Research Interests: Environmental Science, Geology, Geomorphology, Groundwater, Slope Stability, and 15 moreSensitivity Analysis, Stability, Temporal dynamics, Soil moisture, Evapotranspiration, Landslide, Real Time, Spatial Distribution, Soil Water Content, Soil Water, Pore Water Pressure, Hydrological Processes, Factor of Safety, Model performance, and hydrologic model
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In this paper, there is an undergoing effort to simulate and evaluate the sampling properties of the Global Precipitation Measurement Mission (GPM). The sampling quality is described in terms of the percentage of rainfall measured by... more
In this paper, there is an undergoing effort to simulate and evaluate the sampling properties of the Global Precipitation Measurement Mission (GPM). The sampling quality is described in terms of the percentage of rainfall measured by ground instruments recoverable from the GPM measurements. A specific configuration of the constellation is being used. The number of participating satellites and their individual orbital characteristics are selected and calculated. The instruments necessary for measuring precipitation on board of the satellites are selected and configured as well. Two study areas are selected, Rondonia basin in Brazil and Ilarion basin in Greece. Data from rain gages and radar are used. The time step of the data is disaggregated from 1 hour to 1 minute so that they will be comparable to the duration of the satellites’ contact time. The rainfall depth of every snapshot is set equal to the corresponding disaggregated values. The snapshots are then combined and rainfall events are reconstructed.
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This study employs a distributed eco-hydrological-landslide model, the tRIBS-VEGGIE-Landslide, to evaluate the influence of terrain resolution on the hydro-geomorphological processes involved in slope stability analysis. The model... more
This study employs a distributed eco-hydrological-landslide model, the tRIBS-VEGGIE-Landslide, to evaluate the influence of terrain resolution on the hydro-geomorphological processes involved in slope stability analysis. The model implements a Triangulated Irregular Network (TIN) to describe the topography starting from a grid-DEM. Five grid-DEM resolutions of the case study basin, i.e., 10, 20, 30 and 70 m, are used to derive the corresponding TINs. The results show that using irregular meshes reduces the loss of accuracy with coarser resolutions in the derived slope distribution in comparison to slope distributions estimated from the original grid-based DEM. From a hydrological perspective, the impact of resolution on soil moisture patterns and on slope stability is significant mostly when lateral water exchanges are allowed. The degrading of resolution leads to a reduction of the predicted unstable areas, with respect to the highest resolution case, from about 15% (20 m) to more than 40% (70 m)
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Research Interests: Mathematics, Environmental Science, Hydrography, Mass Transfer, Meteorology, and 15 moreRadar, Forecasting, Flood Forecasting, Atmospheric sciences, Developing Country, Flood, Applied, Real Time, Digital Elevation Model, Precipitation, Intensity, HYDROGRAPH, Applied Meteorology, Rainfall Intensity, and Flood Myth
This study proposes a new methodology for estimating the additional shear strength (or cohesion) exerted by vegetation roots on slope stability analysis within a coupled hydrological‐stability model. The mechanical root cohesion is... more
This study proposes a new methodology for estimating the additional shear strength (or cohesion) exerted by vegetation roots on slope stability analysis within a coupled hydrological‐stability model. The mechanical root cohesion is estimated within a Fiber Bundle Model framework that allows for the evaluation of the root strength as a function of stress‐strain relationships of populations of fibers. The use of such model requires the knowledge of the root architecture. A branching topology model based on Leonardo's rule is developed, providing an estimation of the amount of roots and the distribution of diameters with depth. The proposed methodology has been implemented into an existing distributed hydrological‐stability model able to simulate the dynamics of factor of safety as a function of soil moisture dynamics. The model also accounts for the hydrological effects of vegetation, which reduces soil water content via root water uptake, thus increasing the stability. The entire...
