Surface Infiltration Research Articles

A new approach for measuring surface hydrological connectivity

AbstractThe development of surface hydrological connectivity is a key determinant of flood magnitude in drylands. Thresholds in runoff response may be reached when isolated runoff‐generating areas connect with each other to form continuous links to river channels, enabling these areas to contribute to flood hydrographs. Such threshold behaviour explains observed nonlinearities and scale dependencies of dryland rainfall–runoff relationships and complicates attempts at flood prediction. However, field methods for measuring the propensity of a surface to transmit water downslope are lacking, and conventional techniques of infiltration measurement are often inappropriate for use on non‐agricultural drylands. Here, we argue for a reconceptualization of the dryland surface runoff process, suggesting that the downslope transfer of water should be considered alongside surface infiltration; that is, there is a need for the “aggregated” measurement of infiltration and overland flow hydraulics. Surface application of a set volume of water at a standardized rate generates runoff that travels downslope; the distance it travels downslope is determined by infiltration along the flow, integration of flow paths, and flow resistance. We demonstrate the potential of such a combined measurement system coupled with structure‐from‐motion photogrammetry to identify surface controls on runoff generation and transfer on dryland hillslopes, with vegetation, slope, surface stone cover, and surface roughness all having a significant effect. The measurement system has been used on slopes up to 37° compared with the flat surface typically required for infiltration methods. On average, the field workflow takes ~10–15 min, considerably quicker than rainfall simulation. A wider variety of surfaces can be sampled with relative ease, as the method is not restricted to stone and vegetation‐free land. We argue that this aggregated measurement represents surface connectivity and dryland runoff response better than standard hydrological approaches and can be applied on a much greater variety of dryland surfaces.

Field model experiments to determine mechanisms of rainstorm-induced shallow landslides in the Feiyunjiang River basin, China

This paper investigates rainfall infiltration processes and the failure mechanisms of slopes in the Feiyunjiang River basin. Field model experiments were conducted on a selected residual soil slope next to the Fuao landslide, which was about 30 m long and 25 m wide, and failed along the interface between soil and bedrock during typhoon Megi. The results indicated that rainfall infiltration over the slope surface had little impact on pore water pressure and deformation of the slope, while the coupled action of slope surface infiltration and preferential infiltration through an artificial ditch at the back of the slope caused rapid saturation near the interface between the residual soil and bedrock, resulting in significant displacement along the interface. Other preferential infiltration channels on slopes in the Feiyunjiang River basin include tension cracks, water impoundment and intrusive dykes and their weathered layers. The conclusions derived from this study are helpful in understanding rainstorm-induced soil landslides in the Feiyunjiang River basin in China, and possibly in other similar slope settings under comparable climate conditions.

2758 Lymphocytic Gastritis With Hypoproteinemia Treated With Helicobacter pyloriEradication

INTRODUCTION: Lymphocytic gastritis with hypoproteinemia is a rare condition and has been associated with Helicobacter pylori infection. We present the case of a 59-year-old female with hypoproteinemia associated with lymphocytic gastritis. The hypoproteinemia resolved after eradication of H. pylori. CASE DESCRIPTION/METHODS: The patient is a 59-year-old female who presented with complaints of early satiety. She had lost fifteen pounds over a period of six months. The patient had no other significant past medical history, and her clinical examination was normal except for minimal epigastric tenderness. She had no signs of malnutrition and did not have chronic diarrhea. On routine workup, she was found to have low total protein and normal albumin. Total protein on initial presentation was 5.4 g/dL. Eight weeks later, her total protein was still low (5.5 g/dL) with slightly low albumin (3-4 g/dL) as well. She had normal liver function tests and a negative celiac screening. Upper endoscopy revealed some patchy erosion of the antrum and thick gastric folds in the proximal body. Biopsies from the antrum and body revealed severe lymphocytic gastritis with chronic active inflammation. There were significant surface and foveolar epithelial infiltration by T lymphocytes (more than thirty lymphocytes per 100 epithelial cells). Immunohistochemical staining did not show Helicobacter pylori, but she did have positive H. pylori antibodies in the serum. The patient was treated with triple therapy for two weeks. Six weeks after eradication of H. pylori, her total protein increased to 7.5 g/dL. She also gained six pounds and was asymptomatic. DISCUSSION: Very few cases of lymphocytic gastritis-associated hypoproteinemia that resolved after eradication of H. pylori have been described in literature. Previous reports indicate that eradication of H. pylori is associated with prompt and significant improvement of hypoproteinemia as well as eventual disappearance of lymphocytic gastritis. Studies have suggested that lymphocytic gastritis condition is likely a rare and specific immune response to H. pylori. Links have also been described between lymphocytic gastritis and celiac disease as well as between lymphocytic gastritis and varioliform gastritis. This case serves to further establish an etiological link between H. pylori infection and lymphocytic gastritis accompanied by a protein-losing state.

