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Beach changes on the Narusawa, Taga and Kawarago coasts in Hitachi City in Ibaraki Prefecture were investigated on the basis of the aerial photographs and field observation. The shoreline changes between 1984 and 2006 were studied. Sea cliff extends along these coasts, and narrow sandy beaches have been formed mainly by the sand supply from small rivers. The breakwaters of Kawarago port and Ohse fishing port were constructed, resulting in the formation of the wave shelter zone. Longshore sand transport from outside to inside the wave shelter zone was induced, causing erosion outside the wave shelter zone and accretion inside it. In the eroded zone, sea cliff is exposed to waves and abrasion by gravels is underway. To protect these beaches, comprehensive management such as the sand recycling is required.

The Seisho-bypass highway runs along the Seisho coast facing the Sagami Bay. On September 6, Typhoon 0709 attacked this coast with rough waves, and the road of this highway was severely damaged over 1.1km length, resulting in full traffic stoppage. During this typhoon, maximum significant wave height reached 6m with a wave period of 14s. Damages of the road were investigated through the field observation. Strong waves attacked the coastline from the Southeast, which is in contrast to the ordinary wave direction of the Southwest. Due to this oblique wave incidence, westward longshore sand transport was developed. Along this coast, the submarine canyons develop at several locations, and part of sand transported by longshore sand transport is considered to be flowed out of the submarine canyons, causing net loss of sand.

In open coastal sea area in which turbulence by ocean waves constitutes severe conditions for growth of eelgrass, eelgrass grows densely and maintains its own vegetation by stabilizing the sandy substrate. The larger the scale of vegetation, the more effective is this function, but on the other hand, in forming eelgrass beds, it is more effective to allow eelgrass to form in small patchy beds interspersed with bare areas as much as possible. In order to obtain the basic data for formulating this kind of efficient eelgrass bed formation plan, the authors are conducting field observation surveys. The target site is an extremely small-scale eelgrass bedformed like a remote island in the sea, and the prosperity and decay of the eelgrass bed has been observed and surveyed several times a year for the last three years and nearly every month in 2003. In addition, a wave environment that exerts a great influence over the prosperity and decay of eelgrass was observed at that spot.

This paper presents a summary of the special session “Land Reclamation at Seas.” The target of the session is to identify technologies which are necessary to construct man-made land environmental-friendly and economically. The session consists of two parts: one part is presentation of the papers regarding with environmental topics on land reclamation at seas and the other part is a panel discussion among panelists presenting the papers. Presented are four papers concerning field observation on algae growth around coastal structures and one paper concerning the general topics on land reclamation projects in Japan. The evaluating methods of algae growth on artificial structures are introduced and its applicability to seawalls of man-made land is confirmed by the result of monitoring surveys.

As a water quality purification measure for areas such as lakes, a sand capping method by sand-upwelling system was developed. This method involves welling up clean sand from below contaminated sludge by using a water jet. The disposal of sludge and the acquirement of pure sand are not necessary like dredging and conventional sand capping works. Besides, the ecosystem will hardly be disturbed by this method.A scale model test and field tests at Lake Suwa were carried out to study sediment purification effects, sand capping conditions and turbidity range. As a result, it was demonstrated that sand capping was succeeded by this method.Some characteristics of this method were revealed, the thickness and the area of the sand capping depended on the jet discharge rate and the sand diameter, the turbidity range was very small caused by this method. After seven months later, the field observation was carried out in Lake Suwa. The thickness of the sand capping layer and the aerobic environment were maintained. Also, many Limnodius appeared in the sand capping area.

In the design of port structures, it is important to decide actions rationally. When designingport structures by the reliability design method corresponding to international standards, it isnecessary to evaluate probability distributions of actions. Moreover, in order to determine rationally thepartial factors used for the partial factor method, the probability distribution of actions is required.In this research, we took the focus to the surcharge by cargos on a quaywall. Fieldobservation about the surcharge was performed in the berth for general cargos of the Yokohama port in Japan. The observation using a digital video camera was conducted. Analysis was performed based on thevideo image and the cargo size and weight data offered from some ship companies. The probabilitydistribution of surcharge was evaluated. The design values of surcharge at normal time and earthquake timewere estimated using by the probability distribution.

Field observation of spawning ground of horseshoe crab Tachypleus tridentatus was carried out in August 2000 at a river mouth in Seikai-cho in Nagasaki Prefecture. Many eggs spawned under thegroundof river mouth bars were found. Morphological features of spawning ground including surrounding vegetations were investigated and compared with the results of the former studies. Results were well explained by the features summarized in the former studies. A note on conservation of rare species was discussed.

