JP3671373B2

JP3671373B2 - Underground irrigation system

Info

Publication number: JP3671373B2
Application number: JP2003035021A
Authority: JP
Inventors: 恒雄小野寺; 新作藤森
Original assignee: 独立行政法人農業工学研究所; 株式会社パディ研究所
Priority date: 2003-02-13
Filing date: 2003-02-13
Publication date: 2005-07-13
Anticipated expiration: 2023-02-13
Also published as: JP2004242560A

Description

【０００１】
【発明の属する技術分野】
本発明は、地下灌漑システムに関し、詳しくは、地下に埋設した有孔管からの排水水位を調節することによって圃場の地下水位や地表水位を設定する地下灌漑システムに関する。
【０００２】
【従来の技術】
近年行われつつある地下潅漑は、畑作時の圃場の地下水位を調節して毛管現象により水分を補給するものであって、地下水位を作物に適した水位に調節することによって収穫量向上等の効果を得ることができる。この地下潅漑は、圃場の地中に有孔管からなる暗渠排水パイプを埋設し、地中の余剰地下水を排水路に排出するとともに、不足する用水の供給も暗渠排水パイプを利用して行うのが一般的である（例えば、特許文献１参照。）。
【０００３】
【特許文献１】
特開平１０−１５５３７５号公報（第２頁、第１，２図）
【０００４】
【発明が解決しようとする課題】
上述のような地下灌漑において、圃場の水位は、畑作と稲作との相違、作物の生育状況、圃場の地質等の各種条件に応じて適切に設定する必要があり、また、肥料や農薬の流出も最小限に抑える必要がある。さらに、供給される用水中にゴミや土砂のような異物が多く含まれていると、これらの異物が暗渠排水パイプ内に蓄積して通水性能を阻害するおそれもある。
【０００５】
そこで本発明は、圃場からの肥料や農薬の流出を最小限に抑え、各種条件に応じた適切な灌漑を行えるとともに、暗渠排水パイプ（有孔管）内への土砂等の蓄積も抑えることができる地下灌漑システムを提供することを目的としている。
【０００６】
【課題を解決するための手段】
上記目的を達成するため、本発明の地下灌漑システムは、第１の構成として、圃場の地中に有孔管を埋設するとともに該有孔管の下流側に水位設定器を設置し、該水位設定器で排水水位を調節することにより圃場の水位を設定する地下灌漑システムにおいて、給水路からの用水を前記有孔管に供給するための地下給水管を圃場の地中に埋設し、該地下給水管と前記有孔管とを、該有孔管の排水側で接続するとともに、前記給水路から供給される用水を耕作区地表面に供給可能で、かつ、耕作区内の余剰の用水を前記地下給水管に排出可能な給排水枡を設けたことを特徴としている。
【０００７】
本発明の地下灌漑システムの第２の構成は、圃場の地中に有孔管を埋設するとともに該有孔管の下流側に水位設定器を設置し、該水位設定器で排水水位を調節することにより圃場の水位を設定する地下灌漑システムにおいて、給水路からの用水を前記有孔管に供給するための地下給水管を圃場の地中に埋設し、該地下給水管と前記有孔管とを、該有孔管の排水側で接続するとともに、前記地下給水管から供給される用水を耕作区地表面に供給可能で、かつ、耕作区内の余剰の用水を前記水位設定器に排出可能な給排水枡を設けたことを特徴としている。
【０００８】
さらに、本発明の地下灌漑システムの第３の構成は、圃場の地中に有孔管を埋設するとともに該有孔管の下流側に水位設定器を設置し、該水位設定器で排水水位を調節することにより圃場の水位を設定する地下灌漑システムにおいて、給水路からの用水を前記有孔管に供給するための地下給水管を圃場の地中に埋設し、該地下給水管と前記有孔管とを、該有孔管の排水側で接続するとともに、前記給水路から供給される用水を耕作区地表面に供給可能で、かつ、耕作区内の余剰の用水を前記地下給水管に排出可能な給水路側の給排水枡と、前記地下給水管から供給される用水を耕作区地表面に供給可能で、かつ、耕作区内の余剰の用水を前記水位設定器に排出可能な水位設定器側の給排水枡とを設けたことを特徴としている。
【０００９】
また、上記各構成の地下灌漑システムにおいて、前記複数の有孔管の中の一つが前記地下給水管を兼ねる大径有孔管であることを特徴としている。
【００１０】
【発明の実施の形態】
図１乃至図３は、本発明の地下灌漑システムの一形態例を示すもので、図１は地下灌漑システムの断面図、図２は配管系統を示す概略平面図、図３は水位設定器部分を示す断面図である。
【００１１】
圃場の内部は、農道１１や畦畔１２によって複数の耕作区１３に区画されており、一方の農道部分には給水路１４が設けられ、他方の農道部分には排水路１５が設けられている。各耕作区１３には、作物の種類やその生育状況に応じて水位を適切に設定するための地下灌漑システムがそれぞれ設けられている。なお、給水路や排水路は圃場の状況に応じて任意の位置に設けることができ、畦畔の部分に設けられていることもあり、パイプラインで形成されていてもよい。また、同じ農道部分に給水路と排水路とが併設されていてもよい。
【００１２】
地下灌漑システムは、耕作区１３の地中に、集合管２１から分岐した複数の有孔管２２を並列に等間隔で埋設するとともに、集合管２１と排水路１５との間に、地下排水弁２３を有する水位設定器２４を設置している。この水位設定器２４は、有底筒状の水位設定枡２５の内部に下部固定堰２６と上部可動堰２７とを上下動可能に設け、水位設定枡２５内を集合管２１が接続する耕作区側の流入室２８と、排水路１５に至る排水管３０が接続する排水路側の排水室２９とに区画したものであって、通常時は、下部固定堰２６を最下端に固定した状態で、上部可動堰２７の高さ位置を調節したり、上部可動堰２７を取り外したりすることにより、流入室２８内の水位、即ち各耕作区１３内の水位を任意に設定できるように形成されている。下部固定堰２６と上部可動堰２７とは、水位設定枡２５の内壁に形成したガイド溝２６ａ、２７ａに上下動及び抜き差し可能で、かつ、任意の高さ位置に固定可能な状態で設けられており、両堰２６，２７は、ゴム製のパッキン等を介して水密状態で摺接するように形成されている。
