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  • 1
    Language: English
    In: CSA News, 2013, Vol.58(9), p.16
    ISSN: CSA News
    E-ISSN: 1529-9163
    Source: CrossRef
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  • 2
    Language: English
    In: Environmental Management, 2015, Vol.55(6), pp.1262-1275
    Description: We assess the spatial and geomorphic fragmentation from the recent Eagle Ford Shale play in La Salle County, Texas, USA. Wells and pipelines were overlaid onto base maps of land cover, soil properties, vegetation assemblages, and hydrologic units. Changes to continuity of different ecoregions and supporting landscapes were assessed using the Landscape Fragmentation Tool (a third-party ArcGIS extension) as quantified by land area and continuity of core landscape areas (i.e., those degraded by “edge effects”). Results show decreases in core areas (8.7 %; ~33,290 ha) and increases in landscape patches (0.2 %; ~640 ha), edges (1.8 %; ~6940 ha), and perforated areas (4.2 %; ~16230 ha). Pipeline construction dominates landscape disturbance, followed by drilling and injection pads (85, 15, and 0.03 % of disturbed area, respectively). An increased potential for soil loss is indicated, with 51 % (~5790 ha) of all disturbance regimes occurring on soils with low water-transmission rates (depth to impermeable layer less than 50 cm) and a high surface runoff potential (hydrologic soil group D). Additionally, 88 % (~10,020 ha) of all disturbances occurred on soils with a wind erodibility index of approximately 19 kt/km 2 /year (0.19 kt/ha/year) or higher, resulting in an estimated potential of 2 million tons of soil loss per year. Results demonstrate that infrastructure placement is occurring on soils susceptible to erosion while reducing and splitting core areas potentially vital to ecosystem services.
    Keywords: Eagle Ford ; Landscape impacts ; Fragmentation ; Ecosystems
    ISSN: 0364-152X
    E-ISSN: 1432-1009
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  • 3
    Language: English
    In: Soil Science Society of America journal, 2012, Vol.76(6), pp.1965-1977
    Description: Pre- and post-fire measurements were made for a low-intensity prescribed fire in a semiarid, shrub-woodland transition zone, and objectives were to: (i) determine changes in near-saturated hydraulic conductivity (K(f) measured with a tension infiltrometer), air permeability (k(a) measured with an air permeameter), and soil physical properties at shrub undercanopy and interspace microsites immediately before and after a fall burn and for a 13-mo period; and (ii) quantify the importance and effect of post-fire soil structure on hydraulic properties using pre- and post-fire measurements. At undercanopy microsites, structure deteriorated from a moderate to a weak subangular blocky structure after the fire that broke down to a structureless soil 10 mo later. At interspace microsites, post-fire soil structure deteriorated from a moderate-strong subangular blocky structure with hard dry consistency to a weak subangular blocky structure with soft dry consistency. After 10 mo, the intercanopy maintained a weak-moderate soil structure that became structureless-weak after 13 mo. Immediately after the fire, at both microsites, there was incomplete organic combustion, a decrease in bulk density, and an increase in ka; however, at undercanopy microsites, there was no significant change in K(f) even though there was a slight to moderate hydrophobicity, whereas at interspace microsites where no water repellency existed, K(f) increased. These changes may be a result of expansion of vaporized water through soil pores that broke up aggregates, deteriorating soil structure. Thus, mechanisms that contributed to changes immediately and after the first year post-fire were different for low-intensity burns than for higher intensity burns. ; p. 1965-1977.
