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Evaluation of Subsurface Drainage Techniques Used for Dryland Salinity

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Evaluation of Subsurface Drainage Techniques Used for Dryland Salinity EVALUATION OF SUBSURFACE DRAINAGE TECHNIQUES USED FOR DRYLAND SALINITY CONTROL A Thesis Submitted to the College of Graduate Studies and Research in Partial Fulfillment ofthe Requirements for the Degree ofMaster ofScience in the Division ofEnvironmental Engineering University ofSaskatchewan Saskatoon By Warren Douglas Helgason Fall 2000 © Copyright Warren Douglas Helgason, 2000. All rights reserved. PERMISSION TO USE In presenting this thesis in partial fulfillment ofthe requirements for a Postgraduate degree from the University ofSaskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree permission for copYing ofthis thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head ofthe Department or the Dean ofthe College in which my thesis work was done. It is understood that any coPYing or publication or use ofthis thesis or parts thereoffor financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which be made ofany material in my thesis. Requests for permission to copy or to make other use ofmaterial in this thesis in whole or in part should be addressed to: Chair ofthe Division ofEnvironmental Engineering University ofSaskatchewan Saskatoon, Saskatchewan, sm 5A9 1 DATA ACKNOWLEDGEMENTS AND RESTRICTIONS All raw data used in this study dated prior to 1997 were collected by the staffat Agriculture and Agri-Food Canada's Semiarid Prairie Agricultural Research Centre (SPARC) in Swift Current, Saskatchewan. Laboratory analyses were also completed by SPARC staff These data and the information derived from these data are proprietary and are protected under copyright by Agriculture and Agri-Food Canada. All data collected from 1997 through 1999 were collected jointly by Agriculture and Agri-Food Canada and the University ofSaskatchewan under a collaborative agreement funded through Agriculture and Agri-Food Canada. All raw data (all years) were analyzed by the author under the supervision ofC. Maule (University ofSaskatchewan). Please contact the Director (Semiarid Prairie Agricultural Research Centre, P.O. Box 1030, Swift Current, Saskatchewan, S9H 3X2) for permission to use any information resulting from the Agriculture and Agri-Food data used in this thesis. ii ABSTRACT Dryland soil salinity is a major problem throughout much ofthe northern Great Plains region. One method ofcontrolling dryland salinity is through the use of subsurface drainage systems. However, in western Canada there is a general lack of experience in designing drainage systems. Usually those systems that are installed in semiarid dryland areas are based on experiences from more humid or irrigated areas. This study evaluates two types ofsubsurface drainage systems installed in adjacent, similar saline seeps located near Swift Current, Saskatchewan. The two types ofdrainage systems evaluated are: (1) a traditional grid drainage design, typical 0 f humid or irrigated regions and; (2) an experimental drainage design that uses a relatively smaller amount oftubing that is precisely placed and is valve controllable, allowing for the implementation ofa water management plan. The two systems were evaluated based on their ability to control water tables, lower soil salinity, and provide the highest water quality possible so that the environmental impacts associated with re-using or discharging that water are minimized. Climatic, hydrologic, geologic and chemical data were used to characterize each saline parcel and then monitor hydrologic changes caused by the drainage systems. From the results presented in this study, there was evidence that, with modifications to the water management plan, the experimental system would be equally effective at lowering water tables as the traditional system. The study was inconclusive as to which drainage technology had the better ability to reduce soil salinity above the drain lines. Also, the salinity ofthe experimental drainage system effluent was observed to be much lower than that ofthe traditional system. 