JP4338433B2

JP4338433B2 - Method and apparatus for measuring flow velocity using gypsum column

Info

Publication number: JP4338433B2
Application number: JP2003128406A
Authority: JP
Inventors: 義功越川; 信夫柵瀬
Original assignee: Kajima Corp
Current assignee: Kajima Corp
Priority date: 2003-05-06
Filing date: 2003-05-06
Publication date: 2009-10-07
Anticipated expiration: 2023-05-06
Also published as: JP2004333257A

Description

【０００１】
【発明の属する技術分野】
本発明は石膏柱体による流速測定方法及び装置に関し、とくに砂浜や干潟等の沿岸地域の浅瀬での流向・流速の検出に適する測定方法及び装置に関する。
【０００２】
【従来の技術】
生活環境や居住環境の快適性の一要素として、海や河川等の水域・沿岸地における生物生息域の存在が挙げられる。生物生息のために自然の砂浜や干潟等の保存が図られ、更に鳥類や魚介類等が生息する人工干潟の造成等も試みられている。生物定着の可能性を示す目安の一つとして、海岸地域の場合には、アサリやシオフキ、ハマグリ等の生息調査が行われている。最近の研究によれば、水底での水の流れの状況がアサリやシオフキ等の生息にとって重要な因子となっている。
【０００３】
従来、生物の生息を図る観点から、水の流向流速の検出について各種の研究・提案がなされている。例えば特許文献１は、流れの作用で濃度変化を惹起する水溶性物質を、その濃度の対数の時間変化率と流速との間に直線関係が成り立つ状態で内包する測定装置による測定方法を記載している。即ち、その装置を測定地点に配置し、測定開始時の当該水溶性物質の水溶液の濃度C_in(0)と測定終了時におけるその濃度C_in(T)とをそれぞれ測定し、測定期間における平均流速を両濃度C_in(0)及びC_in(T)から所定の計算式によって算出する。
【０００４】
また特許文献２は、水中に、水流の幅方向に揺動自在に円筒形受波体を係留し、この円筒形受波体の底部に錘を配置し、円筒形受波体の内部にこの受波体の水流幅方向の加速度を検出する加速度計を設ける測定方法を記載する。測定時には、水流によって円筒形受波体の後方に発生するカルマン渦に起因する水流幅方向の加速度を検出し、その加速度の変化の周波数fを求め、その周波数を無次元化したストロ−ハル数Stを別途求め、流速Vを、円筒形受波体の直径dと加速度変化の周波数fとストロ−ハル数Stとから所定の数式により算出する。
【０００５】
しかし、特許文献１の濃度測定を含む流速測定方法は、測定装置の構造が複雑であって費用が嵩み、測定装置が重く移動にかなりの労力を要し、従って広い水域での流速分布の測定への適用が難しく、また水底の例えば砂面と水との境界部分での流速測定が困難である等の問題点がある。また、特許文献２の円筒形受波体の係留を含む流速測定方法は、特許文献１と同様に測定装置が複雑な構造を有し高価であり、測定装置が重く移動に労力を要し、広い水域での流速分布測定への適用が難しく、係留による浮遊を要するので浅い水面での流速測定が困難である等の問題点が避けられない。
【０００６】
これに対し非特許文献１は、図１１に示すように、水流１中に球形の石膏測定子51を曝し、溶解による石膏の質量減耗量から流速を算出する方法を記載している。図中、符号52は水流１による減耗後の形状の測定子51を示す。また非特許文献２は、水流１中に半球形の石膏測定子（図示せず）を設置し、溶解による石膏の質量減耗量と塩分含量と水温との三者から流速を算出する方法を記載している。これらの方法は、特許文献１及び２における測定装置が複雑な構造で高価であり、しかも重いという問題点を解決するものといえる。
【０００７】
【特許文献１】
特許第２７４１７３８号公報
【特許文献２】
特開平６−５８９４６号
【非特許文献１】
川俣茂「北日本沿岸におけるウニ及びアワビの摂食に及ぼす波浪の影響とその評価」水産総合研究センター研究報告第１号（平成13年12月）、独立行政法人水産総合研究センター（水研センター）、59-107頁
【非特許文献２】
上月康則他「海岸構造物建設に伴う平均流速の変化と底生生物の応答について」、土木学会第54回年次学術講演会（平成11年9月）、CS-122、244-245頁
【非特許文献３】
Teruhisa Komatsu and Hideo Kawai "Measurements ofTime-Averaged Intensity of Water Motion with Plaster Balls", Journal of Oceanography Vol.48 No.4（1992）、日本海洋学会、pp.353-365
【非特許文献４】
川俣茂「生物の生息環境としての流動とその調査方法」月刊海洋 Vol.24（1992）、海洋出版、492-497頁
【０００８】
【発明が解決しようとする課題】
しかし、非特許文献１〜４が開示する石膏球又は石膏半球からなる石膏測定子51を用いる流速測定方法は、流速の分布の測定に関して、なお困難を残している。即ち、石膏測定子51は、その設置位置のみにおける一箇所の水流の緩急を記録しているに過ぎない。水深による流れの強弱の変化、即ち水平流速の鉛直方向における分布を把握するためには、その分布検出に必要な数の石膏測定子51を夫々所定位置へ個別に設置しなければならず手間がかかる。また、鉛直方向分布の測定値が、石膏測定子51の設置位置のみにおける離散的データになり、鉛直方向における細かな相異を連続性のあるデータとして記録することはできない。
【０００９】
更に非特許文献１〜４は、石膏測定子51が球面又は半球面であるため、流れの方向を識別するために、測定子51の設置方位と流速の座標系との角度関係を計測直後に記録する等の煩雑な作業が必要である。たとえ測定子設置方位のみを測定子51の表面に書込んでも、それだけでは確実な流向の記録が残らない。万一、計測直後の記録を忘れると流向に関るデータは一切失われることになる。
【００１０】
そこで本発明の目的は、流向・流速の分布を一時に検出できる石膏柱体による流速測定方法及び装置を提供することにある。
【００１１】
【課題を解決するための手段】
上記目的を達成するため本発明者は、水流中における石膏塊の溶解速度が水流の流速に比例すること、及び石膏測定子を円筒柱等の柱体とすれば柱体長手方向の流向・流速分布に応じた石膏の減耗を測定子の周面上に記録できることに注目した。この石膏柱体はその軸方向に直角な断面形状が一定のものである。またこの場合の流向・流速とは、測定地点で上記減耗が発生する期間の平均値であって特定瞬時の流向・流速ではない。
【００１２】
図１を参照するに、本発明の石膏柱体による流速測定方法は、複数層の流面がある水流１に軸方向と直角な断面形状が一定の石膏柱体２を交差させて一定時間保持し、石膏柱体２の軸線上の所要点ごとに当該点を過ぎる流面の流向及び流速を、当該点での柱体２の断面の外径減耗量が最大の方向に直交する方向及び外径減耗量の最大値に対応する流速として検出し、複数の前記所要点で検出した流向及び流速の分布を求めてなるものである。
【００１３】
好ましくは、石膏柱体２の一端を水底４（図２参照）に保持し、水底４及び水底４上とほぼ水平な複数の流面の流速を測定する。更に好ましくは、柱体２を水底４から垂直に立上げて保持し、水深方向の流速分布を測定する。
【００１４】
また図１及び２を参照するに、本発明の石膏柱体による流速測定装置は、軸方向と直角な断面形状が一定の石膏柱体２、及びその石膏柱体２が自立姿勢で装着される自立具６付きの水底固着可能な固定装置５を備え、石膏柱体２の軸線上の所要点ごとに柱体２の断面の外径減耗量が最大の方向に直交する方向及び外径減耗量の最大値に対応する流速として水底及び水底上とほぼ水平な流面の流向及び流速を検出してなるものである。図２に示すように、自立具６に石膏柱体２の下端が所定姿勢で嵌入する上向き穴を設けることができる。また図３に示すように、自立具６を方形断面の長尺部材とし、石膏柱体２の軸方向に長尺部材が貫通する穴７を設けてもよい。なお、この方形には多角形の場合も含んでいる。
【００１５】
【発明の実施の形態】
図２は、本発明による流速測定装置の実施例を示す。図２及び図４を参照するに、軸方向と直角な断面形状が一定の石膏柱体２を複数層の流面がある水流１と交差させて保持することにより、石膏柱体２の軸方向における流面の分布に応じた外径減耗の分布が柱体２の外周面に生じる。石膏柱体２をほぼ水平な水流１と交差させて鉛直に保持することにより、水平流速の鉛直方向分布に応じた外径減耗の分布を石膏柱体２の外周面に生じさせることができる。石膏柱体２が円筒形である場合に、水流１の方向から見た減耗後の柱体３の側面図を図４に示す。図示例の場合、単一の石膏柱体２による１回の測定で、水平水流１の流速の鉛直方向分布を、その流速に起因する外径減耗の連続的変化として記録できる。
【００１６】
石膏柱体２を水流１中に一定時間放置したのち、減耗後の柱体３の水深に対応する軸方向の各位置（所要点）で外径減耗量が最大の方向（すなわち、外径が最小の方向）を一定時間の平均流向として検出し、その外径最小方向と直角の方向を一定時間の水流１の平均流向とする。また、その外径最小方向の水平外径を計測し、減耗前の石膏柱体２の初期外径と減耗後の外径との差を例えば外径減耗率（％）として算出する。石膏柱体２を水流１中に一定時間放置した場合の当該水流１の流速と外径減耗との関係を予め求めておけば、減耗後の柱体３について計測した外径減耗率（％）に基づき、柱体３の設置位置の当該外径減耗が生じた水深での流速を算出できる。水流１の流速と外径減耗との関係は、例えば予め実験室での実測その他の方法により図７に示すように求めることができる。
【００１７】
図６は、異なる時間T₁、T₂に対応する石膏柱体２上の位置（所要点）における柱体２の外径減耗を示す。P₁、P₂、P₃及びP₄は、後述の通り測定地点である。同図は３所要点で外径減耗を測定する例を示すが、外径減耗の測定位置（所要点）を更に増やすことにより流速分布の測定精度を高めることができる。本発明では鉛直方向の流速分布が石膏柱体２の周面に連続的に記録されているので、石膏柱体２の軸方向における減耗計測位置を適宜に選定することにより、鉛直方向の連続的な流速分布を測定することが可能である。
【００１８】
水流１に、水底にほぼ水平な複数の水平流面を想定すれば、石膏柱体３の外径の減耗が水平流面に応じて生起するので、柱体３の水平断面からその流面の流向及び流速が検出できる。水流１が水平ではなく傾斜している場合は、石膏柱体３の外径の減耗がその傾斜水流の流面に沿って生起するので、その水流の傾斜の検出が可能であり、その傾斜流面上での水流１の流向及び流速を検出することができる。
【００１９】
水流１が塩水である場合に、塩分濃度による石膏柱体３の外径の減耗への影響の測定結果を図７に示す。図中の記号xは平均流速、yは減耗率、Lnは自然対数、Rは相関係数、psuは塩分を示す。この図から明らかなように、海水と河口域等の汽水あるいは湖沼等の淡水とでは石膏柱体３の減耗速度が異なる。従って、塩分濃度に応じた水流１の流速と外径減耗との関係を予め測定して記録しておき、本発明の流速測定装置に測定対象の水流の塩分濃度を測定するセンサ等を含め、そのセンサの測定結果に応じて水流１の流速と外径減耗との関係を選択することができる。
【００２０】
図８（Ａ）及び図１０は、干潟や潮間帯、あるいは海辺等の水中に干潮時以外は水没する汀線８を想定し、汀線８と平行な複数列に沿って石膏柱体２の群を格子状に設置した本発明の実施例を示す。図示例において、図８に示すように、汀線８上に、汀線８の方向の無単位化距離が100、200、300、及び400である位置として測定地点P1、P2、P3、P4を想定することができる。図６は、測定地点P1、P2、P3、及びP4に設置した石膏柱体2₁₁、2₂₁、2₃₁、2₄₁の水平断面を示す。図４に示すように、各柱体２の底面を水底の砂中に埋め、各柱体２を水底から鉛直に水中へ立上げる。図６では、測定地点P₁、P₂、P₃及びP₄に設置した石膏柱体の所要点の水平断面の時間T₀、T₁、T₂における形状を示す。
【００２１】
好ましくは図５に示すように、石膏柱体２に、長さ方向に延在して外径減耗の向きを可視化する方向指示素子11、12を含める。同図（Ａ）は、石膏柱体２の断面に柱体中心軸で直交する座標軸を示す如く当該中心軸に沿って形成された着色面対11、12を方向指示素子としたものである。Ｘ座標軸表示線11及びＹ座標軸表示線12をそれぞれ異なる色、例えば青・赤で識別した面部材とすることにより、柱体２の全長の如何なる断面においても中心軸で交差する座標軸が明示できる。但し、方向指示素子は着色面対11、12に限定されず、例えば同図（Ｂ）のように石膏柱体２の中心軸に沿って設けた貫通穴７の形状（長方形その他の特定形状）から外径減耗向きを判断することも可能である。なお、この目的において、穴７は貫通せず、柱体２の中心軸に沿って途中まで設けてもよい。
