{"title":"A Method for discriminating Aquifer by Density Logging","authors":"Keiichi Kodai","doi":"10.5917/JAGH1959.15.70","DOIUrl":"https://doi.org/10.5917/JAGH1959.15.70","url":null,"abstract":"","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126401829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Some Information on the Karst-spring Resources","authors":"Kiniti Simizu","doi":"10.5917/JAGH1959.7.6","DOIUrl":"https://doi.org/10.5917/JAGH1959.7.6","url":null,"abstract":"","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130426009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ground Water Flow in Small-Scale Talus Depcsit","authors":"T. Ochiai","doi":"10.5917/JAGH1959.15.20","DOIUrl":"https://doi.org/10.5917/JAGH1959.15.20","url":null,"abstract":"","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"2018 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120909492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper outlines the water resources of the southern area of Madagascar, which is based on the field investigation and several reports concerning with the potable water development plan requested from the government of Madagascar. The area, under the tropical semiarid climate, is classified geographically into the Mahahaly Plateau, the Karimbola Plateau and the Ambovombe Basin, from the west to the east. The average annual precipitation over the area is about 350∼600 mm and it decreases westward. The Karimbola Plateau and the Ambovombe Basin, where the population density is about 15 per one square kilometer, are underlain by continental sediments ranging in age from Tertiary to Quaternary. The Mahahaly Plateau is occupied by Tertiary limestone which yields little groundwater, so that the plateau is not inhabitable. European Communities have been giving assistance to construction of a pipeline from the Menarndra River to the Karimbola Plateau for supplying potable water. On the other hand, Japan will support to develop water resources in the Ambovombe Basin. About 87, 000 people living in a hill, coastal side of the basin, are in great trouble from lack of water. Apart from the hill, they manage to gain perched groundwater as well as surface water. It is very difficult to get water in the hill because the groundwater level is deep, mo:e than 100 meters from the surface, and an inplubia easily dries up at summer season. It is recommended to install more inplubia , to inquire deep groundwater as well as perched groundwater and to increase water wagons for the improvement of water supply. 地質調査所, Geological Survey of Japan.
