Shallow Drainage Systems Research Articles

Impact of Extreme Rainfall Events on the Response of Shallow Land Drainage Systems

Installation of shallow drainage systems (mole drainage, gravel mole drainage, and subsoiling connected to an underlying tile drainage system) is common in fine-textured grassland soils. The performance and efficiency of these systems are known to vary, and a greater understanding of these criteria is needed. This study analyzed shallow drainage systems installed on four sites in southwest Ireland, namely Doonbeg (DG), Athea (AA), Castleisland 1 (C1), and Castleisland 2 (C2), across two high-rainfall periods (8 months in 2015–2016 and 5 months in 2017). Discharge characteristics in terms of peak flow rate, total discharge, and discharge hydrographs were analyzed. All drainage systems were responsive to rainfall events, but efficiency varied both temporally and between systems.

On the problem of durability of underground drainage in the natural and climatic conditions of the Novgorod region

The article deals with the problem of stable operation of various structures of drainage systems on heavy soils in the natural and climatic conditions of the Novgorod region during the first years after construction and after 30 years of operation. The experiment examines the effectiveness of drainage using shallow drainage structures with the depth of 70 cm and two variants of medium-deep drainage (110 cm) with filling the drainage trench with sand-gravel mixture (PGS) and wood chips to the arable horizon. Analysis of groundwater dynamics showed that the rate of groundwater decline in the early spring period in the first years of operation on all experimental variants was approximately the same: 2.0-2.4 cm/day. In recent years in the shallow drainage variant, the decrease in ground water levels occurred more slowly (2.3 cm/day) compared to the standard drainage variants (3.8-3.9 cm/day). The average humidity of the root layer of the soil during the growing season in experimental closed drainage systems has not increased for 30 years. The average moisture reserves for the growing season in the experimental systems were: 177 mm in the shallow drainage variant in 1991, 168 mm in 2018; 165 and 154 mm for the standard drainage with drainage chips backfill, respectively; 164 and 123 mm in the PGS backfill variant, respectively. The highest reliability and durability were shown by collectors with PGS backfill of the drainage trench, which have maintained a consistently high efficiency over a thirty-year period. During the drought period, shallow drainage systems provided more favorable conditions according to the degree of moisture in the root layer: in 2018, the shortest period of moisture lack in the root layer of the soil (10 days) was observed in shallow drainage systems, and the longest (1 month) - in systems with backfill of the drainage trench with PGS.

The intensity of water removal from shallow drainage systems considering the properties of filler materials

To date, there are virtually no experimental studies of drainage structures. The object of the presented study is a road structure with transverse shallow drainage arranged in wet sections of roads. In order to determine the drainage intensity of the drainage structure, an experiment was performed on a special installation for modeling the road structure depending on the properties of filler materials.Parameters of the installation make it possible to arrange a structure that corresponds to real conditions, that is, the parameters of a road of category III and study the processes of formation of the filtration flow in the drainage trench which is impossible with real objects.The laboratory installation was used to study operating conditions of drainage structures: a layer of crushed stone of 20–40 mm fraction and two types of transverse shallow drains with different filler materials in the trench. In the process of a series of experimental studies, the volume of water drained from the trench and drainage time was measured. According to the study results, based on the methods of mathematical statistics, unified equations of the correlation-regression model concerning the mode of operation of the drainage structure were constructed depending on initial soil moisture in the roadbed.According to the results of experimental studies, one of the main indicators of work of shallow drainage structures which depends on the properties of materials of trenches fillers, that is, the drainage intensity was determined. It was found that in contrast to the structure with a PVC pipe filled with coarse sand, the drainage structure with a crushed stone core in the trench worked in one mode of the formed flow. The work of the structure with the pipe is divided into short-term and long-term modes depending on the drainage intensity. The obtained regression dependences enable forecasting of the amount of water drained by the proposed drainage structures in a certain period for field conditions