【００２２】
図６の減耗の前及び後における石膏柱体2₁₁及び3₁₁の水平断面から理解できるように、ことなる時間（図示例ではT1とT2との２回）で石膏柱体３の外径減耗を測定し、その減耗が最大となる向きと最大減耗値とを検出することにより、水中の特定水深における流向・流速、及び水深方向の流向・流速分布を時間経過に応じて測定することができる。
【００２３】
また図８（Ａ）及び図１０では、水深方向の流向・流速分布の測定だけでなく、汀線８に添って設けた複数個の減耗後の石膏柱体3₁₁、3₂₁、3₃₁、3₄₁（この例では４個）の同一深さにおける流向・流速測定値を比較することにより、汀線８上での水平方向の流向・流速分布を求めることができる。沖合における水平方向の流向・流速分布は、図８の汀線と実質上平行な沖合線上における減耗後の石膏柱体列3_1j、3_2j、3_3j、3_4j（図８の例ではｊ＝２、３）の同一深さにおける流向・流速測定値の比較により求めればよい。汀線と交差する任意線の石膏柱体列の同一深さにおける流向・流速測定値の比較により、その任意線上における水平方向の流向・流速分布を求めることも可能である。図８（Ｂ）は、同図（Ａ）に示す石膏柱体２の配置により測定した外径減耗量を流速に換算して得た水平方向の平均流速分布の一例である。
【００２４】
水平方向の流向・流速分布を求める場合は、各位置（測定地点）で流速を同時に測定する必要があり、各石膏柱体２における外径減耗を全て同時に発生させる必要がある。図２の流速測定装置は、石膏柱体２が自立姿勢で装着される自立具６付きの水底固着可能な固定装置５を有し、所定位置（測定地点）の水底に固定装置５を固着したのち石膏柱体２を自立具６へ取り付ける。例えば、図８（Ａ）及び図１０に示す複数の位置にそれぞれ固定装置５を設置しておけば、石膏柱体２の取り付け又は取り外しの操作時間（最先の石膏柱体２の取り付け・取り外し操作から最後の石膏柱体２の取り付け・取り外し操作までの間の時間間隔）が不当に長くない限り、各石膏柱体２の同一時に生起した外径減耗を検出できる。不当に長い時間間隔とは、計測すべき外径減耗が進行する時間（例えば数日）に対して無視できない程度の長さの時間である。
【００２５】
本発明によれば、石膏柱体２の外径減耗の測定に当り石膏柱体２を固定装置５から取り外して陸上の測定室等の適当な測定場所へ運ぶことができるので、従来方法に比し流向・流速の測定の容易化が図れる。また、石膏柱体２の外形減耗という間接量に依存して流速を検出するという限界はあるが、流速の分布を簡易な手段により容易に行うことができる。更に本発明によれば、図４の減耗後の石膏柱体３に示すように、砂面レベル即ち水底４に沿う水流に起因する石膏の減耗を計測できるので、従来困難であった水底面の流速測定も可能となる。
【００２６】
こうして、本発明の目的である「流向・流速の分布を一時に検出できる石膏柱体による流速測定方法及び装置」の提供が達成される。
【００２７】
【実施例】
本発明で用いる石膏柱体２の外形は円筒形に限定されず、外径減耗の計測が正確に行なえる任意の形状とすることができる。例えば、図５（Ｃ）のように、断面が正多角形の角柱とすることができる。角柱型石膏柱体２は、円筒型石膏柱体の場合に比し、測定時における柱体２の中心軸線周りの回転を避け、角度位置を一定に保ち易い特徴がある。また本発明の石膏柱体２は、従来の球形又は半球形の石膏に比して型枠に材料を注入して成形するのみで同一形状に製造することができるので、簡単な装置で量産化が可能である。また、形状的にも積重ねがきくので収納性がよく、大量の長距離輸送にも容易に対応できる。
【００２８】
図２に示す石膏柱体２の自立具６は、石膏柱体２の下端が嵌入する上向き穴を有し、固定装置５へ一体的に取り付けられる。この場合、石膏柱体２を上向き穴へ単に差し込むだけで固定して流速検出を開始することができる。また、石膏柱体２の減耗測定のため、石膏柱体２を自立具６の上向き穴から単に引き抜くだけで分離回収し、陸上での外径減耗の計測に供することができる。好ましくは、測定時における石膏柱体２の軸周りの角度位置を一定に保つため、自立具６及び柱体２に関連する適当な位置合わせ手段（図示せず）を設ける。このような自立具６も、簡易な構造であるため低コストでの製作が可能である。
【００２９】
自立具６は、図３に示すように固定装置５に固定した方形断面の長尺部材としてもよい。この場合、図５（Ｂ）のように、自立具６の長尺部材が貫入する方形断面の貫通孔７を石膏柱体２の軸方向に穿っておくのがよい。こうすれば、単に石膏柱体２を自立具６に差し込むだけで、石膏柱体２を水流１又は地上座標系に対して適切な姿勢に保つことができる。また、水深が深い場合には、長い角形の長尺部材を自立具６として使い、複数の石膏柱体２を縦列にその角形長尺部材へ嵌合させ、深い水深全長に亘る流速の鉛直方向分布を記録することできる。図５（Ｃ）は、断面を正多角形として同図（Ｂ）と同様に適正姿勢での固定装置５への装着の便を図ったものである。
【００３０】
本発明によれば、一度に広範囲にわたって流向や流速を簡単に同時測定することができる。図１０は、人工造成後の干潟21における流速分布の評価に本発明の方法を適用した例を図式的に示す。広い範囲に多数の石膏柱体２を同時に設置し同時に取り外して計測することが、例えば数日間の平均流速の検出を目的する場合には、図２のような自立具６の使用により容易に実現できる。その測定により、例えば図８（Ｂ）に示すような平均流速の分布を把握することができる。
【００３１】
図９（Ａ）はアサリの分布が検出された浅瀬における流速分布の一例を示し、同図（Ｂ）はシオフキの分布についての同様な流速分布の一例である。例えば、このような平均流速分布と生物分布との相関に関する既存データを参照して、図１０（Ａ）の石膏柱体２の配置により得られた平均流速分布に基づき、人工干潟21に同図（Ｂ）のような生物生息ゾーン22を設定することが想定できる。また、実測した平均流速分布の分析により循環滞留ゾーン23を設定し、流れの速いゾーン24に対して消波工25を計画することも考えられる。更に本発明は、人工干潟21等に生物の定着を図る場合だけでなく、今後の環境アセスメントにおいて重要な測定手段となり、環境保全や創造空間のゾーニング、スコーピング等においても有用な技術となる。
【００３２】
【発明の効果】
以上説明したように、本発明の石膏柱体による流速測定方法及び装置は、石膏柱体を水流に交差させて一定時間保持し、石膏柱体の軸線上の所要点ごとに柱体断面の外径減耗量が最大の方向に直交する流向及び外径減耗量の最大値に対応する流速を検出し、複数の所要点での流向・流速の分布を求めるので、次の顕著な効果を奏する。
【００３３】
（イ）一度に広範囲にわたって同時に流向や流速の分布を測定できるようになる。
（ロ）水底が露出し得る潮間帯部分の流速の把握が可能になる。
（ハ）従来数値計算に依存していた内湾の流れの分布を直接測定により把握することが可能になる。
（ニ）従来困難であった干潟等の極めて浅い水域における流速分布の計測による把握が可能になる。
（ホ）人口の干潟造成における生物生息の環境因子として重要な造成干潟内流速分布の把握が可能になる。
（ヘ）自然又は人工の浅瀬や干潟等を含む水域における環境アセスメント及び環境創生空間のゾーニングやスコーピング等に欠かせないデータの取得に必要な技術となる。
【図面の簡単な説明】
【図１】は、本発明の石膏柱体による流速測定方法の原理の図式的説明図である。
【図２】は、本発明の方法で用いる石膏柱体を固定する装置の一実施例を示す斜視図である。
【図３】は、本発明の方法で用いる石膏柱体を支持する自立具の他の実施例を示す斜視図である。
【図４】は、水流による石膏柱体の減耗を示す説明図である。
【図５】は、３種類の石膏柱体の外観を示す斜視図である。
【図６】は、水流による石膏柱体の減耗の時間経過を示す説明用模式図である。
【図７】は、水流の流速と石膏柱体の減耗との関係の一例を示すグラフである。
【図８】は、浅瀬の流速測定における石膏柱体の減耗量及び平均流速の測定値の分布の一例を示す模式図である。
【図９】は、浅瀬におけるアサリとシオフキの分布の一例を示す模式図である。
【図１０】は、干潟造成における本発明方法の利用例の説明である。
【図１１】は、流速測定に使われる従来の石膏球の説明図である。
【符号の説明】
１…水流２…石膏柱体
３…減耗後の柱体４…砂面レベル（水底）
５…固定装置６…自立具
７…（貫通）穴
11…方向指示素子（Ｘ座標軸線）
12…方向指示素子（Ｙ座標軸線）
21…干潟 22…生息可能ゾーン
23…循環滞留ゾーン 24…流れの速いゾーン
25…消波工 51…石膏測定子
52…減耗後の石膏測定子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for measuring a flow velocity using a gypsum pillar, and more particularly to a measuring method and an apparatus suitable for detecting a flow direction and a flow velocity in shallow waters of a coastal area such as a sandy beach or a tidal flat.
[0002]
[Prior art]
One element of comfort in living and living environments is the existence of biological habitats in water and coastal areas such as the sea and rivers. Preservation of natural sandy beaches and tidal flats has been attempted for living organisms, and attempts have been made to create artificial tidal flats where birds and seafood live. As one of the indications of the possibility of colonization, in the case of coastal areas, habitat surveys such as clams, shiofuki and clams are being conducted. According to recent research, the flow of water at the bottom of the water is an important factor for habitats such as clams and shiofuki.
[0003]
Conventionally, various studies and proposals have been made on the detection of water flow velocity from the viewpoint of living organisms. For example, Patent Document 1 describes a measuring method using a measuring device that encloses a water-soluble substance that causes a change in concentration by the action of a flow in a state where a linear relationship is established between the logarithmic change rate of the concentration and the flow rate. ing. That is, the device is placed at the measurement point, and the concentration C _in (0) of the aqueous solution of the water-soluble substance at the start of measurement and the concentration C _in (T) at the end of the measurement are measured, respectively. The flow rate is calculated from both concentrations C _in (0) and C _in (T) by a predetermined calculation formula.
[0004]