【００１３】
さらに、前記耕作区１３の給水路１４側には、取水弁３１を介して給水路側給排水枡３２が設けられるとともに、この給水路側給排水枡３２に、給水路１４から取り入れた用水を前記有孔管２２に向けて供給するための地下給水管３３が地下給水弁３４を介して接続されている。また、水位設定器２４側には、給排水弁３５を備えた水位設定器側給排水枡３６が設けられている。給水路側給排水枡３２及び水位設定器側給排水枡３６は、耕作区１３に連通して用水を給排水するための開口部を備えるとともに、この開口部を閉塞する堰板３２ａ，３６ａを装着できるように形成されている。なお、給水路１４から用水を取り入れる取水口部分には、配管経路内で詰まるおそれのある粗大なゴミを分離するためのフィルターを設けておくことが望ましく、さらに、取水量調節手段や流量確認手段等を設けておくことができる。また、地下給水管３３は、給水路側給排水枡３２を介さずに給水路１４に直接接続するようにしてもよい。
【００１４】
前記地下給水管３３は、耕作区１３の地中に、前記有孔管２２と同程度の深さ、好ましくは有孔管２２よりも深い位置に、水平方向あるいは排水路１５側に向かって適度な水勾配を設けた状態で埋設されており、末端が前記水位設定器２４における流入室２８の下部に接続し、流入室２８を介して有孔管２２の排水側に接続している。
【００１５】
このように形成した地下灌漑システムは、稲作時における地表水位の管理と畑作時における地下水位の管理とを容易かつ確実に行うことができる。例えば、稲作時において、耕作区１３内に用水を供給する際には、水位設定器２４の上部可動堰２７を田面水位に対応した位置に引き上げた状態で、取水弁３１、地下給水弁３４、給排水弁３５及び地下排水弁２３を開いた状態とする。これにより、給水路１４を流れる用水が給水路側給排水枡３２から耕作区１３の地表に直接供給されるとともに、地下給水管３３に流入した用水が水位設定器２４の流入室２８に流入して上部可動堰２７の上端付近まで上昇する。
【００１６】
流入室２８に流入した用水は、その一部が水位設定器側給排水枡３６を通って耕作区１３の地表に直接供給され、残りの用水が集合管２１から有孔管２２を経て耕作区１３の地中に供給される。このようにして耕作区１３に用水を供給することにより、耕作区１３への大量の用水の供給も短時間で行うことができる。この耕作区１３への用水供給は、耕作区１３内の水位が上部可動堰２７の上端を超えるまで継続され、これ以上の余剰の用水は、上部可動堰２７を超えて排水室２９に流下し、排水管３０から排水路１５に排出される。なお、用水の供給箇所は、各弁２３，３４，３５の開閉や堰板３２ａ，３６ａの着脱によって任意に選択することができる。
【００１７】
代掻き等で用水中に耕作区１３内の土が多量に舞い上がるようなときは、給水路側給排水枡３２及び水位設定器側給排水枡３６に堰板３２ａ，３６ａを装着して耕作区１３内の用水が両給排水枡３２，３６内に流入しないようにしておくことにより、両給排水枡３２，３６から配管系統に土砂が進入することを防止できる。この場合も、有孔管２２からの給水を継続することにより、耕作区１３内の水位が低下してしまうことはない。
【００１８】
耕作区１３内の水位を維持する場合、前述のように、有孔管２２、給水路側給排水枡３２及び水位設定器側給排水枡３６からの用水供給を継続した状態としておいてもよいが、給水路側給排水枡３２に堰板３２ａを取り付けて給水路側給排水枡３２から耕作区１３への用水の流入を止めた状態とし、有孔管２２及び水位設定器側給排水枡３６を使用して用水管理を行うようにすることができる。このような用水管理を行うことにより、蒸発や地中への浸透によって耕作区１３内の水量が減少した場合には、主として水位設定器側給排水枡３６から耕作区１３内に用水が流入して水位を維持し、降雨等により耕作区１３内の水位が上昇すると、余剰の用水が水位設定器側給排水枡３６から水位設定器２４の上部可動堰２７を超えて排出される状態となる。
【００１９】
これにより、耕作区１３内の水位が水位設定器２４に設定した水位、例えば、地上１５〜２５ｃｍ、特に２０ｃｍ程度に維持することができる。このように、耕作区１３への給排水を主として水位設定器側給排水枡３６から行うことにより、有孔管２２のみを使用して給排水を行う場合に比べ、用水の給排水を迅速に行うことができる。また、耕作区１３内への用水の給水を給水路側給排水枡３２から行わずに主として水位設定器側給排水枡３６で行うことにより、耕作区１３内に給水路側給排水枡３２から水位設定器側給排水枡３６へ向かう用水の流れが発生せず、この流れに伴って農薬や肥料等が排水路１５に流出することがなくなるので、農薬や肥料等の効果が十分に得られるとともに、農薬等の流出による環境破壊の問題も解消することができる。さらに、有孔管２２からも給水することにより、地表から地下に浸透する水量が減少するので、これによっても農薬や肥料の有効活用が図れる。
【００２０】
また、この状態で地下給水弁３４を閉じるとともに堰板３２ａを取り外すことにより、耕作区１３内に給水路側給排水枡３２からの適度な水の流れを形成することができるので、例えば、夏季に耕作区１３内の水温を下げたり、硫化水素等の有害物質を地中から排出したりすることができる。このとき、給排水弁３５を閉じて水位設定器側給排水枡３６への給水を止めることにより、耕作区１３内の用水の流れを給水路側給排水枡３２から有孔管２２に向かう流れのみとすることができ、地中の有害物質の排出をより効果的に行うことができる。また、地下排水弁２３を閉じることにより、用水の流れを給水路側給排水枡３２から水位設定器側給排水枡３６に向かう流れと地下に浸透する流れとにすることができるので、猛暑時における水温上昇防止効果を増大させることができる。
【００２１】