{"title":"Water Resources of the Southern Semiarid Area of Madagascar","authors":"K. Mori","doi":"10.5917/JAGH1959.24.26","DOIUrl":"https://doi.org/10.5917/JAGH1959.24.26","url":null,"abstract":"This paper outlines the water resources of the southern area of Madagascar, which is based on the field investigation and several reports concerning with the potable water development plan requested from the government of Madagascar. <BR> The area, under the tropical semiarid climate, is classified geographically into the Mahahaly Plateau, the Karimbola Plateau and the Ambovombe Basin, from the west to the east. The average annual precipitation over the area is about 350∼600 mm and it decreases westward. The Karimbola Plateau and the Ambovombe Basin, where the population density is about 15 per one square kilometer, are underlain by continental sediments ranging in age from Tertiary to Quaternary. The Mahahaly Plateau is occupied by Tertiary limestone which yields little groundwater, so that the plateau is not inhabitable. <BR> European Communities have been giving assistance to construction of a pipeline from the Menarndra River to the Karimbola Plateau for supplying potable water. On the other hand, Japan will support to develop water resources in the Ambovombe Basin. About 87, 000 people living in a hill, coastal side of the basin, are in great trouble from lack of water. Apart from the hill, they manage to gain perched groundwater as well as surface water. It is very difficult to get water in the hill because the groundwater level is deep, mo:e than 100 meters from the surface, and an <I>inplubia</I> easily dries up at summer season. <BR> It is recommended to install more <I>inplubia</I> , to inquire deep groundwater as well as perched groundwater and to increase water wagons for the improvement of water supply. 地質調査所, Geological Survey of Japan.","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130176319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The purpose of this survey is to determine the chemical quality of the groundwaters in the Ooyanojima Island and its surrounding islands (Iwajima, Tobasejima, Yushima, and Nokamajima Island). These islands, a small island on the Ariake Sea and Yatsushiro Sea, is situated about fifty kilometers south west of Kumamoto City, Kumamoto Prefecture. In this article, 46 groundwater samples (38 shallow well waters and other samples) in this area were collected in September 1977 (partly during 1979 to 1983) and analyzed for the pH value, potassium permanganate consumed, total residue, major components and some ions dissolved in them. Based on the analytical results of many dissolved components, it was shown that the concentrations of the major components were widely varied in each well (table 1) . There were considerably a large amount of contents of Na+, Ca2+, HCO3—, Cl—, SO42—,and soluble silicate in the groundwaters in this area. The relations of the concentration of cations and anions in the groundwaters were Na+ )Ca2+ )Mg2+ )K+ and HCO3 )C1— )SO42—, respectively. By use of the key diagram method, the chemical composition of the groundwaters in this area was mainly devided into two different composition in each (fig. 2), namely noncarbonate hardness type (Ca—Cl•SO4 type) and carbonate hardness type (Ca—HCO3 type). The concentrations of chemical components dissolved in the shallow well waters were generally larger than that of dissolved in the deep well