In Patent Document 2, a cylindrical receiver is moored in water so as to be swingable in the width direction of the water flow, a weight is disposed at the bottom of the cylindrical receiver, and the cylindrical receiver is placed inside the cylindrical receiver. A measurement method is described in which an accelerometer that detects the acceleration of the wave receiving body in the water flow width direction is provided. At the time of measurement, the acceleration in the direction of the width of the water caused by Karman vortices generated behind the cylindrical receiver by the water flow is detected, the frequency f of the change in the acceleration is obtained, and the Strouhal number obtained by making the frequency dimensionless St is separately obtained, and the flow velocity V is calculated from the diameter d of the cylindrical receiver, the frequency f of the acceleration change, and the Strouhal number St by a predetermined formula.
[0005]
However, the flow velocity measurement method including concentration measurement of Patent Document 1 is complicated and expensive, and the measurement device is heavy and requires a lot of labor to move. There are problems such as difficulty in application to measurement, and difficulty in measuring flow velocity at the boundary of the bottom of the water, for example, between the sand surface and water. Further, the flow velocity measurement method including the tethering of the cylindrical wave receiver of Patent Document 2 is expensive because the measurement device has a complicated structure as in Patent Document 1, and the measurement device is heavy and requires labor. It is difficult to apply to the measurement of flow velocity distribution in a wide water area, and it is necessary to float by mooring. Therefore, it is difficult to measure the flow velocity at shallow water surface.
[0006]
On the other hand, as shown in FIG. 11, Non-Patent Document 1 describes a method in which a spherical gypsum probe 51 is exposed in a water stream 1 and the flow velocity is calculated from the mass loss of gypsum due to dissolution. In the figure, reference numeral 52 denotes a measuring element 51 having a shape after being depleted by the water flow 1. Non-Patent Document 2 describes a method in which a hemispherical gypsum probe (not shown) is installed in the water flow 1, and the flow velocity is calculated from the three factors of mass depletion, salt content and water temperature due to dissolution. is doing. These methods can be said to solve the problem that the measuring devices in Patent Documents 1 and 2 are complicated and expensive, and are heavy.
[0007]
[Patent Document 1]
Japanese Patent No. 2741738 [Patent Document 2]
JP-A-6-58946 [Non-Patent Document 1]
Shigeru Kawamata “Effects and Evaluation of Waves on Feeding of Sea Urchins and Abalones along the Coast of Northern Japan” Fisheries Research Center Research Report No. 1 (December 2001), Fisheries Research Center (Suiken Center) Pp. 59-107 [Non-Patent Document 2]
Kamizuki Yasunori et al. “Changes in mean flow velocity and benthic responses associated with the construction of coastal structures,” Civil Engineering Society 54th Annual Scientific Lecture (September 1999), CS-122, pp. 244-245 [Non-Patent Document 3]
Teruhisa Komatsu and Hideo Kawai "Measurements of Time-Averaged Intensity of Water Motion with Plaster Balls", Journal of Oceanography Vol.48 No.4 (1992), Oceanographic Society of Japan, pp.353-365
[Non-Patent Document 4]
Shigeru Kawamata “Flows of living organisms as habitats and their investigation methods” Monthly Ocean Vol.24 (1992), Marine Publishing, pp. 492-497 [0008]
[Problems to be solved by the invention]
However, the flow velocity measurement method using the gypsum gauge probe 51 made of gypsum sphere or gypsum hemisphere disclosed in Non-Patent Documents 1 to 4 still has difficulty in measuring the flow velocity distribution. In other words, the gypsum probe 51 only records the rate of water flow at one location only at the installation position. In order to grasp the change in the strength of the flow due to the water depth, that is, the distribution of the horizontal flow velocity in the vertical direction, the number of gypsum gauges 51 necessary for detecting the distribution must be individually installed at predetermined positions. Take it. In addition, the measurement value of the vertical direction distribution becomes discrete data only at the installation position of the gypsum probe 51, and fine differences in the vertical direction cannot be recorded as continuous data.
[0009]
Further, in Non-Patent Documents 1 to 4, since the gypsum probe 51 is spherical or hemispherical, in order to identify the flow direction, the angular relationship between the installation direction of the probe 51 and the coordinate system of the flow velocity is measured immediately after measurement. Complicated work such as recording is necessary. Even if only the orientation of the tracing stylus is written on the surface of the tracing stylus 51, that alone will not record a reliable flow direction. In the unlikely event that you forget the record immediately after the measurement, any data on the flow direction will be lost.
[0010]
Accordingly, an object of the present invention is to provide a flow velocity measuring method and apparatus using a gypsum column body that can detect a flow direction / velocity distribution at a time.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present inventor considered that the dissolution rate of the gypsum mass in the water flow is proportional to the flow velocity of the water flow, and that the flow direction and flow velocity in the longitudinal direction of the column body if the gypsum probe is a cylindrical body such as a cylindrical column. We noticed that the wear of gypsum according to the distribution can be recorded on the circumference of the measuring element. This gypsum pillar has a constant cross-sectional shape perpendicular to the axial direction. Further, the flow direction / velocity in this case is an average value of the period during which the above depletion occurs at the measurement point, and is not a specific instantaneous flow direction / velocity.
