DOCSLIB.ORG

Simulation of Flow and Water Quality from Tile Drains at the Watershed and Field Scale Colleen Moloney Purdue University

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Simulation of Flow and Water Quality from Tile Drains at the Watershed and Field Scale Colleen Moloney Purdue University Purdue University Purdue e-Pubs Open Access Theses Theses and Dissertations 8-2016 Simulation of flow and water quality from tile drains at the watershed and field scale Colleen Moloney Purdue University Follow this and additional works at: https://docs.lib.purdue.edu/open_access_theses Part of the Bioresource and Agricultural Engineering Commons, and the Hydrology Commons Recommended Citation Moloney, Colleen, "Simulation of flow and water quality from tile drains at the watershed and field scale" (2016). Open Access Theses. 975. https://docs.lib.purdue.edu/open_access_theses/975 This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact [email protected] for additional information. Graduate School Form 30 Updated 12/26/2015 PURDUE UNIVERSITY GRADUATE SCHOOL Thesis/Dissertation Acceptance This is to certify that the thesis/dissertation prepared By Colleen Moloney Entitled Simulation of Flow and Water Quality from Tile Drains at the Watershed and Field Scale For the degree of Master of Science in Agricultural and Biological Engineering Is approved by the final examining committee: Jane R. Frankenberger Chair Eileen J. Kladivko Kevin King Indrajeet Chaubey To the best of my knowledge and as understood by the student in the Thesis/Dissertation Agreement, Publication Delay, and Certification Disclaimer (Graduate School Form 32), this thesis/dissertation adheres to the provisions of Purdue University’s “Policy of Integrity in Research” and the use of copyright material. Approved by Major Professor(s): Jane R. Frankenberger Approved by: Bernard Engel 7/25/2016 Head of the Departmental Graduate Program Date SIMULATION OF FLOW AND WATER QUALITY FROM TILE DRAINS AT THE WATERSHED AND FIELD SCALE A Thesis Submitted to the Faculty of Purdue University by Colleen A Moloney In Partial Fulfillment of the Requirements for the Degree of Master of Science in Agricultural and Biological Engineering August 2016 Purdue University West Lafayette, Indiana ii To: My parents: Carol and Tom My siblings: Caitlin, Brian, and Matthew and My boyfriend: Ed iii ACKNOWLEDGEMENTS I would like to express my thanks to all the teachers, mentors, fellow students, friends and family who have helped me in many forms throughout my academic career. First, I would like to thank my adviser Dr. Jane Frankenberger for not only helping develop my research project here, but my research technique and career. Without your support and feedback, I would not have been able to become half the researcher I am today. I would also like to thank my committee members Drs. Indrajeet Chaubey, Kevin King, and Eileen Kladivko for the feedback on various aspects of my project and algorithm development as well as access to some amazing data sets. To all the students and professors in both the Ecological Sciences and Engineering Interdisciplinary Graduate Program as well as the Agricultural and Biological Engineering Department. Thank you for the input on my research (even when by accident), coding advice, the coffee breaks, and especially for Margarita Club. Graduate school would not have been half as fun or rewarding without you. iv TABLE OF CONTENTS Page LIST OF TABLES .............................................................................................................................. viii LIST OF FIGURES ............................................................................................................................... x ABSTRACT .......................................................................................................................................xiii CHAPTER 1. INTRODUCTION ...................................................................................................... 1 1.1 Subsurface Drainage .............................................................................................. 1 1.2 Prediction of Subsurface Drain Flow ..................................................................... 1 1.3 Computer Simulation of Drainage ......................................................................... 3 1.4 Tile Drainage Simulations in SWAT ........................................................................ 4 1.5 Objectives .............................................................................................................. 6 1.6 Thesis Organization ................................................................................................ 6 1.7 Bibliography ........................................................................................................... 8 CHAPTER 2. IMPROVEMENT OF SUBSURFACE HYDROLOGY SUBROUTINES IN SWAT AND EVALUATION OF SIMULATIONS ON A TILED FIELD ........................................................... 12 2.1 Introduction ......................................................................................................... 12 2.2 SWAT Improvements ........................................................................................... 13 2.2.1 Percolation through the Soil Profile ....................................................... 13 2.2.2 Definition and Use of the Restrictive Layer Depth ................................. 16 2.2.3 Water Table Depth ................................................................................. 19 2.2.4 Tile Drain Flow Lag .................................................................................. 22 2.2.5 Subroutines Altered for Changes ............................................................ 