waters, except for total iron and soluble silicate. The concentrations of nitrate nitrogen in the shallow well waters in this area were found to be in the range of 0.2 — 39.1mg/1. Their arithmetic mean value (7.0mg/1) was markedly high and became about 10 times larger than that in the deep well waters, however, the source of that was not made to elucidate for this investigation. The concentration of soluble silicate in the groundwaters collected from the Cretaceos period
{"title":"Chemical Water Quality in the Groundwater in the Ooyanojima Island and its Surrounding Islands, Kumamoto Prefecture","authors":"H. Ueki, Y. Otawara","doi":"10.5917/jagh1959.27.129","DOIUrl":"https://doi.org/10.5917/jagh1959.27.129","url":null,"abstract":"The purpose of this survey is to determine the chemical quality of the groundwaters in the Ooyanojima Island and its surrounding islands (Iwajima, Tobasejima, Yushima, and Nokamajima Island). These islands, a small island on the Ariake Sea and Yatsushiro Sea, is situated about fifty kilometers south west of Kumamoto City, Kumamoto Prefecture. In this article, 46 groundwater samples (38 shallow well waters and other samples) in this area were collected in September 1977 (partly during 1979 to 1983) and analyzed for the pH value, potassium permanganate consumed, total residue, major components and some ions dissolved in them. Based on the analytical results of many dissolved components, it was shown that the concentrations of the major components were widely varied in each well (table 1) . There were considerably a large amount of contents of Na+, Ca2+, HCO3—, Cl—, SO42—,and soluble silicate in the groundwaters in this area. The relations of the concentration of cations and anions in the groundwaters were Na+ )Ca2+ )Mg2+ )K+ and HCO3 )C1— )SO42—, respectively. By use of the key diagram method, the chemical composition of the groundwaters in this area was mainly devided into two different composition in each (fig. 2), namely noncarbonate hardness type (Ca—Cl•SO4 type) and carbonate hardness type (Ca—HCO3 type). The concentrations of chemical components dissolved in the shallow well waters were generally larger than that of dissolved in the deep well waters, except for total iron and soluble silicate. The concentrations of nitrate nitrogen in the shallow well waters in this area were found to be in the range of 0.2 — 39.1mg/1. Their arithmetic mean value (7.0mg/1) was markedly high and became about 10 times larger than that in the deep well waters, however, the source of that was not made to elucidate for this investigation. The concentration of soluble silicate in the groundwaters collected from the Cretaceos period","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"153 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134057778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Tiltings of Alluvial ground and Variation of waetr table and qality of free