徳島県

には3つの貯水ダムが連続して設置され（下流より川口ダム，長安口ダム，小見野々ダム），複数の種苗が放流されている。本研究では，集団解析に有効なマイクロサテライト DNA 多型により，のダム湖群に生息しているアユの由来を解明し，適切な資源管理に資することを目的とした。判別の結果，一部を除き放流されている人工種苗の多くは海産由来であったが，それぞれの種苗間の多くでは遺伝的異質性が確認された。のダム湖群で採捕されたアユ仔魚と幼魚は海産由来であり，ダム下流のの天然種苗とは異質性が確認されなかった。一方，2018年10月末に小見野々ダム上流で採捕された仔魚については，特定の人工種苗と似た集団構造が確認された。

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　本研究では，5万分の1地質図幅「北川」の調査・研究の一環として，徳島県西部，上流部の河成段丘を記載し，発達の程度と広域テフラによって段丘を編年する．　吉山・柳田（1995）は，中流部の2地点で酸素同位体ステージ2と6の河成段丘の比高が上流に向かって増大し，それは四国山地の南北軸を持つ東西方向の曲隆によるとした．しかし，段丘の編年の根拠は示されておらず，従来のの段丘の編年は堆積物の風化度のみに基づいていた．　那賀郡那賀町小見野々ダムより上流のに沿っては，現河床と10？15 mの比高を持つ段丘の連続性が最もよく，この段丘をいずはら出原1面と呼ぶ．出原1面の縦断面は上流に向かって収斂する．出原1面を基準として，現河床からの高度，勾配，平面的な広がり，および縦断面の連続性を考慮すると，平面的な広がり，および縦断面の連続性を考慮すると，上流部の河成段丘は，低位のものから，出原2面，出原1面，わんだ和無田 2面，和無田1面，寺ノ内面，川島面，黒野田3面，黒野田2面，黒野田1面および黒野田峠面の10面に細分される．これらの段丘は，すべて侵食段丘である．　和無田2面は，直上を2.6？2.9万年前の姶良Tnテフラ（AT）に覆われることから，約3万年前に形成されたと考えられる．出原2面から和無田1面までの4面は，それぞれの段丘間の比高が小さく，一連の侵食段丘群とみなされることから，それらは最終氷期の後半から末期にかけて形成されたと考えられる．寺ノ内面より上位の段丘の編年は，今後の課題である．

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Takaisoyama and Hose landslides occurred by heavy rainfall of typhoon in 25 July, 1892, in east Shikoku. These landslides blocked rivers and formed landslide dams. Many old documents illustrated outbursts and disasters of Takai-soyama and Hose Landslide dams. Takaisoyama landslide blocked Naka River and formed landslide dam of 71 m in height and 7.25×10⁷ m³ in volume (Terado, 1970). The landslide dam broke down when the dam lake was filled with water after 1.87×10⁵ seconds ( 52 hours), and the big flood rushed down the valley of Naka River, with the damage of more than 300 houses and the victims of 60 persons. Calculating by Manning formula, the peak flood discharge started by velocity of 10-12 m /second(average velocity of 5 m /second)and a volume of 3.0×10⁴ m³/second, and rushed down by 3 hours at the distance of 49.3 km from the landslide dam. This flood reached by 7.5 hours at the distance of 72km in the estuary of Naka River. Hose Landslide blocked Kaifu River and formed landslide dam of 80 m in height and 3.3×10⁷ m³ in volume. The landslide dam broke down after 1.08×10⁵ seconds (30 hours) or 1.94 ×10⁵ seconds (54 hours), and the big flood rushed down the valley of Kaifu River with the damage of more than 20 houses and the victims of 47 persons. This flood rushed down in 3-4 hours at the distance of 23 km in the estuary of Kaifu River.

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徳島県西部, 上流部では, 本流には10面, 支流の海川谷川および南川にはそれぞれ5面および2面の段丘が分布している. 2.6～2.9万年前の姶良Tnテフラ (AT) と約7,300年前の鬼界アカホヤテフラ (K-Ah) との関係, 構成層の風化の程度を露頭観察, およびボーリング掘削調査によって検討した結果, 段丘の多くは酸素同位体ステージ (MIS) 2～4に形成され, MIS6 あるいはそれ以前に形成された可能性を有する段丘があることが判明した. また, 四国山地東部における第四紀後期の平均隆起速度は, 0.45mm/年以上であることは確実であり, 最大では09～1.0mm/年に達することが明らかになった.

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The authors presented a new method, which will appear in this Journal, to solve the problem of the unsteady motion of the interface between fresh water and salt water in confined aquifers.
In this study, the Galerkin-finite element method is used to simulate the two-dimensional movement of the interface in a confined aquifer in the estuary of the Naka River, Tokushima Prefecture. The distributions of the chloride concentration predicted with the numerical model were in satisfactory agreement with the results of field observation.

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Field observation of water quality and investigation of the amount of groundwater use were carried out in the estuary of Naka River, Tokushima Prefecture, Japan. This region has an ongoing salinity problem of the confined groundwater. By using numerical analysis, the reproduction of the present state and prediction of future salinity were made. Though in this region the groundwater is utilized as drinking water, industrial water, fishery product water and agricultural water, the greater part is utilized as industrial water and fishery product water. The amount used for drinking water is 10-20%, and very little is used for agriculture. Most industrial water originates in river-bed water. In the past, the main factor in the salinity of the confined groundwater in this region was superfluous pumping for fishery product water. As the number of culture farms has decreased recently, if the current amount of pumping is maintained, the intrusion of salt water further inland is not expected to occur. However, presently there is a condition in which salt water has intruded about 6 km inland from the coast into a confined aquifer on the right bank of the Naka River. Moreover, in the analysis on the assumption of sea level rise with climatic change as a future prediction, salt water will intrude further inland than in the present state.

