THE_EFFECTS_OF_BIOTURBATION_ON_SOIL.pdf (original) (raw)
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Geomorphology, 1998
Landsat thematic mapper data are used to estimate instantaneous regional-scale surface water and energy fluxes in a semi-arid Great Basin desert of the western United States. Results suggest that it is possible to scale from point measurements of environmental state variables to regional estimates of water and energy exchange. This research characterizes the unif3'ing thread in the classical climate-topography-soil-vegetation relation --the surface water and energy balance--through maps of the partitioning of energy throughout the landscape. The study was conducted in Goshute Valley of northeastern Nevada, which is characteristic of most faulted graben valleys of the Basin and Range Province of the western United States. The valley comprises a central playa and lake plain bordered by alluvial fans emanating from the surrounding mountains. The distribution of evapotranspiration (ET) is lowest in the middle reaches of the fans where the water table is deep and plants are small, resulting in low evaporation and transpiration. Highest ET occurs in the center of the valley, particularly in the playa, where limited to no vegetation occurs, but evaporation is relatively high because of a shallow water table and silty clay soil capable of large capillary movement. Intermediate values of ET are associated with large shrubs and is dominated by transpiration. quent weathering, mass movement and fluvial transport processes are superimposed on the mega-geomorphic processes to produce the current landscape. Geomorphologic evolution is closely coupled with the hydrologic cycle. Moisture and temperature are the two most important aspects of climate in controlling the physical, chemical, and biochemical processes that govern landscape development. Tempera-0169-555X/98/$19.00 ¢)
The estimation of crop water use or evapotranspiration (ET) is an important aspect of water management especially in arid and semi-arid regions. Various methods have been used in the estimation of ET including remote sensing (RS) based models, and these have an added advantage of estimating ET over a large area (e.g., regionally). This study looked at two models of estimating ET; Mapping evapotranspiration at high Resolution with Internalized Calibration (METRIC) and the Surface Energy Balance Algorithm for Land (SEBAL). Satellite images from Landsat 5 for 2010 for two alfalfa fields in Rocky Ford, Colorado, were processed and analyzed to obtain sensible heat flux (H). Both RS models employ the energy balance (EB) method and estimate net radiation (R n ) and soil heat flux (G) similarly.
Data Series
Selected micrometeorological and soil-moisture data were collected at the Amargosa Desert Research Site adjacent to a low-level radioactive waste and hazardous chemical waste facility near Beatty, Nevada, 2001-05. Evapotranspiration data were collected from February 2002 through the end of December 2005. Data were collected in support of ongoing research to improve the understanding of hydrologic and contaminant-transport processes in arid environments. Micrometeorological data include solar radiation, net radiation, air temperature, relative humidity, saturated and ambient vapor pressure, wind speed and direction, barometric pressure, precipitation, near-surface soil temperature, soilheat flux and soil-water content. All micrometeorological data were collected using a 10-second sampling interval by data loggers that output daily and hourly mean values. Daily maximum and minimum values are based on hourly mean values. Precipitation data output includes daily and hourly totals. Selected soil-moisture profiles at depth include periodic measurements of soil volumetric water-content measurements at nine neutron-probe access tubes to depths ranging from 5.25 to 29.25 meters. Evapotranspiration data include measurement of daily evapotranspiration and 15-minute fluxes of the four principal energy budget components of latentheat flux, sensible-heat flux, soil-heat flux, and net radiation. Other data collected and used in equations to determine evapotranspiration include temperature and water content of soil, temperature and vapor pressure of air, and covariance values. Evapotranspiration and flux estimates during 15-minute intervals were calculated at a 0.1-second execution interval using the eddy covariance method. Data files included in this report contain the complete micrometeorological, soil-moisture, and evapotranspiration field data sets. These data files are presented in tabular Excel spreadsheet format. This report highlights selected data contained in the computer generated data files using figures, tables, and brief discussions. Instrumentation used for data collection also is described. Water-content profiles are shown to demonstrate variability of water content with depth. Time-series data are plotted to illustrate temporal variations in micrometeorological, soil-water content, and evapotranspiration data.
Science of The Total Environment, 2018
Land surface temperature (LST) seems to be related to the temperature of shallow aquifers and the unsaturated zone thickness (ΔZ uz). That relationship is valid when the study area fulfils certain characteristics: a) there should be no downward moisture fluxes in an unsaturated zone, b) the soil composition in terms of both, the different horizon materials and their corresponding thermal and hydraulic properties, must be as homogeneous and isotropic as possible, c) flat and regular topography, and d) steady state groundwater temperature with a spatially homogeneous temperature distribution. A night time Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image and temperature field measurements are used to test the validity of the relationship between LST and ΔZ uz at the Pampa del Tamarugal, which is located in the Atacama Desert (Chile) and meets the above required conditions. The results indicate that there is a relation between the land surface temperature and the unsaturated zone thickness in the study area. Moreover, the field measurements of soil temperature indicate that shallow aquifers dampen both the daily and the seasonal amplitude of the temperature oscillation generated by the local climate conditions. Despite empirically observing the relationship between the LST and ΔZ uz in the study zone, such a relationship cannot be applied to directly estimate ΔZ uz using temperatures from nighttime thermal satellite images. To this end, it is necessary to consider the soil thermal properties, the soil surface roughness and the unseen water and moisture fluxes (e.g., capillarity and evaporation) that typically occur in the subsurface.
