with the aim to predict the effect of proposed hydrologic restoration actions within Doñana’s basin. In this work, on-site wind records and concurrent ASAR scenes are used for the calibration of the wind-drag modeling by assessing different formulations. Results show a good adjustment between the modeled and observed wind drag effect. Displacements of up to 2 km in the wind direction are satisfactorily reproduced by the hydrodynamic model, while including an atmospheric stability parameter led to no significant improvement of the results. Such evidence will contribute to a more accurate simulation of hypothetic or design scenarios, when no information is available for the atmospheric stability assessment.

Highlights

Doñana National Park (DNP) extents over 543 km2 of the colmated Guadalquivir River paleo-estuary, in southwestern Spain
This paper describes the implementation of the wind stress action into the hydrodynamic model of Doñana marshes with the aid of Envisat/Advanced Synthetic Aperture Radar (ASAR) imagery
Due to the terrain flatness, the ASAR images approximated fairly the projected geometry of the digital terrain model (DTM), so a first degree polynomial and the nearest neighborhood methods were considered appropriate for the co-registration warping and resampling, respectively

Summary

Introduction

Doñana National Park (DNP) extents over 543 km of the colmated Guadalquivir River paleo-estuary, in southwestern Spain. The area, considered the largest European habitat for migrating waterfowl, was declared a National Park in 1969, a Biosphere Reserve under the UNESCO Man and the Biosphere Programme in 1980, a Wetland of International Importance under the Ramsar Convention in 1982, a Special Protection Area under the European Union Directive on the Conservation of Wild. About half of DNP’s extension is marshland area, which experiences annual cycles of inundation and depletion. The natural hydrological cycle of the marshes, which constitutes the strategic basis for the entire ecosystem functioning, has been threatened by a number of past and present human actions [2,3,4]. The water exchange between the marshes and the Guadalquivir River is managed by DNP’s authorities through a number of sluices located in an artificial 12 km long levee

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