Simple calculations for furrow irrigation - PDF document

IS13026Information Sheet sugarresearch.com.au 1. Average in�ow rate (L/sec)2. Area watered per irriga�on (ha)3. Volume applied per irriga�on (ML)4. Volume applied per hectare (ML/ha)5. Compare applica�on to crop useSome simple measurements and calcula�ons are valuable when evalua�ng a furrow irriga�on system. These The simplest way to measure the in�ow rate is with a bucket and stopwatch. Fill a bucket with water at the cup and record the volume (L) and �me (sec). Take 3-4 readings per row over four or more rows, the more the be�er.Calculate the average volume and �me for each row. Then calculate the average in�ow rate (L/sec) for each row by dividing the average volume by the average �me. Calculate the average in�ow rate across all measured rows by adding the To calculate the area watered per irriga�on: mul�ply the number of rows being watered by the row spacing (metres) and the block length (metres), then divide by 10,000 to get an area in hectares.Area (ha) = ow spacing x no. rows per irriga�on set x row length) / 10,000 The total volume of water applied during an irriga�on event in megalitres (ML) is: the in�ow rate (L/sec) mul�plied by 3,600 �ow rate x 3,600 x rows watered x irriga�on dura�on) To calculate the volume of water applied per hectare, divide the total volume of water applied by the area being irrigated.ML/ha = total volume (ML) / area (ha)Crop water use (mm) can be calculated using WaterSense or crop factors. The crop water use can then be compared to the amount of water applied by irriga�on (mm) to see if the Simple calculations for furrow irrigation IS13026Information Sheet sugarresearch.com.au Copyright © 2013 • All rights reserved. No part of this publica�on may be reproduced, stored in a retrieval system, or transmi�ed in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of SRA. In this disclaimer a reference to ‘we’, ‘us’ or ‘our’ means SRA and our directors, o�cers, agents and employees. Although we do our best to present informa�on that is correct and accurate, we make no warran�es, guarantees or representa�ons about the suitability, reliability, currency or accuracy of the informa�on we present in this Informa�on Sheet, for any purposes. Subject to any terms implied by law and which cannot be excluded, we accept no responsibility for any loss, damage, cost or expense incurred by you as a result of the use of, or reliance on, any materials and informa�on appearing in this Informa�on Sheet. You, the user, accept sole responsibility and risk associated with the use and results of the informa�on appearing in this Informa�on Sheet, and you agree that we will not be liable for any loss or damage whatsoever (including through negligence) arising out of, or in connec�on with the use of this Informa�on Sheet. We recommend that you contact our sta� before ac�ng on any informa�on provided in this Informa�on Sheet. Warning Our tests, inspec�ons and recommenda�ons should not be relied on without further, independent inquiries. They may not be accurate, complete or applicable for your par�cular needs for many reasons, including (for example) SRA being unaware of other ma�ers relevant to individual crops, the analysis of unrepresenta�ve samples or the in�uence of environmental, managerial or other factors on produc�on.1. Measuring and calcula�ng in�ow rates2. Area watered per irriga�on (ha)Area (ha) = ow spacing x no. rows per irriga�on set x row length) / 10,000 Area (ha) wer rounded to 2 decimal places)3. Volume of water applied per irriga�on (ML) �ow rate x 3,600 x rows watered x irriga�on dura�on) ML = (1.1 L/sec x 3,600 x 50 x 24 hr) / 1,000,000 = 4.75 ML (answer rounded to 2 decimal places) olume applied per hectare (ML/ha)ML/ha = total volume (ML) / area (ha) = 1.08 ML/ha (answer rounded to 2 decimal places)Number of rows per irriga�on set: 50Irriga�on dura�on: 24 hoursDays since last irriga�on: 14Average crop water use: 4.8 mm/day5. Compare volume applied to crop water useIrriga�on water applied (mm/ha) = ML/ha x 100Crop water use (mm) = ys between irriga�ons x daily water use (mm/day)Crop water use (mm) = 14 days x 4.8 mm/day a�on applica�on e�cacy = applied water / crop water useIrriga�on applica�on e�cacy = 108 / 67.2 efore, in this scenario the irriga�on is replacing 1.6 �mes the amount of water used by the crop since the last irriga�on.ExampleVariablesRow spacing: 1.52 mRow length: 580 m * answer rounded to one decimal place Row 1Row 2Row 3Row 4Reading7.57.07.57.57.06.57.56.57.26.57.07.08.56.08.07.58.48.08.06.57.07.08.57.56.56.06.57.08.08.07.07.0Average *7.46.97.37.07.66.97.87.1Average for measured rows (L/sec) *