Journal of Marine Science and Engineering Article Micro Sand Engine Beach Stabilization Strategy at Puerto Morelos, Mexico Mireille Escudero , Edgar Mendoza * and Rodolfo Silva Institute of Engineering, National Autonomous University of Mexico, 04510 CdMx, Mexico; [email protected] (M.E.); [email protected] (R.S.) * Correspondence: [email protected]; Tel.: +52-5556-233600 (ext. 8957) Received: 27 February 2020; Accepted: 31 March 2020; Published: 2 April 2020 Abstract: In the last decade, innovative beach nourishment strategies have been developed, driven by the increased worldwide interest in environmentally friendly coastal protection measures. In this context, the massive nourishment project of the Netherlands, known as Sand Engine, begun in 2011, has been hailed as a successful means of beach protection. Continuous monitoring, field campaigns, and numerical modeling have shown that the great volume of sand deployed is gradually transported by the waves and currents along the coastline, avoiding the need for repeated invasive, small scale beach replenishments. A very small, bell-shaped Sand Engine was designed to protect the beachfront at a tourist resort near Puerto Morelos, Mexico. To estimate the morphological response of the beach and the functioning of the micro Sand Engine as a sand reservoir, XBeach numerical modelling was applied to the project. The micro Sand Engine is seen to be a sustainable and eco-friendly coastal protection measure, especially applicable when a large nourishment project is not viable. Maintenance work for the nourishment is cost and time effective, and any negative impacts to sensitive ecosystems nearby can be detected and controlled quickly. Keywords: beach nourishment; sand engine; XBeach; shore protection; beach restoration 1. Introduction International interest in environmentally friendly strategies to protect beaches and dunes against erosion has led to an increasing preference for soft methods over hard engineering [1–4]. Of these soft methods, artificial beach nourishment has been recognized as particularly effective in curbing erosion, as it does not cause harmful effects to nearby areas [5]. Traditional beach nourishments, where the sand is placed directly ono the dry beach and dunes, is being superseded by large-scale shoreface nourishment, where the sand is placed between the low water line and the dry beach; it may be less expensive and provide recreational areas more quickly than the earlier mode. Numerical models have been developed to better understand and optimize shoreface beach nourishment projects. Variations within the one-line shoreline models include that presented by [6], which calculates the shoreline evolution following a beach nourishment project, and considers the effect of using sediment with different characteristics than the native sediment; and the application of the numerical model GENESIS to the long-term simulation of shoreline change following a beach nourishment project in China [7]. Additionally, an analytical model and a One Line model were developed to compare beach performance with measured data in three beach projects in Florida [8]. A wave-sediment transport numerical model based on the higher order Boussinesq equations was developed by [9], which can calculate both cross-shore and planform morphology evolution. For the evaluation of shoreface nourishments specifically, [10] examined the development of a shoreface nourishment off Sylt Island, using a numerical model to simulate the hydro and local sediment J. Mar. Sci. Eng. 2020, 8, 247; doi:10.3390/jmse8040247 www.mdpi.com/journal/jmse J. Mar. Sci. Eng. 2020, 8, x 247 FOR PEER REVIEW 2 of 16 transport processes, and the validity of XBeach numerical model was presented to predict the erosion transportof 19 shoreface processes, nourishments and the at validity different of sections XBeach of numerical the Dutch model coast [11]. was Cross presented‐shore to transport predict (for the erosionshore‐normal of 19 shoreface waves) governed nourishments the first at di‐yearfferent erosion sections rates of theof the Dutch beach coast nourishment [11]. Cross-shore and alongshore transport (fortransport shore-normal only contributed waves) governed about 15% the first-year to 40%, erosionmost erosion rates of being the beach produced nourishment under energetic and alongshore wave transportconditions, only and contributed mild to moderate about waves 15% to propagating 40%, most erosion without being breaking produced over the under nourishment energetic [11]. wave conditions,In [12,13], and high mild energy to moderate events, waves especially propagating the first without storm, sediment breaking grain over thesize, nourishment project extent, [11 and]. longshoreIn [12 transport,13], high