Coastal Sandy Research Articles

LONG-TERM DUNE EVOLUTION UNDER INTERACTING CROSS-SHORE AND LONGSHORE PROCESSES

Coastal dunes play an important role in flood protection and erosion mitigation along sandy coasts. Still, few models are available that predict long-term dune evolution. Dune processes are typically modeled at shorter time scales, focusing on storm impact. Meanwhile, long-term coastline evolution models typically ignore exchange of sediment between the beach and the dune. Instead, these models often consider a fixed profile that moves seaward or landward if gradients in the longshore transport are negative or positive, respectively. Nevertheless, it is evident from field studies and morphological models that longshore transport gradients provide a relevant contribution to both beach and dune evolution (Psuty, 1988), and that the dune and the beach respond to sediment budget changes at different time scales (Stive et al., 2002). As a step towards bridging the gap between nearshore, beach, and dune modelling, this study investigates the interaction between longshore transport gradients and the beach and dune evolution on decadal time scales. This aim is addressed by combining an analysis of a 22- year long data set at IJmuiden (The Netherlands; see Figure 1) with simulations using a semi-empirical crossshore model, the CS-model (Larson et al., 2016).

PREDICTING PORT SEDIMENTATION AND NAVIGATIONAL DEPTHS ON MEDIUM/LONG-TERM TIMESCALES: COMBINING 2D AND SHORELINE MORPHOLOGICAL MODELLING

Navigational depths in entrances of ports located on open sandy coasts are governed by the supply of sediment from adjacent coastlines and the complex morphodynamics in and around the port. To predict the depths, a model encapsulating the transport along adjacent shorelines and the detailed morphology around the port structures is required. To resolve this in a fast and robust manner, a novel model which couples the features of DHI’s shoreline model (MIKE 21 FM Shoreline Morphology) and the morphological area model (MIKE 21/3 FM MD) is developed. Morphological simulations with the new tool show very promising results, when predicting the development over relatively long periods. Such new advances in medium/long term modelling of the temporal changes of the bathymetry in and around ports is key to the prediction of the navigational depth, including seasonal and annual variations.

BEACH RESPONSE TO EXPOSED RIVERINE SEDIMENT AND BEACH NOURISHMENT

Studying the process of riverine sediment at mouths and continental shelves is a critical subject for many engineering applications, such as dredging, navigation, dispersal and remobilization of contaminants. Sediment deposits also determine seabed properties, coastal geomorphology, and the health of coastal habitat/ecology. During extreme conditions, episodic river discharge triggered by large rainfall due to tropical cyclones may contribute significant amount of riverine sediment into the ocean. In the past decade, evidence of severe seabed erosion (up to 1m/year) along the sandy coast of Yunlin County has raised concerns regarding the sustainability of coastal structures. The exposed riverine sediment from the Jhuoshuei River is considered as one of major sources for sediment supply in this region. Bottle samples collected from bridge station in the Jhuoshuei River during the passage of tropical cyclones suggest sediment concentration can exceed 40 g/l for the major duration of the storm (Milliman et al. 2007). To mitigate the damage caused by shoreline retreat, 600,000 cubic meters per month of sand has been placed in two specific locations near the offshore industry park. The overarching goal of this study is to clarify the contribution of exposed riverine sediment and beach nourishment to enhance our understanding on the observed sediment transport and morphological evolution.

EROSION AND BREACHING OF COASTAL BARRIERS IN A CHANGING CLIMATE: ASSOCIATED PROCESSES AND IMPLICATION FOR CONTAMINATION OF COASTAL AQUIFERS

