Performance Of Subsurface Drainage Research Articles

Experimental and modeling evaluation of siphon-type subsurface drainage performance in flooding and waterlogging removal

Agricultural subsurface drainage is necessary for crop production in humid, poorly drained regions with frequent rainfall. Flooding and waterlogging have become more widespread and frequent in recent years, and effective measures should be adopted to increase the subsurface drainage capacity and alleviate flooding and waterlogging disasters after short-term heavy rainfall. However, subsurface drainage focused on the layout parameters (drain depth, drain spacing, etc.) in previous studies, and these measures were limited and cumbersome in the improvement of the flow rate of subsurface drainage. Thus, we aimed to alleviate the flooding and waterlogging threats to farmland and innovatively proposed a new method to increase the flow rate of subsurface drainage, namely siphon-type subsurface drainage. The paper evaluated the performance of the siphon-type subsurface drainage by the indoor sand tank test and the HYDRUS-2D model. Three factors were considered during the experiments: conventional and improved subsurface drainage; shallow, medium, and deep drain depth; and the outlet elevation, including the outlet elevation of the drain pipe under the non-siphon drainage and the outlet elevation of the siphon pipe under the siphon drainage. The results indicated that the siphon-type subsurface drainage performed better under the conditions of steady-state ponding and ponding subsided. The flow rate of the siphon-type subsurface drainage was 27.1–45.7%, 41.8–89.8%, and 39.3–50.5% higher than that of conventional, thin-improved, and thick-improved subsurface drainage with non-siphon drainage under steady-state ponding, respectively. It also had a significant advantage when the outlet elevation was the same. The siphon-type subsurface drainage could increase the flow rate during ponding subsided and reduce the flow rate attenuation degree before the ponding disappears. The flooding removal effect of the siphon-type subsurface drainage was significantly better than that of non-siphon subsurface drainage. The water head and flow rate were used to calibrate and validate the HYDRUS-2D model. The results indicated that the simulated values of flow rate matched well with the measured ones and the relative errors were less than 10%. The influence range and absolute values of the negative water head increased with the decrease of outlet elevation, and the increase effect of flow rate increased with the decrease of the water head. The siphon-type subsurface drainage has more control distance than the non-siphon. The advantages of siphon-type subsurface drainage are not only prominent in quart sand but also applicable to field soil. The results of this study could provide technical support for the application of flooding and waterlogging removal in areas where waterlogging is prone to occur and could improve the ability of agricultural production to address waterlogging disasters.

The life cycle assessment of subsurface drainage performance under rice-canola cropping system

The life cycle assessment (LCA) concept is a widely used tool to assess the environmental aspects of any activity throughout its life cycle. This study is the first application of LCA for assessing the agro-environmental sustainability of subsurface drainage systems under rice-canola cropping rotation. The systems included D0.65L15, D0.65L30, and D0.9L30, consisting of two depths (D=0.65 and 0.9 m) and two spacing (L= 15 and 30 m) and a bi-level drainage system with alternate depths of 0.9 and 0.65 m with 15 m spacing (Bilevel). A paddy plot with conventional surface drainage and similar cropping system was considered as control (Control). Two water management strategies, including mid-season drainage (MSD) and alternate wetting and drying (AWD), were practiced during rice-growing period. Free drainage (FD) was adopted during canola-growing period. Required field data were collected during 2011–2016, including four rice-canola-growing cycles (two MSD-FD cycles and two AWD-FD cycles). Using the LCA concept, the effectiveness of different drainage systems were assessed under the cycles of MSD-FD and AWD-FD. The AWD-FD system showed 7% less environmental impacts than MSD-FD. Also, AWD-FD reduced human health, climate change, and resource depletion indicators by 7.7%, 9.9%, and 8.4%, respectively, compared with MSD-FD, which improved the ecosystem quality index by 7.2%. The Bilevel, D0.9L30, D0.65L30, and D0.65L15 drainage systems, respectively, reduced the environmental impacts by 11.8%, 11.1%, 2.6%, and 5.9% under AWD-FD and 25.4%, 17.6%, 25.1%, and 14.1% under MSD-FD compared with Control. On average, Bilevel reduced the environmental impacts by 18.6% compared with the conventional surface drainage system. Based on the results, the LCA concept can be used as a suitable tool to evaluate the performance of subsurface drainage systems before implementation on a large scale.