Investigating long-term effects of subsurface drainage on soil structure in paddy fields

Subsurface drainage systems provide suitable conditions for annual cropping and crop diversification in northern Iran’s paddy fields. Such structural and managerial changes affect soil structure through influencing saturated hydraulic conductivity and effective porosity of the soil. The aim of this research was to investigate the long-term effects of subsurface drainage systems (D0.90L30: drainage system with 0.90 m depth and 30 m spacing, D0.65L30: drainage system with 0.65 m depth and 30 m spacing and D0.65L15: drainage system with 0.65 m depth and 15 m spacing) on the soil saturated hydraulic conductivity and drainable porosity. Water table and drain discharge were measured daily during different growing seasons (2011–2015) following installation of the subsurface drainage systems in the paddy fields of Sari Agricultural Sciences and Natural Resources University. The saturated hydraulic conductivity was calculated using Hooghoudt and Glover-Dumm equations and the drainable porosity was calculated with Taylor's method. Computed hydraulic conductivities by the Hooghoudt and Glover-Dumm equations were in the range of 0.002 to 1.95 m day−1 and 0.003 to 2.5 m day−1, respectively, that highest value was related to D0.65L15 and lowest value was related to D0.90L30. So, the shallow drainage systems were more effective in improving the soil hydraulic condition compared with the deep ones. The drainable porosity in the D0.90L30, D0.65L30 and D0.65L15 systems ranged from 0.002 to 0.314 m3 m−3, 0.003 to 0.13 m3 m−3 and 0.004 to 0.126 m3 m−3, respectively. In conclusion, the installation of subsurface drainage especially at the shallower depth will improve paddy soil structure during time.

Influence of artificial drainage system design on the nitrogen attenuation potential of gley soils: Evidence from hydrochemical and isotope studies under field-scale conditions

In North Atlantic Europe intensive dairy farms have a low nitrogen (N) use efficiency, with high N surpluses often negatively affecting water quality. Low feed input systems on heavy textured soils often need artificial drainage to utilise low cost grassland and remain profitable. Heavy textured soils have high but variable N attenuation potential, due to soil heterogeneity. Furthermore, drainage system design can influence the potential for N attenuation and subsequent N loadings in waters receiving drainage from such soils. The present study utilises end of pipe, open ditch and shallow groundwater sampling points across five sites in SW Ireland to compare and rank sites based on N surplus, water quality and “net denitrification”, and to develop a conceptual framework for the improved management of heavy textured dairy sites to inform water quality N sustainability. This includes both drainage design and “net denitrification” criterion, as developed within this study.N surplus ranged from 211 to 292 kg N/ha (mean of 252 kg N/sourha) with a common source of organic N across all locations. The predicted soil organic matter (SOM) N release potential from top-subsoil layers was high, ranging from 115 to >146 kg N/ha. Stable isotopes analyses showed spatial variation in the extent of specific N-biotransformation processes, according to drainage location and design. Across all sites, nitrate (NO3-N) was converted to ammonium (NH4+-N), which migrated offsite through open ditch and shallow groundwater pathways. Using the ensemble data the potential for soil N attenuation could be discriminated by 3 distinct groups reflecting the relative dominance of in situ N-biotransformation processes deduced from water composition: Group 1 (2 farms, ranked with high sustainability, NH4+ < 0.23 mg N/l, δ15N-NO3− > 5‰ and δ18O-NO3− > 10‰), low NH4+-N concentration coupled with a high denitrification potential; Group 2 (1 farm with moderate sustainability, NH4+ < 0.23 mg N/l, δ15N-NO3− < 8‰ and δ18O-NO3− < 8‰), low NH4+-N concentration with a high nitrification potential and a small component of complete denitrification; Group 3 (2 farms, ranked with low sustainability, NH4+ > 0.23 mg N/l, 14‰ > δ15N-NO3− > 5‰ and 25‰ > δ18O-NO3− > −2‰), high NH4+-N concentration due to low denitrification. The installation of a shallow drainage system (e.g. mole or gravel moles at 0.4 m depth) reduced the “net denitrification” ranking of a site, leading to water quality issues. From this detailed work an N sustainability tool for any site, which presents the relationship between drainage class, drainage design (if present), completeness of denitrification, rate of denitrification and NH4-N attenuation was developed. This tool allows a comparison or ranking of sites in terms of their N sustainability. The tool can also be used pre-land drainage and presents the consequences of future artificial land drainage on water quality and gaseous emissions at a given site.