この稲作時における田面水位は、上部可動堰２７を上下方向にスライドさせることによって任意に設定することができる。例えば、上部可動堰２７を適度に押し下げることにより、無代掻きで幼苗を移植する際などに適した地下水位、例えば地下０〜２０ｃｍの範囲に設定することができる。
【００２２】
一方、畑作時には、上部可動堰２７を下方に押し下げたり、上部可動堰２７を取り外したり、あるいは、上部可動堰２７を上方（最上方）に引き上げて上部可動堰２７の下端と下部固定堰２６の上端との間に通水部を形成したりすることにより、耕作区１３の地下水位を畑作時に適した地下灌漑用水位、例えば地下３０〜５０ｃｍの範囲に設定することができる。例えば、水位設定器２４で地下水位を設定した状態で全ての弁２３，３１，３４，３５を開いておくことにより、給水路１４から給水路側給排水枡３２に流入した用水が、地下給水管３３を経て水位設定器２４の流入室２８に流入し、地下排水弁２３から集合管２１を通って有孔管２２から耕作区１３の地中に供給される。
【００２３】
また、降雨等によって地下水位が上昇したときには、耕作区１３の余剰の地下水が有孔管２２に流入して集合管２１から水位設定器２４の流入室２８に流入し、上部可動堰２７又は下部固定堰２６を超えて排水室２９から排水管３０を通って排水路１５に排出されるので、耕作区１３の地下水位を水位設定器２４で設定した水位に保つことができる。さらに、大雨によって耕作区１３が冠水状態となるようなときには、地表水を給水路側給排水枡３２や水位設定器側給排水枡３６から直接排出することができるので、耕作区１３の冠水状態を速やかに解消することができる。
【００２４】
このようにして地下水位の管理を行うことにより、給水路１４からの新たな用水は、前記地下給水管３３から有孔管２２の排水側に供給され、余剰分はそのまま水位設定器２４を通って排出されるので、耕作区１３内には不足分の用水だけが供給される状態となる。したがって、耕作区１３内には、用水の流れがほとんど生じない状態となるので、耕作区１３内に温度の低い用水が過度に流れ込んだり、耕作区１３内に施した肥料や農薬が用水と共に流出することもほとんどなくなる。また、畑作時においても、耕作区１３に地表水を供給する必要があるときには、地下給水弁３４を閉じることにより、給水路側給排水枡３２から地表に用水を供給することができる。
【００２５】
そして、このような灌漑状態において、前記有孔管２２には、前記地下給水管３３から水位設定器２４を通り、集合管２１を経て各有孔管２２に分岐した用水がそれぞれ流入する状態となっている。このように、有孔管２２に流入する用水を、給水路１４から直接ではなく、地下給水管３３を通して有孔管２２の排水側から流入するように形成したことにより、給水路１４から供給される用水に土砂等が多く含まれている場合でも、用水中の土砂等を地下給水管３３内で沈降させることができ、有孔管２２に用水と共に流入する土砂等の量を大幅に減少させることができる。このとき、地下給水管３３の口径や取水量を適当に設定して用水の流速を十分に遅くすることにより、地下給水管３３での土砂等の沈降分離を略完全に行うことが可能となり、有孔管２２への土砂等の流入を確実に防止することができる。
【００２６】
したがって、長期間の使用においても、有孔管２２内に土砂等が蓄積して有孔管２２の通水性能を阻害することがなくなる。これにより、取水口に目の細かいフィルターを設置したりする必要がなくなるので、日常的な保守点検作業を省略することが可能となり、農作業の省力化を図ることができる。また、地下給水管３３の敷設は、有孔管２２等の敷設作業と同時に行うことができるので、初期コストの上昇は僅かで済む。
【００２７】
さらに、水位設定器２４の下部固定堰２６を引き上げて水位設定枡２５の底部で流入室２８と排水室２９とを連通させることにより、有孔管２２を通して耕作区１３の排水を行うことができる。このとき、取水弁３１を閉じることによって耕作区１３を乾燥状態にすることができ、また、取水弁３１及び地下給水弁３４を開くことにより、地下給水管３３に十分な速度で用水を流すことができるので、地下給水管３３内に沈降した土砂等を水位設定器２４から排水管３０を通して排水路１５に排出することができる。この地下給水管３３からの土砂等の除去排出は、地下給水管３３に適当な水勾配を設定しておくことによって確実に行うことができる。
【００２８】
特に、地下給水管３３の埋設位置を前記有孔管２２より深い位置にして地下給水管３３内を常時満流状態にしておくことにより、地下給水管３３内で沈降した土砂等が乾燥して地下給水管３３内で固まることを防止できるので、地下給水管３３からの土砂の除去排出をより容易に行うことができる。さらに、地下給水管３３と排水管３０とを直線状に配置しておくことにより、排水管３０からパイプクリーナー等の器具を挿入して地下給水管３３内を容易に清掃することができる。また、給水路１４と排水路１５との間に十分な高低差を得られない場合は、ポンプ等を使用して地下給水管３３内に強制的に水を送り込んで水流を発生させることにより、前記同様にして土砂等を排出することができる。
【００２９】
このように給水路側給排水枡３２と水位設定器側給排水枡３６とを設けた地下灌漑システムでは、畑作時における地下灌漑水位の管理だけでなく、稲作時における地表水の管理も効果的に行うことができるが、給水路側給排水枡３２と水位設定器側給排水枡３６とは、必ずしも同時に設ける必要はなく、いずれか一方のみを設けてもよい。
【００３０】
すなわち、給水路側給排水枡３２又は水位設定器側給排水枡３６のいずれか一方のみを設けた場合でも、稲作時における地表水の給排水や畑作時における雨水の排出を給水路側給排水枡３２又は水位設定器側給排水枡３６から前記同様にして行うことができるので、暗渠排水パイプのみによる従来の地下潅漑に比べて効率のよい水管理を行うことができる。
【００３１】
