Method of carrying out, and apparatus for use in, flood irrigation

Abstract

An apparatus and a method for irrigating land are disclosed. The apparatus comprises a portable sensing device that is anchored at a chosen locality in the land, gripping one end of a control line such as a length of twine. The control line is connected to a flow control mechanism that controls the operation of a mechanism such as a gate through which water flows from an irrigation canal to the land. The sensing device holds the control line under tension. The sensing device is provided with means, such as a float, to detect the arrival of water flowing onto the land and, in response, releases the control line. This actuates the flow control mechanism to close the gate.

1 . Apparatus for use in irrigating land, the apparatus comprising an anchoring device arranged to anchor a control line under tension in the land, means to detect a change in wetness in the land and means to cause the anchoring device to change the tension in the control line in response to a change in such wetness.  
     
     
         2 . Apparatus according to  claim 1 , in which the means to detect the change in wetness comprises means to detect an increase in water level at a chosen locality in the land.  
     
     
         3 . Apparatus according to  claim 2 , in which the means to detect the increase in water level comprises a float, the apparatus comprising means to connect the float to the anchoring device in such manner as to cause the anchoring device to change the tension in the control line when the float rises with a rise in the water level.  
     
     
         4 . Apparatus according to  claim 1 , support means is provided for supporting at least a portion of the anchoring device above the land, the support means being arranged to sink into the land when the land softens as a result of an increase in wetness in the land.  
     
     
         5 . Apparatus according to  claim 4 , in which the support means comprises at least one member having a pointed end that is arranged to sink into the land.  
     
     
         6 . Apparatus according to  claim 1 , in which the means to cause the anchoring device to change the tension in the control line comprises means to grip the control line and to release the control line in response to a change in wetness in the land.  
     
     
         7 . Apparatus according to  claim 6 , in which the means to grip the control line comprises a spring, the apparatus comprising means for putting the spring under load when the control line is to be gripped, and to release the load in response to a change in wetness in the land.  
     
     
         8 . Apparatus for use in irrigating land, comprising delivery means for delivering water to the land, a flow control mechanism movable between first and second operating positions in one of which the flow control mechanism allows water to flow through the delivery means and in the other of which the flow control mechanism prevents the flow of water through the delivery means, an anchoring device arranged to anchor a control line connected under tension to the flow control mechanism, means to detect a change in wetness in the land and means to cause the anchoring device to change the tension in the control line in response to a change in such wetness, the flow control mechanism being arranged to move from the first operating position to the second operating position in response to the change in tension in the control line.  
     
     
         9 . Apparatus according to  claim 8 , in which the flow control mechanism allows water to flow through the delivery means in the first operating position and is arranged to move to the second operating position when the tension in the control line is diminished or released.  
     
     
         10 . Apparatus according to  claim 2 , in which the flow control mechanism is arranged to be held in the first operating position by the control line as long as the control line is under tension and to move to the second operating position when the tension in the control line is released.  
     
     
         11 . Apparatus for use in irrigating land, comprising an anchoring device substantially as herein described with reference to the accompanying drawings.  
     
     
         12 . A method of irrigating land using delivery means for delivering water to the land and a flow control mechanism movable between first and second operating positions in one of which the flow control mechanism allows water to flow through the delivery means and in the other of which the flow control mechanism prevents the flow of water through the delivery means, the method including the steps of anchoring sensing means on the land at a position remote from the delivery means, and connecting the flow control mechanism by a control line under tension to the sensing means, the sensing means being arranged upon sensing a change in wetness in the land to change the tension in the control line and the flow control mechanism being arranged to move from the first operating position to the second operating position in response to such change.