The experimental field is located on the coast of the Japan Sea and in the north of Fukui prefecture. Some experiments with regard to the aquifer thermal-energy strage (ATES) have been carried out in the field for several years and the characteristics of these experiments were as follows;
(1) It was not the recharge through well, but the water spreading with some ditches that was adopted for the artificial recharge.
(2) Reservoir for heat and water was an unconfined aquifer and was located shallow depth below the surface.
(3) Recharge water used for these experiments was river water and it was naturally heated to an average temperature of 25t in summer.
The following are mainly identified by examining the heat balance of aquifer and by trying to compare the observed heat data with the approximate values that were lead from the simplified analytical models.
(1) The principal factor concerning the loss of heat in reservoir was the heat dispersion in aquifer caused by natural groundwater streams at this field.
(2) The heat conduction models are efficient for estimationg the change of heat capacity in the. aquifer after recharge.

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The Kanto Plain is the largest groundwater basin and the largest groundwater used region in Japan. There is a groundwater area with high Cl concentration (from 10 to 150 mg/l) in the depth of GL-100m to -300m of the central part of the plain. This groundwater area is thought to be made by regional groundwater flow, from the viewpoint of three-dimensional observations of groundwater quality, stable isotopes, and subsurface temperature. On the other hand, it has been pointed out the reduction of the high Cl groundwater area since 1960’s. However, the tendency and the process of the reduction have not been clarified yet. In this study, secular change of high Cl groundwater area and distribution of Cl concentration in 40 years was studied. Also, process of the change was considered by comparison with secular change of distribution of hydraulic head and land subsidence area.

From the result, reduction of the high Cl groundwater area and decrease of Cl concentration in the groundwater area was clarified, and these changes were remarkable in the southern part of the high Cl groundwater area. The reduction and the decrease was caused by secular change of groundwater flow according to depression of hydraulic head in depths of GL-100m to -300m, and supply of low Cl groundwater from the shallower part, the deeper part, and the surroundings to the high Cl groundwater area.

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The waters facing Toyama-Shinko Port (Fushiki Toyama Port Shinminato District) in Toyama Bay combine inflows from the Shinbori, Uchi, and Gejou Rivers with those of the open sea. Some unique flows occur in the harbor due to density differences between these two water masses, tidal forces, and the influence of the sea bottom shape. Regarding the coast around Toyama Bay, we have regularly investigated the structure of the water masses since 2003 and found that they are influenced by river water, the Tsushima warm current, and the characteristics of seasonal fluctuations.

In the present study, we conducted an ocean environmental survey using a Conductivity, Temperature, and Depth (CTD) profiler at various points inside the harbor at different locations ranging from the harbor entrance to the rivers in the harbor. In addition, we compared the results of surveys of the open sea and inside the harbor. In the CTD observations conducted in June and Sep. 2017 and Feb. 2018, we found that the influence of river water was strong from the surface to a depth of approximately 2 to 3m, and that dense seawater, similar to that of the open sea, was widely distributed in the deep water below the surface layer. And, we performed Acoustic Doppler Current Profiler (ADCP) observations in the harbor. The results indicated that the flow direction differed between the river water layer and the outer sea water layer.

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The wheel house front glass of a fore-bridge-ship was broken by the shipping of water in rough sea. This breakage of the front glass is incredible because the front glass was in 20(m) above the water surface. In order to analyze the reason of the accident and to avoid similar problems, we demonstrated a flow mechanism causing the strongly rising water flow to the wheelhouse, and then suggested a formula to estimate the rising flow velocity through water tank experiments (1) (2). In this paper, we study experimentally the characteristics of the crash impact water-pressure by using freely falling water mass, and then analyze the breakage condition of the wheelhouse front glass by comparing the above impact water-pressure with the maximum allowable pressure of the designed front glass. In addition a criterion for the breakage avoidance of a wheelhouse front glass is considered from the height of the shipping water level at the fore end over the bow deck. The results are summarized as follows : (1) The non-dimensional coefficient C_<pi> of the impact water-pressure was about 2.8 in the case of the crash angle φ being φ=90°. (2) The characteristics of C_<pi> for φ was able to describe as sin^<10> φ approximately. (3) The breakage of the front glass may occur under the condition that the shipping water level at the fore end reaches to about 2(m) over the bow deck. (4) The above water level would be a useful information for navigator to avoid the breakage of the front glass, because the information can be recognized easily.