24 2.3 Application to a Drained Indiana Field ................................................................ 26 2.3.1 Description of Study Site ........................................................................ 26 2.3.2 Model Set Up .......................................................................................... 27 2.3.2.1 Management Practices .............................................................. 28 v Page 2.3.2.2 Geospatial Input Data ................................................................ 29 2.3.2.3 Weather Data ............................................................................ 30 2.3.2.4 Drainage Parameters ................................................................. 30 2.3.3 Model Calibration Approach ................................................................... 31 2.4 Results .................................................................................................................. 32 2.4.1 Hydrology ................................................................................................ 33 2.4.1.1 Tile Flow Calibration Results ...................................................... 33 2.4.1.2 W20 Water Table ....................................................................... 34 2.4.1.3 W20, W10, and W5 Tile Flow .................................................... 36 2.4.1.4 W20 Tile Flow compared to DRAINMOD study ......................... 39 2.4.2 Tile Nitrate .............................................................................................. 39 2.4.2.1 Calibration Results ..................................................................... 39 2.4.2.2 W20, W10, and W5 Tile Nitrate ................................................. 41 2.4.3 Yield Comparison .................................................................................... 42 2.5 Conclusion ............................................................................................................ 43 2.6 Bibliography ......................................................................................................... 44 CHAPTER 3. EVALUATION OF SWAT MODEL SIMULATIONS OF FLOW AND NUTRIENTS FROM TILE DRAINS IN A SMALL WATERSHED IN OHIO ............................................................... 46 3.1 Introduction ......................................................................................................... 46 3.2 Site Description and Model Set Up ...................................................................... 48 3.2.1 Watershed Discretization ....................................................................... 48 3.2.2 Management Practices ........................................................................... 51 3.2.3 Geospatial Input Data ............................................................................. 54 3.2.4 Weather Data.......................................................................................... 55 3.2.5 Tile Drain Parameters ............................................................................. 56 3.2.6 Model Simulations .................................................................................. 56 3.3 Model Calibration and Parameter Sensitivity ...................................................... 56 3.3.1 Parameter Choice and Range ................................................................. 57 3.3.2 Performance Criteria .............................................................................. 58 3.3.3 Parameter Sensitivity .............................................................................. 58 vi Page 3.3.3.1 Tile Drainage Parameters .......................................................... 58 3.3.3.2 Nitrate Parameters .................................................................... 63 3.3.4 Final Calibration Parameters .................................................................. 67 3.4 Results .................................................................................................................
Load more

Recommended publications
  • A Fast, Physically-Based Subglacial Hydrology Model for Continental-Scale Application
    , BrAHMs V1.0: A fast, physically-based subglacial hydrology model for continental-scale application. Mark Kavanagh1 and Lev Tarasov2 1Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL, Canada 2Dept. of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John’s, NL, Canada Correspondence to: Lev Tarasov ([email protected]) Abstract. We present BrAHMs (BAsal Hydrology Model): a physically-based basal hydrology model which represents water flow using Darcian flow in the distributed drainage regime and a fast down-gradientsolver in the channelized regime. Switching from distributed to channelized drainage occurs when appropriate flow conditions are met. The model is designed for long- 5 term integrations of continental ice sheets. The Darcian flow is simulated with a robust combination of the Heun and leapfrog- trapezoidal predictor-corrector schemes. These numerical schemes are applied to a set of flux-conserving equations cast over a staggered grid with water thickness at the centres and fluxes defined at the interface. Basal conditions (e.g. till thickness, hydraulic conductivity) are parameterized so the model is adaptable to a variety of ice sheets. Given the intended scales, basal water pressure is limited to ice overburden pressure, and dynamic time-stepping is used to ensure that the CFL condition is met 10 for numerical stability. The model is validated with a synthetic ice sheet geometry and different bed topographies to test basic water flow properties and mass conservation. Synthetic ice sheet tests show that the model behaves as expected with water flowing down-gradient, forming lakes in a potential well or reaching a terminus and exiting the ice sheet.