Annual mesoscale study of water balance in a Great Basin heterogeneous desert valley
Journal of Hydrology, 1997
We studied the annual mesoscale water balance in northeastern Nevada, USA, in a Great Basin heterogeneous semi-arid desert valley (the Goshute Valley) at 40"44'N, 114"26'W, with elevation of 1707 m above mean sea-level. This north-south-oriented flat valley has an area of about 1113 km* and is partially covered mostly by sagebrush, grease.wood. shadscale, desert molly, cheatgrass, and winter fat bushes. Five Bowen ratio stations measured the incoming and outgoing (reflected) solar radiation, net radiation, air temperatures and moisture at 1 and 2 m, the aggregated (soil + vegetation) surface temperature, wind speed and direction at 10 m, soil heat flux at 8 cm (three locations at each station), soil temperatures at 2 and 6 cm above each soil flux plate, and precipitation every 5 s averaged to 20 min throughout the valley from 1 May 1993 to 30 September 1994. Locations of stations were based upon the vegetation types and percentage of coverage by bushes. The topsoil (10 cm) moisture content was measured either by time domain reflectometer or gravimetric method at least once a week. We used the Bowen ratio energy balance (BREB) method for the measurement of 20 min evapotranspiration throughout the experiment. During the dry water year 1993-1994 (beginning from 1 October) the average amount of aggregated (soil + bushes) evapotranspiration (ET& among stations measured by the BREB method was almost equal to the average total precipitation for the entire valley (160.9 mm vs. 157.7 mm, respectively). Variations of precipitation among stations (ranging from 173.7 mm at Station 2 to 130.5 mm at Station 1) were attributed to winter orographic effects and summer thermal lows. ET, ranged from 181.2 mm at Station 3 to 142.7 mm at Station 2. Variations were related mostly to vegetation types and percentage of the soil coverage. All stations showed slight water losses (~57'~ greater than precipitation) in the dry water year 1993-1994, except at Station 2, where water gain was about 31.1 mm. The 1993-1994 water losses at Stations 1, 3, 4 and 5 were 29.7 mm, 7.5 mm, 8.1 mm and 2 mm, respectively. The additional water for the process of evapotranspiration at these stations may be due to extraction of moisture from the air during the cool early mornings throughout the water year or to extraction of moisture from the soil. A set of relationships between the incoming solar and net radiation, surface * Corresponding author. 0022-16!44/97/$17.00 0 1997-Elsevier Science B.V. All rights reserved PIf SOO22-1694(96)03055-7 224 E. Malek et al,/Joumal of Hydrology 191 (1997) 223-244 and 2 m air temperatures, and surface and 8 cm soil heat fluxes among stations was also developed.
In semi-arid areas, where vegetation is sparse and clumped, models used to estimate evapotranspiration (kE) consider soil and plants as different sources of evaporation. When working at higher scales of heterogeneity, the modelling of surface fluxes introduces effective parameters that enclose the sub-grid heterogeneity. In this work we used both approaches to estimate the kE of a sparse-vegetation patch of Retama sphaerocarpa (L.) Boiss in a semi-arid area in southeast Spain. Firstly, we used a multi-layer model considering plant, soil under plant and bare soil, each with its own surface and aerodynamic resistances and available energy, interacting at a within canopy height. Secondly, we used a single-layer model that uses the effective surface and aerodynamic resistances of the patch, calculated by different aggregations of the soil and plant resistances considered in the multi-layer model. The estimates of kE were compared with measured values obtained by an Eddy covariance system. Results show that the use of effective surface resistances aggregated in parallel and effective aerodynamic resistances aggregated in series in a single-layer model produced similar estimates of kE as a multi-layer model. When compared to the measured values, the estimates of the single-layer model were even more accurate than the estimates of the multi-layer model. The results of this paper show that, in areas with low vegetation cover, a simple model, where patch-scale heterogeneity is 0022-1694/$ -see front matter ª
2002
: Selected micrometeorological and soil moisture data were collected at the Amargosa Desert Research Site adjacent to a low-level radioactive waste and hazardous chemical waste facility near Beatty, Nev., 1998 2000. Data were collected in support of ongoing research studies to improve the understanding of hydrologic and contaminant transport processes in arid environments. Micrometeorological data include precipitation, air temperature, solar radiation, net radiation, relative humidity, ambient vapor pressure, wind speed and direction, barometric pressure, soil temperature, and soil-heat flux. All micrometeorological data were collected using a 10-second sampling interval by data loggers that output daily mean, maximum, and minimum values, and hourly mean values. For precipitation, data output consisted of daily, hourly, and 5-minute totals. Soil-moisture data included periodic measurements of soil-water content at nine neutron-probe access tubes with measurable depths ranging from ...