[0012]
Referring to FIG. 1, the flow rate measuring method using a gypsum column of the present invention is a method in which a gypsum column 2 having a constant cross-sectional shape perpendicular to the axial direction is intersected with a water flow 1 having a plurality of flow surfaces and held for a certain period of time. For each required point on the axis of the gypsum column 2, the flow direction and the flow velocity of the flow surface passing the point are set in the direction perpendicular to the direction in which the outer diameter reduction amount of the cross section of the column 2 at the point is maximum. It is detected as the flow velocity corresponding to the maximum value of the diameter depletion amount, and the flow direction and the flow velocity distribution detected at a plurality of the required points are obtained.
[0013]
Preferably, one end of the gypsum pillar body 2 is held on the water bottom 4 (see FIG. 2), and the flow speeds of the water bottom 4 and a plurality of flow surfaces substantially horizontal to the water bottom 4 are measured. More preferably, the column body 2 is vertically raised from the bottom 4 and held, and the flow velocity distribution in the water depth direction is measured.
[0014]
1 and 2, the gypsum pillar flow velocity measuring device according to the present invention is mounted with the gypsum pillar body 2 having a constant cross-sectional shape perpendicular to the axial direction and the gypsum pillar body 2 in a self-supporting posture. A fixing device 5 having a self-supporting tool 6 and capable of fixing to the bottom of the water is provided , and the outer diameter reduction amount of the cross section of the column 2 is perpendicular to the maximum direction and the outer diameter reduction amount for each required point on the axis of the gypsum column 2 As the flow velocity corresponding to the maximum value, the flow direction and the flow velocity of the water bottom and the flow surface substantially horizontal to the water bottom are detected . As shown in FIG. 2, the self-supporting tool 6 can be provided with an upward hole in which the lower end of the gypsum pillar body 2 is fitted in a predetermined posture. As shown in FIG. 3, the self-supporting tool 6 may be a long member having a rectangular cross section, and a hole 7 through which the long member passes in the axial direction of the gypsum column 2 may be provided. This square includes a polygon.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 shows an embodiment of a flow velocity measuring device according to the present invention. Referring to FIGS. 2 and 4, the gypsum column 2 having a constant cross-sectional shape perpendicular to the axial direction is held in a crossing manner with the water flow 1 having a plurality of layers of flow surfaces. The outer diameter wear distribution according to the flow surface distribution in the column 2 is generated on the outer peripheral surface of the column 2. By holding the gypsum pillar body 2 perpendicular to the substantially horizontal water flow 1, a distribution of outer diameter wear according to the vertical distribution of the horizontal flow velocity can be generated on the outer peripheral surface of the gypsum pillar body 2. FIG. 4 shows a side view of the post-wearing column 3 viewed from the direction of the water flow 1 when the gypsum column 2 is cylindrical. In the case of the illustrated example, the vertical distribution of the flow velocity of the horizontal water flow 1 can be recorded as a continuous change in the outer diameter loss due to the flow velocity by a single measurement with the single gypsum column 2.
[0016]
After leaving the gypsum column 2 in the water flow 1 for a certain period of time, the outer diameter depletion amount is maximized at each axial position (required point) corresponding to the water depth of the column 3 after depletion (ie, the outer diameter is The minimum direction) is detected as the average flow direction for a fixed time, and the direction perpendicular to the minimum outer diameter direction is set as the average flow direction of the water flow 1 for a fixed time. Further, the horizontal outer diameter in the minimum direction of the outer diameter is measured, and the difference between the initial outer diameter of the gypsum column body 2 before wear and the outer diameter after wear is calculated as, for example, the outer diameter wear rate (%). If the relationship between the flow velocity of the water flow 1 and the outer diameter reduction when the gypsum column body 2 is left in the water flow 1 for a certain period of time is determined in advance, the outer diameter reduction rate (%) measured for the post-wearing column body 3 Based on the above, it is possible to calculate the flow velocity at the water depth at which the outer diameter reduction of the installation position of the column 3 occurs. The relationship between the flow velocity of the water flow 1 and the outer diameter wear can be obtained in advance by, for example, actual measurement in a laboratory or other methods as shown in FIG.
[0017]