groundwater","authors":"C. Kondo","doi":"10.5917/JAGH1959.15.57","DOIUrl":"https://doi.org/10.5917/JAGH1959.15.57","url":null,"abstract":"","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130985846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a hydraulic analysis of unconfined ground water with the rainfall infiltration around the cut-off wall, based on Dupiut's assumption as used in hydraulics. Flow analysis is concerned with change of water depth, change of flow rate and storage volume originated in construction of cut-off wall on the declined impermeable bed. It is clearly found that different flow characters are formed by existing the rainfall infiltration compared with those of flow ignored the infiltration. Available informations are proposed by detail examinations of theoretical results and computation examples for steady flow of unconfined aquifer having the cut-off wall.
{"title":"Hydraulic Analysis of Ground Water with Rainfall Infiltration around Cut-Off Wall","authors":"Kuniaki Sato","doi":"10.5917/JAGH1959.23.65","DOIUrl":"https://doi.org/10.5917/JAGH1959.23.65","url":null,"abstract":"This paper presents a hydraulic analysis of unconfined ground water with the rainfall infiltration around the cut-off wall, based on Dupiut's assumption as used in hydraulics. Flow analysis is concerned with change of water depth, change of flow rate and storage volume originated in construction of cut-off wall on the declined impermeable bed. It is clearly found that different flow characters are formed by existing the rainfall infiltration compared with those of flow ignored the infiltration. Available informations are proposed by detail examinations of theoretical results and computation examples for steady flow of unconfined aquifer having the cut-off wall.","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132326260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes a theoretical consideration about the effect of pumping of fresh water on the motion of seawater interface already formed in a confined aquifer. At first, the differential equation of interface is derived from the fundamental equation of confined water in the case where the aquifer is impervious at its lower surface and has the pumping well distributed continuously at its upper one, and is solved under the conditions that the constant supply of fresh water is given at a fixed point of the upper course and the pressure of water is taken as a hydrostatic distribution. From this solution, it is found that the toe of the interface is moved backward or forward by the inerease of fresh water inflow or of the amount of pumping, respectively and is also, moved more back according to the more concentration of pumping intensity on the lower course of aquiter. Finally, an example is shown for the method through which, in the coastal region where the residual flow of fresh water into the sea exists, this residue is fully pumped up within the limit that the present toe of interface remains immoved. ま え が き. 臨海地域における地下水の塩水化が,そ の地域の工業用水や灌がい用水に重要な支障をきた してい ることはずい分前か ら提起 され,各 方面から検討 されてい ることは衆知の ことである.