Phosphorus balance and risk assessment in the rice–canola cropping system under different drainage strategies

ABSTRACTThis research was conducted to quantify total phosphorus (TP) losses in poorly drained-consolidated paddy fields equipped with different surface and shallow subsurface drainage systems including drain depth of 0.9 m and drain spacing of 30 m (D0.9L30), drain depth of 0.65 m and drain spacing of 30 m (D0.65L30), drain depth of 0.65 m and drain spacing of 15 m (D0.65L15), drain spacing of 15 m and drain depths of 0.65 and 0.9 m as alternate depths (Bilevel). Typical surface drainage system of consolidated paddy fields was also considered as conventional practice of the study area (control). The subsurface drained fields were under year-round crop production of rice-canola, while the surface drained fields experienced only rice cropping once a year. During three rice-canola-rice growing seasons, TP losses through drainage and leaching in the D0.9L30, Bilevel, D0.65L30, D0.65L15 and control treatments were respectively, 1.12, 0.98, 1.44, 1.53 and 24.48 kg ha−1, equivalent to about 3.9%, 3.4%, 5.1%, 5.3% and 85.7% of applied triple superphosphate fertilizer. In the rice growing seasons, TP losses through surface runoff were higher than those through subsurface drainage effluents. Shallow subsurface drainage systems were promising for the study area compared surface drainage as phosphorus risks were reduced by 79%, 77%, 64% and 57% through D0.9L30, Bilevel, D0.65L30 and D0.65L15, respectively. These results demonstrated that, by providing suitable condition for winter cropping, subsurface drainage systems can diminish concerns related to phosphorus losses from poorly drained paddy fields in the north of Iran.

Improvement of the Calculation Method for the Sand Layer of a Shallow Drainage System

Improvement of the Calculation Method for the Sand Layer of a Shallow Drainage System

Leaching of Glyphosate and Aminomethylphosphonic Acid from an Agricultural Field over a Twelve‐Year Period

The globally used herbicide glyphosate [N‐(phosphonomethyl)glycine] and its most frequently detected metabolite, aminomethylphosphonic acid (AMPA), were studied in a unique 12‐yr field‐scale monitoring program. The leaching of glyphosate, AMPA, and soil particles was studied in a shallow drainage system beneath a 1.26‐ ha field. Five annual glyphosate applications were applied with different autumn application dates. Solute mass flux from the drain system following the five glyphosate applications were compared to determine how different factors affect the leaching of glyphosate, AMPA, and particles. Glyphosate and AMPA leaching were highly event driven, controlled by the time and intensity of the first rainfall event after glyphosate application. A high similarity in cumulative drainage and leached pesticide masses with time suggests near‐constant drainage and leaching rates. There was no clear relationship between particle‐facilitated transport and the transport of glyphosate or AMPA. However, soil particles, glyphosate, and AMPA all showed distinct, simultaneous concentration curves, indicating common dominant transport mechanisms. Also, soil‐water content at the time of application and the level of the groundwater table relative to the drain depth exerted clear controls on detection of solutes in the drainage water. To summarize our findings, we present a leaching risk chart to illustrate the dependence of glyphosate, AMPA, and soil particle leaching based on rainfall intensity and the timing of rainfall events after glyphosate application.