FIG. 6 shows the outer diameter reduction of the column 2 at a position (required point) on the gypsum column 2 corresponding to different times T ₁ and T ₂ . P ₁ , P ₂ , P ₃ and P ₄ are measurement points as described later. The figure shows an example in which the outer diameter wear is measured at three required points, but the measurement accuracy of the flow velocity distribution can be increased by further increasing the outer diameter wear measurement positions (required points). In the present invention, since the flow velocity distribution in the vertical direction is continuously recorded on the peripheral surface of the gypsum column 2, the vertical direction is continuously selected by appropriately selecting the wear measurement position in the axial direction of the gypsum column 2. It is possible to measure a simple flow velocity distribution.
[0018]
Assuming that the water flow 1 has a plurality of horizontal flow surfaces that are substantially horizontal to the bottom of the water, the outer diameter of the gypsum column 3 is reduced according to the horizontal flow surface. The flow direction and flow velocity can be detected. When the water flow 1 is inclined rather than horizontal, the outer diameter of the gypsum column 3 is reduced along the flow surface of the inclined water flow, so that the inclination of the water flow can be detected. The flow direction and flow velocity of the water flow 1 on the surface can be detected.
[0019]
FIG. 7 shows the measurement results of the influence of the salinity concentration on the wear of the outer diameter of the gypsum column 3 when the water flow 1 is salt water. In the figure, the symbol x is the average flow velocity, y is the depletion rate, Ln is the natural logarithm, R is the correlation coefficient, and psu is the salinity. As is clear from this figure, the depletion rate of the gypsum column 3 differs between seawater and brackish water such as estuaries or fresh water such as lakes. Therefore, the relationship between the flow velocity of the water flow 1 according to the salinity concentration and the outer diameter depletion is measured and recorded in advance, and the sensor for measuring the salinity concentration of the water flow to be measured is included in the flow velocity measuring device of the present invention, The relationship between the flow velocity of the water flow 1 and the outer diameter wear can be selected according to the measurement result of the sensor.
[0020]
FIGS. 8A and 10 assume a coastline 8 that is submerged in water such as a tidal flat, an intertidal zone, or the seaside except at low tide, and a group of gypsum columns 2 along a plurality of rows parallel to the coastline 8. The Example of this invention installed in the grid | lattice form is shown. In the illustrated example, as shown in FIG. 8, measurement points P1, P2, P3, and P4 are assumed as positions on the shoreline 8 where the unitless distances in the direction of the shoreline 8 are 100, 200, 300, and 400. be able to. Figure 6 shows the measurement points P1, P2, P3 gypsum pillar 2 ₁₁ and installed in the P4,, 2 _21, 2 _31, 2 ₄₁ horizontal section. As shown in FIG. 4, the bottom surface of each column 2 is buried in the sand at the bottom of the water, and each column 2 is raised vertically from the water bottom into the water. 6 shows the shape of the measurement points P _1, P _2, P ₃ of the horizontal cross-section of the required points of the installed plaster pillar and P ₄ time _{_{_{T 0, T 1, T 2}}} .
[0021]
Preferably, as shown in FIG. 5, the gypsum column 2 includes direction indicating elements 11 and 12 that extend in the length direction and visualize the direction of outer diameter wear. FIG. 4A shows a direction indicating element that is a pair of colored surfaces 11 and 12 formed along the central axis so as to indicate a coordinate axis orthogonal to the central axis of the column body in the cross section of the gypsum column body 2. By making the X coordinate axis display line 11 and the Y coordinate axis display line 12 into surface members identified by different colors, for example, blue and red, the coordinate axes intersecting with the central axis can be clearly shown in any cross section of the entire length of the column 2. However, the direction indicating element is not limited to the colored surface pairs 11 and 12, and for example, the shape of the through hole 7 provided along the central axis of the gypsum column 2 (rectangular or other specific shape) as shown in FIG. It is also possible to determine the direction of outer diameter wear from the above. For this purpose, the hole 7 does not penetrate and may be provided partway along the central axis of the column 2.
[0022]
As can be seen from a horizontal cross section of the plaster pillar 2 ₁₁ and 3 ₁₁ in the depletion of the before and after of Fig. 6, different time (2 times T1 and T2 in the illustrated example) outside diameter depletion of plaster pillar 3 By measuring the direction and the maximum depletion value, the flow direction / velocity at a specific depth in the water and the flow direction / velocity distribution in the depth direction can be measured over time. .
[0023]