Human-induced alterations were investigated at sixty sea turtle nesting sites based on field surveys. Alterations were classified into 6 types due to the effects to the nesting behavior of loggerhead turtle Caretta caretta. The 63% of the nesting sites are suffering from decrease of nesting areas caused by construction of seawall, beach erosion and excess usage of back-shore. In order to monitor and restore sandy beaches, cooperation between amateur turtle surveyors and coastal engineers is required.

It was confirmed that the horizontal recession made from the visor and notch was effective to expand the inhabitables pacef or marinep eriphytonsi n mediolittoralz one (Hiyama, et. al 2001). However, it was thought that this was a peculiar phenomenon because the field investigationw as conducted at a single point. Therefore, we conduct field observationa t otherp oints to verifyt he effect of the horizontalr ecession.From the observations at the Miura Peninsula and Manazuru Peninsulai n the Sagami Bay, it was reconfiremed that the horizontal recession is effective to expand the inhabitable space for marine periphytons

A filed observation on waves and long-period waves were conducted at the nearshore area of Naoetsu port during winter. Water surface elevations and water velocities were measured at 9 points inside and outside the Naoetsu port. The spectral properties of long-period waves were investigated. Comparing between observed long-period and bound waves calculated from primary wave spectra, it is confirmed that the long-period wave comporment in the nearshore area is mostly free wave.

Field observation of the Manly Beach in the suburb of Sydney in Australia was carried out to investigate coastal zone environment. Coastal zone in this area has a much better environment compared with the Japanese coast, much of which is covered artificially by concrete blocks. One of the utilizations, which is new in Japan, is the natural pool built at the corner of the pocket beach. This is a good idea in order to create safe, natural recreational zone for swimming and it may be introduced in Japan. Improvement method in building gently sloping revetment is discussed.

Under the new seacoast law, protection of coastal environment became important target of the law.In order to promote protection of coastal environment, understanding of topographic changes of the shore and conditions materializing coastal vegetations is important.This study introduces ergodic reasoning regarding beach changes and its related change in vegetation area, taking the Isewan-Seinan coast as the example.Field observation was made as well as the investigation of aerial photograph of the coast.

Field observation of natural and artificial spawning sites of horseshoe crab Tachypleus tridentatus was conducted at Sone tidal flat in Kita-Kyushu City. Natural spawning site is located at the sandy beach at the comet tail extending landward from the lee side of Mashima island on tidal flat. Beach profile and grain size distribution of the spawning site were measured. Artificial nourishment was carried out in front of the gently sloping coastal revetment. Spawning of horseshoe crab was confirmed on this nourished beach, but nourished sand on the artificial beach was carried away by longshore sand transport under wave action. In order to create a stable spawning site for horseshoe crab, it is necessary to build groins to stabilize sandy beach.

Beach erosion of the Ventura coast in California was investigated by field observation. On this beach, located on the downcoast of the Ventura River mouth, where eastward longshore sand transport dominates, beach erosion was triggered by the obstruction of continuous sediment supply from the Ventura River by the construction of Matilija Dam. Removal methods of deposited sediment in upstreamregion of this dam, and their effects and influences to the riverbed and the coastline were discussed in Sand Right '99 symposium held in Ventura. This study summarizes the results of this symposium as wellas the results of field observation, and future measures in Japan are discussed through the comparison.

Topographic features of coastal sand dune located very close to the south end of Monterey Bay in California was observed on September 3, 1999. On this sand dune, landward winds formed blowout at many places and they often block traffic in the Highway. Detailed observation of topographic changes caused by blowout was made. Based on the field observation, longitudinal and vertical change of the sand dune associated with the formation of the blowout is summarized in the schematic diagram.

Field observation of movement of nourished gravels was carried out at Kashiwazaki area in Lake Kasumigaura. Beach changes after the nourishment using gravels of median diameter 5.3mm were measured by beach surveys. Aerial photographs were taken by using a model airplane, and shoreline changes were compared. Longshore sediment transport rate was estimated to be around 2.4m3/d (868m3/yr) from July 25, 1997 to October 28 from thecomparison of beach profiles. Nourished gravels mainly moved in the longshore direction whileforming berms.

In the university education, acquirement of the proper judging ability of the adequate natural and social systems on the basis of the enough knowledge and philosophy is important. Artificial beach in the city is an adequate site for education to realize techniques to create artificial environment. A trial of field education for undergraduate students in multi-disciplinary sciences was conducted in Odaiba Park in Tokyo Port. Students carried out field observation and beach survey by themselves as well as analysis of beach materials. Conditions of this artificial beach were compared with that of natural beaches. Various issues associated with planning of the beach park were discussed through the young users' eyes.

Beach erosion of the Hitotsumatsu beach on the Kujukuri coast in Chiba Prefecture facing the Pacific Ocean was investigated by field observations in 1997 and 1998. The Kujukuri coast has been formed by the deposition of sediment supplied from the sea cliffs located both ends of a 60km long stretch of coastline. Disappearance of sand source of the sea cliff due to the construction of wave dissipating works on foot of sea cliff as a measure against erosion and obstruction of continuous sand movement by breakwaters of the harbors caused severe beach erosion on the downcoast. Here such a situation is studied and future measures against beach erosion is discussed.