Biocementation of sand by Sporosarcina pasteurii strain and technical-grade cementation reagents through surface percolation treatment method

The use of microbially induced carbonate precipitation (MICP) to produce biocementitious material for soil stabilization has emerged in recent decades as a sustainable alternative approach to conventional methods. However, the use of standard analytical-grade reagents for various MICP studies makes this technology very expensive and unsuitable for field-scale consideration. In this present study, the feasibility of using commercially available and inexpensive technical-grade reagents for the cultivation of ureolytic bacteria and enhancement of soil stabilization was investigated. Low-cost growth media prepared in deionized water and tap water were used to cultivate Sporosarcina pasteurii as a replacement to standard laboratory-grade media. Biocement treatment was carried out on sand columns using different concentrations (0.25–1.0 M) of technical-grade and analytical-grade cementation solutions via surface percolation method. After 92 h of treatment, the columns were cured for 3 weeks at room temperature (26 ± 2 °C) before analysing their respective surface strengths, CaCO3 content, pH of effluents and sand microscopic structures. The results indicated that the growth of bacteria in low-cost cultivation medium was similar to that observed in the standard cultivation medium. Surface strengths and CaCO3 contents of the consolidated samples were in the ranges of 11448.00 ± 69.00–4826.00 ± 00 kPa and 5.56 ± 1.15–33.24 ± 0.59%, respectively. Overall, the obtained results of the current study encourage future MICP studies to utilize commercially available technical-grade reagents for economical MICP field-scale trials.

Planning MAR Schemes Using Physical Models: Comparison of Laboratory and Field Experiments

Infiltration experiments in the context of managed aquifer recharge (MAR) are often conducted to assess the processes influencing the operation of full-scale MAR schemes. For this, physical models such as laboratory experiments and, less often, field experiments are used to determine process specifics or operational parameters. Due to several assumptions, scale-related limitations, and differing boundary conditions, the upscaling of results from the physical models is not straightforward. Investigations often lead to over- or underestimations of flow processes that constrain the translation of results to field-like conditions. To understand the restrictions and potential of different physical models for MAR assessment, surface infiltration experiments in different scales and dimensions, which maintained the same operational parameters, were conducted. The results from the different setups were compared against each other regarding the reproduction water flow in the vadose zone and the influence of parameters such as soil type and climate. Results show that mostly qualitative statements can be made, whereas quantitative analysis through laboratory experiments is limited.

SMODERP2D SOIL EROSION MODEL ENTERING AN OPEN SOURCE ERA WITH GPU-BASED PARALLELIZATION

Abstract. SMODERP2D is a runoff-soil erosion physically-based distributed episodic model used for calculation and prediction processes at agricultural areas and small watersheds. The core of the model is a raster based cell-by-cell mass balance calculation which includes the key hydrological processes, such as effective precipitation, surface runoff and stream network routing. Effective precipitation, the forcing of the runoff and erosion processes, is reduced by surface retention and infiltration. Surface runoff consists of two components: slower sheet and concentrated rapid rill flow. Stream network routing is performed line-by-line in the user predefined polyline layer.SMODERP is a long-term project driven by the Department of Landscape Water Conservation at the Czech Technical University in Prague. At the beginning, SMODERP has been developed as a surface runoff simulated by profile model (1D). Later the model has been redesigned using a spatially distributed method. This version is named SMODERP2D. Ongoing development is focused on obtaining parameters of the hydrological models, incorporating new infiltration and flow routing routines, and conceptualization of a rill flow and rill development. The model belongs to a family of so-called GIS-based hydrological models utilizing capabilities of GIS software for geospatial data processing. Importantly, the SMODERP2D project is currently entering an open source world. Originally the model could be run only in proprietary Esri ArcGIS platform. A new version of the model presented by this manuscript adds support for two key open source GIS platforms, GRASS GIS and QGIS. A newly developed GRASS module and QGIS plugin significantly increases the accessibility of the SMODERP2D model for research purposes and also for engineering practice.Middle scale distributed hydrological models often encounter with high computation costs and long model runtime. Long runtime is caused by high-resolution input data which is easily available nowadays. The project also includes an experimental version of the SMODERP2D model enabling the parallelization of computations. This parallelization is done using TensorFlow, and its goal is to decrease the time needed for its run. It is supported by both CPU and GPU. Parallelization of computations is an important step towards providing SMODERP2D web processing services in order to allow quick and easy integration to highly specialized platforms such as Atlas Ltd.