    [Show full text]
  • Drainage Engineering
    Drainage Engineering Dr. M K Jha Prof. K Yellareddy Drainage Engineering -: Course Content Developed By:- Dr. M K Jha Professor Dept. of Agricultural and Food Engg., IIT Kharagpur -: Content Reviewed by :- Prof. K Yellareddy Director (A&R) Walamtari, Rajendranagar, Hyderabad Index Lesson Page No Module 1: Basics of Agricultural Drainage Lesson 1 Introduction to Land Drainage 5-12 Lesson 2 Land Drainage Systems 13-15 Module 2: Surface and Subsurface Drainage Systems Lesson 3 Design of Surface Drainage Systems 16-33 Lesson 4 Design of Subsurface Drainage Systems 34-48 Lesson 5 Investigation of Drainage Design Parameters 49-64 Module 3: Subsurface Flow to Drains and Drainage Equations Lesson 6 Steady-State Flow to Drains 65-83 Lesson 7 Unsteady-State Flow to Drains 84-95 Lesson 8 Special Drainage Situations 96-104 Module 4: Construction of Pipe Drainage Systems Lesson 9 Materials for Pipe Drainage Systems 105-111 Lesson 10 Layout and Installation of Pipe Drains 112-119 Module 5: Drainage for Salt Control Lesson 11 Drainage of Irrigated, Humid and Coastal 120-130 Regions Lesson 12 Vertical Drainage and Biodrainage Systems 131-138 Lesson 13 Salt Balance of Irrigated Land 139-149 Lesson 14 Reclamation of Chemically Degraded Soils 150-163 Lesson 15 Salient Case Studies on Drainage and Salt 164-186 Management Module 6: Economics of Drainage Lesson 16 Economic Evaluation of Drainage Projects 187-193 ******☺****** This Book Download From e-course of ICAR Visit for Other Agriculture books, News, Recruitment, Information, and Events at www.agrimoon.com Give FeedBack & Suggestion at [email protected] Send a Massage for daily Update of Agriculture on WhatsApp +91-7900 900 676 Disclaimer: The information on this website does not warrant or assume any legal liability or responsibility for the accuracy, completeness or usefulness of the courseware contents.
    [Show full text]
  • Development of Technical and Financial Norms and Standards for Drainage of Irrigated Lands
    DEVELOPMENT OF TECHNICAL AND FINANCIAL NORMS AND STANDARDS FOR DRAINAGE OF IRRIGATED LANDS Volume 1 Research Report Report to the WATER RESEARCH COMMISSION By AGRICULTURAL RESEARCH COUNCIL Institute for Agricultural Engineering Private Bag X519, Silverton, 0127 Mr FB Reinders1, Dr H Oosthuizen2, Dr A Senzanje3, Prof JC Smithers3, Mr RJ van der Merwe1, Ms I van der Stoep4, Prof L van Rensburg5 1ARC-Institute for Agricultural Engineering 2OABS Development 3University of KwaZulu-Natal; 4Bioresources Consulting 5University of the Free State WRC Report No. 2026/1/15 ISBN 978-1-4312-0759-6 January 2016 Obtainable from Water Research Commission Private Bag X03 Gezina, 0031 South Africa [email protected] or download from www.wrc.org.za This report forms part of a series of three reports. The reports are: Volume 1: Research Report. Volume 2: Supporting Information Relating to the Updating of Technical Standards and Economic Feasibility of Drainage Projects in South Africa. Volume 3: Guidance for the Implementation of Surface and Sub-surface Drainage Projects in South Africa DISCLAIMER This report has been reviewed by the Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. © Water Research Commission EXECUTIVE SUMMARY This report concludes the directed Water Research Commission (WRC) Project “Development of technical and financial norms and standards for drainage of irrigated lands”, which was undertaken during the period April 2010 to March 2015. The main objective of the Project was to develop technical and financial norms and standards for the drainage of irrigated lands in Southern Africa that resulted in a report and manual for the design, installation, operation and maintenance of drainage systems.