Field observation on wave, current and long-period motions of a moored vessel at Reihoku Port was conducted. Highly accurate data of six motions around the center of gravity of the vessel, the tension of the mooring ropes and the displacement of the fender were obtained. It was confirmed that the longperiod motions, such as surging, swaying and yawing, were strongly affected by mooring system. By considering multi-directionality and frequency bandwidth of incident waves as input conditions for a numerical simulation, the calculation results of the vessel motions agree with the field observation data well.

Field observations of wave run-up height for Gentle-slope sea dike facing the Bay of Ishinomaki were carried out. The correlations between the representative waves were obtained as follows: H1/10=1.265H1/3, H1/3=1.590H in offshore waves and R1/10=1.146R1/3, R1/3=1.263R in wave run-up heights and V1/10=1.122V1/3, V1/3=1.234V in wave uprush velocity. Frequency distribution of wave run-up heights and wave uprush velocity on this Gentle-slope sea dike were obtained. The values of rerative run-up heights (R/Ho) tended to decrease, as wave deep steepness (Ho/Lo) was bigger, and as relative depth (hi/Lo, hi: water depth at toe of sea dike) was smaller.

Gently-sloping coastal revetments have been widely used in Japan for creating easy access to the beach. However, most of them were built on the sandy beach, whose foreshore width isaround 30m or less, and the construction of mild concrete slope of around 1: 4 with the top height of over 5m on the beach causes artificial beach erosion due to the coverage of natural sandy beach. Nevertheless gently-sloping coastal revetment is widely believed to be useful to create attractive coastal environment. Field observations were made to investigate this issue, and it is concluded that the present usage of the gently-sloping coastal revetment is a mistake.

Beach changes triggered by the construction of detached breakwaters and harbor breakwaters were investigated through comparison of aerial photographs on the Yotsukura and Natsui coasts both located in a pocket beach of 11km long stretch facing the Pacific Ocean. Formation of wave calm zone behind these breakwaters induced severe beach erosion on the surrounding beaches as well as sand accumulation in the lee side of the structures. Further the construction of gently-sloping coastal revetment covered vast area of natural sandy beaches. Deep concern should be paid to the change in this coastal situation in order to preserve and recover natural coastal environment.

Relation between configuration of a comet tail formed in the lee side of an island and the predominant wave direction was investigated at Himeshima and Mashima islands in northern Kyushu. The direction of a comet tail shows the direction of predominant wave incident to that island. Field observation was carried out at Mashima island. The difference of coastline features around this island can be well explained by oblique wave incidence predicted by the shape of a comet tail. The existence of rocky north coast covered by boulder and south coast composed by shell beach is explained by this fact. The predominant wave direction was also determined from the shoreline shape in a pocket beach and compared with that obtained from the shape of the comet tail.

Field investigation of formative mechanism of scarp around headland built on the Chigasaki coast facing Sagami Bay in Kanagawa Prefecture was carried out. Beach nourishment was conducted at this coast against beach erosion and beach changes after the nourishment were measured. Formation of double scarps were found at the lower and upper levels of the beaches depending on eastward longshore sand transport associated with rough waves and westward longshore sand transport generated in calm wave condition.

Aerial photographs were taken to investigate beach changes on coral coasts and sand movement around reef gap at Sanur and Nusa Dua Beaches on Bali Island by using a ultra light plane. At Sanur dominant beach changes can be observed around groins because of obstruction of longshore sand transport. On both beaches, beach erosion has become serious problem and various measures were taken, but lack of overall comprehensive plan reduces natural sandy beach to artificial coastline protected by many kinds of structures.

Topographic features of a sandspit and ebb tidal flat on the Natsume coast located at Konoshima Channel in Kasaoka City in Okayama Prefecture were investigated through field observation. The sandy beaches of this coast have been utilized as a spawning site of horseshoe crab Tachypleus tridentatus but recently large beach changes have been observed, narrowing the horseshoe habitat located at the downcoast of the spawning site. The beach changes were triggered by waves produced by ship navigation in narrow, funnel-shaped channel. A measure to stabilize the sand spit is proposed in order to prevent diffusion of sand over the ebb tidal flat.

To carry out marine construction works smoothly, it is important to understand t he limit conditions for marine construction works and ship's navigation for refuge in severe sea conditions and to establish countermeasures for safe marine construc tion works. In this research, the limit conditions of marine construction works are discussed based on the results of long duration field observation of ship motio ns during marine construction works and navigation for refuge, and numerical simulations on ship motions in waves and winds.