Europe and many other countries all over the world are often surrounded by coastal defence systems (e.g. protective dunes and dykes) in order to protect coastal areas from threats of wave attack, storm surges and subsequent coastal floods. During moderate sea conditions, wave attack and coastal erosion is limited to nearshore areas and may only cause shore erosion. Under the same conditions, fresh groundwater, which is hydraulically interconnected with seawater, is in equilibrium with the laterally intruding seawaters. Such equilibrium prevails as long as the moderate sea level (MSL) and the hydrogeological conditions at the sea/land boundary are stationary. However, during extreme storm surges, the higher water levels may temporally threaten the coastal defence systems. In fact, shortwaves riding on the temporally rising sea level during storm surge events may directly runup, rundown and/or impact on barriers, possibly causing seaward erosion followed by lowering of barrier’s crest and hence wave overtopping or overflow through combined surge and waves. As a result, barriers may breach, inducing coastal inundation and subsequent vertical saltwater intrusion (VSWI) behind the breached barriers due to the vertical infiltration of inundating seawater into the fresh groundwater. In this study, a new integral physically based methodology is developed to reliably assess the possible implications of extreme storm surges on the safety of coastal barriers and the implications of possible breaching for contamination of coastal aquifers. The integral model is therefore capable to successively simulate breaching/overtopping of coastal barriers forced by storm surges as a hydraulic load, induced flood propagation in the hinterland and subsequent VSWI into coastal aquifers while considering the complexity of these processes and mutual interaction among them. The modelling methodology consists of an improved XBeach code (Roelvink et al., 2009) for hydro-morphodynamics unidirectionally coupled with the SEAWAT code (Langevin et al., 2008) for groundwater flow. The model is applied to a case study in northern Germany, showing that marine floods represent a serious threat to usability of coastal aquifers which are extremely important water resources. Outcomes of model application showed that a coastal flood event of a few hours may contaminate coastal aquifers for many decades, thus reducing the agricultural yield and hindering the sustainable development in coastal areas prone to coastal floods. This study represents, to the knowledge of the author, the first systematic research study that addresses the safety of natural coastal sandy barriers under extreme storm surge conditions together with the consequences of possible barrier breaching and overwash on subsequent flooding and saltwater intrusion into fresh groundwater. Moreover, it is probably the foremost study that attempts to mitigate storm-driven saltwater intrusion through the use and modelling of a subsurface drainage network. Besides improving the agricultural yield in coastal areas, the use of subsurface drainage network significantly reduces the natural remediation interval required for aquifers recovery after a coastal flood event. Moreover, it limits the vertical extent of the salt intrusion. The multiple flow domains and aspects discussed in this research make it a multi-disciplinary study that is quite relevant for the coastal engineering community, for flood risk managers, for coastal hydrologists, for groundwater suppliers as well as for sustainable development planners.

A cost-effective method for estimating long-term effects of waves on beach erosion with application to Sitia Bay, Crete

Considering the significant role of beaches for the sea environment and welfare of coastal communities, a variety of process-based models are applied in order to examine and understand the interaction of hydrodynamic processes with seabed material at different time scales. However, a long-term view of this interaction requires a great amount of computational time. In this work a cost-effective methodology is proposed to surpass this shortcoming and estimate bed level evolution. The technique is relied on an objective criterion to assess spectral wave time series of wave height, period and direction and identify the wave conditions that contribute to the initiation of sediment movement. After implementing the so-called Shields criterion, the full wave climate is reduced to two classes of representative wave conditions: the over-critical ones, mainly responsible for long-term erosion, and the sub-critical wave conditions. By applying a well-known process-based model, the representative wave conditions are used as input for the wave-current-sediment transport simulation and rates of bed level changes are obtained, on the basis of which the long-term effects of waves on beach erosion are estimated. Taking into account that erosion is a threatening phenomenon along the sandy beaches of Mediterranean Sea, the present method is demonstrated at a sandy coast of Sitia Bay, Crete. The bed levels derived from the proposed methodology and the full time series are compared. The results indicate reasonable agreement at the selected locations with deviations under 7%, and conformity of the tendency of seabed evolution, rendering the new methodology a useful tool.