    [Show full text]
  • Modeling Subsurface Drainage to Control Water-Tables in Selected Agricultural Lands in South Africa
    Institute of Water and Energy Sciences (Including Climate Change) MODELING SUBSURFACE DRAINAGE TO CONTROL WATER-TABLES IN SELECTED AGRICULTURAL LANDS IN SOUTH AFRICA Cuthbert Taguta Date: 05/09/2017 Master in Water, Policy track President: Prof. Masinde Wanyama Supervisor: Dr. Aidan Senzanje External Examiner: Dr. Kumar Navneet Internal Examiner: Prof. Sidi Mohammed Chabane Sari Academic Year: 2016-2017 Modeling Subsurface Drainage in South Africa Declaration DECLARATION I Taguta Cuthbert, hereby declare that this thesis represents my personal work, realized to the best of my knowledge. I also declare that all information, material and results from other works presented here, have been fully cited and referenced in accordance with the academic rules and ethics. Signature: Student: Date: 05 September 2017 i Modeling Subsurface Drainage in South Africa Dedication DEDICATION To the Taguta Family, Where Would I be Without You? Continue to Shine! My son Tawananyasha and new daughter Shalom, may you grow to heights greater than mine! ii Modeling Subsurface Drainage in South Africa Abstract ABSTRACT Like many other arid parts of the world, South Africa is experiencing irrigation-induced drainage problems in the form of waterlogging and soil salinization, like other agricultural parts of the world. Poor drainage in the plant root zone results in reduced land productivity, stunted plant growth and reduced yields. Consequentially, this hinders production of essential food and fiber. Meanwhile, conventional approaches to design of subsurface drainage systems involves costly and time-consuming in-situ physical monitoring and iterative optimization. Although drainage simulation models have indicated potential applicability after numerous studies around the world, little work has been done on testing reliability of such models in designing subsurface drainage systems in South Africa’s agricultural lands.
    [Show full text]
  • Comparing Drain and Well Spacings in Deep Semi-Confined Aquifers for Water Table and Soil Salinity Control R.J
    Comparing drain and well spacings in deep semi-confined aquifers for water table and soil salinity control R.J. Ooosterbaan, 16-09-2019. On www.waterlog.info public domain Abstract For the control of the water table in a thick soil layer with low hydraulic conductivity underlain by a deep aquifer with high hydraulic conductivity, it may be recommendable to use a pumped well drainage system (vertical drainage) instead of a horizontal subsurface drainage system by ditches, tiles or pipes owing to the relatively large well spacings compared to the drain spacings. The drainage by wells can also help in soil salinity control. This article shows the calculation of the required well and drain spacings in the kind of semi confined aquifer described. In those aquifers the drainage by wells may be more economical due to the large spacings, but when the horizontal drainage can be done by gravity, the well drainage system has the disadvantage of pumping costs. Contents 1. Introduction 2. Horizontal drainage 3. Vertical drainage 4. Comparison 5. Conclusion 6. References 1. Introduction Subsurface drainage systems are used for the control of the water table in otherwise waterlogged soils. They are also used to control the soil salinity by evacuating saline soil moisture. Subsurface drainage is usually done by horizontally placing drain pipes at some depth below the soil surface ,often around 1 to 1.2 m depth, but sometimes also shallower or deeper than that. The water removed by the drainage system may have a gravity outlet, but in low lands pumping may be required to evacuate the drainage water.
