Surface Runoff Calculator Widget
This Wolfram-Alpha widget calculates the surface runoff (mm) based on the value of precipitation (mm) and the Natural Resource Conservation (NRCS) Curve Number (CN). More information on the methodology can be obtained from the following reference: Fangmeier, D. D., W. J. Elliot, S. R. Workman, R. L. Huffman, and G. O. Schwab, 2005. Soil and Water Conservation Engineering, Fifth Edition. pp. 528. Values of CN for various land covers, soils and antecedent moisture conditions are available in the NRCS Pond Construction Handbook. Click here to download
Note to user: Sorry about all the digits to the right of the decimal point. I couldn’t find a way to control this when creating the widget.
Time of Concentration Calculator Widget
The widget calculates the time of concentration in hours. The equation used was obtained from the textbook Soil and Water Conservation Engineering, 2005, Fifth Edition by Fangmeier, D. D., W. J. Elliot, S. R. Workman, R. L. Huffman, and G. O. Schwab.
LONG-TERM AVERAGE PRECIP AND TEMPERATURE DATA FOR PUERTO RICO Puerto Rico Observed Climate Normals (1981-2010)
VLAB: FREE ONLINE HYDRAULIC/HYDROLOGIC CALCULATIONS
VLab: An excellent free Online Resource for Hydraulics/Hydrologic Calculations: http://onlinecalc.sdsu.edu/. Thank you to Dr. Victor Miguel Ponce for your contribution to an Open Source web!
CROP WATER USE ( HARGREAVES ET EQUATION) NEW WOLFRAM ALPHA WIDGET. Reference: Hargreaves, G. H. and Z. A. Samani, Reference Crop Evapotranspiration from Temperature. Appl. Eng. Agric., ASAE. 1(2). 1985,. pp.96-99.
Widget Application: Suppose you want to schedule irrigation by replacing the water evapotranspired by your crop each day. 1. Click on the appropriate link to get yesterdays solar radiation for your location: Puerto Rico or Northern Caribbean, 2. Check the internet for the average daily air temperature at your location (average = (minimum + maximum)/2), 3. Get the appropriate crop coefficient for your crop from this link, and 4. Finally, enter solar radiation, air temperature and crop coefficient into the widget to estimate ET. Multiply ET x acres x 1069.0663 to get the number of gallons of water you need to apply to your field.
SIMPLE SPREADSHEET PROGRAM FOR SCHEDULING IRRIGATION Download Excel Spreadsheet
PUERTO RICO EVAPOTRANSPIRATION PROGRAM (PRET) Click here
Online version of Crop evapotranspiration – Guidelines for computing crop water requirements – FAO Irrigation and drainage paper 56. Note that Table 2.6 Extra Terrestrial Radiation (Ra) and Table 2.6 Potential Hours of Sunshine (N) are missing from the online version. Click here to download tables. The total potential sunshine hours (N) can also be estimated online at the following website: http://astro.unl.edu/classaction/animations/coordsmotion/daylighthoursexplorer.html
DISCLAIMER: The information on this website is provided “as is”. The authors and publishers of this information disclaim any loss or liability, either directly or indirectly as a consequence of applying the information provided herein, or in regard to the use and application of said information. No guarantee is given, either expressed or implied, in regard to the accuracy, or acceptability of the information.
Recommended Books and Articles
Evapotranspiration: Potential or Reference? by Suat Irmak and Dorota Z. Haman
The Harvest of Reason – a novel about women in science by Rhea harmsen
Allan, R. G., L. S. Pereira, Dirk Raes and M. Smith, 1998. Crop evapotranspiration – Guidelines for computing crop water requirements – FAO Irrigation and drainage paper 56. Food and Agriculture Organization of the United Nations, Rome. (Spanish Version)
Labedzki, L. (editor), 2011. Evapotranspiration. InTech Open Source Publishers, ISBN 978-953-307-251-7. 446 pages.
Manejo De Riego Por Goteo by M. R. Goyal, 1989 Universidad De Puerto Rico Servicio de Extension Agricola.
Sprinkle and Trickle Irrigation by J. Keller and R. D. Bliesner. Nostrand Reinhold Publisher.
Drip and Microirrigation for Trees, Vines and Row Crops, 1st edition, by Charles M. Burt and Stuart W. Styles, published by the Irrigation Training and Research Center (ITRC), 2nd Ed.
Goyal, M. R. (editor) 1989. Irrigation Research and Extension Progress in Puerto Rico. Prepared for the First Congress on “Irrigation in Puerto Rico,” March 8th, 1989, Ponce, Pr. UPR-Ag. Experiment Station.
Goyal M. R., 1989. Estimation of Monthly Water Consumption by Selected Vegetable Crops in the Semiarid and Humid Regions of Puerto Rico. AES Monograph 99-90, June, Agricultural Experiment Station, University of Puerto Rico Rio Piedras, PR.