Influence of clay and organic amendments on the yield and zinc nutrition of blackgram in coastal sandy soil

Influence of clay and organic amendments on the yield and zinc nutrition of blackgram in coastal sandy soil

The Growth of Two Cultivars Mung Bean under different Sweet Corn Shelter Density in Sandy Soil Coastal Area

The experiment had been conducted from August to November 2016 at Samas sandy soil coastal area. The research aimed to determine growth response of mung bean sheltered by various density of sweet corn on coastal sandy soil. The experiment used the nested design with two factors with three replications.The first factor was density of sweet corn as shelter consisting of without shelter (S0), planting space of 15 × 40 cm (S1), and planting space of 30 × 40 cm (S2). The second factor was mung bean cultivars compiled of Vima 1 (V1) and Purworejo local cultivar (V2). The data of soil temperature, soil moisture content at the depth of 10 and 20 cm, soil salt content at 10 and 20 cm depth, leaf fresh and dry weight, root fresh and dry wieght, plant fresh and dry weight were collected. The effect of shelter density was on the leaves dry weight at 6 week after planting (WAP), meanwhile the mung bean cultivars influenced the soil moisture at 10 and 20 cm depth; leaves fresh weight, leaves dry weight, root fresh weight, and plant dry weight at 4 WAP. Vima 1 resulted in significantly higher compared to Purworejo local cultivar on soil moisture content in 10 and 20 cm, leaves fresh and dry weight, root fresh weight, plant fresh and dry weight at 4 WAP. There was interaction between sweet corn shelter density and mung bean cultivar on soil salt content at 10 cm (2 WAP), 20 cm (6 WAP), plant fresh weight at 4 and 6 WAP, and plant dry weight at 6 WAP. The best growth of mung bean was observed under higher level density shelter with 15 × 40 cm square planting space due to the deeper soil layer and lower salt content.

Growth and Yield of Upland Rice Under Intercropping System with Soybean in Sandy Coastal Area

Sandy coastal area in Indonesia is potential for upland rice cultivation, but it has constraints low of nutrient availability such as nitrogen. To solve the low fertility of the sandy land can be done by planting soybean between upland rice under intercropping system due to the soybean is able to provide nitrogen in soil through fixation of N2 in the air by root nodules. Intercropping is an alternative cropping system to increase land productivity, but there is competition between crops under an intercropping system. Reducing of the competition on the system is needed by crops proportion adjustment. The objective of the study is to examine growth and yield component of upland rice at different crops proportion under an intercropping system with soybean in the sandy coastal area. The research was conducted in Samas sandy coastal area, Bantul, Yogyakarta. This research used randomized complete block design (RCBD) with one factor and three blocks. The treatment of this research was five level crops proportion between upland rice and soybean under intercropping system, namely: 100:0; 80:20; 60:40; 40:60; and 20:80, respectively. The results showed that crop growth rate and yield per clump of upland rice increased on crops proportion adjustment under intercropping system with soybean. The crops proportion of 60:40 and 40:60 gave higher crop growth rates that were 1.45 g.dm-2.wk-1 and 1.44 1.45 g.dm-2.wk-1 than upland rice under monoculture (100:0) that was 1.09 g.dm-2.wk-1. The higher crop growth rates in crops proportion of 60:40 and 40:60 were able to give better yield per clump than other that were 17.17 g and 16.46 g, respectively. The yield of upland rice was not different under crops proportion of 100:0, 80:20, and 60:40 and decreased of upland rice proportion until ≤ 40% affected the low yield of upland rice.