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Electrical prospecting method is traditionally used to obtain an information of geological profile, as one of geophysical prospecting methods for hydrogeological survey. However, recently, we need to develop a new technique which provides a moving profile of resistivity due to the groundwater flow.
A new technique, in which movement of an electrolyte tracer is obtained by means of resistivity measurements and the feature of the tracer movement beneath a survey line is visually displayed, is demonstrated in this paper. Sodium chloride is used as a tracer. The effectiveness of this method is ensured with the result of borehole loggings.

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海洋亜表層の溶存窒素、アルゴン濃度は、そのが表面で形成された時の大気-海洋間の気体交換や気泡貫入量によってのみ決まるため形成時の海況を復元する指標となりうる可能性がある。そこで高精度な溶存窒素、アルゴンの分析装置を開発し北西部北太平洋においてその分布を明らかにした。その結果、海洋亜表層の各の濃度、飽和度は各ごとにそれぞれ異なっていた。また、非平衡の差から求めた気泡貫入量も各で異なっており、形成時の海況を復元する指標となりうることを示した。

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要旨：近年有明海の環境悪化と諫早湾潮受堤防の関係が社会問題になっている。堤防は明らかに諫早湾近傍の潮流速度を減少させたが，生態系変化，特に漁業事情の悪化の原因を堤防のみに帰するかはさらなる検討を要する。しかし現場の漁業関係者からは緊急な対策が要求されており，それが局所的であれ，工学的手法の検討も為されるべきである。そこで三重県五ヶ所湾で効果のあった密度流拡散装置を諫早湾口の竹崎島沖に適用し，既存の海洋物理モデルに生態系モデルを組み入れることにより，この装置の貧酸素

低減化に関する効果について調べた。その結果，深層及び表層から給水した海水を1日当たり100万トン規模で中層に放流した場合，装置稼動8週間後に諌早湾内の貧酸素の約16%を，1000万トンの放流では約52％減少できることが予測された。今後の課題として，貧酸素の形成と深く係わっている底生生態系モデルを生態系モデルに組み込むなどしてより詳細なモデルを構築し，観測結果との比較・検証によりモデルの信頼性を高めていくことがあげられる。

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黒潮の流軸の変動は、気象・漁業に大きな影響を与え、その長期連続観測が望まれている。本論文では、この黒潮の状況を広域に高精度で連続観測する新しい計測法を提案し検討を行っている。本方法は、黒潮海域の音速鉛直分布を、場所に依存する係数を含む深度の関数として近似表現し、25km隔てて設置した送受波器アレー間を伝搬する水平伝搬音波の上方伝搬波と下方伝搬波の伝搬時間差から、音速近似式中の係数を反復逆演算により求め、その海域の詳細な音速鉛直分布を推定するものである。誤差のある伝搬時間差測定から音速鉛直分布を推定する計算機シミュレーションを行ったところ、黒潮海域の音速鉛直分布を十分な精度で推定することができた。

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第四紀古海洋復元のための基礎研究として, 日本列島太平洋側海底の表層堆積物中の浮遊性有孔虫遺骸群集を調べ, 表層との関係を検討した. この結果に基づき, 四国沖, 遠州灘沖, 房総沖および鹿島灘沖の4海域より採取したコアの浮遊性有孔虫化石群集の垂直的分布から, 過去2万年間の黒潮の流路の変遷を推論した.
20,000～16,000年前には, 西南日本沖の黒潮の流路は現在より南にあり, 四国沖や遠州灘沖では冷が頻発していた. 15,000～14,000年前には, 黒潮は西南日本沖で南に大きく蛇行し, 黒潮前線は房総沖にあった. その時期には四国沖や遠州灘沖で冷が発生していた. その後, 11,000年前までに西南日本沖では黒潮の影響が強くなった. 房総沖と鹿島灘沖では, 11,000年前頃短期的な寒冷化があった後, 急速に温暖化した. 10,000～9,000年前には黒潮の流軸は本州に近づき, 黒潮前線も北に移動しはじめた. 9,000～6,000年前には黒潮はさらに西南日本に接近し, 黒潮前線は6,000年前に最も北上した. 5,000年前以降, 黒潮は西南日本沖で現在の流路に近づいたが, 4,500～1,500年前には, 房総沖や鹿島灘沖で冷が発達していた.