なお、前記集合管２１や地下給水管３３は、複数の有孔管２２の全体に用水を供給可能な状態とするため、有孔管２２より口径の大きなものが用いられており、例えば有孔管２２の口径の２倍程度の口径、具体的には、呼び径５０程度の有孔管２２に対して呼び径１００程度のパイプを用いるようにする。また、前記各弁は、少なくとも水の流れを遮断することができればよく、各種構造の弁だけでなく、堰や水閘を使用することもでき、流量制御機能を付加することもできる。さらに、水位設定器２４の構造も任意であり、堰に代えて二重構造のスライドパイプ型式のものなど、任意の水位設定手段を使用することが可能である。また、下部固定堰２６の大きさを、畑作時の作物に最適な地下水位に対応した高さとしておくことにより、稲作時と畑作時との切り換えを、上部可動堰２７を最上方に引き上げて固定するだけの操作で行うことができる。
【００３２】
図４は、本発明の地下灌漑システムの他の形態例を示す断面図である。本形態例に示す灌漑システムでは、複数設けられている有孔管２２の中の一部、通常は１本に大径の有孔管２２ａを使用して前記地下給水管と同等の機能を持たせ、この大径有孔管２２ａの給水路側を地下給水弁３４を介して前記給水路側給排水枡３２に接続し、その他の各有孔管２２への用水の供給を、この大径有孔管２２ａを介して行うようにしたものである。
【００３３】
このように、地下給水管として大径有孔管２２ａを使用した場合でも、前記同様の用水管理、地下灌漑を行えるとともに、大径有孔管２２ａ内で土砂等の沈降分離を行うことができる。この大径有孔管２２ａ内に沈降した土砂等は、水位設定器２４の下部固定堰２６を引き上げることにより、前記地下給水管の場合と同様にして排出することができる。
【００３４】
【発明の効果】
以上説明したように、本発明の地下灌漑システムによれば、肥料や農薬の流出を最小限に抑え、各種条件に応じた適切な灌漑を行えるとともに、暗渠排水パイプ（有孔管）内への土砂等の蓄積も抑えることができ、長期間にわたって確実な地下灌漑を行うことができる。
【図面の簡単な説明】
【図１】本発明の地下灌漑システムの一形態例を示す断面図である。
【図２】配管系統を示す概略平面図である。
【図３】水位設定器部分を示す断面図である。
【図４】本発明の地下灌漑システムの他の形態例を示す断面図である。
【符号の説明】
１１…農道、１２…畦畔、１３…耕作区、１４…給水路、１５…排水路、２１…集合管、２２…有孔管、２２ａ…大径有孔管、２３…地下排水弁、２４…水位設定器、２５…水位設定枡、２６…下部固定堰、２７…上部可動堰、２８…流入室、２９…排水室、３０…排水管、３１…取水弁、３２…給水路側給排水枡、３３…地下給水管、３４…地下給水弁、３５…給排水弁、３６…水位設定器側給排水枡[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an underground irrigation system, and more particularly, to an underground irrigation system that sets a groundwater level and a surface water level of a field by adjusting a drainage water level from a perforated pipe buried underground.
[0002]
[Prior art]
Underground irrigation, which is being carried out in recent years, is to replenish water by capillary action by adjusting the groundwater level of the field during field cultivation.By adjusting the groundwater level to a water level suitable for crops, etc. An effect can be obtained. Underground irrigation involves burying underground drainage pipes with perforated pipes in the ground of the field, draining excess underground water into the drainage channel, and supplying insufficient water using the underground drainage pipes. Is common (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-155375 (second page, FIGS. 1 and 2)
[0004]
[Problems to be solved by the invention]
In underground irrigation as described above, the water level in the field must be set appropriately according to various conditions such as the difference between field cultivation and rice cultivation, the growth situation of the crop, the geology of the field, and the outflow of fertilizers and pesticides. Should be kept to a minimum. Furthermore, if the supplied water contains a large amount of foreign matters such as dust and earth and sand, these foreign matters may accumulate in the underdrain drainage pipe and impede water flow performance.