8A and 10, not only the measurement of flow direction and flow velocity distribution in the depth direction, but also a plurality of depleted gypsum pillars 3 ₁₁ , 3 ₂₁ , 3 ₃₁ , 3 provided along the shoreline 8. ₄₁ By comparing the flow direction / velocity measurement values at the same depth (four in this example), the horizontal flow direction / velocity distribution on the shoreline 8 can be obtained. The horizontal flow direction / velocity distribution in the offshore direction is the gypsum columns 3 _1j , 3 _2j , 3 _3j , 3 _4j after depletion on the offshore line substantially parallel to the shoreline in FIG. 8 (j = 2 in the example of FIG. 8). What is necessary is just to obtain | require by the comparison of the flow direction and the flow velocity measured value in the same depth of 3). It is also possible to obtain the horizontal flow direction / velocity distribution on the arbitrary line by comparing the flow direction / velocity measurement values at the same depth of the gypsum column body line of the arbitrary line intersecting the shore line. FIG. 8B is an example of the horizontal average flow velocity distribution obtained by converting the outer diameter depletion amount measured by the arrangement of the gypsum column 2 shown in FIG.
[0024]
When obtaining the horizontal flow direction and flow velocity distribution, it is necessary to simultaneously measure the flow velocity at each position (measurement point), and it is necessary to simultaneously generate all the outer diameter wear in each gypsum column 2. The flow velocity measuring device of FIG. 2 has a fixing device 5 that can fix the water bottom with a self-supporting tool 6 on which the gypsum pillar body 2 is mounted in a self-supporting posture, and the fixing device 5 is fixed to the water bottom at a predetermined position (measurement point). After that, the gypsum pillar body 2 is attached to the self-supporting tool 6. For example, if the fixing devices 5 are installed at a plurality of positions shown in FIGS. 8A and 10, respectively, the operation time for attaching or removing the gypsum pillar body 2 (attachment / removal of the first gypsum pillar body 2) As long as the time interval between the operation and the last operation of attaching / removing the gypsum column 2 is not unduly long, it is possible to detect the outer diameter loss occurring at the same time of each gypsum column 2. An unreasonably long time interval is a time that is not negligible with respect to the time (for example, several days) during which the outer diameter reduction to be measured proceeds.
[0025]
According to the present invention, the gypsum column body 2 can be removed from the fixing device 5 and transported to an appropriate measurement place such as a land measurement chamber when measuring the outer diameter reduction of the gypsum column body 2. The flow direction and flow velocity can be easily measured. In addition, although there is a limit that the flow velocity is detected depending on the indirect amount of external wear of the gypsum pillar body 2, the flow velocity distribution can be easily performed by simple means. Furthermore, according to the present invention, as shown in the gypsum pillar body 3 after depletion in FIG. 4, it is possible to measure gypsum depletion due to the water level along the bottom surface 4, that is, the bottom surface of the water bottom, which has been difficult in the past. Flow velocity measurement is also possible.
[0026]
Thus, the provision of “a method and an apparatus for measuring a flow velocity using a gypsum column body capable of detecting a flow direction / flow velocity distribution at a time” which is an object of the present invention is achieved.
[0027]
【Example】
The external shape of the gypsum pillar body 2 used in the present invention is not limited to a cylindrical shape, and can be any shape that can accurately measure the outer diameter reduction. For example, as shown in FIG. 5C, a prism having a regular polygonal cross section can be used. The prismatic gypsum pillar body 2 has a feature that it can easily keep the angular position constant while avoiding rotation around the central axis of the pillar body 2 at the time of measurement, as compared with the case of the cylindrical gypsum pillar body. Further, the gypsum pillar body 2 of the present invention can be manufactured in the same shape by simply injecting and molding the material into the mold as compared with the conventional spherical or hemispherical gypsum. Is possible. In addition, stacking is easy in terms of shape, so that it is easy to store, and can easily handle a large amount of long-distance transportation.
[0028]
The self-supporting tool 6 of the gypsum pillar body 2 shown in FIG. 2 has an upward hole into which the lower end of the gypsum pillar body 2 is fitted, and is attached to the fixing device 5 integrally. In this case, the flow rate detection can be started by fixing the gypsum pillar body 2 simply by inserting it into the upward hole. Further, for the measurement of the wear of the gypsum pillar body 2, the gypsum pillar body 2 can be separated and recovered by simply pulling it out from the upward hole of the self-supporting tool 6, and used for the measurement of the outer diameter wear on land. Preferably, in order to keep the angular position around the axis of the gypsum column 2 at the time of measurement, an appropriate alignment means (not shown) associated with the self-supporting tool 6 and the column 2 is provided. Such a self-supporting tool 6 also has a simple structure and can be manufactured at a low cost.
[0029]
As shown in FIG. 3, the self-supporting tool 6 may be a long member having a square cross section fixed to the fixing device 5. In this case, as shown in FIG. 5 (B), it is preferable to pierce the through hole 7 having a rectangular cross section through which the long member of the self-supporting tool 6 penetrates in the axial direction of the gypsum column 2. In this way, the gypsum pillar body 2 can be kept in an appropriate posture with respect to the water flow 1 or the ground coordinate system simply by inserting the gypsum pillar body 2 into the self-supporting tool 6. When the water depth is deep, a long rectangular long member is used as the self-supporting tool 6, and a plurality of gypsum pillars 2 are fitted to the rectangular long member in a vertical row so that the flow velocity in the vertical direction of the deep water depth is full. Distribution can be recorded. FIG. 5C shows the convenience of mounting the fixing device 5 in an appropriate posture in the same manner as FIG.