Effectiveness of Denitrifying Bioreactors on Water Pollutant Reduction from Agricultural Areas

HighlightsDenitrifying woodchip bioreactors treat nitrate-N in a variety of applications and geographies.This review focuses on subsurface drainage bioreactors and bed-style designs (including in-ditch).Monitoring and reporting recommendations are provided to advance bioreactor science and engineering.Abstract. Denitrifying bioreactors enhance the natural process of denitrification in a practical way to treat nitrate-nitrogen (N) in a variety of N-laden water matrices. The design and construction of bioreactors for treatment of subsurface drainage in the U.S. is guided by USDA-NRCS Conservation Practice Standard 605. This review consolidates the state of the science for denitrifying bioreactors using case studies from across the globe with an emphasis on full-size bioreactor nitrate-N removal and cost-effectiveness. The focus is on bed-style bioreactors (including in-ditch modifications), although there is mention of denitrifying walls, which broaden the applicability of bioreactor technology in some areas. Subsurface drainage denitrifying bioreactors have been assessed as removing 20% to 40% of annual nitrate-N loss in the Midwest, and an evaluation across the peer-reviewed literature published over the past three years showed that bioreactors around the world have been generally consistent with that (N load reduction median: 46%; mean ±SD: 40% ±26%; n = 15). Reported N removal rates were on the order of 5.1 g N m-3 d-1 (median; mean ±SD: 7.2 ±9.6 g N m-3 d-1; n = 27). Subsurface drainage bioreactor installation costs have ranged from less than $5,000 to $27,000, with estimated cost efficiencies ranging from less than $2.50 kg-1 N year-1 to roughly $20 kg-1 N year-1 (although they can be as high as $48 kg-1 N year-1). A suggested monitoring setup is described primarily for the context of conservation practitioners and watershed groups for assessing annual nitrate-N load removal performance of subsurface drainage denitrifying bioreactors. Recommended minimum reporting measures for assessing and comparing annual N removal performance include: bioreactor dimensions and installation date; fill media size, porosity, and type; nitrate-N concentrations and water temperatures; bioreactor flow treatment details; basic drainage system and bioreactor design characteristics; and N removal rate and efficiency. Keywords: Groundwater, Nitrate, Nonpoint-source pollution, Subsurface drainage, Tile.

Qualitative evaluation of organic envelopes on subsurface drainage performance*

AbstractThe purpose of this study was to investigate the efficiency of organic matter such as rice husk and palm‐leaf stalk as envelopes in drainage pipes. For this purpose, to simulate field conditions in vitro, we used a physical model consisting of a plexiglass cylinder with a height of 200 mm and diameter of 100 mm, with five holes attached to the manometers and an inlet at the bottommost part and an outlet at the topmost part with a water tank which provided a fixed head. Experiments were carried out with five types of organic matter (i.e. rice husk, three types of powder and palm‐leaf fibres) on Ramshir agricultural soil which required envelopes according to existing standards. The results showed that among the envelopes utilized, the highest outflow (discharge) rate was related to powder No. 3 (the most coarse‐grained powder) in a gradient of 0.5. By increasing the gradient to 2, envelope hydraulic fracturing was observed, which means that it was unable to retain soil particles with finally an inadequate filtering function for this organic material. In gradient 2, the highest output discharge was related to palm stalk and leaf fibres, which is reflected in the proper hydraulic performance of this envelope and its high filtering properties. Finally, comparing the value of the gradient ratio in the higher gradients confirmed the results.