ISOLATION, CHARACTERIZATION AND INOCULUM FORMULATION OF NODULE FORMING BACTERIA OF KUDZU (Pueraria phaseoloides (Roxb.)Benth.) FOR COASTAL SANDY LAND CONSERVATION

Kudzu plantation (Pueraria phaseoloides) as legume cover crop is one of alternatives in coastal sandy land conservation. The crops are known to associate with a root nodule-forming bacteria (Rhizobium sp.) which give some benefits to nutrient cycling i.e. : atmospheric N2 fixing and play role as soil conditioner; soil Nitrogen enrichment; nutrient cycling; and increasing other nutrients availability. A research to study the isolation dan bacterial inoculum multiplication from wild kudzu root nodules, compatible isolates screening and selected isolates multiplication, and examining the form, amounts and most proper inoculum application method was conducted in Greenhouse and Laboratory of Microbiology in Yogyakarta province.The research were held in four phases : (1) isolation, purification and characterization of isolates; (2) reinoculation dan compatibility testing of isolates to kudzu seeds; (3) inoculum multiplication; and (4) examination of the form, amounts and most proper inoculum application method. Physical and biochemical properties of the isolates were observed during the isolation phase. Infection and nodulation activity were observed during the reinoculation phase. Indirectly counting of the microbial numbers to obtain the cell numbers was conducted during the inoculum multiplication. While infection and nodulation activity and plant growth were observed during the inoculum testing phase.Isolates purification on Yeast Mannitol Agar + congo-red media gave 5 different isolates named RP-Etp1, RP-Etp2, RP-Etp3, RP-Etp4, RP-Etp5. The RP-Etp4 isolate had the highest compatibility to the kudzu seeds (number of effective nodules >100 per plant), followed by RP-Etp5 (medium compatibility, number of effective nodules 50–100 per plant), RP-Etp1 and RP-Etp3 (low compatibility, number of effective nodules < 10). Isolate RP-Etp2 was incompatible to the kudzu.Optimum cell numbers was reached in 48 hours incubation time. Application of broth/liquid inoculum of Rhizobium sp. has advantages over solid inoculum (in peat) as it gives the highest number of nodules, and the optimum dosage was 2 – 4 ml per plant. The highest infection-nodulation activity and plant growth were reached in 4 ml inoculum per plant (direct application) or 2 ml inoculum per plant (weekly applied in two weeks).

Effect of clay and manure addition on soil properties and Zn availability for blackgram in coastal sandy soils

Effect of clay and manure addition on soil properties and Zn availability for blackgram in coastal sandy soils

Patterns of early-colonising species on eroding to prograding coasts; implications for foredune plant communities on retreating coastlines

Shoreline erosion is predicted to increase as the result of climate change, yet the effects on foredune-building species and associated dune processes remain poorly understood. To predict the response of foredune plant communities to increased erosion we examined the abundance of six early colonising dune-building species across 71 beach-foredune sites in south-east Australia. The assumption being that those species better adapted to shoreline retreat will be more frequent and have increased abundance on erosional coasts than species lacking the capacity to withstand or re-establish following periods of storm-induced erosion. All species were frequently recorded regardless of the rate of shoreline progradation or erosion, which ranged 3.8 to −2.2 m year−1. Species presence was not related to erosion rates; however, there was a significant association between the rate of shoreline change and abundance for some of the studied species. Variation in traits related to tolerance to salinity and burial and the ability to establish following erosion appear to correspond to the observed patterns of species abundance. While this study examined only six species, it appears that species that are restricted to zones closer to the spring-tide level, that have a persistent rather than opportunistic growth-history or that are limited in their ability to recolonise following erosion, are more likely to be negatively impacted by increased rates of coastal erosion. Given the association between vegetation and foredune morphology these findings have important implications for the management of sandy coasts.

Morpho-sedimentary characteristics and generated primary sedimentary structures on the modern microtidal sandy coast of eastern Nile Delta, Egypt