[0030]
According to the present invention, the flow direction and flow velocity can be easily and simultaneously measured over a wide range at a time. FIG. 10 schematically shows an example in which the method of the present invention is applied to the evaluation of the flow velocity distribution in the tidal flat 21 after artificial construction. The installation and removal of a large number of gypsum pillars 2 in a wide range at the same time, and measurement, for example, can be easily realized by using the self-supporting tool 6 as shown in FIG. it can. By the measurement, for example, the distribution of the average flow velocity as shown in FIG. 8B can be grasped.
[0031]
FIG. 9A shows an example of the flow velocity distribution in the shallows where the clam distribution is detected, and FIG. 9B shows an example of a similar flow velocity distribution for the Shiofuki distribution. For example, referring to the existing data on the correlation between the average flow velocity distribution and the biological distribution, the artificial tidal flat 21 is shown in FIG. 10A based on the average flow velocity distribution obtained by the arrangement of the gypsum pillar body 2 in FIG. It can be assumed that a biological habitat zone 22 as shown in (B) is set. It is also conceivable to set the circulation residence zone 23 by analyzing the measured average flow velocity distribution and to plan the wave-dissipating work 25 for the zone 24 with a fast flow. Furthermore, the present invention will be an important measurement means in future environmental assessments as well as in the case of establishing organisms on the artificial tidal flat 21 and the like, and will be a useful technique in environmental conservation, creation space zoning, scoping, and the like.
[0032]
【The invention's effect】
As described above, the method and apparatus for measuring the flow velocity by the gypsum column of the present invention keeps the gypsum column crossing the water flow for a certain period of time, and removes the outside of the column cross section for each required point on the axis of the gypsum column. The flow direction perpendicular to the direction with the largest diameter depletion amount and the flow velocity corresponding to the maximum value of the outer diameter depletion amount are detected, and the flow direction / velocity distribution at a plurality of required points is obtained.
[0033]
(A) The flow direction and flow velocity distribution can be measured simultaneously over a wide range at once.
(B) It is possible to grasp the flow velocity in the intertidal zone where the bottom of the water can be exposed.
(C) It becomes possible to grasp the distribution of the flow in the inner bay, which used to depend on numerical calculations, by direct measurement.
(D) It becomes possible to grasp by measuring the flow velocity distribution in extremely shallow water such as tidal flats, which was difficult in the past.
(E) It becomes possible to grasp the flow velocity distribution in the constructed tidal flat which is important as an environmental factor of living organisms in the tidal flat construction of the population.
(F) It will be a technology necessary for the acquisition of data that is indispensable for environmental assessment in water areas including natural or artificial shallows and tidal flats, and for zoning and scoping of environmental creation spaces.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of the principle of a flow velocity measuring method using a gypsum pillar of the present invention.
FIG. 2 is a perspective view showing an embodiment of an apparatus for fixing a gypsum pillar body used in the method of the present invention.
FIG. 3 is a perspective view showing another embodiment of a self-supporting tool for supporting a gypsum pillar body used in the method of the present invention.
FIG. 4 is an explanatory view showing wear of a gypsum column body due to water flow.
FIG. 5 is a perspective view showing the appearance of three types of gypsum pillars.
FIG. 6 is a schematic diagram for explaining the time course of depletion of the gypsum pillar body due to water flow.
FIG. 7 is a graph showing an example of the relationship between the flow velocity of water flow and the depletion of gypsum pillars.
FIG. 8 is a schematic diagram showing an example of the distribution of measured values of the amount of depletion of the gypsum column and the average flow velocity in the flow velocity measurement in shallow water.
FIG. 9 is a schematic diagram showing an example of the distribution of clams and shiouki in shallow water.
FIG. 10 is an explanation of an application example of the method of the present invention in tidal flat development.
FIG. 11 is an explanatory diagram of a conventional gypsum sphere used for flow velocity measurement.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Water flow 2 ... Gypsum pillar 3 ... Column after wear-out 4 ... Sand level (water bottom)
5 ... Fixing device 6 ... Self-supporting tool 7 ... (through) hole
11 ... Direction indicating element (X coordinate axis)
12 ... Direction indicating element (Y coordinate axis)
21 ... Tidal flats 22 ... Inhabitable zone
23… Circulation residence zone 24… Fast flow zone
25… Wavebreaker 51… Gypsum measuring element
52… Gypsum gauge after wear

