scholarly journals Investigating bioretention cell performance: A large-scale lysimeter study 

2021 ◽  
Author(s):  
Daniel Green ◽  
Ross Stirling ◽  
Simon De Ville ◽  
Virginia Stovin ◽  
Richard Dawson
Keyword(s):  
Mass Balance ◽  
Soil Water ◽  
Green Infrastructure ◽  
Large Scale ◽  
Water Movement ◽  
Reference Evapotranspiration ◽  
Soil Water Potential ◽  
Cell Performance ◽  
Base Layer ◽  
Bioretention Cell

<div> <p>Sustainable Drainage Systems (SuDS) are a widely adopted approach for managing excess urban runoff by intercepting, retaining and attenuating the flow of water through the built environment, playing a key role in reducing urban flood risk. Vegetated bioretention cells (‘rain gardens’) are one of the most simple, practical and commonly implemented SuDS options and can be easily retrofitted into urban spaces to deal with surface water from paved areas. Although current UK and international guidance provides design guidance for SuDS, no quantitative indications on their hydrological performance are currently available. This study aims to provide evidence to assess the effectiveness of such systems to support optimal implementation of vegetated bioretention cells for stormwater management. </p> </div><div> <p>Four purpose built, large-scale lysimeter experiments (2.0 m x 2.0 m, each divided into two isolated 1.0 m x 2.0 m cell pairs) were designed to provide long-term monitoring data of key hydrological variables and demonstrate the capacity and effectiveness of monitored bioretention systems. The lysimeters were filled with an engineered soil profile consisting of a surface SuDS substrate (700 mm depth) to sustain vegetation growth and store/attenuate flows, and drainage layers (300 mm depth) consisting of a fine gravel transition layer to prevent the movement of fine sediments and a course gravel base layer to allow free drainage into gauged outflow units. </p> </div><div> <p>Each of the lysimeter cells feature a dense sensor network, allowing spatiotemporal soil-atmosphere interactions to be observed and changes in relation to rainfall events to be quantified. Tipping bucket rain gauges situated on each of the lysimeters allow the quantification of local precipitation inflows, which are also analysed in the context of site-wide weather monitoring stations to calculate Penman-Monteith reference evapotranspiration. Outflow from the drainage layer of each lysimeter cell is measured using an outflow gauge. Additionally, a network of in-situ soil sensors were deployed throughout the substrate profile at various depths to quantify soil water movement and changes in volumetric water content, soil temperature, electrical conductivity, soil-water potential and hydrostatic water level in accordance with localised weather conditions. Quantifying inflows, storages and losses allows an understanding of the lysimeter mass balance. Further, each of the lysimeter cell pairs were planted with different planting styles (unvegetated control, reference short grass and two uniform mono-cropped shrub species) to provide differing reference evapotranspiration scenarios and to understand the influence of vegetation on bioretention cell performance.  </p> </div><div> <p>This paper outlines the commissioning of a large-scale lysimeter study at the National Green Infrastructure Facility and presents results from mid-2020 onwards, highlighting the hydrological performance of the bioretention cells under a range of natural storm events and climatic conditions. Lysimeter mass balance and retention efficiencies are presented for each of the vegetation scenarios. Further, differences in soil-water retention ability between the lysimeters are examined in relation to the efficiency of various planting styles and their comparative evapotranspirative behaviour. Working together with a range of stakeholders involved in UK SuDS schemes, this work is helping to inform design criteria and anticipated bioretention cell performance using a quantified evidence base.</p> </div>

EFFECT OF SOIL WATER POTENTIAL AND BULK DENSITY ON WATER UPTAKE PATTERNS AND RESISTANCE TO FLOW OF WATER IN WHEAT PLANTS

1971 ◽  
Vol 51 (2) ◽  
pp. 211-220 ◽  
Author(s):  
S. J. YANG ◽  
E. DE JONG
Keyword(s):  
Water Potential ◽  
Bulk Density ◽  
Soil Water ◽  
Water Uptake ◽  
Water Movement ◽  
Soil Column ◽  
Soil Water Potential ◽  
Moisture Uptake ◽  
The Mathematical Model ◽  
Water Uptake Patterns

Water uptake patterns of wheat plants were studied in a growth chamber by using two soils packed to three different bulk densities. The resistances to water movement in the soil and in the plant were calculated from the mathematical model for water uptake published in the literature. When the capillary potential of the soils was near −⅓ bar, withdrawal of water by plants was relatively small and most of the water was taken from the top 25 cm of the soil column. As soil water potential decreased, water uptake increased progressively toward the lower part of the soil column. The resistance to water movement in the plant increased from the top to the bottom of the root system and increased with increasing bulk density of the soils. For wet soils, unrealistic values were obtained which could be due to the fact that the interaction between aeration and moisture uptake is not taken into account in the theoretical equations for moisture uptake.