[0005]
Therefore, the present invention can minimize the outflow of fertilizers and agricultural chemicals from the field, can perform appropriate irrigation according to various conditions, and can also suppress accumulation of earth and sand in the underdrain drainage pipe (perforated pipe). The purpose is to provide an underground irrigation system.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the underground irrigation system of the present invention has, as a first configuration, a perforated pipe embedded in the ground of a farm field and a water level setting device installed on the downstream side of the perforated pipe. In an underground irrigation system in which the water level of a field is set by adjusting the drainage water level with a setting device, an underground water supply pipe for supplying water from the water supply channel to the perforated pipe is buried in the ground of the field. The water supply pipe and the perforated pipe are connected on the drain side of the perforated pipe, and the water supplied from the water supply channel can be supplied to the surface of the cultivated area, and surplus water in the cultivated area can be supplied. The underground water supply pipe is provided with a water supply / drainage tub that can be discharged.
[0007]
The second configuration of the underground irrigation system according to the present invention is to embed a perforated pipe in the ground of a farm field, install a water level setting device downstream of the perforated pipe, and adjust the drainage water level with the water level setting device. In the underground irrigation system for setting the water level of the field, an underground water supply pipe for supplying water from the water supply channel to the perforated pipe is embedded in the ground of the field, and the underground water supply pipe and the perforated pipe are Can be connected to the drainage side of the perforated pipe, the water supplied from the underground water supply pipe can be supplied to the surface of the cultivation area, and excess water in the cultivation area can be discharged to the water level setting device It is characterized by the provision of an appropriate water supply and drainage dredger.
[0008]
Furthermore, the third configuration of the underground irrigation system according to the present invention is to embed a perforated pipe in the ground of a field and install a water level setting device on the downstream side of the perforated pipe. In the underground irrigation system that sets the water level of the field by adjusting, an underground water supply pipe for supplying water from the water supply channel to the perforated pipe is buried in the ground of the field, and the underground water supply pipe and the perforated hole A pipe is connected to the drainage side of the perforated pipe, and water supplied from the water supply channel can be supplied to the surface of the cultivation area, and excess water in the cultivation area is discharged to the underground water supply pipe. A water supply / drainage basin on the possible water supply channel side and the water level setter side that can supply the water supplied from the underground water supply pipe to the surface of the cultivated area and discharge excess water in the cultivated area to the water level setter It is characterized by having a water supply and drainage basin.
[0009]
Moreover, in the underground irrigation system having the above-described configurations, one of the plurality of perforated pipes is a large-diameter perforated pipe that also serves as the underground water supply pipe.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 to 3 show an embodiment of the underground irrigation system of the present invention. FIG. 1 is a sectional view of the underground irrigation system, FIG. 2 is a schematic plan view showing a piping system, and FIG. FIG.
[0011]
The inside of the farm field is divided into a plurality of cultivated areas 13 by a farm road 11 and a shore 12, a water supply path 14 is provided on one farm road part, and a drainage path 15 is provided on the other farm road part. . Each cultivated area 13 is provided with an underground irrigation system for appropriately setting the water level in accordance with the type of crop and its growth condition. In addition, a water supply channel and a drainage channel can be provided in arbitrary positions according to the condition of a farm field, may be provided in the part of a shore, and may be formed with the pipeline. Moreover, a water supply channel and a drainage channel may be provided along the same agricultural road.
[0012]
In the underground irrigation system, a plurality of perforated pipes 22 branched from the collecting pipe 21 are buried in parallel at equal intervals in the ground of the cultivation area 13, and an underground drainage valve is provided between the collecting pipe 21 and the drainage channel 15. A water level setting device 24 having 23 is installed. This water level setting device 24 is provided with a bottom fixed weir 26 and an upper movable weir 27 in a bottomed cylindrical water level setting rod 25 so as to be movable up and down, and a cultivation zone in which the collecting pipe 21 is connected within the water level setting rod 25. The inflow chamber 28 on the side and the drainage chamber 29 on the drainage channel side to which the drainage pipe 30 leading to the drainage channel 15 is connected. In a normal state, the lower fixed weir 26 is fixed to the lowermost end, By adjusting the height position of the upper movable weir 27 or removing the upper movable weir 27, the water level in the inflow chamber 28, that is, the water level in each cultivated area 13 can be arbitrarily set. . The lower fixed weir 26 and the upper movable weir 27 are provided in a state that can be moved up and down in and out of the guide grooves 26a and 27a formed on the inner wall of the water level setting rod 25 and can be fixed at an arbitrary height position. The both weirs 26 and 27 are formed so as to be in sliding contact with each other in a watertight state through rubber packing or the like.
[0013]
Further, a water supply side drainage basin 32 is provided on the side of the water supply channel 14 of the cultivation area 13 via a water intake valve 31, and water taken from the water supply channel 14 is supplied to the water supply channel side water supply / drainage basin 32. An underground water supply pipe 33 for supplying the air to 22 is connected via an underground water supply valve 34. Further, a water level setting device side water supply / drainage basin 36 provided with a water supply / drainage valve 35 is provided on the water level setting device 24 side. The water supply-side water supply / drainage basin 32 and the water level setting device-side water supply / drainage basin 36 are provided with openings for communicating with the cultivation area 13 to supply and discharge water, and dam plates 32a, 36a for closing the openings can be mounted. Is formed. In addition, it is desirable to provide a filter for separating coarse trash that may be clogged in the piping path at the intake port portion for taking in water from the water supply path 14, and further, a water intake amount adjusting means and a flow rate confirming means. Etc. can be provided. In addition, the underground water supply pipe 33 may be directly connected to the water supply path 14 without going through the water supply side water supply / drainage trough 32.
