Agricultural Land Drainage Research Articles

Analytical solutions of unsteady drainage problems for soils subjected to variable recharge from a semi-confined aquifer

In drainage of agricultural lands, the upward vertical recharge from a semi-confined aquifer depends on the difference of the piezometric heads on the two sides of the semi-impermeable layer through which this recharge takes place. This means that the recharge through the semi-impermeable base depends on the unknown height of the unsteady water table. In the nonhomogeneous Boussinesq equation, which describes the drainage problems, the downward uniform rate of the recharge from rain or irrigation and the recharge from the semiconfined aquifer are expressed by two terms. By solving the Boussinesq equation expressions for the nondimensional height of the water table and the nondimensional discharge of the drains per unit drained area are obtained for three different initial conditions. Some known solutions are shown as special cases of the present solutions. Variation of nondimensional water table heights at half distance of the drain spacing and the nondimensional discharge of the drains with nondimensional time have been graphically illustrated with the help of synthetic examples.

Agricultural land drainage, land use change and economic performance: Experience in the UK

Agricultural land drainage, land use change and economic performance: Experience in the UK

Aquifer Parameters from Constant Discharge Nonsteady‐Leaky Type Curves

AbstractA drain function and set of type curves were defined for a simplified mathematical solution that represents one‐dimensional flow under nonsteady conditions in a leaky aquifer for the constant discharge boundary condition. The mathematical solution is in the form of exponential and complementary error functions, and it can be calculated using a polynomial approximation for the complementary error function. The mathematical solution and drain function are computationally easier to use than an equivalent integral‐form solution and drain function, which must be integrated numerically. A match‐point procedure was developed for determining aquifer diffuisivity (T/S), transmissivity (T), storage coefficient (S), and leakance (K′/b′) based on using the drain function and type curves. Use of the procedure is illustrated by an example that utilizes simulated aquifer drawdown and flowrate data. The match‐point procedure can be used to analyze drawdown data in leaky and nonleaky aquifers in cases where the flow is one‐dimensional and the discharge from the aquifer is constant. Applications of this procedure would include flow to a canal or river, flow to a highly permeable fracture that acts as a line sink, drainage of agricultural lands, and dewatering associated with strip mining operations.

Analysis of flow into draintile in three-dimensional flow field

Draintiles (impervious lengths of pipe laid end to end with gaps between adjacent sections to permit water entry) are commonly used in the drainage of agricultural lands and airport runways, and are employed to ensure foundational stability of many structures. The rate of flow into a line of draintiles buried in water-saturated soil depends upon the width and spacing of the gaps between the tiles as well as other parameters. A formula is developed in this paper for the general, non-axisymmetric case to determine the flow rate into a single gap. The differences between the formula developed in this paper and that developed earlier are discussed in terms of their derivation. A numerical example provides details on the essential differences between the two formulae.

IS IRRIGATION SUSTAINABLE? AN APPROACH TO SUSTAINABLE INTERNATIONAL IRRIGATION DEVELOPMENT

Canada has been assisting several developing countries in Asia, Africa and Latin America to implement irrigation development projects. The types of projects include: irrigation, drainage and flood control of agricultural lands. Assistance has varied from the supply of technical assistance to infrastructure development, training, and on-farm improvements.Program orientation has been changing over the last two decades reflecting international development priorities, policy changes, emerging needs of developing countries and changes in technology.Sustainability of irrigation development will depend to an increasing extent on adequately addressing the environmental, economic, cultural, social and political issues, and integrating these with the available technology.This will cause more emphasis to be placed on salinity and waterlogging control, flood management, small farmer irrigation schemes, more farmer managed schemes, and a higher level of participation by farmers in the planning, design, construction operation and maintenance of those schemes.Soil and water conservation schemes aimed at reducing soil degradation and increasing the efficiency of irrigation utilization will receive higher priority.