Spatial distribution and implication of primary sedimentary structures are combined with morpho-sedimentary features to suggest a sedimentologic–neoichnological model for the low microtidal sandy coast of eastern Nile Delta. Ten linear transects normal to the shoreline were investigated across four to five parallel geomorphic landforms. Intertidal sub-environment is characterized by abundant marine-affinity surface sedimentary structures (such as beach cusps, swash marks, air holes/volcanoes, foam impressions, raindrop imprints, rill marks and tool marks) in addition to the parallel lamination and oscillation ripples. Lower supratidal sub-environment is characterized by parallel lamination, current and wind ripples. Nebkas and wind ripples dominate the nebka/inter-nebka landforms, whereas microbial-induced sedimentary structures which including cyanobacterial mats, efflorescent salt crusts, polygonal cracks and tepee structures prevail in salinas and sabkhatized landform. Marine life-trace assemblage in the intertidal zone, belonging to infaunal and epifaunal bivalves and gastropods, resembles the poor expressions of shallow-marine Skolithos ichnofacies. Predation holes in bivalves and clavate borings in drifted tree trunks are analogous to Oichnus simplex and Teredolites isp., respectively. Transitional marine life-trace assemblage of abundant ghost crab burrows and trackways represents a modern example of seaward suites of the paleoichnological backshore Psilonichnus ichnofacies. Terrestrial life-trace assemblage of beetles, ants, vertebrate tracks and rhizoliths show similarity to the landward expression of Psilonichnus ichnofacies. Despite low to moderate preservation potentiality of modern microtidal sedimentary structures, the preserved structures are invaluable in revealing depositional processes and paleoenvironments of ancient coastal systems.

XÁC SUẤT PHÁT HIỆN LOÀI NHÔNG CÁT SỌC (Leiolepis guentherpetersi) Ở VÙNG CÁT VEN BIỂN HUYỆN PHÚ LỘC, TỈNH THỪA THIÊN HUẾ

Peter’s Butterfly Lizard (Leiolepis guentherpetersi) is an endemic species of Vietnam with a narrow distribution. However, no information related to detection probability and site occupancy of this species in Vietnam was published. We monitored Leiolepis guentherpetersi in the coastal sandy areas of Phu Loc District, Thua Thien Hue Province through nine surveys at 50 sites from September to December 2017. We used the PRESENCE 12.10 software to analyze the data. The results showed that the detection probability of L. guentherpetersi, when combined with environmental factors, was 0.39, which was higher than the probability of naive detection of 0.34. The total AIC (Akaike’s Information Criteria) weight GB (near sea ecosystem) was 86% while the total AIC weight XB (ecosystem far from the sea) was only 14%; the AIC weight M (rainfall) was 99.41% while the total AIC weight N (temperature) was 62.31% and the total AIC weight DA (humidity) was 27.20%. This shows that the probability of detecting L. Guentherpetersi is influenced by both site covariates (near the sea or far from the sea) and sample covariates (temperature, humidity, and rainfall). It was found that the near sea ecosystem is the best habitat for L. guentherpetersi, and rainfall is the sample covariate that has the greatest influence on the probability of detecting this species in the coastal sandy areas of Phu Loc District.

Beach litter in Mediterranean coastal dunes: an insight on the Adriatic coast (central Italy)

Beach litter is an increasingly important threat, causing a drastic loss of natural biodiversity and the associated ecosystem services. Even if beach litter accumulation in oceanic coasts has been analyzed quite well, new research efforts are still necessary to better understand this phenomenon along the Mediterranean coasts. This work sets out to analyze the sources of beach litter, the type of material, and the distribution and accumulation trend along the sandy coasts of the Adriatic Sea in central Italy (Abruzzo and Molise Regions, Italy). In particular, we focus on the following questions: (i) Which are the most frequent beach litter items and materials on sandy coasts? (ii) How is beach litter distributed on the different coastal dune habitats along the sea–inland gradient? Data were collected and categorized during spring 2014–2015 following the OSPAR guidelines in belts parallel to the shoreline and in transects perpendicular to the shoreline. Before analyzing litter abundance by classes of material, source types, and floating capacity, the spatial trends of waste accumulation along the dune zonation was also explored. Most of litter elements are in plastic, followed by styrofoam with good floating capacity. Majority of the debris derive from food packaging, fishing and recreational activities. The distribution of litter along the sea–land eco-morphological gradient is heterogeneous. The unequal accumulation amounts of debris on the upper beach, embryodunes, mobile dunes and fixed dunes threaten natural EC habitats in different ways. Our results stress the need of specific conservation and cleaning actions able to preserve the ecological value of EC coastal dune habitats.