[0014]
The underground water supply pipe 33 is moderately deep in the ground of the cultivated area 13 at the same depth as the perforated pipe 22, preferably deeper than the perforated pipe 22, in the horizontal direction or toward the drainage channel 15. The end of the water level setter 24 is connected to the lower part of the inflow chamber 28 and is connected to the drainage side of the perforated tube 22 through the inflow chamber 28.
[0015]
The underground irrigation system thus formed can easily and reliably manage the surface water level during rice cultivation and the groundwater level during field cultivation. For example, when supplying water into the cultivation area 13 during rice cultivation, the water intake valve 31, the underground water supply valve 34, and the upper movable weir 27 of the water level setting device 24 are lifted to a position corresponding to the surface water level. The water supply / drainage valve 35 and the underground drainage valve 23 are opened. As a result, the water flowing through the water supply channel 14 is directly supplied from the water supply channel water supply / drainage basin 32 to the surface of the cultivation area 13, and the water flowing into the underground water supply pipe 33 flows into the inflow chamber 28 of the water level setter 24 and enters the upper part. It rises to the vicinity of the upper end of the movable weir 27.
[0016]
A part of the irrigation water flowing into the inflow chamber 28 is directly supplied to the ground surface of the cultivated area 13 through the water level setting device side water supply / drainage basin 36, and the remaining irrigation water is supplied from the collecting pipe 21 through the perforated pipe 22. Supplied into the ground. By supplying the water to the cultivation area 13 in this way, a large amount of water can be supplied to the cultivation area 13 in a short time. The supply of irrigation water to the cultivated area 13 is continued until the water level in the cultivated area 13 exceeds the upper end of the upper movable weir 27, and excess excess water flows down to the drainage chamber 29 beyond the upper movable dam 27. The water is discharged from the drain pipe 30 to the drain 15. In addition, the supply location of water can be arbitrarily selected by opening / closing each valve 23, 34, 35 and attaching / detaching the weir plates 32a, 36a.
[0017]
When soil in the cultivated area 13 soars in the irrigation water by scraping or the like, the irrigation plates 32a and 36a are attached to the water supply side water supply / drainage basin 32 and the water level setting side water supply / drainage basin 36 to use the water in the cultivated area 13 Is prevented from flowing into the two water supply / drainage basins 32, 36, so that it is possible to prevent earth and sand from entering the piping system from both the water supply / drainage basins 32, 36. Also in this case, the water level in the cultivated area 13 is not lowered by continuing the water supply from the perforated pipe 22.
[0018]
When maintaining the water level in the cultivated area 13, as described above, the water supply from the perforated pipe 22, the water supply channel side water supply / drainage basin 32 and the water level setting device side water supply / drainage basin 36 may be continued. A weir plate 32a is attached to the roadside water supply / drainage basin 32 to stop the inflow of water from the waterway side water supply / drainage basin 32 to the cultivated area 13, and the water management is performed using the perforated pipe 22 and the water level setting device side water supply / drainage basin 36. Can be done. By performing such irrigation management, when the amount of water in the cultivated area 13 decreases due to evaporation or penetration into the ground, the irrigation water mainly flows into the cultivated area 13 from the water supply / drainage basin 36. When the water level is maintained and the water level in the cultivated area 13 rises due to rain or the like, excess water is discharged from the water level setting device side water supply / drainage basin 36 beyond the upper movable weir 27 of the water level setting device 24.
[0019]
Thereby, the water level in the cultivation area 13 can be maintained at the water level set in the water level setting device 24, for example, about 15 to 25 cm, especially about 20 cm above the ground. In this way, water supply / drainage to the cultivation area 13 is performed mainly from the water level setting device side water supply / drainage basin 36, so that water supply / drainage can be performed more quickly than when water supply / drainage is performed using only the perforated tube 22. . In addition, water supply to the cultivated area 13 is not performed from the water supply-side water supply / drainage basin 32 but mainly from the water level setter-side water supply / drainage basin 36, so There is no flow of irrigation water toward the paddle 36, and with this flow, agricultural chemicals, fertilizers, etc. do not flow out into the drainage channel 15, so that the effects of agricultural chemicals, fertilizers, etc. can be obtained sufficiently and the outflow of agricultural chemicals, etc. The problem of environmental damage caused by can also be solved. Furthermore, by supplying water from the perforated pipe 22, the amount of water penetrating from the ground surface to the underground is reduced, so that effective use of agricultural chemicals and fertilizers can be achieved.
[0020]
In addition, by closing the underground water supply valve 34 and removing the dam plate 32a in this state, an appropriate flow of water from the water supply side drainage basin 32 can be formed in the cultivation area 13, so that, for example, in the summer The water temperature in the ward 13 can be lowered, and harmful substances such as hydrogen sulfide can be discharged from the ground. At this time, by closing the water supply / drainage valve 35 and stopping the water supply to the water level setting device side water supply / drainage basin 36, the flow of water in the cultivation area 13 is limited to the flow from the water supply side water supply / drainage basin 32 toward the perforated pipe 22. It is possible to discharge harmful substances in the ground more effectively. In addition, by closing the underground drain valve 23, the flow of water can be changed from the water supply side water supply / drainage basin 32 to the water level setter side water supply / drainage basin 36 and the flow that penetrates underground. The prevention effect can be increased.
[0021]
The water level at the time of rice cultivation can be arbitrarily set by sliding the upper movable weir 27 in the vertical direction. For example, by appropriately pressing down the upper movable weir 27, it is possible to set the groundwater level suitable for transplanting young seedlings without scraping, for example, in the range of 0 to 20 cm below the ground.