Rational Approach for Characterizing In Situ Infiltration Parameters of Two-Layered Pervious Concrete Pavement Systems

Pervious concrete (PC) has gained acceptance as a sustainable pavement material because of its ability to capture and infiltrate stormwater through the pavement system, and subsequently augment groundwater recharge. However, a systematic methodology that estimates and assesses the in situ infiltration characteristics of pervious concrete pavement (PCP) systems has yet to be developed. The objective of this study was to establish a rational methodical approach that evaluates the infiltration rates through PC and granular subbase (GSB) layers in a PCP system by utilizing experimental and analytical techniques. Over 20 field test slabs, each measuring 4×4×0.15 m, were constructed along a 120-m long stretch using one single PC mix type overlaid on a 0.25-m GSB layer. An experimental field test was designed to estimate the in situ infiltration rate through the PCP system, and was found to vary between 0.11 and 0.32 cm/s. Further, an infiltration test was performed on PC slabs to measure the surface infiltration rate (SIR), which ranged from 0.10 to 1.28 cm/s. Using the principle of conservation of mass, which assumes that the flow rate through each layer in a PCP system is identical, the infiltration rate of the GSB layer was found to be 0.07–0.11 cm/s. A significant contribution of this study was the development of a generic approach toward characterizing the major in situ infiltration parameters of multilayered PCP systems that incorporate a base and subbase layer, which have the potential to serve as effective hydraulic conduits through the system.

The use of watershed geomorphic data in flash flood susceptibility zoning: a case study of the Karnaphuli and Sangu river basins of Bangladesh

The occurrence of heavy rainfall in the south-eastern hilly region of Bangladesh makes this area highly susceptible to recurrent flash flooding. As the region is the commercial capital of Bangladesh, these flash floods pose a significant threat to the national economy. Predicting this type of flooding is a complex task which requires a detailed understanding of the river basin characteristics. This study evaluated the susceptibility of the region to flash floods emanating from within the Karnaphuli and Sangu river basins. Twenty-two morphometric parameters were used. The occurrence and impact of flash floods within these basins are mainly associated with the volume of runoff, runoff velocity, and the surface infiltration capacity of the various watersheds. Analysis showed that major parts of the basin were susceptible to flash flooding events of a ‘moderate’-to-‘very high’ level of severity. The degree of susceptibility of ten of the watersheds was rated as ‘high’, and one was ‘very high’. The flash flood susceptibility map drawn from the analysis was used at the sub-district level to identify populated areas at risk. More than 80% of the total area of the 16 sub-districts were determined to have a ‘high’-to-‘very-high’-level flood susceptibility. The analysis noted that around 3.4 million people reside in flash flood-prone areas, therefore indicating the potential for loss of life and property. The study identified significant flash flood potential zones within a region of national importance, and exposure of the population to these events. Detailed analysis and display of flash flood susceptibility data at the sub-district level can enable the relevant organizations to improve watershed management practices and, as a consequence, alleviate future flood risk.

Understanding the multiple functions of styrene-co-maleic anhydride in fabricating polyvinylidene fluoride hollow fiber membrane via coupled phase inversion process and its effect on surface infiltration behavior and membrane permeability