Research Interests: Environmental Engineering, Civil Engineering, Environmental Science, Geology, Water resources, and 9 moreSlope Stability, Vegetation Effects on Slope Hydrology and Stability, Applied Economics, Hydrological modelling, Landslide, Water Science and Technology, Hydrological Modeling, Shallow landslides, and physically based models
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This document presents the data sample size of the SMAP L2 Version 4 soil moisture retrievals for each month during 2016 and the percentages of the soil moisture data within some quality control limits defined by NASA. The soil moisture... more
This document presents the data sample size of the SMAP L2 Version 4 soil moisture retrievals for each month during 2016 and the percentages of the soil moisture data within some quality control limits defined by NASA. The soil moisture retrievals of each 36-km grid cell are associated by NASA to a surface condition and retrieval quality flag. Each half orbit was obtained from https://nsidc.org/data/SPL2SMP/versions/4. There are 11 surface conditions defined in the SMAP data: static water, radar-derived water, coastal proximity, urban area, precipitation, snow, permanent ice, frozen ground from SMAP radiometer-derived freeze/thaw state, frozen ground from GMAO TSURF model, mountainous terrain, and dense vegetation. For each surface condition, a lower threshold T1 and a higher threshold T2 are defined. Only data with all surface conditions under the T1 threshold are flagged as high quality. In this document, we use three variables (i.e., soil_moisture, surface_flag, and retrieval_qua...
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This paper presents a framework that enables simultaneous assimilation of satellite precipitation and soil moisture observations into the coupled Weather Research and Forecasting (WRF) and Noah land surface model through variational... more
This paper presents a framework that enables simultaneous assimilation of satellite precipitation and soil moisture observations into the coupled Weather Research and Forecasting (WRF) and Noah land surface model through variational approaches. The authors tested the framework by assimilating precipitation data from the Tropical Rainfall Measuring Mission (TRMM) and soil moisture data from the Soil Moisture Ocean Salinity (SMOS) satellite. The results show that assimilation of both TRMM and SMOS data can effectively improve the forecast skills of precipitation, top 10-cm soil moisture, and 2-m temperature and specific humidity. Within a 2-day time window, impacts of precipitation data assimilation on the forecasts remain relatively constant for forecast lead times greater than 6 h, while the influence of soil moisture data assimilation increases with lead time. The study also demonstrates that the forecast skill of precipitation, soil moisture, and near-surface temperature and humid...
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Statistical bias correction methods are inferred relationships between inputs and outputs. The constructed functions are based on available observations, which are limited in time and space. This study investigates the ability of... more
Statistical bias correction methods are inferred relationships between inputs and outputs. The constructed functions are based on available observations, which are limited in time and space. This study investigates the ability of regression models (linear and nonlinear) to regionalize a domain by defining a minimum number of training pixels necessary to achieve a good level of bias correction performance. Linear regression is used to divide northern South America into five regions. To correct the biases of temperature and precipitation, an artificial neural network (ANN) model was trained with selected pixels within each region and then used to reproduce bias‐corrected temperature and precipitation at all pixels within the delineated regions. The Community Climate System Model (CCSM) provided the climate model data. Results confirm that it is possible to identify regions in terms of physical features such as land cover, topography, and climatology over which models trained with a fe...
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The dynamics of soil organic carbon (SOC) in tropical forests play an important role in the global carbon (C) cycle. Past attempts to quantify the net C exchange with the atmosphere in regional and global budgets do not systematically... more
The dynamics of soil organic carbon (SOC) in tropical forests play an important role in the global carbon (C) cycle. Past attempts to quantify the net C exchange with the atmosphere in regional and global budgets do not systematically account for dynamic feedbacks among linked hydrological, geomorphological, and biogeochemical processes, which control the fate of SOC. Here we quantify effects of geomorphic perturbations on SOC oxidation and accumulation in two adjacent wet tropical forest watersheds underlain by contrasting lithology (volcaniclastic rock and quartz diorite) in the Luquillo Critical Zone Observatory. This study uses the spatially explicit and physically based model of SOC dynamics tRIBS‐ECO (Triangulated Irregular Network‐based Real‐time Integrated Basin Simulator‐Erosion and Carbon Oxidation) and measurements of SOC profiles and oxidation rates. Our results suggest that hillslope erosion at the two watersheds may drive C sequestration or CO2 release to the atmospher...