gradients energy events, have been especially reported the as first important storm, sedimentfactors in grainthe first size,‐year project response extent, of andshoreface longshore beach transport nourishments gradients in a have micro been‐tidal reported environment as important on the factors Florida in Gulf the first-yearCoast. response of shorefaceImprovements beach nourishments in alongshore in a sediment micro-tidal transport environment physics on and the Floridain the knowledge Gulf Coast. on mechanical propertiesImprovements of sediment in alongshore and placement, sediment besides transport wave climatology physics and forcing in the knowledgeduring the onproject, mechanical would propertieslead to better of sediment prediction and of placement, project evolution besides [14]. wave The climatology behavior forcingof shoreface during nourishment the project, would is not well lead tounderstood better prediction [11] and of it projectmay be evolution less effective [14]. if Thelarge behavior beach nourishments of shoreface are nourishment carried out is in not places well understoodwhere the possible [11] and beach it may response be less e hasffective not been if large previously beach nourishments well documented are carried [14]. out That in is places the case where for themany possible sand beaches beach response in developing has not countries. been previously well documented [14]. That is the case for many sandModern beaches coastal in developing engineering countries. requires sustainable coastal zone development that is compatible with Modernthe natural coastal environment engineering [15,16], requires thus sustainable Building with coastal Nature zone development(BwN) approaches that is compatibleare increasingly with thesought. natural In 1990, environment the Dutch [15 ,government16], thus Building stated with that Nature beach (BwN)nourishment approaches was the are preferred increasingly option sought. in Inadapting 1990, the to Dutch climate government change. In stated consequence, that beach nourishmentan innovative was large the preferredscale “sandscaping” option in adapting beach tonourishment climate change. project In was consequence, begun in the an Netherlands, innovative largeusing scalethe so “sandscaping”‐called ‘Sand Motor’, beach ‘Zandmotor’, nourishment projector ‘Sand was Engine’ begun strategy in the Netherlands, [17–20]. An using enormous the so-called volume ‘Sand of sand, Motor’, approximately ‘Zandmotor’, 20 or Mm ‘Sand3 (~10,000 Engine’ strategym3/m), was [17 put–20 ].onto An the enormous beach face volume between of sand,Ter Heijde approximately and Kijkduin, 20 Mmin South3 (~10,000 Holland, m3 /fromm), was the low put ontowater the mark beach to a face distance between of several Ter Heijde kilometers and Kijkduin, off the coast, in South 20 m Holland,deep. The from natural the re low‐distribution water mark of tosediments a distance to ofthe several nearby kilometers beaches and off thedunes coast, is taking 20 m deep. place Thethrough natural the re-distribution action of wind, of waves, sediments and tocurrents the nearby over several beaches years and [17]. dunes The is main taking objectives place through of this theinnovative action of BwN wind, solution waves, [17,19,21] and currents were overthe creation several yearsof recreational [17]. The mainareas objectivesthat were of environmentally this innovative BwNsafe. solutionThe project [17, 19uses,21] the were local the creationhydrodynamics of recreational in order areas to that induce were sedimentation environmentally through safe. The natural project beach uses the processes, local hydrodynamics rather than inmechanical order to inducemeans, sedimentationwhich can produce through unfavorably natural beach steep processes,beach slopes rather or bury than marine mechanical organisms means, in whichthe sand. can Several produce Sand unfavorably Engine designs steep beach were slopes discussed or bury before marine the organisms pilot project in the was sand. untaken Several in 2011, Sand Enginesuch as designs Full beach were discussedface nourishment, before the Peninsula pilot project or was bell untaken‐shaped in nourishment 2011, such as and Full beachthe Hook face nourishment,configuration, Peninsula which was or bell-shapedeventually nourishmentselected, Figure and 1. the This Hook design configuration, was recommended which was eventuallyfor South selected,Holland Figurein the EIA1. This (Environmental design was recommended Impact Assessment, for South 2010), Holland based in theon costs, EIA (Environmental safety, environmental Impact Assessment,and recreational 2010), criteria based [17]. on costs, safety, environmental and recreational criteria [17]. Figure 1. Three types of SandSand EngineEngine