AQUIFER PARAMETERS FROM CONSTANT DRAWDOWN NONSTEADY‐LEAKY TYPE CURVES1

ABSTRACT: A drain function and set of type curves were defined for the mathematical solution that represents one‐dimensional flow under nonsteady conditions in a leaky aquifer for the constant drawdown boundary condition. A match point procedure was developed for determining the aquifer parameters transmissivity, storage coefficient, and leakance based on the drain function and type curves. Use of the procedure is illustrated by an example that utilizes simulated aquifer drawdowns and flowrate data. The drain function and type curves developed in this investigation include the effects of leakage for the constant drawdown boundary condition, which is not included in the existing drain function and type curve found in the literature. Thus, a new set of type curves was developed that can be used to analyze drawdowns for one‐dimensional flow in a leaky aquifer with constant drawdown at a line sink. Applications would include flow to a canal or river, drainage of agricultural lands, and dewatering associated with strip mining operations.

Land Drainage: Agricultural Benefits and Environmental Impacts

AbstractThe paper reviews the context and contribution of agricultural land drainage in the UK and discusses the design and performance of land drainage improvement and maintenance schemes. The environmental impacts of land drainage are considered, and how drainage activities can be, and are being, modified to meet environmental criteria.

Watertable control indices for drainage of agricultural land in humid climates

Annual and seasonal watertable regimes of agricultural land have in many cases succesfully been related to drainage objectives characterising these regimes by such indices as average watertable depths, duration and frequencies of occurrence of high watertables, etc. The merits and applicability of these indices have been analysed in this paper.

Development and testing of an agricultural land drainage simulation model

A deterministic computer model was developed to simulate runoff, on an hourly basis, from agricultural lands with surface and subsurface drainage. The model simulates the major hydrologic and hydraulic processes occurring both above and below the soil surface. The theoretical concepts of the algorithms are described. The model was tested on two fields, one with subsurface drainage and the other with surface drainage only. Simulated hydrographs were compared with measured hydrographs during the 1985 growing season. The results showed that the model performed reasonably well. There was no difference between the measured and simulated parameters of peak discharge, runoff depth and time of peak discharge at the 0.05 level of significance.

Farmer Uptake of Agricultural Land Drainage Benefits

Grant aid for land drainage improvements by Regional Water Authorities has been an important feature of agricultural support in Britain. The paper reports a study undertaken to evaluate and explain the nature and rate of farmer uptake of benefits on sixteen publicly financed projects involving flood alleviation and improved arterial drainage in central England. A total of 177 farmers, 880 blocks of land, and 5500 hectares were surveyed, with data collected on the changes over time in drainage status, land use, and farming system and performance attributable to the improvement schemes. Physical data were converted into standardised enterprise and farm budgets. Particular attention was given to assessing grassland productivity. Benefits were perceived on 58% of the areas. The highest value of benefit uptake was associated with land-use change, field drainage installation, increased nitrogen use on grass, and changes in grass management. Early uptake was associated with land-use change and field drainage. Influencing factors related to a combination of field, farm, and farmer variables. The best performing schemes contained farmer drainage organisations. An S-shaped aggregate uptake curve was derived which, together with the formulation of ‘benefit scenarios’, could be used to help predict uptake on future schemes.

The status of wetlands in southern Ontario

Although it is generally accepted that wetlands have been progressively altered in large sections of the province of Ontario, little is known about the status of wetlands or of the magnitude of wetland loss in the province. An analysis of the processes acting to impair wetland areas reveals that agricultural land drainage exerts the most widespread and significant impact on wetlands. At the same time, the practice of agricultural land drainage does not lend itself to adequate control over the loss of wetlands. Drainage is most intense in those areas where wetlands are most rare and is continuing to expand into fringe areas where wetlands may be placed in jeopardy. A geographical analysis of agricultural land drainage reveals areas of potential concern.

The composition and ecology of periphyton communities in freshwaters. II. Inter-relationships between water chemistry, phytoplankton populations and periphyton populations in a shallow lake and associated experimental reservoirs (‘Lund tubes’)

Water chemistry, phytoplankton populations and periphyton populations on Potamogeton pectinatus, have been compared in a shallow, brackish lake, Hickling Broad, and in two enclosed, 20 m diameter butyl rubber reservoirs, placed in it. The seasonal changes of periphyton on Hippuris vulgaris and Myriophyllum spicatum in the lake have also been examined. The lake has been made more eutrophic by agricultural land drainage and roosting gull populations, the tubes to a greater extent by gulls perching on their rims. The water in the tubes became persistently dominated by colonial blue-green algae, a spring diatom pulse was absent, and severe nitrogen limitation was found. Periphyton on P. pectinatus in the tubes was scanty. In the lake, however, though phytoplankton chlorophyll a levels were lower, an alternation of spring diatom and summer colonial blue-green algae was recorded. Nitrogen limitation was less severe in the lake and abundant periphyton crops, mainly of diatoms, developed on P. pectinatus and to a...

