Juan J. Muñoz-Perez

Sand dune management problems and techniques, Spain.

ABSTRACT Extensive Spanish dune areas were totally altered and destroyed in the course of massive tourist urbanization and road construction projects during the 1960s–1970s. Littoral drift interruption by harbour and marinas as well as sand mining for construction and agriculture purposes also contributed to accelerated dune erosion. Furthermore, human trampling, refuse dumping, excessive dune recreational pressure, use of all-terrain vehicles and cropping, are amongst the main causes contributing and accelerating physical and ecological degradation of most Spanish dune systems. Before 1988, Spanish coastal dunes were totally unprotected. The 1988 Spanish Shore Act (“Ley de Costas”) arose with the aim of regulating the coastal activities and preventing littoral destruction. The Spanish Shore Act protects all coastal dunes precludes their destruction by sand mining and any other form of development, . However, this law still does not prevent some of the above negative activities occuring. Furthermore, the complexity of existing boundaries of the different authorities involved in coastal zone management policy makes integrated dune management a difficult task. The National Spanish Coastal Authority, Ministry of Environment, have been aware of this problem and undertook a strong policy on dune restoration which has been incremented yearly. In this paper the main dune problems found along the Spanish coastline are outlined, paying particular attention to the analysis of certain case studies and an overview of the different dune restoration techniques used is given. Seven representative examples in which the authors were involved are discussed.

Cost of beach maintenance in the Gulf of Cadiz (SW Spain)

Beach erosion problems have been solved by adding sand to the beaches along the Gulf of Cadiz. The Gulf is located in SW Spain between the Portuguese border and the Strait of Gibraltar. During the last decade, more than 12×106 m3 of sand have been nourished in 38 restoration operations carried out on 28 beaches. The main characteristics of the nourishment campaigns (year, volume, budget, transport method, sand data, etc.) are presented. Location of sand borrow sites and distance to the beaches are also shown. Monitoring programs have been performed in order to calculate sediment loss rates. These results have been related to the beach length, the berm width and the budget in order to obtain a variety of relationships for maintenance cost as, for example, the total annual cost for each beach. This information is very useful when developing a strategy in coastal zone management. Furthermore, at least in reef-protected beaches, small yearly renourishments similar to the yearly losses, instead of greater nourishments performed with a periodicity of many years, lead to an economical saving, as well as to a better use of the natural resources.

Multicycle sediments on the continental shelf of Cadiz (SW Spain)

Abstract The study of recent sedimentation in the Gulf of Cadiz continental shelf (SW Europe) is of interest due to its proximity to the Strait of Gibraltar, where the Atlantic and Mediterranean waters are interchanged and the Western Mediterranean Alpidic Orogen closes through the Gibraltar Arch. The existence of relict materials hinders the distinction of the past and present hydrodynamic regimes in present day sediments. An adequate combination of techniques has allowed the establishment of the multicyclic character of the sediments, as well as the stages undergone by the terrigenous grains. Different stages were identified: eolian and energetic fluvial provenance, chemical alterations acquired in a pedological environment, and a marine coastal origin. To verify the source areas, textural and mineralogical features of marine sediments were compared with those found in geological units from fluvial basins. Three zones were differentiated: (a) a sandy littoral, which receives local sediment supplies; (b) a clayey zone between the Guadalquivir River and Cadiz, controlled by contributions from this river provenant of the Iberian Massif and Betic Mountain range; and (c) a sandy continental shelf, between Cadiz and the Cape of Trafalgar, with a low rate of supplies coming from the Guadalete and Barbate rivers, which include materials from the Occidental Betic Mountain range and Neogene units.

A CRITICAL REVIEW OF BEACH RESTORATION PROJECTS IN THE NORTHERN COAST OF CADIZ (SPAIN) AFTER THIRTEEN YEARS

The main purpose of this paper is to present a crit ical review of different beach restoration projects conducted since 1992 till toda y at the northern coast of Cadiz (Chipiona and Rota counties) by analyzing the diffe rent coastal engineering and coastal management considerations used in their design. In particular, four different cases of beach nourishment projects are analyzed, having eac h one specific and interesting points to be stressed : a) Regla beach nourishment project ; b) Rota beach nourishment project; c) Punta Candor dune restoration project ; and d) L a Ballena nourishment project.

Comments on “Confirmation of beach accretion by grain-size trend analysis: Camposoto beach, Cádiz, SW Spain” by E. Poizot et al. (2013) Geo-Marine Letters 33(4)

This Discussion provides comments on the application of grain-size trend analysis to Camposoto beach (SW Spain) reported by Poizot et al. (2013) in Geo-Marine Letters 33(4):263–272. Some of their results are updated or complemented by existing data from other studies carried out on Camposoto and other nearby beaches. For example, a detailed breakdown of beach nourishment volumes and costs is presented, and the influence of a horizontal reef flat on the tilting of the beach profile around the mean or the low water level is highlighted. Moreover, data from the displacement of dyed samples are used to evaluate the relationship between sediment transport speed (va) and current speed (V), the corresponding ratio being consistent with the range of values reported by several other authors. Finally, some minor, although still significant, differences are detected in some granulometric parameters as well as in the profile shape. Determining the reason for these discrepancies could enhance our current knowledge about the factors controlling short-term beach profile responses.