Polyvinylidene fluoride/styrene-co-maleic anhydride (SMA) hollow fiber membranes were prepared via coupled phase inversion (thermally induced phase separation-nonsolvent induced phase separation) process. The multiple functions of SMA, such as surface enrichment, non-diluent, dispersion, pore-former, hydrophilicity and surface infiltration behavior, were discussed. The membrane formation mechanisms about surface deposition of SMA for the outer surface and pore-former of micelle for the matrix were proposed. The membrane microstructure for the matrix changed from the spherulite to the interconnected cellular pores enclosed by the stackage of small size spherulite and the porosity of the membrane increased from 57.22% to 74.62% with the addition of SMA. Interestingly, the continuous SMA deposition layer as thin as 50~160 nm can be fabricated by this coupled phase separation process, which in turn not only decreased the thickness of outer skin-layer and the pore size, but also enriched the SMA content on outer surface markedly, improved the hydrophilicity, flux and the anti-fouling performance. Finally, based on the traditional hydration layer (HL) notion, the anti-fouling mechanism of the membrane was further developed from the point of “building-foundation” relationship via the surface infiltration of SMA. The purpose of this manuscript is to offer a simple and effective way to regulate the membrane microstructure, introduce functional group and propose a revised anti-fouling mechanism.

Performance of a Hydraulically Linked and Physically Decoupled Stormwater Control Measure (SCM) System with Potentially Heterogeneous Native Soil

This study shows that a physically decoupled but hydraulically linked design focusing on surface infiltration components (i.e., excluding underdrain and infiltration bed systems) can be the preferred way to have a low-cost and robust stormwater control measure (SCM) system. The SCM under investigation in Philadelphia, PA, is a green infrastructure (GI) and has a mirrored design of two sets of hydraulically linked planters. Each planter has an overflow pipe connected to an underground infiltration bed. The system showed excellent overall performance as no overflow/bypass entering the combined sewer. A large variation of saturated hydraulic conductivity was found for the planter soil, and the planter with lower saturated hydraulic conductivity created surface runoff that overflows to the next planter in line. Due to the linked design, the unexpected deviation of performance of a single planter did not affect overall system performance. The infiltration bed showed great variation in water drawdown rate at different water depth, which could be caused by the possible high heterogeneity of the native soil. The study argued that overflow systems, which handled only about 18% of runoff in this study, can be replaced by slightly larger surface area for lower building cost, lower maintenance cost, and more reliable performance.

Copper and zinc in vineyard and orchard soils at millimeter vertical resolution

Intensive uses of agrochemicals and soil amendments often cause the elevation of Cu and Zn concentrations in vineyard (VY) and orchard soils. The concentration and speciation of Cu and Zn in the soils at millimeter resolution is critical to understanding the risk of transport of these metals via surface runoff and infiltration. The objective of this study was to investigate the concentration and chemical species of Zn and Cu in VY and persimmon (PS) soils at millimeter vertical resolution. The soils were collected with 5 mm increments down to 5 cm depth and with 5 cm increments down to 25 cm depth. The total concentration and chemical species of Zn and Cu were determined by total digestion and X-ray absorption fine structure (XAFS) spectroscopy, respectively. The Zn concentration of VY soil reached a maximum of 290 mg kg−1 at the uppermost layer of the profile (0.5–1.0 cm). The Cu concentration of VY soil reached a maximum of 201 mg kg−1 (10–15 cm). These Zn and Cu concentrations were greater than background levels. Zinc K-edge XAFS spectroscopy determined that the uppermost layer of VY soil (0–0.5 cm) contained 42% Zn associated with humus and lesser extent of Zn associated with gibbsite (37%) and kaolinite (21%). Zinc associated with humus was not observed in the VY soil profiles below 0.5 cm, whereas Zn associated with gibbsite and kaolinite contributed >83% of total Zn species. Copper K-edge XAFS spectroscopy determined the presence of Cu bonded with humus (40–67%) and Cu adsorbed on kaolinite (26–45%) in the entire soil profile. Our study found the remarkable variation of Cu and Zn concentration and speciation within several centimeters from the soil surface in vineyard and orchard landscapes.

Large-area mechanical interlocking via nanopores: Ultra-high-strength direct bonding of polymer and metal materials

This study employed an effective and economical strategy of chemical treatments to achieve the direct bonding of polymer and metal materials. The bonding strength of the prepared polymer-metal structure could easily reach 20 MPa or more, which far exceeded the data that used to bond polymers and metals in other ways. The results of characterizations confirmed that the large-area mechanical interlocking of nanopores between polymer and metal was the essential reason for obtaining excellent performance. The countless nanopores were formed on the surface of the Al alloy due to the chemical reactions after treatments. Therefore, the countless nano-rivets could be naturally formed at the interface. Besides, a good infiltration of the metal surface caused by nanopores also had a contribution, because the contact angle was only 21.9° after treatments. We also confirmed that the size of nanopores was directly related to the mechanical strength of the polymer-metal structure. Bonding strength was >20.0 MPa when the average diameter was 30.3 nm. From SEM, EDX, and XPS, the chemical mechanism and the principle for each treatment step were proposed. This simple strategy will have potential application prospects in the field of automobile, shipping, and electronics where polymer-metal structures are needed.

