Seadedrenaaži regulaatorkaevu veevastuvõtuvõime uurimine ja veetaseme reguleerimine
Laen...
Kuupäev
2023
Kättesaadav alates
08.09.2023
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Seadedrenaažiga on võimalik vähendada taimetoitainete (N ja P) väljakannet
eesvooludesse. Reostuse väljakande vähendamiseks peab veetase olema reguleeritav,
aga enamasti on seadedrenaažikaevudel ainult kaks erinevat äravoolu kõrgust ja
puuduvad erineva läbimõõduga äravoolutorude veevastuvõtuvõime alased teadmised
dimensioneerimiseks.
Käesoleva magistritöö eesmärgiks on laborikatsega uurida seadedrenaaži äravoolutoru
veevastuvõtuvõimet ja voolurežiime ning analüüsida veetaseme reguleerimise vajadust
põllul, tuginedes veebilansi arvutusele.
Laboris ehitati kaevu mudel, surve mõõdeti Thalimedes limnigraafiga, vooluhulk
kolmnurkülevooluga. Katses kasutati torusid DN110, DN160 ja DN110 koos lehtriga
(läbimõõt 215 mm). Katse ajal fikseeriti ülevoolul toimuvaid voolurežiimi muutuseid.
Katse tulemustest järeldati: 1. Lehter parandab äravoolutoru veevastuvõtuvõimet. 2.
Pikk äravoolutoru peale drenaažikaevu halvendab veevastuvõtuvõimet. 3. Suurem toru
läbimõõt on efektiivsem lahendus ainult suurte vooluhulkade puhul. 4. Surve ja lehtri
raadiuse seos (H/R) on voolurežiimide määramisel abiks. 5. Veebilansi arvutusega saab
hinnata veetaseme reguleerimise vajadust.
Controlled drainage (CD) can reduce the amount of plant nutrients (N and P) that flow out of our fields with rainfall. To help reduce plant nutrient flow, water levels must be adjustable, but controlled drainage wells mostly have only two water levels available to switch between and also there is a lack of knowledge about pipe intake values for dimensioning new CD wells. The aim of this research is to investigate pipe intake values and flow regimes with an experiment and analyse the importance of water level management in a field based on water balance calculation. A model of a CD well was built, the water head was measured with a Thalimedes limnigraph. The flow rate was calculated, using a triangular cross-section equation. Different sized were used in the experiment: DN110, DN160 and DN110 pipe with a cone shaped inlet (D=215 mm). During the experiment, different types of flow regimes were observed and fixed visually. The results of this research: 1. A Cone shaped inlet helps to increase intake value of a pipe. 2. A Long outflow pipe after a CD well worsenes the intake value. 3. Using a bigger pipe diameter is effective only with large flow rates. 4. The correlation between water head and a cone shaped inlets diameter (H/R) is useful when determening different flow regimes. 5. Water balance calculation can help determine the need of water level management.
Controlled drainage (CD) can reduce the amount of plant nutrients (N and P) that flow out of our fields with rainfall. To help reduce plant nutrient flow, water levels must be adjustable, but controlled drainage wells mostly have only two water levels available to switch between and also there is a lack of knowledge about pipe intake values for dimensioning new CD wells. The aim of this research is to investigate pipe intake values and flow regimes with an experiment and analyse the importance of water level management in a field based on water balance calculation. A model of a CD well was built, the water head was measured with a Thalimedes limnigraph. The flow rate was calculated, using a triangular cross-section equation. Different sized were used in the experiment: DN110, DN160 and DN110 pipe with a cone shaped inlet (D=215 mm). During the experiment, different types of flow regimes were observed and fixed visually. The results of this research: 1. A Cone shaped inlet helps to increase intake value of a pipe. 2. A Long outflow pipe after a CD well worsenes the intake value. 3. Using a bigger pipe diameter is effective only with large flow rates. 4. The correlation between water head and a cone shaped inlets diameter (H/R) is useful when determening different flow regimes. 5. Water balance calculation can help determine the need of water level management.
Kirjeldus
Magistritöö
Maaehituse ja veemajanduse õppetool
Märksõnad
magistritööd, seadedrenaaž, regulaatorkaev, kaevülevool, veebilanss