    Keywords: Bulk Density ; Soil Degradation ; Soil Pore System ; Air ; Ecosystems ; Hydraulic Conductivity ; Hydrophobicity ; Combustion ; Infiltrometers ; Permeability ; Prescribed Burning ; Shrubs
    ISSN: 0361-5995
    E-ISSN: 14350661
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  • 4
    Language: English
    In: Water, Air, & Soil Pollution, 2010, Vol.212(1), pp.309-317
    Description: Linear anionic polyacrylamide (LA-PAM) is being considered as a soil amendment to reduce seepage and infiltration in unlined earthen canals. While polyacrylamides have been extensively used for potable water treatment, dewatering sewage sludge, coal and mine processing, paper manufacturing, and agriculture, little is known about its ecological impact to aquatic ecosystems. Acute toxicity (LC 50 , 24 and 48 h) and chronic exposure tests (limited and continuous exposures) were conducted on Daphnia magna . In the chronic limited exposure experiments, Daphnia were exposed to LA-PAM for only 24 h whereas for the chronic continuous exposure the concentrations of 0, 0.5, 1, 5, 10, and 100 mg/L were tested and the endpoints of growth, onset to reproduction, fecundity, and mortality were measured for the duration of 32 days. There was no significant difference among the chronic, limitedly exposed organisms. The acute toxicity for LA-PAM was measured at 100, 150, 200, 250, and 300 mg/L. The acute test showed that the LC 50 for LA-PAM was at 152 mg/L. Overall in the chronic, continuous exposure test, D. magna was negatively impacted by LA-PAM at levels as low as 1 mg/L. Growth was reduced by 37% and 89% at 1 and 100 mg/L, respectively. Fecundity and onset to reproduction was impaired at 10 and 100 mg/L. Kinematic viscosity ranged from 0.98 cSt at 1 mg/L to 2.9 at 100 mg/L. At these levels, mechanical and physiological impairments due to the viscous properties of LA-PAM are the proposed mechanisms of reduction in the life history traits of D. magna .
    Keywords: LA-PAM ; Polymer ; physiology ; Growth rate and toxicity ; Viscosity ; Canal sealant
    ISSN: 0049-6979
    E-ISSN: 1573-2932
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  • 5
    In: Ecohydrology, October 2015, Vol.8(7), pp.1218-1228
    Description: Evapotranspiration (ET) dominates water fluxes in arid and semiarid ecosystems. The partitioning of ET into transpiration (T) and evaporation (E) has drawn increasing attention, particularly with respect to quantifying the control of shrub cover on water budget studies. The main objective of this study was to simulate the effects of shrub coverage spatial patterns on water partitioning into T and E and its relation to the simulation cell sizes. Correlation lengths of spatially distributed shrub cover in fine resolution grid cells were used to distinguish spatial patterns (i.e. patchiness) of shrub distributions. We then aggregated the fine resolution grid cells into larger cells of various hierarchies, calculated the potential T of each large cell as a portion of potential ET in the aggregated cell, and simulated the partitioning of actual ET into T and E. Results illustrated that simulated T increases with aggregated cell size, while E rate and total E do not change significantly (i.e. T/ET increases with aggregated cell size). The spatial distribution of shrub pattern influences the partitioning of ET: T increases with decreasing correlation length of shrub spatial pattern. Significant differences in T/ET are linked to the different correlation lengths, as a result of the highly non‐linear relationship between potential T and % shrub cover, which indirectly take into account subsurface lateral flows in the root zone. Copyright © 2014 John Wiley & Sons, Ltd.
    Keywords: Evapotranspiration ; Partitioning ; Shrub Spatial Pattern ; Modelling
    ISSN: 1936-0584
    E-ISSN: 1936-0592
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  • 6
    Language: English
    In: Geography Compass, 03/2011, Vol.5(3), pp.112-127
    Description: Drylands have been radically through transformed forces set in motion by humans - including agricultural conversion, overgrazing, and invasion by non-native plants. Relatively new global change drivers will ensure that drylands will continue their transformation. In this review, we discuss recent progress in understanding how global climate and land cover changes are affecting the ecohydrology of drylands, and we highlight some challenges faced by the research community. We argue that an imperative for dryland ecohydrologists is to not only work to better understand and anticipate global changes, but to devise strategies for adapting to and, where possible, mitigating the effects of these changes. The fundamental challenge we face is how to ensure clean water and adequate food for humanity while at the same time maintaining the Earth's life-support systems. Moreover, we suggest that scientific efforts and social policy can - and indeed must - become more strongly linked. The ecological and earth science communities benefit from interactions with social scientists, and social policy made without consideration of the long-term impacts on dryland processes can jeopardize the sustainability of natural resources.
