(1) 年間を通じて常時qなる水量を利用する際の貯水池規模決定に関する計算方法を述べ, 下流においてq=10m3/secの水を常時利用するためにはダムの貯水池規模は12,500万tonの容積が必要であることを計算例をもって示した。
(2) データは長期間, とくに渇水年を含むことの必要性を例示した。
(3) 水文諸量のデータの集収に際しては非常な困難を感じたが, 特に中小河川についても長期の地味なデータの集積が望まれる。

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Unprecedented heavy rainfall occurred in Yamaguchi and Shimane Prefectures on July 2013. These regions suffered severe damage brought by floods during the rainfall. In order to investigate the characteristics of the damage and the mechanisms of land erosion by the floods, post-disaster survey and numerical simulation were conducted for Abu River in Yamaguchi along which three railway bridges were washed out and soil in agricultural lands was intensively eroded. The results of the field observations and the two-dimensional flow analysis indicate that the overflow at a meandering point of the river caused land erosion, and the strong flows were induced at the points where one of the railway bridges was washed out.

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Semimountainous areas in Yamaguchi and Shimane Prefectures suffered severe damage brought by floods on July 2013. The damages in these areas were characterized by the vulnerability of their backlands that consists of agricultural lands. In order to investigate the mechanisms of land erosion on these areas where existing high-resolution data was not prepared, post-disaster RTK-GPS surveys and numerical simulations were conducted for Abu River in Yamaguchi. The surveys were aimed at providing the high-resolution topographic datasets of these regions in order to evaluate the influences of micro-topography on channel incisions by the flood flow. The results of the numerical calculations of movable bed-evolution well reproduced the process of the channel incisions on these areas, and it implies that the micro-topography is one of the most influential factors on erosion and channel formation processes on such semimountanious regions.

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Distribution pattern and introgression of two groups of Odontobutis obscura, West Seto and Hikimi Groups, around the Takatsu River were surveyed utilizing six diagnostic allozyme markers. West Seto Group fish were distributed to the middle to lower reaches of the Takatsu River and the upper reaches of the Abu River, while Hikimi Group fish occurred in the upper reaches of the Takatsu River, the Tama River and the Masuda River. West Seto Group population must have invaded the Takatsu River from the Abu River through presumed tributary exchanges between the upper reaches of the Abu River and the Tsuwano River, atributary of the Takatsu River. Slight accidental introgressions were recognized in two localities from Hikimi to West Seto Group populations. However, these two groups were distributed parapatrically and well isolated each other in the Takatsu River basin.

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Recent years, “nature-oriented river works” taking riverine landscape and biota into consideration have been conducted on river management. One of the techniques in the nature-oriented river works is “ductile iron net method”. This study has evaluated the function of the ductile iron net method named “Chutaro” for habitats of fishes and decapods, using environmental DNA (eDNA) methods. On the eDNA quantification of Japanese eel (Anguilla japonica) by the real-time qPCR, the eDNA concentrations of Japanese eel at the sites with Chutaro tended to be higher than those of Japanese eel in the sites with concrete revetment. On the other hand, there were not significant differences in species richness and compositions of fishes and decapods regardless of the presence and absence of Chutaro. These results suggest that Chutaro could provide A. japonica with their habitats and could be useful for the nature-oriented river works.

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　長門峡は, 中流の山口県阿武郡阿東町御堂原から萩市川上の滝橋に至る約9kmの区間と, 佐々並川の佐々並川ダムから下流約1kmの区間である. ここは大正12(1923)年に『名勝及び天然記念物』の指定を受けるとともに, 昭和35(1960)年に県立自然公園に指定されている. 長門峡の開発と観光化には, わが国で最初の地質屋である高島北海(本名 : 得三)が大きく貢献している. 長門峡と命名したのも北海である. しかしながら, その経緯や高島北海の貢献についてはほとんど知られていない. 本資料では長門峡の開発の歴史をたどりながら, 高島北海の果たした役割とその偉業について紹介する.