Assessing "Urban Karst" Effects from Groundwater-Storm Sewer System Interaction in a Till Aquitard.

Storm sewer systems and their associated utility trenches may strongly influence the effects of urbanization on a groundwater system. This study was undertaken to identify the causes of district-wide basement infiltration in an aquitard system. It comprised widespread continuous monitoring of utility trench wells and dye tracing from storm sewer system exfiltration tests. The results indicate that a major effect of urbanization on shallow groundwater is related to storm sewer system exfiltration, which is marked by a characteristic pattern of head variations in the aquitard unrelated to distributed surface infiltration. The aquitard constrains flow from storm sewer system exfiltration to the utility trench, creating an urban flow path for groundwater discharge. Temporary buildup of water levels in the utility trench drives relatively high-velocity flow through the permeable sewer bedding material of the utility trench to a separate foundation drainage collector system, ultimately causing a severe "urban karst" effect that produces system surcharging and widespread basement water infiltration. The main conditions causing the "urban karst" are the large hydraulic conductivity ratio between the utility trench material and the aquitard, and the shallow depth and low gradient of the storm sewer system imposed by a very flat drainage basin.

Geomorfología paraglacial asociada a la inestabilidad de laderas en el Brazo Norte del Lago Argentino, Patagonia, Argentina

El retroceso y adelgazamiento de los glaciares a nivel mundial en las últimas décadas inciden directamente sobre la estabilidad de las laderas. La cuenca del glaciar Upsala y los glaciares del Brazo Norte del lago Argentino, han sufrido un marcado retroceso generando valles con pronunciadas pendientes y cubiertas con depósitos morrénicos inestables. Las laderas se encuentran fuertemente desestabilizadas, favoreciendo la generación de procesos geomorfológicos paraglaciales. El objetivo de este estudio es identificar y analizar la geomorfología paraglacial, asociada a los procesos de inestabilidad. Se realiza un análisis geomorfológico del terreno a través de la combinación de parámetros morfométricos y factores intervinientes que condicionan y desencadenan estos procesos, mediante el uso de imágenes de satélite. Los resultados muestran que la geomorfología paraglacial se encuentra influenciada por la combinación de: (i) parámetros morfométricos del terreno, entre ellos, elevaciones del terreno superiores a 700 m, pendientes promedios con un rango entre 25º-45º, orientación de las laderas este-noroeste con mayor insolación, curvatura cóncava del terreno y rugosidad leve a moderada (0,40-0,65); (ii) factores condicionantes, material morrénico depositado por los glaciares, afloramientos rocosos meteorizados y cobertura vegetal; (iii) factores desencadenantes, aporte de agua subterránea por infiltración de lagunas proglaciales y aporte superficial por precipitaciones, deshielo y escurrimiento, variación de temperaturas del aire y del suelo y variación del nivel del lago. En síntesis, las laderas que presentan mayores procesos geomorfológicos paraglaciales, producto de procesos de remoción en masa, son las que se encuentran en contacto directo con los glaciares Upsala, Bertacchi y Cono, la ladera occidental del canal Upsala y algunas zonas de los valles Moyano y Norte. El área se caracteriza por una combinación de ambientes glacial y paraglacial, siendo cada uno parte integral de la evolución del entorno.

Hydrologic Performance of Permeable Pavement as an Adaptive Measure in Urban Areas: Case Studies near Montreal, Canada

AbstractThe infiltration capacity of permeable interlocking concrete pavement (PICP) was characterized on five sites located in the greater Montreal area (Canada). Surface infiltration rates up to ...