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The behaviors of hypoxic water mass in Isahaya Bay have been investigated by analyzing the data of water quality and wind measured from June to September of 2009 by the Kyushu Regional Agricultural Administration Office. The front of hypoxic water mass responds sensitively to wind and tends to be perpendicular to the prevailing wind direction. When the southerly wind blows, the low density water mass near the water surface, which is rich of dissolved oxygen, is transported to the mouth of Isahaya Bay and the hypoxic water mass near the seabed is transported to the inner area. On the other hand, the northerly wind drifts the water mass near the water surface to the inner area and the hypoxic water mass near the seabed moves to the offshore direction. The continuous blowing of the southerly wind decreases the concentration of dissolved oxygen in the inner area, and that of the northerly wind increases it.

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The review on the variation of the Kuroshio extending from several hours to ten years is described here. We have had no clear understandings on the mechanisms of occurrence of large and comparatively stable meander off Kisyu-Ensyu Nada. It is known, at present, that the selected several small meanders in spring off the east coast of Kyusyu progress towards east along the south coasts of Shikoku and Kii Peninsular and stop its advance off Ensyu Nada and become large. This large meander is always accompanied, inside of it, with the ascending cold intermediate water in the Pacific. We cannot fully understand the mechanisms of occurrence and continuation of this large meander without knowledges of the deep and bottom current based on the direct measurement and the long-term variation in the atmosphere over the Pacific especially subtropical western Pacific.
There exist middle and small scale meanders which progress easterly almost every time except the period of large stable meander off Kisyu-Ensyu Nada. The Kuroshio which flows along the south coast of Japan might exist in the duration only about 1/4-1/6 of total period after the World War II. Therefore the paths of large scale meander off Kisyu-Ensyu Nada and Middle and small scale meanders traveling easterly must not be considered abnormal. The very short-period fluctuations, one or half a day, of the velocity and direction of the Kuroshio were observed only by several systematic programmes with several vessels in Japan. From these simultaneous observations, comparatively large variations of velocity of the Kuroshio which may mask the amplitude of long-period variation of the Kuroshio were found. The observations of detailed pattern and direction of propagation of disturbed wave will be necessary to get the causes of these variations.

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2007–2008年の観測データから，東京湾の盤洲干潟沖へ貧酸素

が分布する現象は，2つのパターンに類別されることを明らかにした．その一つは，南偏風が連吹するときに外海から冷たく重い海水が浸入するときに発生し，それまで湾中央部の底層に分布していた貧酸素が同域で中層へ分布深度が変わるとともに，盤洲干潟沖へも移動した．このとき盤洲干潟沖では，貧酸素がごく浅い水深にまで及ぶため，これが干潟へ波及する危険性が高まった．もう一つは，北偏風が数日以上吹き続く時に，湾中央部の底層に分布していた貧酸素が盤洲干潟沖へ移動する現象であった．この時，盤洲干潟沖では貧酸素はごく底層にのみ分布するので，干潟の貝類に影響を与える可能性は低い．しかし，同海域にはトリガイ等有用生物が生息しており，これらの漁場形成には影響を与えると考えられた．

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海域での大規模埋立工事において一般的に採用される底開バージによる土砂直投工において生じる濁りの拡散, 特に投下土砂が水中を鉛直落下する際に誘起する流動場に起因する濁りの拡散過程について水理実験および理論解析により検討する. 土砂直投工をモデル化した実験を実施して, 誘起流動により形成される濁の挙動の概要を示すとともに, 実験結果を基礎とした濁挙動に関する解析モデルを開発する.

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