[0022]
On the other hand, at the time of farming, the upper movable weir 27 is pushed down, the upper movable weir 27 is removed, or the upper movable weir 27 is pulled upward (upward) to lower the lower movable weir 27 and the lower fixed weir 26. By forming a water flow portion between the upper end and the upper end, the groundwater level of the cultivated area 13 can be set to a subsurface irrigation water level suitable for field cultivation, for example, a range of 30 to 50 cm underground. For example, when all the valves 23, 31, 34, and 35 are opened with the groundwater level set by the water level setter 24, the water that has flowed from the water supply channel 14 into the water supply / drainage basin 32 is supplied to the underground water supply pipe 33. Then, it flows into the inflow chamber 28 of the water level setting device 24 and is supplied from the underground drainage valve 23 through the collecting pipe 21 to the ground of the cultivation area 13 through the perforated pipe 22.
[0023]
Further, when the groundwater level rises due to rainfall or the like, surplus groundwater in the cultivation area 13 flows into the perforated pipe 22 and flows into the inflow chamber 28 of the water level setting device 24 from the collecting pipe 21, and the upper movable weir 27 or lower Since it is discharged from the drainage chamber 29 through the drainage pipe 30 to the drainage channel 15 beyond the fixed weir 26, the groundwater level of the cultivated area 13 can be kept at the water level set by the water level setting device 24. Further, when the cultivated area 13 becomes flooded due to heavy rain, the surface water can be directly discharged from the water supply / drainage basin 32 or the water level setting / water supply basin 36 so that the flooded condition of the cultivated area 13 can be quickly changed. Can be resolved.
[0024]
By managing the groundwater level in this way, new water from the water supply channel 14 is supplied from the underground water supply pipe 33 to the drainage side of the perforated pipe 22, and the surplus is passed through the water level setting device 24 as it is. As a result, only insufficient water is supplied into the cultivation area 13. Therefore, since there is almost no flow of irrigation water in the cultivated area 13, low temperature irrigation water flows excessively into the cultivated area 13, or fertilizers and pesticides applied in the cultivated area 13 flow out together with the irrigated water. There is little to do. Further, even in the field cultivation, when it is necessary to supply the surface water to the cultivation area 13, the water can be supplied from the water supply side water supply / drainage basin 32 to the surface by closing the underground water supply valve 34.
[0025]
In such an irrigation state, the perforated pipe 22 is in a state where irrigation water branched from the underground water supply pipe 33 through the water level setting device 24 to the perforated pipes 22 via the collecting pipe 21 flows. It has become. In this way, the water that flows into the perforated pipe 22 is supplied from the water supply path 14 by forming the water to flow from the drainage side of the perforated pipe 22 through the underground water supply pipe 33 instead of directly from the water supply path 14. Even when the irrigation water contains a lot of earth and sand, the earth and sand in the irrigation water can be settled in the underground water supply pipe 33, and the amount of earth and sand flowing into the perforated pipe 22 together with the water is greatly reduced. be able to. At this time, by appropriately setting the diameter and amount of water intake of the underground water supply pipe 33 and sufficiently slowing the flow rate of the water, it becomes possible to perform sedimentation separation of earth and sand in the underground water supply pipe 33 almost completely, Inflow of earth and sand to the perforated tube 22 can be reliably prevented.
[0026]
Therefore, even when used for a long period of time, sediment and the like are not accumulated in the perforated pipe 22 and the water passage performance of the perforated pipe 22 is not hindered. As a result, it is not necessary to install a fine filter at the water intake, so that daily maintenance and inspection work can be omitted, and labor saving in farm work can be achieved. In addition, since the underground water supply pipe 33 can be laid simultaneously with the laying work of the perforated pipe 22 and the like, the initial cost is only slightly increased.
[0027]
Furthermore, the lower fixed weir 26 of the water level setting device 24 is pulled up to allow the inflow chamber 28 and the drainage chamber 29 to communicate with each other at the bottom of the water level setting rod 25, whereby the cultivation area 13 can be drained through the perforated pipe 22. . At this time, the cultivation area 13 can be dried by closing the intake valve 31, and by opening the intake valve 31 and the underground water supply valve 34, water can be supplied to the underground water supply pipe 33 at a sufficient speed. Therefore, the earth and sand settled in the underground water supply pipe 33 can be discharged from the water level setting device 24 to the drainage channel 15 through the drainage pipe 30. The removal and discharge of sediment and the like from the underground water supply pipe 33 can be reliably performed by setting an appropriate water gradient in the underground water supply pipe 33.
[0028]
In particular, by setting the underground water supply pipe 33 to a position deeper than the perforated pipe 22 and keeping the underground water supply pipe 33 in a full flow state at all times, sediment or the like that has settled in the underground water supply pipe 33 is dried. Since it can prevent hardening in the underground water supply pipe 33, the removal and discharge of earth and sand from the underground water supply pipe 33 can be performed more easily. Furthermore, by arranging the underground water supply pipe 33 and the drain pipe 30 in a straight line, it is possible to easily clean the inside of the underground water supply pipe 33 by inserting an instrument such as a pipe cleaner from the drain pipe 30. In addition, when a sufficient height difference cannot be obtained between the water supply channel 14 and the drainage channel 15, by using a pump or the like to force water into the underground water supply pipe 33 to generate a water flow, In the same manner as described above, earth and sand can be discharged.
[0029]
In this way, in the underground irrigation system provided with the water supply-side water supply / drainage basin 32 and the water level setter-side water supply / drainage basin 36, not only the underground irrigation water level during field cultivation but also surface water management during rice cultivation can be effectively performed. However, the water supply channel side water supply / drainage basin 32 and the water level setting device side water supply / drainage basin 36 are not necessarily provided at the same time, and only one of them may be provided.