    [Show full text]
  • Part 624, Chapter 10, Water Table Control
    United States Department of Part 624 Drainage Agriculture National Engineering Handbook Natural Resources Conservation Service Chapter 10 Water Table Control (210-VI-NEH, April 2001) Chapter 10 Water Table Control Part 624 National Engineering Handbook Issued April 2001 The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 20250-9410 or call (202) 720-5964 (voice and TDD). USDA is an equal opportunity provider and employer. (210-VI-NEH, April 2001) Acknowledgments National Engineering Handbook Part 624, Chapter 10, Water Table Control, was prepared by Ken Twitty (retired) and John Rice (retired), drainage engineers, Natural Resources Conservation Service (NRCS), Fort Worth, Texas, and Lincoln, Nebraska respectively. It was prepared using as a foundation the publication Agricultural Water Table Management “A Guide for Eastern North Carolina,” May 1986, which was a joint effort of the USDA Soil Conservation Service, USDA Agriculture Research Service (ARS), the North Carolina Agriculture Extension Service and North Caro- lina Agricultural Research Service. Leadership and coordination was provided by Ronald L. Marlow, national water management engineer, NRCS Conservation Engineering Division, Washington, DC, and Richard D.
    [Show full text]
  • A Comparison Between Horizontal and Vertical Drainage Systems (Include Pipe Drainage, Open Ditch Drainage, and Pumped Wells) in Anisotropic Soils
    IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) ISSN: 2278-1684 Volume 4, Issue 1 (Nov. - Dec. 2012), PP 07-12 www.iosrjournals.org A Comparison between Horizontal and Vertical Drainage Systems (Include Pipe Drainage, Open Ditch Drainage, and Pumped Wells) in Anisotropic Soils Mohammad Valipour Department of Irrigation and Drainage Engineering, College of Abureyhan, University of Tehran, Pakdasht, ABSTRACT : Selecting a proper drainage system always has been discussed in agricultural or other fields. In anisotropic soils, this problem is more sensitive for experts. In this study, a comparison has been done between horizontal and vertical drainage in anisotropic soils. For this purpose, using EnDrainWin and WellDrain softwares drain spacing and well spacing, respectively, determined. The results showed that in the same situation, horizontal drainage systems due to the higher spacings between drains (reducing number of drainage and thus reducing the cost) were better than vertical drainage systems. However, vertical drainage systems due to the lower changes in well spacing in different anisotropic soils were suitable for conditions that soil hydraulic conductivity was likely to change. Keywords: Drain discharge, subsurface drainage systems design, watertable control I. INTRODUCTION The design of horizontal and vertical drainage in terms layout, depth and spacing of the drains is often done using subsurface drainage equations with parameters like drain depth, depth of the watertable, soil depth, hydraulic conductivity of the soil and drain discharge. The design of horizontal and vertical drainage systems has been aimed at many researches, which some of them will be described in the following. Geng et al. (2012) presented analytical solutions for a single vertical drain with vacuum and time- dependents preloading in membrane and membraneless systems.
