Trent Biggs

San Diego State University | SDSU · Department of Geography

Farmworkers, the frontline workers of our food system, are often exposed to heat stress that is likely to increase in frequency and severity due to climate change. Irrigation can either alleviate or exacerbate heat stress, quantification of which is crucial in intensely irrigated agricultural lands such as the Imperial Valley in southern California...

The Amazon Basin is experiencing large-scale land use conversion from primary forest to pasture. While several land cover datasets map cleared areas in the Amazon, the percent cover of woody vegetation (trees and shrubs) in cleared areas and its association with clearing age, soil type, and geology is poorly understood, despite its importance for c...

Farmworkers, the ‘frontline workers’ of our food system, are often exposed to heat stress that is likely to increase in frequency and severity due to climate change. Irrigation can exacerbate heat stress, quantification of which is crucial in intensely irrigated agricultural lands such as the Imperial Valley (IV) in southern California. We present...

Prioritizing watershed management interventions relies on delineating homogeneous precipitation regions. In this study, we identify these regions in the Brazilian Legal Amazon based on the magnitude of Sen’s Slope trends using annual precipitation data from September to August, employing the Google Earth Engine platform. Utilizing the silhouette me...

Analyzing water resources in areas with few hydrometeorological stations, such as those in post-Soviet countries, is difficult due to station closures after 1989. In Caucasus, evaluations often rely on outdated data from nearby rivers. We evaluated one national-level precipitation dataset, the Water Balance of Georgia (WBG) with two satellite-based...

Permafrost soils contain approximately twice the amount of carbon than the atmosphere, which could be released as global warming continues. Increasing global temperatures have in fact the potential to result in increased permafrost degradation, and carbon loss into the atmosphere. To properly understand the potential release of the carbon stored in...

Land use and cover change (LUCC) in Brazil encompass a complex interplay of diverse factors across different biomes. Understanding these dynamics is crucial for informed decision-making and sustainable land management. In this study, we comprehensively analyzed LUCC patterns and drivers using 30 m resolution MapBiomas Collection 6.0 data (1985-2020...

Water is redistributed from evaporation sources to precipitation sinks through atmospheric moisture transport. In the Brazilian Amazon, the spatial and temporal variability of dry season moisture sources for key agricultural regions has not been investigated. This study investigates moisture sources for dry season rainfall in the state of Rondônia...

Evapotranspiration (ET) connects the land to the atmosphere, linking water, energy, and carbon cycles. ET is an essential climate variable with a fundamental importance, and accurate assessments of the spatiotemporal trends and variability in ET are needed from regional to continental scales. This study compared eight global actual ET datasets (ETg...

Mass movement hazards in the form of mega-gullies and landslides pose significant risks in urbanizing areas, yet they are poorly documented. To obtain primary data on the size, frequency, and triggers of abrupt mega-gullies and landslides in urban areas, rapid assessment methods based on structure-from-motion (SfM) photogrammetric techniques and wa...

A sub-bacia do rio Branco contém duas Terras Indígenas, duas Unidades de Conservação, oito Pequenas Centrais Hidrelétricas e 3.939 propriedades rurais, além de ser legalmente um berçário para proteção da fauna ictiológica e flora aquática. Diante da importância socioeconômica e ambiental da sub-bacia, objetivou-se avaliar a dinâmica temporal na cob...

Major land use land cover changes (LULCC) have taken place in Brazil, including large scale conversion of forest to agriculture. LULCC alters surface-atmosphere interactions, changing the timing and magnitude of energy fluxes, impacting the partitioning of available energy, and therefore the climate and water balance. The objective of this work was...

Deforestation and global climate change are predicted to affect precipitation and agricultural productivity in the Amazon. Anecdotal evidence suggests that farmers are already being affected by changes in the timing and amount of precipitation, but there is little quantitative evidence on the mechanism by which precipitation affects production. Thi...

Accurate long-term estimates of rainfall at fine spatial and temporal resolution are vital for hydrometeorology and climatology studies, but such data are often unavailable in remote regions. We assessed the accuracy of three satellite-based precipitation products that have data from 1981 to 2019 over the state of Rondônia in the Brazilian Amazon:...