そ の主要な原 因が過剰な揚水にもとつ くことは明らかで,塩 水化の進行を防 ぐために揚水を制限した り,表 流水の 高度な利用計画が進め られているが,こ の塩水化の現象を揚水分布 と関連 させて,理 論的に統一 した 考察を進める とい う試みは充分なされていない ように思 う. 最近では,地 方の町村にもこの塩水化問題が起 り,飲 料水生活用水な ど上水道 としての利用に も支 障を きた しつつある.そ のため,簡 易上水道 としての淡水源を上流地域に設けた井戸か ら揚水 した り, さらに深 く井戸を掘って新 しい被圧地下水を揚水 した りして,現 状を しのいでいる例を多 くみる.地 下水の塩水化域が どのよ うに進行す るかを理解 してお くことは,こ の ような計画をたてる上で是非必 要 なことである1). *京 都大学防災研究所 被圧地下 水 の場合 には,過 剰 な揚水 のために地下水圧が低下 し,滞 水層 の末端 をおお う被 ふ く層が 破れ て,海 水が浸入 しだす ことに よって,塩 水化が始 まるにちが いない.こ の論文 では,海 水 が浸入 して塩水化域 が生 じてい る所 で,揚 水分布 の変動が塩水化域 を どの よ うに前進後退 させ るかを主な対 象 として考察 した. 臨海地 域 では,潮 汐に もとつ く塩水化 の進 行 も考 え られ る.潮 汐振動 に よって,淡 塩水界面 は振動 しなが ら前 後進 し,界 面 の混 合が促進 されて,拡 散 に よる塩水化域 の拡 大が生 じるであろ う◎ この拡 大 の規模 は,滞 水層 中におけ る淡 水 と塩水 の混合 の難 易に起 因す る ことは明 らかで2),こ の問題 の解 明に努 力 したい と思 ってい るが,こ こでは,そ の準備 として,定 常状態 を取 り上げ.地 下水流 量や揚 水量 の変動に よって,こ の状態 が変化す る様i子を論 じた◎ 1.塩 水化域 の基本式 の導 出 被圧地下 水 の基礎方程式 は,地 下水 の圧 力水頭 くpiezometrichead)を ψ とす る と.次 式 の よ うに 表わ され る3). ここに,tは 時間,8は 重力加速度,toes地 下水密度 であ り,ん お よびG+2μ)は それぞれ被圧滞水 層 の透水 係数 お よび体積弾 性率 であ る. 鉛 直上方に2軸 を とる と,水 頭 ψは水圧Pを 用 いて, 滞水 層の形 は軸方 向には一様で地下水流 は二次 元流 として取扱 え る と仮定す る.滞 水層 の下面 は完全に不透 であ り,上 面 では まえが きで 述べ た よ うに塩水化 をひ きお こす揚水が存在す る場合を考察す る. 下面9=ζi(x)で の境界条件 は,図1で 見 られ る よ うに,.y軸 方 向 に単位厚,κ 軸 方 向に微小長 を もち,こ の下面が斜面 にな ってい る微 小 プ リズム1を 考 え,こ の プ リズム中に地下水が溜 らない ことを表現 すれ ば得 られ る. 上面2瓢 ζ2(x)に おける境界条件は,下 面 と同 じよ うに,こ の上面 を斜面 に もつ微小 プ リズム]1を 考 え,さ らに κ軸 の単 位長 当 りq(t,x)の 揚水 が存在す る ことを考 慮 して,こ の プ リズム中の水 収支を表現す れば よい. (1)をzに 関 して ζiか ら ζ2ま で積 分 し,3.(4)を 入 れ る と が得 られ る.κ ≡ρ9/(λ+2μ)は,滞 水 層が単位長水頭 に相当す る圧 力を周囲か ら受 けた ときに収縮 す る体積 歪に相 当す る量 で,そ の次元 は.[κ]=11Lで あ る. 一般 ,滞 水層 は水平に近 く,し たが って地下 水流 もほ とん ど水平 方 向で鉛直流 はない と近似 で き る.こ の場 合には,図2の よ うに,滞 水層下面 を ζ1-O,上 面 をk-D(Dは 滞水 層厚)に と る と都 合が よい.揚 水q(t.x)の ために地下水 圧 ρは低下 し.滞 水層 の海水 と接 してい る境界 面 が透水状態 に
本文从理论上考虑了抽取淡水对承压含水层中已形成的海水界面运动的影响。首先从承压水基本方程出发，在含水层下部不透水、上部连续分布抽水井的情况下，推导出界面微分方程，并在上部某定点有恒量淡水供应、水压力为静力分布的条件下进行求解。由该解可知，界面趾部分别随着淡水流入量的增加或抽水量的增加而向后移动或向前移动，并且随着抽水强度在含水层下部的集中而向后移动。最后，举例说明了在存在淡水入海余流的沿海地区，在当前界面趾保持不动的范围内，充分抽吸淡水入海余流的方法。。臨海地域における地下水の塩水化が,その地域の工業用水や灌がい用水に重要な支障をきたしていることはずい分前から提起され,各方面から検討されていることは衆知のことである。その主要な原因が過剰な揚水にもとつくことは明らかで,塩水化の進行を防ぐために揚水を制限したり,表流水の高度な利用計画が進められているが,この塩水化の現象を揚水分布と関連させて,理論的に統一した考察を進めるという試みは充分なされていないように思う。最近では,地方の町村にもこの塩水化問題が起り,飲料水生活用水など上水道としての利用にも支障をきたしつつある。そのため,簡易上水道としての淡水源を上流地域に設けた井戸から揚水したり,さらに深く井戸を掘って新しい被圧地下水を揚水したりして,現状をしのいでいる例を多くみる。地下水の塩水化域がどのように進行するかを理解しておくことは,このような計画をたてる上で是非必要なことである1)。*京都大学防災研究所被圧地下水の場合には,過剰な揚水のために地下水圧が低下し,滞水層の末端をおおう被ふく層が破れて,海水が浸入しだすことによって,塩水化が始まるにちがいない。この論文では,海水が浸入して塩水化域が生じている所で,揚水分布の変動が塩水化域をどのように前進後退させるかを主な対象として考察した。臨海地域では,潮汐にもとつく塩水化の進行も考えられる。潮汐振動によって,淡塩水界面は振動しながら前後進し,界面の混合が促進されて,拡散による塩水化域の拡大が生じるであろう◎この拡大の規模は,滞水層中における淡水と塩水の混合の難易に起因することは明らかで2),この問題の解明に努力したいと思っているが,ここでは,その準備として,定常状態を取り上げ。★★★★★★★★★★★★★★★★塩水化域の基本式の導出被圧地下水の基礎方程式は,地下水の圧力水頭くpiezometrichead)をψとすると。3)。ここにtは時間8は重力加速度,脚趾地下水密度であり,んおよびG + 2μ)はそれぞれ被圧滞水層の透水係数および体積弾性率である。鉛直上方に2軸をとると,水頭ψは水圧Pを用いて,滞水層の形は軸方向には一様で地下水流は二次元流として取扱えると仮定する。滞水層の下面は完全に不透であり,上面ではまえがきで述べたように塩水化をひきおこす揚水が存在する場合を考察する。齐格9=ζi(x)，。y軸方向に単位厚,κ軸方向に微小長をもち,この下面が斜面になっている微小プリズム1を考え,このプリズム中に地下水が溜らないことを表現すれば得られる。