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Hybrid-ramjet is proposed in this paper. It is the combined engine of a liquid fuel ramjet and a ducted rocket. The high Isp performance and the wide fuel flow control range of a liquid fuel ramjet and the high combustion stability of a ducted rocket are expected. Theoretical calculations of the hybrid-ramjet which has same mass solid fuel and liquid fuel, were conducted. The results shows 50% higher Isp and twice fuel control range compared with a ducted rocket.

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　浸水被害をハード整備で防ぐには膨大な時間と経費を要するため，整備途上でも被害の最小化を図るソフト対策の充実が喫緊の課題である．本研究は2014年8月に那賀町で発生した水害時の行政と住民の対応を検証する．また，過去のにおける出水状況を踏まえ，はん濫発生と水位や上流のダムからの放流量の相関関係等を検証するとともに，行政が発信する災害関連情報の種類や伝達方法，住民の避難完了までに必要な時間等も検討する．その結果，住民の避難等が適正に実施されるよう，災害発生前の行政や住民の対応を時系列に沿って「いつ，だれが，何をする」を明確にした「防災行動計画」を提案する．

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近年,わが国におけるアユ養殖業の発展は,一方において養殖地域の再編成を伴いながら進行している.そこで本稿では,全国最大の産地,平野のアユ養殖地域を事例に,地域分化の形でみられる再編成の実態とその要因を総合的視野から検討した.結果を要約すると以下のとおりである.
平野におけるアユ養殖地域は, 1964年以降産地化を進め,共撰共販体制下で生産性を飛躍的に高めて,全国最大の産地に発展してきた.しかし,この発展は産地全体に一律にはみられず,自然的・社会的条件の違いに基づいて,地区ごとに地域差が生じた.すなわち,平野のアユ養殖業は,産地形成の当初段階から,地下水が豊富な旧河道の有無に基づく左右両岸での経営形態の地域差を生じていた.その後,主産地形成事業に伴う支部制共撰共販体制の導入は,経営形態の地域差をより拡大化・固定化すると同時に,左右両岸での流通組織の地域差も顕在化させていった.第一次石油危機以降,生産費の高騰とアユ卸売価格の低下で,経営規模の内面的拡充による生産費の軽減がより重要視されるに至った.その結果,基本的に養殖業を支えている水条件の優劣が,経営の収益性を通して黒字・赤字地域という2つの地域分化を促すことになった.
以上に述べた,経営形態・流通組織・収益性を指標にして平野におけるアユ養殖地域を区分すると,左岸上・中・下流部,右岸上・中・下流部の6地区に類型化できる.なお,地域分化を規定する主たる要因としては,水条件(主要因)と流通組織(副次的要因)の2点を指摘することができる.

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From the point of view that the recent alluvial plains are formed by running water and man's activities, the writer made a thorough investigation of the Naka River's deltaic plain in order to survey the growth of plain and the development of the plain.
The result can be summarized as follows:
1) Plain of the lower Naka has 10 topographical features. The fan surface is composed within the sphere of a circular arc (semidiameter: 6km) traced with Kami Ôno as the vertex, and delta higher and delta lower lie in the margin. The former occupies the central part of plain, the latter is developed mostly on the delta side, excepting some lines radiately stretching in the central plain. Beach ridge and sand shore are largely growing at the advancing shores, but in the retreating shores they could not be found.
2) At the time of the last glacial age, this region was covered all over with depesits of coarse gravels and formed a fan land which had moresteep slope than the surface of present land; later, clayey soil beds (about 10m deep) were deposited as the result of submergence. The basis of plain was gradually formed with the submergence after the middle part of Jômon Age. There were two old distributary channels, at first, flowing from the hills towards the north-east by east and the south-east by east. Therefore, alluvial action in this region had its origin in depositing on the delta side. With natural agency and artificial activities, after that, these channels changed by slow degrees their courses from west to east. Then the deposition in the central part of plain began. The number of distributary channels has become larger on the north side of the present course. This may be attributed it diastrophic movements in the direction of SW-NE. The changes of shore line are conspicuous on the north-side of the mouths of principal dis tributaries. Though the shore line that links river mouth and Wada Jima (lies to the north; not island) had taken a shape of convex about two handred years ago, it became to be in straight-line about 1870 and shows a concave shore line at present.
3) In ancient times, the development of land reclamations on clearing was set forward around delta side, and in the Middle Ages it was gradually expanded into the central part of plain. The development of tidal land is characteristic of the Tokugawa-era, and nowadays the reclaiming work is kept on to make a new arable land at the rising part of delta.
4) The land development in ancient times was selective, and in the Middle Ages the land utilization was made according with physical formation. The development in the Tokugawa-era, however, is getting to urge the slow physical development of plain. This artificial urging of development began from about 1750. And at present the inhabitants are reclaiming the foreshore from the sea.
In short, the developments in ancient times and the Middle Ages were passive, leaving itself to circumstances; men were in the situation of being acted upon. In the Tokugawa-era and present times, on the contrary, challenges to the circumstances are being made actively.
Not that the plains keep a record of the victory of man's activities over the physical history. In the Middle Ages, the land system of Jôri type buried in the ground, and breaks of Bandai artificial levees and the other breakwaters shows a case of a temporary defeat of human history in the Tokugawa-era. Even now, shore lines are gradually receding because of erosion. The land depression attributable to earthquakes is increasing the damaged districts from sea-water.
Concerning the study of recent alluvial plains, there is much that requires consideration from various angles in human activities.

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