Browsing by Author "Martinez, Sofia I."

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    A Combined and Extended Procedure for Measuring the Soil Water Retention and Hydraulic Conductivity Curves
    (2025) Contreras Torres, Cristina Pamela; Acevedo Godoy, Sara Ester; Avila Gorostiaga, Carlos Javier; Martinez, Sofia I.; Bonilla Melendez, Carlos Alberto
    Soil-specific properties like water retention and hydraulic conductivity are largely used in soil and environmental modelling and are typically obtained after laboratory analyses. So far, no single method is available to measure the entire suction range for water retention or hydraulic conductivity. Common methods for describing the soil water retention curve (SWRC) include simplified evaporation, pressure plates, neutron spectroscopy, and dewpoint. Regarding hydraulic conductivity, the techniques vary for the saturated or unsaturated condition, using tension disks and transient evaporation methods. In the search for a procedure to describe the entire water retention and hydraulic conductivity curves, the objective of this study was to illustrate the combination and use of a series of laboratory methods in eight different semi-hierarchical combinations to cover the whole suction range (0 <=$$ \le $$ pF <=$$ \le $$ 7). The data obtained from each combination was used to fit the van Genuchten-Mualem equation and compared using the RMSE and Akaike statistics. The main results show that using a combination of many methods for the water retention and hydraulic conductivity curves did not necessarily improve the curve fitting. However, adding data points at near saturation (pF close to 0) or from the driest part of the curve (pF >=$$ \ge $$ 4) improved the estimates on both curves. Specifically, for the clay soil, the RMSE for the hydraulic conductivity curve decreased from 0.0372 to 0.0369 cm/d when measurements from near saturation were added. For the sandy loam 2 soil, the RMSE for the water retention curve decreased from 0.039 to 0038 when including data from the driest part of the curve. Among all the soil-water-related parameters tested in this study, the estimates for the water retention content at the permanent wilting point (theta 1500 kPa) showed the largest difference among all the combinations of methods, up to 52%. In contrast, the difference in the water content at field capacity (theta 33 kPa) estimates was only 3%. This study provides an evaluation and insights to identify the best combination of methods when measuring or parametrizing the soil water retention and hydraulic conductivity curves.
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    Effect of data availability and pedotransfer estimates on water flow modelling in wildfire-affected soils
    (2023) Acevedo, Sara E.; Martinez, Sofia I.; Contreras, Cristina P.; Bonilla, Carlos A.; CEDEUS (Chile)
    Understanding the impact of wildfires on soils exposed to fire is critical, especially in the current climate sce-nario, where an increase in the occurrence of wildfires is expected. Near-surface soil physical properties are affected by temperature increases caused by wildfires; therefore, changes in the soil water retention curve (SWRC) are expected. Parameters describing the SWRC can be obtained either by measuring or deriving using pedotransfer functions (PTF). However, PTFs have been developed using data from agricultural soils without major heating events; therefore, it is uncertain whether the estimation of parameters in fire-affected soils is reliable. This study evaluated changes in the hydraulic properties of near-surface soil due to fire during three wildfire events of different magnitudes. The objectives were: a) to identify changes in soil properties and SWRC due to wildfires, b) to assess the PTF performance (Rosetta versions 1, 2, and 3) of non-affected and fire-affected soils and (c) to evaluate changes in SWRC due to wildfires and water flow behavior changes through modelling using the HYDRUS-1D model. Decreases in organic matter (OM) and Ksat and increases in pH and bulk density (BD) were observed in fire-affected soils compared to non-affected soils. Based on sand, silt, clay, bulk density, and field capacity, Rosetta version 1 had the lowest values of root-mean-square error for the entire range of suctions, although it did not accurately estimate theta s or Ksat. Among Rosetta's estimations, Ksat showed the highest variations, which were more marked in fire-affected soils, when measured values were 15.85 cm d-1 while those estimated were 79.14 cm d-1 on average. The implications for hydrologic modelling were translated into lower annual water content and higher infiltration when using Rosetta inputs compared to inputs based on the measured SWRC.