上面2瓢ζ2 (x)における境界条件は、下面と同じように,この上面を斜面にもつ微小プリズム]1を考え,さらにκ軸の単位長当りq (t, x)の揚水が存在することを考慮して,このプリズム中の水収支を表現すればよい。(1)をzに関してζ我からζ2まで積分し,3。(4)を入れるとが得られる。κ≡ρ9 /(λ+ 2μ)は滞水層が単位長水頭に相当する圧力を周囲から受けたときに収縮する体積歪に相当する量で,その次元は。[κ]= 11l。一般,滞水層は水平に近く,したがって地下水流もほとんど水平方向で鉛直流はないと近似できる。この場合には図2のように,滞水層下面をζ10,上面をk D (Dは滞水層厚)にとると都合がよい。。滞水層の海水と接している境界面が透水状態になっているときには,海水圧に押されて,海水が滞水層中に浸入する。この浸入した海水は地下水と混合し,一般には有限厚の淡塩水界面層ができるが,ここでは,混合が起らないと仮定し,淡塩水界面をz =ζ(t.x)と表現しよう,この2一ζ(t.x)がどのような関数になるかが考察の対象である。界面2澱ζ(t.X)が決定されれぽ,これが滞水層下面2 = = Oと交わる点x = 1も求まる。1、中文:。滞水層の上流では,この滞水層に水を供給する作用が存在する筈で,たとえば,ダムの水位一定という操作があるならば,ダムの存在する地点x = xLで水頭9謂一定という境界条件を置くことができる。またダムの放流量が測定されているならば,xlで滞水層流量Qが与えられるというのが境界条件となる。★★★★★★★★★★★★★★★★★★★★★★地下水流が水平に近く鉛直流速がないと近似できるときには,水圧は静水圧として扱い得る。淡水層静水圧P1の水頭を,x dの面より計った高さηで表わすと,圧力水頭η,淡塩水界面ζあるいは塩水化域長1を時間的に変化させる原因は,揚水量q (t.X)上流からの流入量R(のおよび海面高H(のである。(1)、(1)、(2)、(2)、(3)。月間とか一年間をとれば,その期間中の平均値とそのまわりの変動量との和で表わせる。R(の= =“建”トγ(t) H(の=識H + H (t)ζ”(t 'x) - q (x)十问”(t x)(11、12、13)年平均で考えれば,R(のは豊水期や渇水期の変動流入量に相当し,问”(t.x)は灌瀧用水量や工場用水量の変動に対応するであろう。日平均では,潮位変化h (t)が卓越し,r (t)や问”(t.X)は無視できるかも知れない。η，ζ(1 2。定常塩水化域R, q H (x)によって定められる状態すなわち定常塩水化域の基本式は。(9)。10に18代。◎15を入れて,時間変動の項を除けば得られる◎入れると。以後定常状態のみを考察するので,平均操作の記号一を省略する◎時間変動に関する考察は別の機会にゆづりたいo x = 1でζ一。0すなわち(η1一H *) =γ1)に留意して,境界条件鱒を用いると積分常数は決定されてこの積分常数は次のようにして近似的に求められる。上流よりの平均流入量Rが平均全揚水量Qより大きい時には,x = Oにおける淡水層断面で(R - Q)の流量が海へ流出しているはず,したがって,その通過断面(1)一ζ)は零ではあり得ない。ところで,水圧を静水圧と仮定するかぎり,この淡水出口の通過断面(1)一一ζ)の全面で,海水側の水圧と地下水側の水圧とを一致させることはできない。現実にはここでは,淡塩水界面2 ntζの傾きは大きくなり,鉛直流を無視できなくなる5)。したがって,正確には地下水圧が静水圧分布であるという仮定を捨て,x - = Oの断面でπ=ρ29 (H + 1)一一2),すなわちη1 (O.2) x H * +γ(d2)という境界条件で解かなければならない。この解法はηエをx 2の関数として取り扱うことを要求するが,界面の形2一ζ(x)も決定しなけれぽならないので,非常に困難となる。この困難をさけるために,って流速を無限大にする)というよく用いられる便法を採用しよう。この近似法に
{"title":"Motion of the Seawater Interface in Confined Aquifer: The relation between the motion of the seawater interface and the spatial distribution of pumping intensity@@@揚水分布変動と塩水化域との関係","authors":"Y. Fukuo","doi":"10.5917/JAGH1959.14.33","DOIUrl":"https://doi.org/10.5917/JAGH1959.14.33","url":null,"abstract":"This paper describes a theoretical consideration about the effect of pumping of fresh water on the motion of seawater interface already formed in a confined aquifer. At first, the differential equation of interface is derived from the fundamental equation of confined water in the case where the aquifer is impervious at its lower surface and has the pumping well distributed continuously at its upper one, and is solved under the conditions that the constant supply of fresh water is given at a fixed point of the upper course and the pressure of water is taken as a hydrostatic distribution. From this solution, it is found that the toe of the interface is moved backward or forward by the inerease of fresh water inflow or of the amount of pumping, respectively and is also, moved more back according to the more concentration of pumping intensity on the lower course of aquiter. Finally, an example is shown for the method through which, in the coastal region where the residual flow of fresh water into the sea exists, this residue is fully pumped up within the limit that the present toe of interface remains immoved. ま え が き. 