Performance of subsurface drainage implemented with trencher and trenchless machineries

The trenchless (T0) and trencher (T1) drainage installation methods are widely applied in Finland. There is an ongoing debate and a lack of science-based information about the performance differences between the methods. The objective was to assess drainage performance differences between T0 and T1 by analyzing groundwater table observations from field sections drained with the two methods. The differences were studied by using statistical analysis over a two-year period after the drainage installation. An experimental field in middle-Finland was divided into four T0 sections and four T1 sections. The groundwater level was manually measured about twice a week from seven locations in each section. Automatic recording was installed in one T0 section and one T1 section. The manual observations formed 56 time series, which were tested between the same-method plots (T0-T0 and T1-T1) and the different-method plots (T0-T1). Automatic data was used to validate the manual observations. In the T0 sections, 60–90% of the groundwater level observations were higher than those in the T1 sections. These observations had an average difference of 0.14–0.25 m. The variation in the groundwater level time series was larger between the T0 sections than between the T1 sections. Statistically significant differences between the same method field sections indicated that other factors also affected the groundwater table (soil type, etc.). However, the differences between T0 and T1 were stronger than those between the same-method sections, and the differences were clearest when the groundwater levels were above the drain depth (1.0 m). In the seasonal time series, the biggest differences were found during the autumn and winter periods. The average differences between T0 and T1 might not be significant in practice, but occasional larger (> 0.4 m) differences may have a short-term influence on field activities and crop growth.

Subsurface Drainage System Performance, Soil Salinization Risk, and Shallow Groundwater Dynamic Under Irrigation Practice in an Arid Land

In recent years, several arid lands have faced the major challenge of increasing risk of soil salinity caused by improper irrigation and drainage practices. Evaluating the relationship between soil salinity, drainage, and irrigation is therefore essential for understanding how to sustain the use of salinized soils in these lands. In this study, subsurface drainage performance, soil salinization risk, and shallow groundwater dynamic were evaluated under irrigation practice in a Tunisian arid land during two successive cropping years (2012–2013 and 2013–2014). Special attention was paid to the effect of subsurface drainage system on soil desalinization. Based on the analysis of the collected data, the following results were found: (1) frequent irrigation was a major factor in the rapid rise of shallow groundwater above critical soil depths; (2) inferior irrigation scheduling (i.e. large irrigation interval of 16–42 days) was the main cause of high soil salinization $$(\hbox {EC}_{\mathrm{e}})$$ around crop roots $$(\hbox {EC}_{\mathrm{e}} > 4\hbox { dS m}^{-1})$$ ; (3) the installed subsurface drainage system in the studied area (i.e. perforated corrugated pipe at a soil depth of 1.5 m) resulted in a substantial soil desalinization rate from the first to the second studied year, the average decrease in $$\hbox {EC}_{\mathrm{e}}$$ was 23.3%; (4) the drainage system was unable to drain more than 27% of the salt introduced by the irrigation water due to the clogging of the gravel filter by sand. These results may provide a reference for appropriate restoration in the studied area and in other arid farmlands with similar condition.

Subsurface drainage for promoting soil strength for field operations in southern Manitoba

Successful field operations depend on the ability of the soil to provide traction and support for agricultural traffic and be workable in a desirable manner. This minimizes the risk of soil structural damage to ensure soil conservation and long-term crop yield. In the present study, the objective was to evaluate the performance of subsurface drainage in promoting soil strength for field operations in southern Manitoba. Data obtained from a field study and modeling exercise were used to achieve the objective. The field data include soil water content and watertable depth, which were measured in a potato field during the 2011 growing season. Soil samples were also collected from the field to determine the lower plastic limit (LPL) of the soil. Seventeen-year weather data were used to estimate the reference crop evapotranspiration. The soil strength of drained and undrained sandy-loam fields was compared to evaluate subsurface drainage in promoting soil strength for field operations. The subsurface tile drain was installed at 0.9-m depth and at 15-m spacing. A validated HYDRUS (2D/3D) model was used to extend the study by simulating soil water content dynamics due to different drain spacings (8 m, 10 m, 12 m, 15 m, 20 m, and 30 m) for different years and weather conditions. The soil strength to allow field operations was assessed based on soil water content corresponding to 90% of the LPL in the top 0.3-m depth of the soil, and soil water content corresponding to the LPL in the soil layer between 0.3-m to 0.5-m depth of the soil profile. The soil strength was sufficient to allow field operations when the two criteria were met. In the top 0.3-m depth, the soil strength was sufficient to allow field operations for all the years with or without drainage. Drainage impact was found to be more significant within the 0.3-m to 0.5-m depth of the soil profile throughout the years. Drain spacing less or equal to 12 m promoted soil strength to allow field operations without any significant impact on the number of field workable days during the growing season.