Effect of Climate Change in the Stream Flow, Crop Yields and NP Levels at White Oak Bayou Watershed Using SWAT simulation: A Case Study

Projected changes in temperature due to global climate change may have serious impacts on hydrologic processes, water resources availability, irrigation water demand, and thereby affecting the agricultural production and productivity. Therefore, understanding the impacts of climate change on crop production and water resources is of utmost importance for developing possible adaptation strategies. The White Oak Bayou, one of the several waterways that give Houston, Texas, United States its popular nickname "The Bayou City" was selected in this case study.
 SWAT model is process based and can simulate the hydrological cycle, crop yield, soil erosion and nutrient transport. It is operated with an interface in ArcView GIS using raster or vector datasets including the digital elevation model (DEM), soil properties, vegetation, LULC, and meteorological observations observed which were derived from the Consortium for Geospatial Information, National Cooperative Soil Survey, National Land Cover Database 2006, NCEP Climate Forecast System Reanalysis and USGS website in 2005-2008. The climate change scenario was based on the projected increase in temperature by the IPCC by 2100.
 This case study showed a decrease in streamflow from observed actual scenario (2005-2008) to projected increase of 4°C temperature in future climate change scenario by 2100. The evapotranspiration increased but there was a decrease in surface runoff and percolation.
 Moreover, there were greater average plant biomass and more average plant yields. Hence, the nitrogen and phosphorus uptake and removed in yield increased. Thus, the total nitrogen decreased while the total phosphorus is zero indicating loss of the Phosphorus content in the soil. Yet, this case study needs to be validated and calibrated with actual data to support the projected outcome.

Forests as ‘sponges’ and ‘pumps’: Assessing the impact of deforestation on dry-season flows across the tropics

Forests act as ‘pumps’ through their evapotranspiration (Etot) and as ‘sponges’ by enhancing soil infiltration capacity and moisture retention. Tropical deforestation and poor post-forest land management generally result in lower Etot, but also reduce infiltration. Strongly diminished infiltration is typically accompanied by enhanced overland flow and can cause reduced groundwater recharge and baseflows. A grid-based land surface hydrological model (W3RA–LUM) was tailored to incorporate the trade-offs between the ‘pump’ and ‘sponge’ effects to investigate where deforestation can be expected to have the greatest impacts on dry-season flows. Streamflow sensitivity analyses for scenarios with or without full forest cover and/or good versus poor surface infiltration were performed for: (i) selected tropical catchments with documented changes in streamflow after deforestation; and (ii) the tropics at large (23.5°N to 35°S, to include important seasonal montane forests). The catchment sensitivity analyses showed that W3A–LUM captured the streamflow response to imposed deforestation and changes in surface conditions reasonably well. For the tropics as a whole, an increase in mean annual streamflow of 18% was obtained for forest conversion (to pasture) only, versus 26% after an additional imposed reduction in surface infiltration. Much of the inferred flow increases concerned water-limited regions. A reduction in dry-season flows was predicted for nearly one-fifth of all grid cells (despite lower Etot after forest conversion) after impaired infiltration, marking potential 'hot spots' of hydrological change after deforestation and reduced infiltration due to surface degradation. The affected grid cells shared the following key characteristics: (i) strong seasonality; (ii) high infiltration capacity under forested conditions; (iii) sufficient wet-season precipitation to recharge deep soil- and groundwater stores; (iv) sufficient soil water storage under forested conditions to ‘carry over’ infiltrated wet-season rainfall into the subsequent dry season; and (v) slow groundwater recession maintaining baseflow throughout the dry season.Our results demonstrate that forest removal in highly seasonal tropical catchments, whilst typically increasing mean annual water yield, can indeed decrease dry-season flows, depending on pre- and post-forest removal surface conditions and groundwater response times.

Evaluation of surface infiltration performance of permeable pavements

Many different test methods are used in practice to evaluate the surface infiltration performance of permeable pavements. This has led to inconsistency in reporting of test results. This study recognizes the differences in nature between a soil infiltration study and the surface infiltration evaluation of permeable pavements, and identifies the main issues associated with the current practice of surface infiltration testing. It proposes that hydraulic conductivity be adopted as the flow property for measurement and reporting instead of the commonly used infiltration rate. The advantages of measuring hydraulic conductivity are elaborated from both theoretical and practical implementation points of view. The theoretical merits of providing a consistent and integrated treatment of surface infiltration performance of a permeable pavement during the design, construction and maintenance phases are presented. The practical benefits are addressed from the following aspects: consistency between laboratory and field testing, uniformity in reporting of test measurements, rationality in construction quality control and acceptance checking, effectiveness in surface infiltration performance monitoring, and enhanced ability in implementing effective maintenance management. It is emphasized that the techniques and methods needed for measuring hydraulic conductivity of permeable pavement materials, for laboratory testing as well as on-site field testing, are already readily available and have been used by researchers and some practitioners for surface infiltration testing. Two falling-head test methods are recommended: one applies Darcy's law and determines hydraulic conductivity in the conventional way; another measures the time history of falling head and calculates hydraulic conductivity using a modified Darcy equation. It is also highlighted that the measurement of hydraulic conductivity offers a convenient platform for assessing the durability of a permeable pavement against clogging.