    [Show full text]
  • A Model to Simulate Pesticide Movement Into Drain Tiles A
    ADAPT - A MODEL TO SIMULATE PESTICIDE MOVEMENT INTO DRAIN TILES A Thesis Presented in Partial Fulfillment of the Requirements for the degree Master of Science in the Graduate School of the Ohio State University by Cathy Ann Alexander, B.S. ***** The Ohio State University 1988 Master's Examination Committee: Approved by Andrew D. Ward E. Scott Bair jvisor Norman R. Fausey Department/of Agricultural Engineering Acknowledgements I express sincere appreciation to my advisor Dr. Andy Ward for his guidance and assistance in this research. Thanks also go to the other members of my committee, Dr. Norm Fausey and Dr. Scott Bair, for their input into this project. For providing me with the background information on the GLEAMS model, and for their ever helpful attitudes, I thank Dr. Walt Knisel, Dr. Ralph Leonard, and Frank Davis of the USDA-ARS in Tifton, Georgia. The technical assistance of Eric Desmond and the helpful suggestions of the other graduate students, especially Lou Seich and Leonard Ndlovu1, is much appreciated. Thank you. And to my husband, Walter, I offer a sincere thank you for the love and support you've given me, and the patience you've had in seeing me through this endeavor. VITA July 30, 1963 Born - Mt. Vernon, Ohio 1985-1986 Laboratory Technician, Dept. of Ag. Eng., Ohio State University 1986 B.S.Ag.Eng., Ohio State University FIELDS OF STUDY Major Field: Agricultural Engineering Studies in: Agronomy - Dr. Ed McCoy, Dr. Norm Fausey, Dr. Terry Logan Civil Engineering - Dr. Vincent Ricca, Dr. Alan Rubin, Dr. Charles Moore, Dr. Robert Sykes, Dr.
    [Show full text]
  • An Assessment of Shallow Water Tables and the Development of Appropriate Drainage Design Criteria for Sugarcane in Pongola, South Africa
    AN ASSESSMENT OF SHALLOW WATER TABLES AND THE DEVELOPMENT OF APPROPRIATE DRAINAGE DESIGN CRITERIA FOR SUGARCANE IN PONGOLA, SOUTH AFRICA M Malota Submitted in fulfilment of the requirements for a research Masters degree in Engineering College of Agriculture, Engineering and Science University of KwaZulu-Natal Pietermaritzburg South Africa September, 2012 EXAMINER’S COPY ABSTRACT South Africa, in common with all countries with arid or semi-arid climatic conditions, is facing the consequences of irrigation development without effective subsurface drainage. The quality of irrigation water is also decreasing and hence more water is required for leaching. This is resulting in low irrigation water productivity, as a consequence of shallow water tables, thus limiting crop growth. This study investigated the nature and causes of shallow water table problems in the sugarcane fields of Pongola, South Africa. The DRAINMOD model was also assessed for its reliability to be used as drainage design tool in the area. A water table map of a 32 ha sugarcane field was generated using groundwater table data monitored in 36 piezometers from September 2011 to February 2012. Nearly12 % of the 32 ha sugarcane field was found to be affected by shallow water tables of less than the 1.0 m Design Water Table Depth (WTD). The inability of the adopted Drainage Design Criteria (DDC) to cope with drainage needs was found to be the cause of the poor drainage problem. On the other hand, analysis of WTDs in a field with a poorly-maintained subsurface drainage system confirmed that the drainage problem is exacerbated by poor drainage maintenance.
    [Show full text]
  • BWSR Guidance Concerning NRCS – Developed Drainage Setback Tables
    BWSR Guidance Concerning NRCS – Developed Drainage Setback Tables October 2013 Version 2.0 Document date Purpose: Promote consistency among wetland managers when determining the impact of a drainage system on wetland hydrology. Audience: Wetland managers Rule reference or statute: Not applicable Intended use: Guidance intended to complement USDA NRCS Drainage Setback Tables and Corps of Engineers Regional Supplements for wetland delineation. Table of Contents 1. Executive Summary ............................................................................................................................................ 2 2. Purpose and Applicability ................................................................................................................................... 2 3. Background ......................................................................................................................................................... 2 4. Discussion ............................................................................................................................................................ 3 5. Drainage setback tables, their use and limitations ............................................................................................ 5 5a. Tables ............................................................................................................................................................ 5 5b. How to use the tables .................................................................................................................................