Monitoring Retreat of Coastal Sandy Systems Using Geomatics Techniques: Somo Beach (Cantabrian Coast, Spain, 1875–2017)

The dynamics and evolution of a coastal sandy system over the last 142 years (1875–2017) were analyzed using geomatics techniques (historical cartography, photogrammetry, topography, and terrestrial laser scanning (TLS)). The continuous beach–dune system is a very active confining sand barrier closing an estuarine system where damage is suffered by coastal infrastructures and houses. The techniques used and documentary sources involved historical cartography, digitalizing the 5-m-level curve on the maps of 1875, 1908, 1920, 1950, and 1985; photogrammetric flights of 1985, 1988, and 2001 without calibration certificates, digitalizing only the upper part of the sandy front; photogrammetric flights of 2005, 2007, 2010, and 2014, using photogrammetric restitution of the 5-m-level curve; topo-bathymetric profiles made monthly between 1988 and 1993 using a total station; a terrestrial laser scanner (TLS) since 2011 by means of two annual measurements; and the meteorological data for the period of 1985–2017. The retreat of the sandy complex was caused by winter storms with large waves and swells higher than 6 m, coinciding with periods demonstrating a high tidal range of over 100 and periods with a large number of strong storms. The retreat was 8 m between December 2013 and March 2014. The overall change of the coastline between 1875 and 2017 was approximately 415 m of retreat at Somo Beach. The erosive processes on the foredune involved the outcrop of the rock cliff in 1999 and 2014, which became a continuous rocky cliff without sands. To know the recent coastal evolution and its consequences on the human environment, the combined geomatic techniques and future TLS data series may lead to the improvement in the knowledge of shoreline changes in the context of sea level and global changes.

A reduced-complexity shoreline change model combining longshore and cross-shore processes: The LX-Shore model

A reduced-complexity numerical model, LX-Shore, is developed to simulate shoreline evolution along wave-dominated sandy coasts. The model can handle any sandy shoreline geometries (e.g. sand spits, islands), including non-erodible areas such as coastal defenses and headlands, and is coupled with a spectral wave model to cope with complex nearshore wave fields. Shoreline change is primarily driven by the gradients in total longshore sediment transport and by the cross-shore transport owing to variability in incident wave energy. Application to academic cases and a real coast highlights the potential of LX-Shore to simulate shoreline change on timescales from hours (storm) to decades with low computational cost. LX-Shore opens new perspectives in terms of knowledge on the primary mechanisms locally driving shoreline change and for ensemble-based simulations of future shoreline evolution.

Variation of Beach Profile Along Pahang Coast in Malaysia

Pahang is placed at the east coast of Peninsular Malaysia and has a lot of attractive coasts with interesting scenery, which can capture the attention of people to the coasts. The seven (7) of significant coasts namely Pantai Cherating, Holiday Villa beach, Pantai Balok, Sungai Ular, Pantai Sepat, Pantai Cheruk Palok and Pantai Tanjung Agas are classified has experienced about erosion coastal problem especially having significantly for social, environment and economic value recreational activities along of this shoreline. Coastal erosion is recognized as the permanent loss of land and habitats along of the coast. The variation of beach profile characteristics along the shoreline of Pahang will be identified and described using the beach profile survey and interpolation technique. From that, the information of erosion and accretion for topography surface of coastal was generated by calculating distance and elevation of coasts. Most of these study are consist the sandy coastal. Hence the ranges value of coastal width for Tanjung Agas is shows high value of erosion and accretion with -7.74 and 3.93 m/year. To sum up, the findings of study might be useful in significant decision making for protecting and mitigation measures towards sustainable coastal management along the Pahang coastal.