Performance of Sub-surface Drainage under ORP trial in Sandy Loam Sodic Soils with High Water Table Condition

A sub-surface drainage system using corrugated perforated PVC pipe was installed in a plot area of 33m x 60 m size sub-surface with 100 m lateral drains and 100 m collector drain having surrounded by a 5 cm thick envelope of 2-6 mm sized mineral components. The lateral drains were installed at 18m spacing and 0.6 m depth and collector drain was at a depth of 0.7 m. The study revealed that provision of sub surface drainage in sodic sandy loam soils improve the yields of Til (TKG- 55), Wheat (HD -4672), Pearl millet (JVB - 3) and Bengal Gram (PG - 5) over undrained condition by 15, 12, 19 and 18 percent, respectively.

Subsurface drainage performance study using SALTMOD and ANN models

Relative performance of artificial neural networks (ANNs) and the conceptual model SALTMOD was studied in simulating subsurface drainage effluent and root zone soil salinity in the coastal rice fields of Andhra Pradesh, India. Three ANN models viz. Back Propagation Neural Network (BPNN), General Regression Neural Network (GRNN) and Radial Basis Function Neural Network (RBFNN) were developed for this purpose. Both the ANNs and the SALTMOD were calibrated and validated using the field data of 1998–2001 for 35 and 55 m drain spacing areas. Data on irrigation depth, evapotranspiration, drain discharges, water table depths, mean monthly rainfall and temperature and drainage effluent salinity were used for ANN model training, testing and validation. It was observed that the BPNN model with feed forward learning rule with 6 processing elements in input layer and 1 hidden layer with 12 processing elements performed better than the other ANN models in predicting the root zone soil salinity and drainage effluent salinity. Considering coefficient of determination, model efficiency and variation between the observed and predicted salinity values as the evaluation parameters, the SALTMOD performed better in predicting root zone soil salinity and the BPNN performed better in predicting the drainage effluent salinity. Therefore, it was concluded that the BPNN with feed forward learning algorithm was a better model than SALTMOD in predicting salinity of drainage effluent from salt affected subsurface drained rice fields.

Evaluation of subsurface drainage performance in Lithuania

In Lithuania, knowledge of subsurface drainage performance is important in order to use reclaimed land rationally and to apply the scarce available financial means to repair improperly functioning drains. Subsurface drainage is also instrumental in the improvement of non-productive soils and it can assist in avoiding unsuitable soil conditions during farming operations. The experimental site, situated at Pikeliai in the K≐dainiai district of central-Lithuania, consists of seven plots with various combinations of drainage materials. To evaluate drainage performance, discharges and water heads on top of and midway between drains were measured during four consecutive seasons. Low rainfall during the second and third seasons resulted in small discharges and low groundwater tables compared to the first and fourth seasons. A second degree polynomial, similar to Hooghoudt’s equation, was used to express the relationship between hydraulic head loss and discharge for each of the plots during each of the measuring seasons. Comparison of the data for the four measuring seasons clearly shows completely different equations for the low rainfall second- and third-year observations. Although applicable within the measured range, extrapolation with the equations beyond the measuring range are less accurate. The results clearly illustrate that the original design criteria are not satisfied and that the drains may be too widely spaced in all the plots. The true cause of drain malfunctioning cannot be established with the existing measuring set-up, neither can differences in performance of the drainage materials used be evaluated, mainly due to differences in hydraulic conductivity of the respective plots. Only the evolution with time of the drainage performance of the different material combinations will permit the drawing of some conclusions on their behaviour. The data analyses clearly show that a more elaborate measuring set-up as well as long-term observations are required to ascertain the cause of drain malfunctioning and to compare the performance of the various drainage materials. Only then, more conclusive results will be obtained.