METHODOLOGY FOR THE SOCIO-ECONOMIC EVALUATION OF LAND DRAINAGE IN THE SOUTH NATION RIVER BASIN OF ONTARIO

This paper discusses the application of economic efficiency analysis methodology to the evaluation of agricultural land drainage projects. The methodology provides a rigorous framework for the analysis of both economic and social costs and benefits. The framework is based on a private financial analysis of the project, followed by quantification of societal costs and benefits. The decision maker’s activities are strengthened through application of the methodology as important questions of resource allocation and equity can be explicitly defined. Two municipal drainage projects in the South Nation River Basin were selected as case studies.

THE DRAINAGE ACT, 1975: ITS EVOLUTION AND POSSIBLE IMPACTS

In 1972 the Ontario Legislature established a Select Committee to study agricultural land drainage in Ontario. The terms of reference and the final report of the Select Committee are discussed and the resulting new legislation is examined. The possible impacts of the new drainage legislation and the remaining problem areas are outlined.

Drainage of Agricultural Land

Drainage of Agricultural Land

BOOK REVIEWS

Book review in this Article Drainage of Agricultural Land, by S.C.S., U.S. Dept. of Agriculture. Water Information Center, Inc. Electricity and the Environment, by a Special Committee on Electric Power and the Environment of the Association of the Bar of the City of New York. Western North Atlantic Ocean: Topography, Rocks, Structure, Water, Life and Sediments, by K.O. Emery and Elazar Uchupi.

Control of algae

Certain algae have direct benefit as food or fertilizer. Excessive growths of algae in fresh water, however, reduce water quality and make it less suitable for drinking or amenity use. They also present difficulties in freshwater fisheries, in industrial cooling systems, and in drainage and irrigation of agricultural land. In salt water, certain algae cause fouling of ships’ hulls. Although some control is possible by means of chemical algicides there are many problems still to be solved.

The future of Finnish forest resources and forest landscapes

Because of an increasing world demand for paper and other forest products, the Finnish wood-using industries are expanding rapidly. This has raised serious concern about the future of forest resources. Clearing of land for agriculture has slightly decreased the forest area during recent decades. Today, however, the forest area is increasing, owing to peatland drainage and afforestation of surplus agricultural land. The growing stock of the forests has remained approximately unchanged during all the fifty years covered by repeated national forest inventories. Due to the present expansion of industry, however, intensive silvicultural measures are required to balance the increasing drain from the forests. Calculations show that, with feasible methods, by the year 2000 the annual increment of the forests could be raised by over 50 per cent, and measures have been taken to finance such a programme. Intensive silviculture (artificial reforestation, drainage, fertilization, etc.) will also change the forest scenery. In general, however, the changes will be small, as domestic tree species are favoured and rough terrain, rocky ground, and the Finnish type of forest ownership, prevent the establishment of large uniform monocultures. The biggest change in the scenery will be caused by the large-scale drainage of peat-bogs for forestry.

Drainage of Agricultural Land—A Bibliography

Soil Science Society of America JournalVolume 31, Issue 4 p. iv-iv Book Review Drainage of Agricultural Land—A Bibliography By C. A. de Vries and B. C. P. H. van Baak. International Institute for Land Reclamation and Improvement, P. O. Box 45, Wageningen, The Netherlands. 28 pages. 1966. $1.00 RCD, RCDSearch for more papers by this author RCD, RCDSearch for more papers by this author First published: 01 July 1967 https://doi.org/10.2136/sssaj1967.03615995003100040004xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume31, Issue4July-August 1967Pages iv-iv RelatedInformation

Agricultural Land Drainage and Stream Pollution

Agricultural Land Drainage and Stream Pollution