111 Overall, both systems performed as they were designed indicating that both technologies can be successfully used in a dryland situation. However, in consideration ofthe reduced cost and installation effort and the more flexible operation options ofthe experimental system, the experimental design concept is perhaps better suited to modem agriculture on the semiarid prairies. Recommendations for use ofthis technology include adaptations to the water management plan that would further minimize salinization hazards. tV ACKNOWLEDGEMENTS I am extremely indebted to my advisors: Harold Steppuhn for providing research vision, field supervision, and technical support throughout my program; Charles Maule for supplying a tremendous amount ofinput into the analysis ofdata and review ofthe thesis; and also to Jon Gillies and JeffSchoenau for providing technical assistance and support. I would also like to thank the people at Agriculture and Agri-Food Canada's Semiarid Prairie Agricultural Research Centre (SPARC) in Swift Current for providing data, resources, and technical support throughout this project. In particular, I would like to mention Ken Wall, Ken Deobald and Harold Steppuhn for collecting a large part of the raw data. Without their gracious assistance, this project would not have been possible. Financial support for the project came from the Canada-Saskatchewan Agri-Food Innovation Fund, Agriculture and Agri-Food Canada (SPARC), and the University of Saskatchewan. I would also like to thank all ofthose people at the university and in Swift Current who greatly contributed to my enjoyment while completing this work. I would like to grant special thanks to my family, and ofcourse to my wife, Bobbi for providing unconditional support while I was completing this study. v TABLE OF CONTENTS PERMISSION TO USE DATA ACKNOWLEDGEMENTS AND RESTRICTIONS 11 ABSTRACT 111 ACKNOWLEDGEMENTS v TABLE OF CONTENTS vi LIST OF TABLES IX LIST OF FIGURES X LIST OF ABBREVIATIONS XlII 1. INTRODUCTION 1 1.1 Background ............................... ....................................... 1 1.2 Specific Objective .......... ... ... ... ............... ......... ... ...... ...... ..... 4 2. LITERATURE REVIEW 6 2.1 Saline Seep Development .. 6 2.1.1 Types ofsaline seeps ............. ... ............ ......... ............... 7 2.1.2 Seep hydraulics ....... ......... ... ... ...... ...... ...................... 9 2.1.3 Seep chemistry .......... ... ... ...... ...... ... ......... ......... ....... 10 2.1.4 Methods ofcontrolling saline seeps .......... ... ............... .... 10 2.2 Subsurface Drainage Technology................ 12 2.2.1 Flow to a subsurface drain 12 2.2.2 Types ofsubsurface drainage systems .... ............... ...... ...... 13 2.2.3 Drainage investigations 15 2.2.4 Installation methods 16 2.2.5 Drainage criteria for dryland salinity 17 2.3 Drainage Testing 17 2.3.1 Drainage efficiency ................... ...... ............ ................. 18 2.3.2 Evaluation ofthe direct effects ofdrainage 18 2.3.3 Evaluation ofthe indirect effects ofdrainage .................... 19 3. MATERIALS AND METHODS 21 3.1 Project Description ............................................................. 21 3.2 Site Description 21 3.3 Experimental Design . 23 3.3.1 Traditional drainage system ........................................ ... 23 3.3.2 Experimental drainage system ...................................... 25 a Shallow option ...................... ............... ......... .......... 27 VI b Deep option 27 3.3.3 Instrumentation 28 a Discharge measurement . 28 b Potentiometric surface monitoring 29 3.4 Experimental Procedures 30 3.4.1 Hydrological investigation procedures 30 3.4.2 Soil Moisture investigation procedures .......... ......... ......... ... 31 3.4.3 Hydro-chemical investigation procedures 31 3.4.4 Soil chemical investigation procedures 32 3.4.5 Initial site characterization procedures 33 3.4.6 Saturated hydraulic conductivity testing procedures 33 3.4.7 Geological characterization 33 3.5 Analytical Procedures 35 4. RESULTS 36 4.1 Climate 36 4.2 Baseline Conditions 38 4.2.1 Physical characteristics 38 a Geo10gical properties .................................................... 38 i Factors contributing to saline seep development 38 ii Saturated hydraulic conductivity . 39 b Soil properties ........................................................ 41 i Soil texture ........................................................ 41 ii Bulk density .......... ... ...... ... ......... ...... ... ... ... ......... .. 42 4.2.2 Chemical characteristics . 43 4.3 Seasonal and Continuous Site Monitoring . 47 4.3.1 Hydrology 47 a Water table position . 47 b Soil moisture . 53 c Drainage effluent ..................................................... 54 i Traditional drainage system (south parcel) ................. 54 ii Experimental drainage system (north parcel) 57 4.3.2 Chemistry........ 62 a Soil chemistry 62 b Water chemistry....... 65 i Monitoring wells ................... ... ... ......... ... ................. 65 ii Drainage effluent ~ .................... 69 5. DISCUSSION .. 72 5.1 Traditional Drainage System (South Parcel) 72 5.1.1 Water table control........... 72 5.1.2 Soil salinity control 77 5.1.3 Water quality 79 5.2 Experimental Drainage System
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