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Three principles of optimal energy expenditure are used to derive the most important structural characteristics observed in drainage networks: (1) the principle of minimum energy expenditure in any link of the network, (2) the principle... more
Three principles of optimal energy expenditure are used to derive the most important structural characteristics observed in drainage networks: (1) the principle of minimum energy expenditure in any link of the network, (2) the principle of equal energy expenditure per unit area of channel anywhere in the network, and (3) the principle of minimum total energy expenditure in the network as a whole. Their joint application results in a unified picture of the most important empirical facts which have been observed in the dynamics of the network and its three‐dimensional structure. They also link the process of runoff production in the basin with the characteristics of the network.
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From rainfall interception at the canopy to added soil cohesion within the root zone, plants play a significant role in directing local geomorphic dynamics, and vice versa. The consequences at the regional scale, however, are known in... more
From rainfall interception at the canopy to added soil cohesion within the root zone, plants play a significant role in directing local geomorphic dynamics, and vice versa. The consequences at the regional scale, however, are known in less quantitative terms. In light of this, the numerical Channel‐Hillslope Integrated Landscape Development model is equipped with coupled vegetation‐erosion dynamics, allowing for sensitivity analysis on the various aspects of vegetation behavior. The processes considered are plant growth, plant death, and the additional resistance imparted by plants against erosion. With each process is associated a single parameter, whose effects on the spatiotemporal nature of a 1 km2 basin is studied. Through their inhibition of erosion, plants steepened the topography and reduced drainage density, yet, in doing so, made erosive events more extreme. Plants more susceptible to erosion act to decouple neighboring cells and cause extensive and perennial network and c...
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Research Interests: Environmental Engineering, Civil Engineering, Mathematics, Stochastic Process, Hydrogeology, and 14 moreWater resources, Geostatistics, Applied Economics, Maximum Likelihood, Advection, Travel Time, Spatial Variability, AQUIFER, Groundwater flow, Fast Fourier Transform, Inverse, Variogram, Aquifer Properties, and Synthetic Data Generation
Abstract Stochastic models of spatial variation as they apply to both saturated and unsaturated flow and transport problems are examined in this paper. Both modeling and data interpretive geostatistical approaches are reviewed and an... more
Abstract Stochastic models of spatial variation as they apply to both saturated and unsaturated flow and transport problems are examined in this paper. Both modeling and data interpretive geostatistical approaches are reviewed and an integrated discussion combining the two approaches given. The probabilistic content is of special interest for reliability and risk calculations for waste management and groundwater pollution studies.
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ABSTRACT
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ABSTRACT In this study we propose a probabilistic approach for coupled distributed hydrological-hillslope stability models that accounts for soil parameters uncertainty at basin scale. The geotechnical and soil retention curve parameters... more
ABSTRACT In this study we propose a probabilistic approach for coupled distributed hydrological-hillslope stability models that accounts for soil parameters uncertainty at basin scale. The geotechnical and soil retention curve parameters are treated as random variables across the basin and theoretical probability distributions of the Factor of Safety (FS) are estimated. The derived distributions are used to obtain the spatio-temporal dynamics of probability of failure, in terms of parameters uncertainty, conditioned to soil moisture dynamics. The framework has been implemented in the tRIBS-VEGGIE (Triangulated Irregular Network (TIN)-based Real-time Integrated Basin Simulator - VEGetation Generator for Interactive Evolution) - Landslide model and applied to a basin in the Luquillo Experimental Forest (Puerto Rico) where shallow landslides are common. In particular, the methodology was used to evaluate how the spatial and temporal patterns of precipitation, whose variability is significant over the basin, affect the distribution of probability of failure, through event scale analyses. Results indicate that hyetographs where heavy precipitation is near the end of the event lead to the most critical conditions in terms of probability of failure. This article is protected by copyright. All rights reserved.
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Knowledge of initial conditions is very important to correctly model the basin response at the storm event scale. Of particular interest is the influence of topography and soil type on the principal hydrologic variables and runoff... more
Knowledge of initial conditions is very important to correctly model the basin response at the storm event scale. Of particular interest is the influence of topography and soil type on the principal hydrologic variables and runoff generation mechanisms as a function of ...