Soil and plant resistances to water absorption by plant root systems

1979 ◽  
Vol 30 (2) ◽  
pp. 279 ◽  
Author(s):  
GJ Burch
Keyword(s):  
Water Absorption ◽  
Root System ◽  
Soil Water ◽  
Water Movement ◽  
Plant Root ◽  
Unit Length ◽  
Water Flux ◽  
Soil Water Potential ◽  
Root Systems ◽  
Soil Resistance

A study of water absorption by root systems of two herbage species, white clover (Trifolium repens L.) and tall fescue (Festuca arundinacea Schreb.), was used to partition the resistances to water flux between the soil and plant. A large and almost constant plant resistance influenced the pattern of water absorption until the soil resistance reached about 1.5 x 103 MPa s cm-3. This corresponded to an extraction of almost 80% of the available soil water. Water absorption from progressively deeper soil layers showed no evidence of any substantial resistance to water flux through the root xylem. Therefore, in wet soils, water movement into and through a root system is predominantly influenced by a large resistance to the radial water flux through root tissues outside the xylem. The radial resistance values for unit (cm) length of root were 6.49 x 106 and 6.54 x 106 MPa s cm-2 for clover and fescue respectively. A model of water uptake has been described which introduces two modified parameters for integrating the soil water potential (ψ) and the soil-root conductance (κ), over an entire root system. This study, along with other evidence from the literature, would indicate that for unit length of root the radial resistance to water absorption is reasonably similar, not only for an entire root system but also for a number of different species. An underestimation of the radial soil resistance (Rsr) to water absorption suggests that a root contact resistance (Rc) exists which could be due to the shrinkage of the soil or root, or both, with drying of the soil. This effect caused an increase in resistance to water absorption of about 48 x Rsr for fescue and 71 x Rsr for clover. This difference in Rc between the two species was attributed to a contrast in root morphology, especially a difference in the average root diameters of the two species.

scholarly journals Soil Water Movement Changes Associated with Revegetation on the Loess Plateau of China

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 731 ◽  
Author(s):  
Haocheng Ke ◽  
Peng Li ◽  
Zhanbin Li ◽  
Peng Shi ◽  
Jingming Hou
Keyword(s):  
Soil Water ◽  
Loess Plateau ◽  
Large Scale ◽  
Plant Density ◽  
Water Movement ◽  
Temporal Distribution ◽  
Semiarid Region ◽  
The Loess Plateau ◽  
Vegetation Growth ◽  
Soil Water Movement

Soil water is the limitation factors in the semiarid region for vegetation growth. With the large scale “Grain for Green” implementation on the Loess Plateau of China, an amount of sloping cropland was converted to forestland, shrubland, and grassland. The spatial and temporal distribution of soil water was changed. However, the effect of revegetation on soil water movement is still unclear. In this study, we analyze the stable isotopes changes in precipitation and soil water in sloping cropland, forestland, shrubland, and grassland to trace the movement of moisture in soil. The results showed that δ18O in shallow layers (<20 cm depth) of sloping cropland, forestland, shrubland, and grassland were −3.54‰, −2.68‰, −4.00‰, and −3.16‰, respectively. The δ18O in these layers were higher than that in the lower layers, indicating that evaporation was mainly from the shallow layers. The δ18O for the soil water in the unsaturated zone in the grassland, shrubland, and forestland of the temporal variability decreases with depth and approaches a minimum value at 160 cm, 180 cm, and 200 cm, respectively, suggesting that the soil water is relatively stable many months or even longer. Precipitation was infiltrated with piston and preferential modes, and infiltration demonstrated obvious mixing. Present study demonstrated the δ18O was more sensitive than the soil water content for tracing the maximum infiltration depth of event water and recharge mechanisms. Consequently, we suggested that the land user management such as type, plant density should be considered in the revegetation.

Response of the components of sugar beet leaf water potential to a drying soil profile

1987 ◽  
Vol 109 (3) ◽  
pp. 437-444 ◽  
Author(s):  
Kay F. Brown ◽  
M. McGowan ◽  
M. J. Armstrong
Keyword(s):  
Sugar Beet ◽  
Water Potential ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Osmotic Potential ◽  
Seasonal Changes ◽  
Water Movement ◽  
Soil Water Potential ◽  
Leaf Water ◽  
Leaf Osmotic Potential