臨海地域における地下水の塩水化が,そ の地域の工業用水や灌がい用水に重要な支障をきた してい ることはずい分前か ら提起 され,各 方面から検討 されてい ることは衆知の ことである.そ の主要な原 因が過剰な揚水にもとつ くことは明らかで,塩 水化の進行を防 ぐために揚水を制限した り,表 流水の 高度な利用計画が進め られているが,こ の塩水化の現象を揚水分布 と関連 させて,理 論的に統一 した 考察を進める とい う試みは充分なされていない ように思 う. 最近では,地 方の町村にもこの塩水化問題が起 り,飲 料水生活用水な ど上水道 としての利用に も支 障を きた しつつある.そ のため,簡 易上水道 としての淡水源を上流地域に設けた井戸か ら揚水 した り, さらに深 く井戸を掘って新 しい被圧地下水を揚水 した りして,現 状を しのいでいる例を多 くみる.地 下水の塩水化域が どのよ うに進行す るかを理解 してお くことは,こ の ような計画をたてる上で是非必 要 なことである1). *京 都大学防災研究所 被圧地下 水 の場合 には,過 剰 な揚水 のために地下水圧が低下 し,滞 水層 の末端 をおお う被 ふ く層が 破れ て,海 水が浸入 しだす ことに よって,塩 水化が始 まるにちが いない.こ の論文 では,海 水 が浸入 して塩水化域 が生 じてい る所 で,揚 水分布 の変動が塩水化域 を どの よ うに前進後退 させ るかを主な対 象 として考察 した. 臨海地 域 では,潮 汐に もとつ く塩水化 の進 行 も考 え られ る.潮 汐振動 に よって,淡 塩水界面 は振動 しなが ら前 後進 し,界 面 の混 合が促進 されて,拡 散 に よる塩水化域 の拡 大が生 じるであろ う◎ この拡 大 の規模 は,滞 水層 中におけ る淡 水 と塩水 の混合 の難 易に起 因す る ことは明 らかで2),こ の問題 の解 明に努 力 したい と思 ってい るが,こ こでは,そ の準備 として,定 常状態 を取 り上げ.地 下水流 量や揚 水量 の変動に よって,こ の状態 が変化す る様i子を論 じた◎ 1.塩 水化域 の基本式 の導 出 被圧地下 水 の基礎方程式 は,地 下水 の圧 力水頭 くpiezometrichead)を ψ とす る と.次 式 の よ うに 表わ され る3). ここに,tは 時間,8は 重力加速度,toes地 下水密度 であ り,ん お よびG+2μ)は それぞれ被圧滞水 層 の透水 係数 お よび体積弾 性率 であ る. 鉛 直上方に2軸 を とる と,水 頭 ψは水圧Pを 用 いて, 滞水 層の形 は軸方 向には一様で地下水流 は二次 元流 として取扱 え る と仮定す る.滞 水層 の下面 は完全に不透 であ り,上 面 では まえが きで 述べ た よ うに塩水化 をひ きお こす揚水が存在す る場合を考察す る. 下面9=ζi(x)で の境界条件 は,図1で 見 られ る よ うに,.y軸 方 向 に単位厚,κ 軸 方 向に微小長 を もち,こ の下面が斜面 にな ってい る微 小 プ リズム1を 考 え,こ の プ リズム中に地下水が溜 らない ことを表現 すれ ば得 られ る. 上面2瓢 ζ2(x)に おける境界条件は,下 面 と同 じよ うに,こ の上面 を斜面 に もつ微小 プ リズム]1を 考 え,さ らに κ軸 の単 位長 当 りq(t,x)の 揚水 が存在す る ことを考 慮 して,こ の プ リズム中の水 収支を表現す れば よい. (1)をzに 関 して ζiか ら ζ2ま で積 分 し,3.(4)を 入 れ る と が得 られ る.κ ≡ρ9/(λ+2μ)は,滞 水 層が単位長水頭 に相当す る圧 力を周囲か ら受 けた ときに収縮 す る体積 歪に相 当す る量 で,そ の次元 は.[κ]=11Lで あ る. 一般 ,滞 水層 は水平に近 く,し たが って地下 水流 もほ とん ど水平 方 向で鉛直流 はない と近似 で き る.こ の場 合には,図2の よ うに,滞 水層下面 を ζ1-O,上 面 をk-D(Dは 滞水 層厚)に と る と都 合が よい.揚 水q(t.x)の ために地下水 圧 ρは低下 し.滞 水層 の海水 と接 してい る境界 面 が透水状態 に","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"10 19","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114085621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fresh Water-Salt Water Interface Model and Hydrodynamic Dispersion Model in Coastal Aquifers","authors":"T. Kakinuma, Y. Kishi, Kunimitsu Inouchi","doi":"10.5917/JAGH1959.27.141","DOIUrl":"https://doi.org/10.5917/JAGH1959.27.141","url":null,"abstract":"","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133873367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Model Studies of Salt Water Intrusion by Pumping Up","authors":"H. Kawabata","doi":"10.5917/JAGH1959.16.19","DOIUrl":"https://doi.org/10.5917/JAGH1959.16.19","url":null,"abstract":"","PeriodicalId":422881,"journal":{"name":"THE JOURNAL OF THE JAPANESE ASSOCIATION OF GROUNDWATER HYDROLOGY","volume":"165 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116124268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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