[0030]
That is, even when only one of the water supply-side water supply / drainage basin 32 or the water level setting device-side water supply / drainage basin 36 is provided, the water supply / drainage basin 32 or the water level setting device can be used to supply surface water supply / drainage during rice cultivation or rainwater discharge during field cultivation. Since it can be carried out in the same manner as described above from the side supply / drainage basin 36, it is possible to perform water management more efficiently than conventional underground irrigation using only a culvert drainage pipe.
[0031]
The collecting pipe 21 and the underground water supply pipe 33 have a diameter larger than that of the perforated pipe 22 so as to be able to supply water to the whole of the plurality of perforated pipes 22. A pipe having a nominal diameter of about 100 is used for a perforated pipe 22 having a diameter of about twice the diameter of the pipe 22, specifically, a nominal diameter of about 50. Moreover, each said valve should just be able to interrupt | block the flow of water at least, and can use not only a valve of various structures but a weir and a water tank, and can also add a flow control function. Furthermore, the structure of the water level setting device 24 is also arbitrary, and it is possible to use any water level setting means such as a double structure slide pipe type instead of the weir. In addition, by setting the size of the lower fixed weir 26 to a height corresponding to the optimum groundwater level for crops during field cultivation, the upper movable weir 27 is pulled up to the top to switch between rice cultivation and field cultivation. This can be done by simply fixing.
[0032]
FIG. 4 is a cross-sectional view showing another embodiment of the underground irrigation system of the present invention. In the irrigation system shown in this embodiment, a part of the plurality of perforated pipes 22, usually one having a large diameter perforated pipe 22 a, has the same function as the underground water supply pipe. The large diameter perforated pipe 22a is connected to the water supply side drainage basin 32 through the underground water supply valve 34, and the water supply to each other perforated pipe 22 is supplied to the large diameter perforated pipe 22a. This is performed via 22a.
[0033]
Thus, even when the large-diameter perforated pipe 22a is used as an underground water supply pipe, water management and underground irrigation can be performed in the same manner as described above, and sedimentation and separation of sediment and the like can be performed in the large-diameter perforated pipe 22a. . The earth and sand settled in the large-diameter perforated pipe 22a can be discharged in the same manner as in the case of the underground water supply pipe by lifting the lower fixed weir 26 of the water level setting device 24.
[0034]
【The invention's effect】
As described above, according to the underground irrigation system of the present invention, it is possible to minimize the outflow of fertilizers and pesticides, to perform appropriate irrigation according to various conditions, and to enter the underdrain drainage pipe (perforated pipe). Accumulation of earth and sand can be suppressed, and reliable underground irrigation can be performed over a long period of time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of an underground irrigation system of the present invention.
FIG. 2 is a schematic plan view showing a piping system.
FIG. 3 is a cross-sectional view showing a water level setter portion.
FIG. 4 is a cross-sectional view showing another embodiment of the underground irrigation system of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Agricultural road, 12 ... Bank side, 13 ... Cultivation zone, 14 ... Water supply channel, 15 ... Drainage channel, 21 ... Collecting pipe, 22 ... Perforated pipe, 22a ... Large diameter perforated pipe, 23 ... Underground drainage valve, 24 DESCRIPTION OF SYMBOLS ... Water level setting device, 25 ... Water level setting dredge, 26 ... Lower fixed weir, 27 ... Upper movable weir, 28 ... Inflow chamber, 29 ... Drainage chamber, 30 ... Drain pipe, 31 ... Intake valve, 32 ... Water supply side drainage trough, 33 ... underground water supply pipe, 34 ... underground water supply valve, 35 ... water supply / drainage valve, 36 ... water level setter side water supply / drainage tank

Claims

In an underground irrigation system in which a perforated pipe is embedded in the ground of a field and a water level setter is installed downstream of the perforated pipe, and the water level is set by adjusting the drainage water level with the water level setter, An underground water supply pipe for supplying water from the water supply channel to the perforated pipe is buried in the ground of a farm field, and the underground water supply pipe and the perforated pipe are connected on the drain side of the perforated pipe. An underground irrigation system provided with a water supply / drainage basin capable of supplying water supplied from the water supply channel to the surface of the cultivated area and discharging excess water in the cultivated area to the underground water supply pipe .

In an underground irrigation system in which a perforated pipe is embedded in the ground of a field and a water level setter is installed downstream of the perforated pipe, and the water level is set by adjusting the drainage water level with the water level setter, An underground water supply pipe for supplying water from the water supply channel to the perforated pipe is buried in the ground of a farm field, and the underground water supply pipe and the perforated pipe are connected on the drain side of the perforated pipe. An underground irrigation comprising a water supply / drainage basin capable of supplying the water supplied from the underground water supply pipe to the surface of the cultivated area and discharging excess water in the cultivated area to the water level setting device system.

In an underground irrigation system in which a perforated pipe is embedded in the ground of a field and a water level setter is installed downstream of the perforated pipe, and the water level is set by adjusting the drainage water level with the water level setter, An underground water supply pipe for supplying water from the water supply channel to the perforated pipe is buried in the ground of a farm field, and the underground water supply pipe and the perforated pipe are connected on the drain side of the perforated pipe. The supply water from the water supply channel can be supplied to the surface of the cultivated area, and the excess water in the cultivated area can be discharged to the underground water supply pipe and supplied from the underground water supply pipe An underground irrigation system comprising a water level setter side water supply / drainage basin capable of supplying water to be cultivated to the surface of the cultivated area, and discharging excess water in the cultivated area to the water level setter .

4. The underground irrigation system according to claim 1, wherein one of the plurality of perforated pipes is a large-diameter perforated pipe that also serves as the underground water supply pipe.