Environmental Impact of Beach Nourishment: A Case Study of the Rio San Pedro Beach (SW Spain)~!2010-01-13~!2010-03-29~!2010-06-10~!

The beaches on the left bank of Rio San Pedro (SW Spain) are in a regressive state because of the human activities of recent decades. With the objective of minimizing the effects of the erosion, the Spanish Coastal Department (Ministry of the Environment) decided that the most suitable solution was to provide sand nourishment. Previously, an environmental impact study (EIS) was carried out on these beaches, and an environmental monitoring campaign was also completed during that nourishment. A new methodology to perform this kind of studies is proposed in the present report. Moreover, a form is proposed for establishing the degree of observance of the EIS. Additionally, discrepancies in opinions on the alleged environmental impact of the sand nourishment on the Uca tangeri (European Fiddler crab), a representative but not protected species that lives in the area of research, led to the development of a complementary study. Therefore, observations, experimentations and calculations were carried out on individuals of this species of crab. It was concluded that there was no significant impact on this crab’s population. With respect to the impact of the sand nourishment project, the overall impact was negative but negligible during the nourishment phase. Once the project was finished, the total environmental impact was also negligible but positive overall.

Reversal in Longshore Sediment Transport without Variations in Wave Power Direction

Abstract The mouth of the Guadiaro River (SW Spain), oriented in a NE-SW direction, is often closed, resulting in environmental, social, and economic problems. An analysis of the factors influencing this phenomenon was performed using the Coastal Modeling System, a numerical model based on the mild slope equation (waves, currents, and sediment transport), and a coastal evolution study was performed comparing aerial photographs to the monitoring campaigns carried out in 2005 and 2006 (topographic surveys, current meters, tidal gauges, and water quality parameters). Global transport at the Spanish south Mediterranean coast occurs in a southwestern direction. However, the spit that closes the Guadiaro River grows in the opposite direction. The points and conditions where transport direction changes occur along the coastline were identified. The results, obtained from 200 different propagations, were consistent with field data, showing that northeastern littoral transport during easterly waves was sufficient to block the river mouth. Furthermore, significant differences in sediment transport patterns were found despite the existence of a fixed wave power direction. Through this research we also learned that use of wave propagation numerical models by nonexperts is prone to error, as small variations in input parameters can induce dramatically different results that may be contradictory in certain bathymetric configurations.

Discussion of Ford, M.R.; Becker, J.M., and Merrifield, M.A. 2013. Reef Flat Wave Processes and Excavation Pits: Observations and Implications for Majuro Atoll, Marshall Islands. Journal of Coastal Research, 29(3), 545–554.

ABSTRACT Payo, A. and Muñoz-Perez, J.J., 2013. Discussion of Ford, M.R.; Becker, J.M., and Merrifield, M.A., 2013. Reef flat wave processes and excavation pits: Observations and implications for Majuro Atoll, Marshall Islands. Ford, Becker, and Merrifield observed reef flat wave conditions during two deployments over a 41 day period to investigate the impact of reef flat excavation pits on wave processes at Majuro Atoll. They noticed that the shoreline with the excavation pit received wave heights slightly less (∼8%) than those recorded at the nearby unmodified cross section. They suggested that this net decrease was the net product of a slight increase in sea and swell (SS) wave energy due to a bottom roughness reduction and a decrease in infragravity (IG) wave energy due to the disruption of the cross-shore quasi-standing modes caused by the excavation pit. We argue that, for this particular experiment, the coupling between the SS and IG energy waves may provide an alternative explanation of the observations, and we suggest that further investigations are needed. Although the coupling between SS and IG waves may be important for assessing the impact of excavation pits on IG-dominated shorelines, we show that these excavation pits in SS-dominated surf zones can lead to events such as the observed destruction of the Cadiz (SW Spain) seawall in 1792.

Short Term Variability of Reef Protected Beach Profiles: An Analysis Using EOF

Victoria beach (SW Spain) has a rocky flat at the northernmost zone. This has allowed to choose one profile and monitoring the changes induced by a single day storm. Topographic data taken during 21 days and different tendencies of the beach profile, as the accretion rate, were identified. The analysis is carried out by means of Empirical Orthogonal Function (EOF) techniques, in order to separate the spatial from the temporal variability of the beach profile data. Among the conclusions, it should be highlighted that a swing or oscillation point of the profile was found around the intertidal zone. Furthermore, the erosion has been irreversible in a short term, and the recuperation consisted only in a modification of the slopes of the emerged part, trying to assimilate them to the ones before the storm.