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Climate Change in Grassland Ecosystems
Published in Brenda Groskinsky, Climate Actions, 2022
Jesse Nippert, Seton Bachle, Rachel Keen, Emily Wedel
In addition to increases in evapotranspiration, the proliferation of deeper, coarser root systems of woody species can impact water flow paths through the vadose zone (Zou et al. 2014; Acharya et al. 2018). Root systems have substantial impacts on the flow and retention of water in the soil profile (Cresswell et al. 1992; Scholl et al. 2014) as well as connectivity between water sources on a landscape. Coarse woody roots form large soil macropores more readily than finer grass roots, and these soil pores can alter flow paths and cause shifts in hydrologic partitioning in grassland systems by creating preferential flow paths deeper into the soil profile (Sullivan et al. 2019). These shifts have the potential to alter stream discharge and drainage through the vadose zone into groundwater, particularly during large rainfall events (Vero et al. 2018).
Comparison of 1D and 2D infiltration results using unsaturated transparent soil
Published in N. Khalili, A.R. Russell, A. Khoshghalb, Unsaturated Soils: Research & Applications, 2020
Moisture migration in the unsaturated zone between the soil surface and the water table is in a perpetual state of flux. Heavily dependent on seasonal climatic conditions precipitation, runoff, evaporation and evapotranspiration can all have a large impact on the amount of water in this unsaturated (vadose) zone. Due to the impact variable moisture conditions have on the effective stresses and the associated mechanical properties of unsaturated soil, this has sparked considerable interest in the field of unsaturated fluid flow in a number of different applications from foundations and slope stability, to waste management facilities and contaminant flow applications.
Fundamentals of Pathway Transport Assessment
Published in Jack Daugherty, Assessment of Chemical Exposures, 2020
Soil Transportation. Both the resident population and nearby populations are threatened by contaminated soils. Whether a pure chemical stream contacts soil or contaminated water the chemicals do migrate outward and downward. The data requirements for studying soil or groundwater as a pathway of concern are given in Table 9.21. A description of the geology underneath the source is needed to evaluate the migration and/or stabilization of the contaminant in the porous media. Soil is composed of two kinds of particles: minerals and organics. An unsaturated zone exists from the surface level of the ground down to the underground water table which is the saturated zone. Above the water table the unsaturated zone of soil is called the vadose zone and generically the water there is called vadose water. Figure 9.1 shows the divisions of water under the surface. Vadose water is composed of three types of water: soil water, intermediate vadose zone water and capillary water. For the purposes of our discussion this is all we need to know of underground water types for the moment.
Investigation of the matric suction role on the curing mechanism of foamed asphalt stabilised mixtures
Published in Road Materials and Pavement Design, 2019
André Kazuo Kuchiishi, Camila Christine dos Santos Antão, Kamilla Vasconcelos, José Pires, Olga Maria de Oliveira Araújo, Liedi Legi Bariani Bernucci, Ricardo Tadeu Lopes
The unsaturated soil zone, in which the unsaturated soil mechanics theory is valid, is usually located between the ground surface and the water table, and is commonly referred as “vadose zone”. The vadose zone depth is highly dependent on the climatic conditions (e.g. temperature, relative humidity, precipitation) and consists of a transition zone in which the soil is partially saturated (Fredlund, Rahardjo, & Fredlund, 2012). In terms of paving materials, the dynamic relation between the amount of water and gas inside the materials pores is supposed to cause approximately corresponding effects. For example, in the case of a material composed by mineral grains, bitumen and inherent pores with variable percentage of air and water, the variation of the water content/saturation degree can cause important changes in the general material behaviour. In this case, it is considered that the suction pressure can have a singular importance. The increase in the suction pressure indicates a higher contact force between the grains that, in turn, is influenced by the presence of the binder.
Modified-DRASTIC, modified-SINTACS and SI methods for groundwater vulnerability assessment in the southern Tehran aquifer
Published in Journal of Environmental Science and Health, Part A, 2018
Roohollah Noori, Hooman Ghahremanzadeh, Bjørn Kløve, Jan Franklin Adamowski, Akbar Baghvand
The vadose zone is located above the aquifer and below the soil zone and its effect on the potential for aquifer pollution depends on its permeability and the attenuation features of the media. This zone plays a significant role in decreasing GWR pollution through contaminant attenuation processes, especially filtration.[3] A map of the vadose zone media in the southern part of the Tehran plain was developed from the lithologic data of observation and exploration wells collected in an IWRMC archive. Developed using this map and guidelines proposed by Aller et al.[5], the raster map of vadose zone impacts for the area (Fig. 2(f)) shows most of the vadose zone in the study area to be made up of sand and gravel.
Sensitivity analysis and mapping the potential groundwater vulnerability zones in Birbhum district, India: A comparative approach between vulnerability models
Published in Water Science, 2018
Raju Thapa, Srimanta Gupta, Shirshendu Guin, Harjeet Kaur
In the study area, ferruginous sand with clay, alluvium, and clay with lateritic nodules encompasses an area of 1090.07 sq.km (23.59%), 1294.82 sq.km (28.02%) and 2236.81 sq.km (48.40%) respectively (Fig. 8). Vadose zone is a complex medium for transport of groundwater where the flow rate can vary significantly. The discontinuously saturated or unsaturated soil horizon both above and below the water table is the vadose zone. Vadose zone facilitates the filtration out of harmful chemical through the soil matrix from recharging water entering into the aquifer.