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The Abu river with 83km in length and 593km^2 in drainage area has its drainage in the northwestern part of Yamaguchi prefecture and pours into the Ses of Japan in the City of Hagi. It is generally believed that volcanic activies and resultant changes of river system occurred in the upper part of this river. Except for M. Oga's study there is no detailed geomorphological study based on field survey of the process of these changes The authors conducted investigation of remnant geomorphic surfaces (mainly their altitudes and surface conditions) and their deposits, in order to understand the geomorphological history of this area. The process of changes of this river system may be sumarized as follows: 1) The upper branches upwards than the Deaibuchi depths of the Abu river was the upper ones of the Tsuwano river and flewn towards north-east. The upper streams upwards than Yokoyama of the Saba river jointed the Tsuwano river at Yoro. On the other hand, the Ikumo river, one of the bra nches of the Abu river, belonged to the drainage of the Abu river before. These phenomena are deduced by the altitude of the surface of basement complex. 2) Eruptions of the Miharayama lava dome group took place just on the river course of the Tsuwano. 3) There emerged former lake Tokusa dammed by the above volcanic bodies. The altitude of the lake level was about 320m. in height and the lake extended its area as far as the upper parts of the rivers Shinome and Saba. However, the basin of the Ikumo river was not covered with the lake. These occurences are deduced from the distribution of the lacustrine terraces and the above-mentioneed deposits. Emergence of the former lake is urgued by E.Takahashi to be dated in the lacustrine deposits. However, geomorphological evidences to fully support his thesis has not yet obtained by the present writers. 4) The lake water began to drain from the Deaibuchi depths of the Chomon gorge and river courses were converted from the former direction to present-day ones. On the other hand near Tokusa town-ship, there remained a small dammed-lake. by meanes of deltaic doposits of the branch 5) Following the subsidence, the lacustrine terraces were dissected or covered with talus deposits and the branches made fans on and/or blow the lacustrine terrace. In the basin of the Matsumoto river, the river meandered and formed terraces at several levels. At early tme of the subsiding the Saba river captiured.

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Yang (1999) revealed that fish home range is an essential factor to estimate theimportance of the coexistence of pools and rapids in river habitat. Minns' formula, which is defined for rivers and fish in North America, is one of the rare studies on fish home range. In this paper we examined the applicability of the formula to Japanese rivers and fish by using radio telemetry technique. We attacheda radio transmitter to dark chub, crucian carp, common carp, Japanese dace and pike gudgeon, and tracked their behavior in rivers. The observations support the importance of the coexistence of pools and rapids. Shelters during the flood periods are also indispensable for fish. Although they showed a similar home range size with Minns' formula during one to three days, they showed much larger home range for longer periods' observation. Usually they stay within Minns' home range but occasionally they trip a long distance to a nearby habitat.

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中学校および高等学校の学習指導要領の改訂により，中学校の理科では新単元「生物の変遷と進化」が導入され，また，高等学校の「生物」においては生物の進化の仕組みについて学習することが示された。現在，中学校および高等学校における進化に関する教材開発は喫緊の課題といえる。そこで，本研究では身近に生息しているセトウチフキバッタParapodisma setouchiensisを材料として，進化に関する教材化のための基礎研究を行った。その結果，本種の色形質が

という地理的障壁を境に分かれていること，体のサイズは標高が高くなるほど小さくなることが明らかになった。このことから，本種は地理的変異，地理的隔離，種分化，適応（自然選択）などの進化に関する学習において活用可能であると考えられた。

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2013年7月28日に発生した山口・島根豪雨災害や近年の異常気象によるゲリラ豪雨に伴う洪水災害で，橋梁が倒壊する事例が頻発している．橋梁が倒壊すると長期にわたり地域住民の生活や全ての経済活動に大きな影響を与えるため，致命的な損傷を免れるべく対処が必要である．本研究では，その基本として橋脚への作用外力を適切に評価するべく，河川内橋梁の流体解析と橋脚への作用外力の評価を行った．橋脚への作用外力（流体力）が橋脚の上下流間の表面水位差と非常に大きな相関を有することから，橋脚への作用外力について，上下流間の表面水位差を指標とする評価式の構築を行ったので報告する．

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