    Keywords: Scientific Research ; Mitigation ; Overgrazing ; Reviews ; Natural Resources ; Invasions ; Sustainability ; Geography ; Social Policy ; Adaptability ; Issues in Sustainable Development ; General;
    ISSN: Geography Compass
    E-ISSN: 17498198
    Source: Wiley (via CrossRef)
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  • 7
    Language: English
    In: Journal of Hydrology, October 2017, Vol.553, pp.160-171
    Description: Water resources development and landscape alteration exert marked impacts on water-cycle dynamics, including areas subjected to hydraulic fracturing (HF) for exploitation of unconventional oil and gas resources found in shale or tight sandstones. Here we apply a conceptual framework for linking baseflow analysis to changes in water demands from different sectors (e.g. oil/gas extraction, irrigation, and municipal consumption) and climatic variability in the semiarid Eagle Ford play in Texas, USA. We hypothesize that, in water-limited regions, baseflow ( ) changes are partly due (along with climate variability) to groundwater abstraction. For a more realistic assessment, the analysis was conducted in two different sets of unregulated catchments, located outside and inside the Eagle Ford play. Three periods were considered in the analysis related to HF activities: pre-development (1980–2000), moderate (2001–2008) and intensive (2009–2015) periods. Results indicate that in the Eagle Ford play region, temporal changes in baseflow cannot be directly related to the increase in hydraulic fracturing. Instead, substantial baseflow declines during the intensive period of hydraulic fracturing represent the aggregated effects from the combination of: (1) a historical exceptional drought during 2011–2012; (2) increased groundwater-based irrigation; and (3) an intensive hydraulic fracturing activity.
    Keywords: Hydraulic Fracturing ; Baseflow Recessions ; Drought ; Texas ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 8
    Language: English
    In: Journal of Arid Environments, July 2017, Vol.142, pp.41-49
    Description: Biological soil crusts (hereafter, “biocrusts”) dominate soil surfaces in nearly all dryland environments. To better understand the influence of water content on carbon (C) exchange, we assessed the ability of dual-probe heat-pulse (DPHP) sensors, installed vertically and angled, to measure changes in near-surface water content. Four DPHP sensors were installed in each of two research plots (eight sensors total) that differed by temperature treatment (control and heated). Responses were compared to horizontally installed water content measurements made with three frequency-domain reflectometry (FDR) sensors in each plot at 5-cm depth. The study was conducted near Moab, Utah, from April through September 2009. Results showed significant differences between sensor technologies: peak water content differences from the DPHP sensors were approximately three times higher than those from the FDR sensors; some of the differences can be explained by the targeted monitoring of biocrust material in the shorter DPHP sensor and by potential signal loss from horizontally installed FDR sensors, or by an oversampling of deeper soil. C-exchange estimates using the DPHP sensors showed a net C loss of 69 and 76 g C m in control and heated plots, respectively. The study illustrates the potential for using the more sensitive data from shallow installations for estimating C exchange in biocrusts.
    Keywords: Soil Water Content ; Biological Soil Crusts ; Monitoring ; Dual-Probe Heat Pulse ; Environmental Sciences ; Geography ; Ecology
    ISSN: 0140-1963
    E-ISSN: 1095-922X
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  • 9
    Language: English
    In: Hydrological Processes, 30 April 2012, Vol.26(9), pp.1352-1360
    Description: In this work, we study groundwater system temporal scaling in relation to plant water use and near‐river‐stage fluctuations in riparian zones where phreatophytes exist. Using detrended fluctuation analysis (DFA), we investigate the influence of regular diurnal fluctuations due to phreatophyte water use on temporal scaling properties of groundwater level variations. We found that groundwater use by phreatophytes, at the field site on the Colorado River, USA, results in distinctive crossovers (slope changes when the plots are fitted with straight lines) in the logarithm plots of root‐mean‐square fluctuations of the detrended water level time series time scales of groundwater level dynamics. For groundwater levels monitored at wells close to the river, we identified one crossover at ∼1 day in the scaling characteristics of groundwater level variations. When time scale exceeds 1 day, the scaling properties decrease from persistent to close to 1/ noise, where is the frequency. For groundwater levels recorded at wells further away from the river, the slope of the straight line fit (i.e. scaling exponent) is smallest when the time scale is between 1 and 3 days. When the time scale is 3 days. Copyright © 2011 John Wiley & Sons, Ltd.
    Keywords: Scaling Analysis ; Detrended Fluctuation Analysis ; Groundwater Level Fluctuation ; Riparian Zone
    ISSN: 0885-6087
    E-ISSN: 1099-1085
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  • 10
    Language: English
    In: Vadose Zone Journal, 2013, Vol.12(4), p.0
    Description: Celebrating ten years of publication, the authors introduce a special section commemorating the anniversary of Vadose Zone Journal and reviewing the journal's role in an evolving understanding of vadose zone science. © Soil Science Society of America, All rights reserved.
    Keywords: Agriculture;
    ISSN: Vadose Zone Journal
    E-ISSN: 1539-1663
    Source: CrossRef
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