    [Show full text]
  • Phd Thesis, Université Laval, Quebec City, QC, Canada
    Simulating surface water and groundwater flow dynamics in tile-drained catchments Thèse Guillaume De Schepper Doctorat interuniversitaire en Sciences de la Terre Philosophiæ doctor (Ph.D.) Québec, Canada © Guillaume De Schepper, 2015 Résumé Pratique agricole répandue dans les champs sujets à l’accumulation d’eau en surface, le drainage souterrain améliore la productivité des cultures et réduit les risques de stagnation d’eau. La contribution significative du drainage sur les bilans d’eau à l’échelle de bassins versants, et sur les problèmes de contamination dus à l’épandage d’engrais et de fertilisant, a régulièrement été soulignée. Les écoulements d’eau souterraine associés au drainage étant sou- vent inconnus, leur représentation par modélisation numérique reste un défi majeur. Avant de considérer le transport d’espèces chimiques ou de sédiments, il est essentiel de simuler correcte- ment les écoulements d’eau souterraine en milieu drainé. Dans cette perspective, le modèle HydroGeoSphere a été appliqué à deux bassins versants agricoles drainés du Danemark. Un modèle de référence a été développé à l’échelle d’une parcelle dans le bassin versant de Lillebæk pour tester une série de concepts de drainage dans une zone drainée de 3.5 ha. Le but était de définir une méthode de modélisation adaptée aux réseaux de drainage complexes à grande échelle. Les simulations ont indiqué qu’une simplification du réseau de drainage ou que l’utilisation d’un milieu équivalent sont donc des options appropriées pour éviter les maillages hautement discrétisés. Le calage des modèles reste cependant nécessaire. Afin de simuler les variations saisonnières des écoulements de drainage, un modèle a ensuite été créé à l’échelle du bassin versant de Fensholt, couvrant 6 km2 et comprenant deux réseaux de drainage complexes.
    [Show full text]
  • E. J. Carlson I
    i ST*. E. J. Carlson ~ I Engineering and Research Center I I, Bureau of Reclamation ; I=--4- , , . I i 4 , ,, I ;;k l1 I I I December 1971 ! i Drainage from Level and Sloping Land - - 7. AUTHCRlSl 8. PERFOR~IN~~~.ORGANIZAT~ON REPORT NO. E. J. Carlson REC-ERt-714 9. PE~FORMING'ORGANIZATION XAME AND ADDRESS ., :: 10. WORK UNIT NO. % ., . Erigineering and Research center^ Bureau of Reclamation 11. CONTRACT~~RGRANT NO. penver. Colorado 80225 -..,,.., 11. TYPE CE REPORT AN0 PERIOD COVERED I2. SPONSORING AGENCY NPUE AND ADDRESS ,.:, \I/ :' ~ .--. -<A; v, 14. SPOhSORING AGENCY CODE 16. ABSTRACT A sand tank model study of'drainage by pipedrains on level and .;loping land was made in a 60-ft long,,2-h wide, and 2.112-ftdeep flume. The f::me could be tilted to a 12 percent slope. Theoretical equations developed for steady-state drainage coniltions on level land were verified. The study showed that drain spacing formulas developed for level iand can bc used for spacing midslope drains on sloping land which has a shallow impermeable berrier. Computer programs using-verified formulas to determine drain spacing and maximum water table height between drains were developed and checked with data obtained from the flume study. The timesharing computer programs have been- entered into the Bureau of Reclamation Engineering Compute1 System (BRECS). ;' ;' 17. KEY WORDS AND DOCUMENT ANALYSIS - a. DESCRiPTORs-- / hydraulic models/ 'drainage1 water table1 aquifers1 flow nets1 'drain spacing/ deep percolation1 infiliration ratel slapesl *compu:5r programs: tile drains1 percolation1 groundwater recharge1 I, , ~ "hydraulic conductivity,recharge, 11 b. IDENTIFIERS--- 1BRECS (romputer system) c.
    [Show full text]