Improving hydrological simulation in the Upper Mississippi River Basin through enhanced freeze-thaw cycle representation

Freeze-thaw cycles are important processes relevant to terrestrial hydrological cycling. However, the representation of freeze-thaw cycles has been often simplified in large scale watershed models. The Soil and Water Assessment Tool (SWAT), which has been widely used to understand and assess hydrologic budgets and water resources management, employs a simplified empirical approach to estimate soil temperature and determine the freezing and thawing status of soils. Here, we compared the performance of a physically-based soil temperature module and the built-in empirical approach in SWAT against field measurements at surface and 5, 10, 20, 50, and 100 cm depths at six stations of the U.S. Climate Reference Network (USCRN) within the Upper Mississippi River Basin (UMRB). In general, SWAT consistently underestimated winter soil temperatures and overestimated frozen days at all soil depths, while the modified version of SWAT (equipped with the physically-based soil temperature model; referred to as TSWAT) pronouncedly reduced the bias in estimated winter soil temperatures and frozen days compared with SWAT. Model performance assessment is conducted with three statistical coefficients, i.e., Bias (°C), the coefficient of determination (R2), and Nash-Sutcliffe coefficient (NS). Statistical analyses show that TSWAT accurately simulated surface and soil temperatures at the five depths with R2 and NS values greater than 0.82 at most sites, and Bias values were generally within the range of −1 to 1 °C during winter and ranged between −2.09 and 2.58 °C in non-winter seasons. The differences in freeze-thaw cycle representation between SWAT and TSWAT translate into noticeable discrepancies in simulated key hydrologic variables, such as surface runoff, percolation, and baseflow. Compared against long-term observed streamflow (1980–2015), TSWAT outperformed SWAT in capturing variations in monthly streamflow in both winter and non-winter seasons. These results and analyses highlight the value of improving freeze-thaw cycle representation for enhanced hydrologic modeling in large watersheds that are subject to freeze-thaw cycles.

Silica-Based Infiltrations for Enhanced Zirconia-Resin Interface Toughness

Novel silica-based infiltrations on the surface of zirconia have the potential to improve their bondability, allowing for the etching/silane adhesive bonding technique. Nonetheless, adhesively bonded joints are subject to mixed tensile and shear stresses when the restoration is in occlusal service. Thus, we aimed to investigate the effect of 2 novel silica-based infiltrations on the interfacial toughness of adhesively bonded zirconia using the Brazil nut method, which allows for controlled types of stresses to be applied at the interfaces. In total, 150 3Y-TZP (In-Ceram YZ; Vita) Brazil nuts were machined and randomly assigned to 3 groups: C, control (air abraded); SG, sol-gel silica infiltration; and GI, glass infiltration. SG specimens were immersed twice in silicic acid for 20 min and dried (100°C, 1 h). GI specimens were presintered (1,400°C, 1 h) before a glass powder slurry was applied to the intaglio surface. All specimens were then sintered (1,530°C, 2 h). Following adhesive bonding (Panavia F 2.0, Kuraray) and water storage (37°C) for 10 d, the Brazil nuts were subdivided into groups baseline and aged (40,000 thermal cycles between 5°C and 55°C, with a dwell time of 30 s). The Brazil nuts were subjected to axial-loading tests using various inclinations (precrack angle with load direction): Θ = 0°, 5°, 10°, 15°, or 25°, which define the stress type at the interface, from pure tension (0°) to increasing levels of shear. Under pure tension (0°), GI yielded superior interfacial fracture energy, SG and C were similar, and aging had no effect. Under predominantly shear stresses (25°), aging significantly decreased interfacial fracture energy of C and SG, while GI remained stable and was superior. The glass infiltration of the zirconia intaglio surface increases its adhesive bonding interfacial toughness. The sol-gel silica infiltration method requires improvement to obtain a homogeneous surface infiltration and an enhanced bond strength.