Claims

Crossing a gypsum column with a constant cross-sectional shape perpendicular to the axial direction into a water flow with multiple layers of flow surface, holding it for a certain period of time, and for each required point on the axis of the gypsum column, the flow direction of the flow surface past that point And the flow velocity at a plurality of the required points are detected as a flow velocity corresponding to a direction orthogonal to the direction in which the outer diameter depletion amount of the column cross section at the relevant point is orthogonal to the maximum direction and the maximum value of the outer diameter depletion amount. A flow velocity measurement method using a gypsum pillar body for obtaining the distribution of water.

The method according to claim 1, wherein one end of the gypsum column is held at the bottom of the water, and the flow rate is measured by a gypsum column formed by measuring the flow rate of the water bottom and a flow surface substantially horizontal to the bottom of the water.

3. The method according to claim 1 or 2, wherein the column body is held upright from the bottom of the water and is measured by measuring the flow velocity distribution in the depth direction.

The method according to claim 3, wherein the column body is set up at a plurality of shallow water positions, and the flow velocity distribution is simultaneously measured at each position to obtain a shallow water flow distribution.

5. The method according to claim 4, wherein the pillar body is vertically held at a plurality of positions on the bottom of the shallow water, and the horizontal flow velocity distribution at the bottom of the shallow water and each water depth is obtained by simultaneously measuring the flow velocity at each position. Flow rate measurement method by the body.

6. The method according to claim 2, wherein said column body is separably attached to a self-supporting tool fixed to the water bottom.

The method according to claim 6, wherein the self-supporting tool is provided with an upward hole in which a lower end of the gypsum pillar body is fitted in a predetermined posture.

The method according to claim 6, wherein the self-supporting tool is a long member having a square cross section, and a hole through which the long member passes in the axial direction of the gypsum column is provided.

The method according to any one of claims 1 to 8, wherein the gypsum column includes a direction indicating element that extends in the length direction and visualizes the direction of outer diameter reduction.

The method according to claim 9, wherein the direction indicating element is a flow rate measuring method using a gypsum column body as a colored surface pair formed along the central axis so as to indicate a coordinate axis orthogonal to the cross section of the gypsum column body. .

Axially perpendicular sectional shape constant plaster pillar, and it comprises a water bottom anchoring anchoring device with autonomous tools that gypsum pillar is mounted in a free standing position, for each desired point on the axis of the plaster pillar A gypsum column that detects the flow direction and flow velocity of the water surface and the flow surface almost horizontal to the bottom as the flow velocity corresponding to the direction in which the outer diameter depletion amount of the column body is orthogonal to the maximum direction and the maximum outer diameter depletion amount. Flow rate measuring device by the body.

The apparatus according to claim 11, wherein the self-supporting device has a gypsum column body flow rate measuring device provided with an upward hole into which a lower end of the gypsum column body is fitted in a predetermined posture.

The apparatus according to claim 11, wherein the self-supporting tool is a long member having a rectangular cross section, and a flow rate measuring device using a gypsum column body provided with a hole through which the long member passes in the axial direction of the gypsum column body.

14. The apparatus according to claim 11, wherein the gypsum column body includes a direction indicating element that extends in a length direction and visualizes the direction of outer diameter reduction.

15. The apparatus according to claim 14, wherein the direction indicating element is a flow rate measuring device using a gypsum columnar body as a colored surface pair formed along the central axis so as to indicate a coordinate axis perpendicular to the central axis of the columnar body in the cross section of the gypsum columnar body. .