SummaryFor many field-grown crops, including sugar beet, there is little information on the seasonal changes in leaf water potential and its components as the soil dries. Therefore, seasonal changes in leaf water, osmotic and turgor potentials of sugar beet were measured in two seasons, in crops that experienced differing degrees of soil moisture stress. In 1983 potentials of crops exposed to early and late droughts were compared with those of irrigated crops, and in 1984 measurements were made in a non-irrigated crop. In the irrigated crop the midday leaf water potential changed little during the season, except in response to fluctuating evaporative demand. In the drought and non-irrigated treatments there was a sharp fall in leaf water potential as soon as the soil water potential decreased. The size of the midday leaf water potential was primarily determined by soil dryness. However, the leaf water potential did not decrease below about — 1·5 MPa in either year. The leaf osmotic potential declined at the same time as the leaf water potential, but the extent to which this happened differed in the two years. Only in the 1984 non-irrigated crop did the osmotic potential continue to decrease as the soil dried, suggesting that osmotic adjustment had taken place in 1984 but not in 1983. Thus higher turgor was maintained in the 1984 crop than in the 1983 drought-affected crops. Some turgors were recorded as apparently negative in 1983.Since the leaf water potential declined to a minimum of about — 1·5 MPa, the soil water potential minima were also about — 1·5 MPa. However, deeper soil was not dried to this extent, suggesting that the extra resistance for water uptake from deep soil was limiting or the rooting density was too low.The pattern of recovery of leaf water potential overnight suggested that the rhizosphere resistance to water movement was small, even as the soil dried. However, measurement of stem water potentials in 1984 indicated that a significant resistance to water flow existed within the aerial part of sugar beet plants. This shows that the use of the water potential in leaves as an estimate of that in stems or roots can be misleading.

scholarly journals A brief review of soil water, solute transport and regionalized variable analysis

1997 ◽  
Vol 54 (spe) ◽  
pp. 89-115 ◽  
Author(s):  
D.R. Nielsen ◽  
J.W. Hopmans ◽  
M. Kutílek ◽  
O. Wendroth
Keyword(s):  
Liquid Phase ◽  
Soil Water ◽  
Water Movement ◽  
Relative Concentration ◽  
Soil Water Potential ◽  
Field Research ◽  
State Variables ◽  
Soil Water Retention ◽  
Quality Of Water ◽  
Basic Ideas

We initially review basic concepts of the forces acting on soil water, soil water potential and soil water retention, and equations to describe soil water movement under water-saturated and unsaturated conditions. Processes of infiltration, evaporation and redistribution of water will be presented for simple initial and boundary conditions occurring within homogeneous soil columns. Next we consider the physical, chemical and biological processes within a soil profile that distribute, dilute or concentrate solute species within the liquid phase of a soil The relative concentration of solutes in the liquid phase governs not only the retention and transport of water within soils but also contributes to our understanding of managing the quality of water within soils and that moving below the recall of plant roots deeper into the vadose zone. A complete set of references about this subject is available in Kutílek & Nielsen (1994). In the last section we recall the differences between classical statistical concepts and those that utilize the coordinates of space and time at which state variables across the landscape are observed. Our presentation win cover the basic ideas about autocorrelation, crosscorrelation, applied time series analyses, state space analyses and similar techniques currently being used to enhance field research and investigations of land and water management.

Effect of Soil Water Potential of Two Soils on Soybean Emergence 1

1979 ◽  
Vol 71 (6) ◽  
pp. 980-982 ◽  
Author(s):  
L. G. Heatherly ◽  
W. J. Russell
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential

Tiered Sampling

2021 ◽  
Vol 15 (5) ◽  
pp. 1-52
Author(s):  
Lorenzo De Stefani ◽  
Erisa Terolli ◽  
Eli Upfal
Keyword(s):  
Large Scale ◽  
Analysis Of Algorithms ◽  
Base Layer ◽  
Single Edge ◽  
Real World Data ◽  
High Quality ◽  
Large Graphs ◽  
Massive Graphs ◽  
Variance Estimate ◽  
Low Probability

We introduce Tiered Sampling , a novel technique for estimating the count of sparse motifs in massive graphs whose edges are observed in a stream. Our technique requires only a single pass on the data and uses a memory of fixed size M , which can be magnitudes smaller than the number of edges. Our methods address the challenging task of counting sparse motifs—sub-graph patterns—that have a low probability of appearing in a sample of M edges in the graph, which is the maximum amount of data available to the algorithms in each step. To obtain an unbiased and low variance estimate of the count, we partition the available memory into tiers (layers) of reservoir samples. While the base layer is a standard reservoir sample of edges, other layers are reservoir samples of sub-structures of the desired motif. By storing more frequent sub-structures of the motif, we increase the probability of detecting an occurrence of the sparse motif we are counting, thus decreasing the variance and error of the estimate. While we focus on the designing and analysis of algorithms for counting 4-cliques, we present a method which allows generalizing Tiered Sampling to obtain high-quality estimates for the number of occurrence of any sub-graph of interest, while reducing the analysis effort due to specific properties of the pattern of interest. We present a complete analytical analysis and extensive experimental evaluation of our proposed method using both synthetic and real-world data. Our results demonstrate the advantage of our method in obtaining high-quality approximations for the number of 4 and 5-cliques for large graphs using a very limited amount of memory, significantly outperforming the single edge sample approach for counting sparse motifs in large scale graphs.

Sign in / Sign up

Export Citation Format

Share Document