Linking source with consequences of coastal storm impacts for climate change and risk reduction scenarios for Mediterranean sandy beaches

Abstract. Integrated risk assessment approaches to support coastal managers' decisions when designing plans are increasingly becoming an urgent need. To enable efficient coastal management, possible present and future scenarios must be included, disaster risk reduction measures integrated, and multiple hazards dealt with. In this work, the Bayesian network-based approach to coastal risk assessment was applied and tested at two Mediterranean sandy coasts (Tordera Delta in Spain and Lido degli Estensi–Spina in Italy). Process-oriented models are used to predict hazards at the receptor scale which are converted into impacts through vulnerability relations. In each site, results from 96 simulations under different scenarios are integrated by using a Bayesian-based decision network to link forcing characteristics with expected impacts through conditional probabilities. Consultations with local stakeholders and experts have shown that the tool is valuable for communicating risks and the effects of risk reduction strategies. The tool can therefore be valuable support for coastal decision-making.

A new instability mechanism related to high-angle waves

Waves with a large incidence angle in deep water can drive a morphodynamic instability on a sandy coast whereby shoreline sand waves, cuspate forelands, and spits can emerge. This instability is related to bathymetric perturbations extending offshore in the shoaling zone. Here, we explore a different mechanism where the large incidence angle is supposed to occur at breaking and the bathymetric perturbations occur only in the surf zone. For wave incidence angles at breaking above ≈ 45∘, the one-line approximation of coastal dynamics predicts an unstable shoreline. This instability (EHAWI) is scale-free and the growth rate increases without bound for decreasing wavelength. Here we use a 2DH morphodynamic model resolving surf zone instabilities to investigate whether EHAWI could approximate a real instability in nature with a characteristic length scale. Assuming very idealized conditions on the bathymetric profile and sediment transport, we find a 2DH instability mode consisting of shore-oblique up-current bars coupled to a meandering of the longshore current. This mode grows for high-angle waves, above about 30∘ (offshore) and the maximum growth rate occurs for the angle maximizing the angle at breaking, about 70∘ (offshore). The dominant wavelength is of the order of the surf zone width. Interestingly, for long sand waves, the growth rate never becomes negative and it matches very well the anti-diffusive behavior of EHAWI. This distinguishes the present instability mode from other modes found in previous studies for other bathymetric and sediment transport conditions. Thus, we conclude that EHAWI approximates a real morphodynamic instability only for quite particular conditions. In such case, a characteristic length scale of the instability emerges thanks to surf zone processes that damp short wavelengths.

Responses Growth and Yield of Three Shallot Cultivars in Sandy Coastal Land with PGPR (Plant Growth Promoting Rhizobacteria)

Plant Growth Promoting Rhizobacteria (PGPR) is a group of bacteria rhizosphere used to a biological fertilizer on agricultural activities. The purpose of this research got the kind of PGPR which was effective against the growth of three cultivars at sandy coastal land. The research was conducted from August - November 2015 in coastal sandy land Samas-Bantul. This research used a randomized block design ( RCBD ) with two factor such us cultivar of shallot and suspension PGPR . The first factor s were the Crok cultivar, Tiron, and Tuk-tuk and the second factors were Control (without PGPR), PGPR isolates BP25.2 (Bacillus methylotrophic), BP25.6 (Bacillus amyloliquofaciens), BP25.7 (Bacillus subtilis), BrSM 4 (Burkholderia cepacian), and BrSG 5 (Burkholderia seminalis). Data were analyzed by using ANOVA α 5%. If there were a significant difference between treatments , so it was analyzedby DMRT α 5%. Results showed significant through interactions every variable generated, such as isolates BP25.2 that can enhance seed vigor index Tiron cultivars, isolates BrSG 5 and BP25.7 capable of inducing number of leaves in the vegetative phase and is capable of stimulating content proline in the face of stress shallot plant at sandy coastal, isolates BrSM 4 is able to increase the number of total chlorophyll Tuk-tuk cultivars and isolates BrSG 5 is able to increase the dry weight of bulbs production Tuk-tuk cultivars.