A survey of soil salinity and groundwater level control systems in irrigated fields in the Jezre’el Valley, Israel

The Jezre’el Valley, Israel has inherent drainage problems; high water tables are common. Intensive irrigation has led to the development of salinity problems. A number of drainage system designs were installed in the same field to manage the prevailing causes of the salinity hazards. The shallow drainage system was designed to prevent damage to the winter crops and especially to enable early seeding of summer crops. The deep drainage system was designed to maintain a relatively low water table, thereby avoiding concentration of salts in the root zone. The combined drainage system with relief wells was designed to relief upward hydraulic pressure exerted by the semi-confined shallow aquifer. To study the mechanisms of salinization and the nature of the water table regime, soil salinity and water table monitoring systems were installed perpendicular to the parallel subsurface drains. The water table monitoring systems consisted of batteries of piezometers installed at different depths and located between the drainage lines. The most efficient method of drainage was found to be a combination of shallow and deep drains with relief wells wherever the semi-confined shallow aquifer was present. A noticeable improvement of the soil salinity, to below 4 dS/m, was observed 2–3 years after the drainage system was installed. It was found that the water table should be more than 1 m below the soil surface, in the spring season, to prevent soil salinization.

SHALLOW SUBSURFACE DRAINS TO REDUCE NITRATE LOSSES FROM DRAINED AGRICULTURAL LANDS

Nitrate losses from subsurface drainage systems remain an important environmental concern. Data were collected from two drainage systems near Plymouth, North Carolina, to evaluate the effect of subsurface drain depth on nitrate-nitrogen (NO3 --N) losses. Drains in plot 1 were 1.5 m deep and 25 m apart, and drains in plot 2 were 0.75 m deep and 12.5 m apart. Both plots received swine wastewater applications. Overall, the shallow drainage system had 42% less outflow than the deeper drainage system. Lower NO3 --N concentrations were observed in the shallow groundwater beneath the shallow drainage plots as a result of higher water tables and likely increased denitrification. However, NO3 --N concentrations in the drainage water from the shallow drains were not reduced. On average, NO3 --N export from the shallow subsurface drains was 8 kg ha-1 in 2001 and 27 kg ha-1 in 2002. Nitrate export from the deeper drains was 6 kg ha-1 in 2001 and 37 kg ha-1 in 2002. Decreased export observed in 2002 from the shallow subsurface drainage system was significant at the 10% level, but not for the entire 21-month period. Longer-term field studies, which incorporate variable climatological events, are needed to conclude whether shallower drain depth will reduce NO3 --N export from subsurface drainage systems.

Water-table shapes and drain flow rates in shallow drainage systems

A relationship between drain flow rate, elevation and shape of the water-table and recharge intensity in shallow drainage systems is developed. From an analytical spatial integration of the Boussinesq equation in transient conditions, drain flow rates are shown to be the sum of three terms; the first one is proportional to the maximum water-table elevation and more generally to the steady state flow rate at the same water-table elevation; the second one is a fraction of the recharge rate of the water-table depending on the water-table shape; the third one accounts for possible changes in water storage in the water-table due to its shape changes. Drain flow rates in shallow drainage systems are shown to be fully predicted by one unique variable that is a function of a combination of the hydraulic conductivity ( K), the drainable porosity ( f), and the drain spacing (2 L), namely σ= K/ f 2 L 2. This variable also determines the dynamics of changes in the water-table shape and in turn the respective parts of the three terms in the equation. It is shown that drainage systems with values of σ>1 m −1 h −1 respond very fast to recharge events: water-table shape changes occur very quickly so that the third component of the drain flow can be neglected; in that case, the equation results in a simplified analytical relationship. The reliability of the complete and simplified equations to predict drain flow rates in transient conditions is discussed in relation to in situ measurements.

Evaluation of water management strategies for acid sulphate soils using a simulation model: A case study in Indonesia

Reclamation and drainage of potential acid sulphate soils results in pyrite oxidation, acidification and release of toxic elements, hampering it's use for agriculture. Moreover, forest reserves and other ecologically valuable habitats located downstream of reclamation areas may be disrupted. Proper water management is essential for a sustainable reclamation of acid sulphate soils. The computer model SMASS (Simulation Model for Acid Sulphate Soils) was developed to predict the effects of water management on soil and water quality in acid sulphate soil areas. SMASS was applied to evaluate six different water management strategies for the Barambai area in South Kalimantan, Indonesia. These strategies were aimed at oxidation of all pyrite in the topsoil to prevent recurrent acidification during dry periods in the future. Model computations showed that all the proposed water management strategies will fail to achieve good soil and water conditions within a few years. Continuation of the present water management will result in poor rice yields and environmental damage for at least another 10 years. By application of a shallow drainage system to 30–40 cm, soil and water quality will strongly deteriorate during the first 3 years. Thereafter, the soil will be less unfavourable than if the present water management had been continued. The case study presented illustrates how the SMASS model can be applied to make a scientifically based evaluation of water management strategies. However, technical, economical and social factors should be considered as well, when deciding which water management strategy should be implemented in practice.

Desalting and ground water management in the San Joaquin Valley, California

Desalting brackish ground water can be combined with ground water management in the San Joaquin Valley to partially alleviate environmental and economic problems caused by agricultural drainage water. Desalting subsurface drainage water produced from on—farm shallow drainage systems is costly due to high salinity and the potential for scaling and fouling of reverse osmosis (RO) membranes. When subsurface drainage water is transported in open canals, algal growth and accompanying organic transformations present pretreatment problems that have yet to be solved. Similar problems have been experienced at desalting facilities outside the San Joaquin Valley using comparable feed waters. The proposed pumping of usable ground water from the semiconfined aquifer on the Valley's west side to lower the shallow water table and thus eliminate waterlogging of crop root zones may result in degradation and mining of usable ground water and contamination of the confined aquifer below the Corcoran clay, the principal confining layer in the Valley. A combination of brackish ground water desalting and ground water management by pumping unusable shallow ground water from an interval between the crop root zones and the usable water body at the bottom of the semiconfined aquifer would result in (1) a lower salinity feed water that will reduce the cost of desalting, (2) a feed water that requires little, if any, filtration to protect RO membranes, and (3) the removal of the body of water containing high levels of salt and selenium that endanger usable water in both aquifers. The combination of brackish ground water desalting and ground water management would result in the production of usable quantities of fresh water for California's ever-increasing population and a reduction in the cost of reclaiming and managing drainage water by desalination.

DRAINAGE OF AN IRRIGATED SALINE SOIL IN ALBERTA

A shallow subsurface drainage system effectively controlled a high water table and reduced salinity in an irrigated soil near Magrath, Alberta. Plastic corrugated tubing was installed in 1976 at depths of 1.1–1.5 m and spacings of 15 and 30 m in a moderately saline soil. During the irrigation period, the water table rose to within 0.3 m of the surface but was lowered to pre-irrigation levels within 48 h. The water table was maintained at, or below, the depth of the drains between irrigations. The 15- and 30-m spacings of the drain lines were equally effective in providing water table control in this lacustrine soil which was underlain by a coarse sand and gravel layer. Salinity levels were decreased substantially only within the surface 0.3-m soil depth. Quality of the drainage effluent remained constant throughout the growing season with only small dilution effects detected during irrigations. Barley yields increased to 3900 kg/ha in 1978, 2 yr following drainage of this saline soil which had been out of crop production for 20 yr.

Shallow Subsurface Drainage-Field Performance

ABSTRACT THIS field study shows that shallow subsurface drains (40 cm deep) remove as much soil water as deeper drains (95 cm deep) during the growing season in the Toledo soil. There was no structural damage to the shallow plastic draintubes from farming operations. Thus, shallow drainage systems offer great promise as a drainage technique for a large group of soils for which subsurface drain-age is not now recommended