Forests are a key component of hydrological cycles, and thus deforestation is likely to affect the availability and quality of water for downstream agricultural production. However, in humid tropical regions where water is relatively abundant and the terrain is relatively flat, it is unclear whether these changes in ecosystem services matter to loc...

Study region In this study, we use stable isotopes of water to quantify the flow pathways delivering water to the tributaries, mainstem river and groundwater basin underlying urban San Diego. Information about sources of stormflow and recharge are necessary to maintain the health of waterways and aquifers, but studies of these processes are scarce...

Mega-gullies and landslides pose significant hazards to urban development on steep terrain. Water resources infrastructure failures (WRIFs), such as leaks and breaks in water supply pipes, have been postulated as a trigger of mass movement events but data for validation has been challenging to acquire since earthwork proceeds quickly after events t...

Tropical rainforests provide essential ecosystem services to agricultural areas, including moisture recycling. In the Amazon basin, drought frequency has increased in the late 20th and early 21st centuries, but the role of forests, ocean, and non‐forested areas in causing or mitigating drought has not been determined. Using a precipitationshed mois...

Amazonian tropical rainforest is being converted to other land cover types including crops and pasture. In deforested areas, secondary forest grows after pastures are abandoned, and ‘dirty pasture’ that has trees and shrubs but is actively used for grazing are also regionally important land cover types following forest conversion. This study descri...

Rainforest in protected areas in the Brazilian Amazon is at risk due to increasing economic pressures and recent weakening of environmental agencies and legislation by the federal administration. This study examines the impacts of deforestation in protected areas on dry‐season precipitation in the Brazilian state of Rondônia located in the southwes...

Sugarcane is often portrayed as one of the most environmentally sustainable food and energy crops, yet evidence of the crop's social and environmental impacts in Africa's growing sugarcane industry remains scarce. The land cover replaced by cane and subsequent land use practices play important roles in shaping the environmental impacts of expansion...

Image network geometry, including the number and orientation of images, impacts the error, coverage, and processing time of 3‐D terrain mapping performed using Structure‐from‐Motion and MultiView‐Stereo (SfM‐MVS). Few studies have quantified tradeoffs in error and processing time or ways to optimize image acquisition in diverse topographic conditio...

Land subsidence (LS) is a significant problem that can cause loss of life, damage property, and disrupt local economies. The Semnan Plain is an important part of Iran, where LS is a major problem for sustainable development and management. The plain represents the changes occurring in 40% of the country. We introduce a novel-ensemble intelligence a...

Algal blooms and the resulting deterioration of water quality have threatened the environmental health of inland lakes. This study investigated the spatiotemporal dynamics of gypsum blooms in the Salton Sea, the largest inland water body in California. An innovative gypsum bloom index (GI) was proposed to detect gypsum blooms based on Moderate Reso...

Características morfométricas e cobertura da terra influenciam na dinâmica de uma bacia hidrográfica e a quantificação das mesmas é necessária para um planejamento ambiental adequado. Objetivou-se caracterizar a morfometria e as taxas de desflorestamento da micro-bacia do rio Tinguí, onde ocorreram inundações em áreas urbanas, danificando proprieda...

The Brazilian Forest Code (BFC) requires the preservation and restoration of forests in riparian preservation areas (RPAs). The total area in RPAs and the impacts of changes in the BFC on RPA requirements are uncertain due to lack of clarity about how RPAs are defined in practice. We reconstruct the history of the RPA rule, use a recent cadastral d...

The project Improving the CalEnviroScreen score at the US-Mexico border report identifies air pollution sources in Baja California that might affect communities on the US side and model effects. This proposal is to improve environmental justice screening tools in California to best serve affected communities.

A quantitative understanding of the hydro-environmental factors that influence the occurrence of agricultural drought events would enable more strategic climate change adaptation and drought management plans. Practical drought hazard mapping remains challenging due to possible exclusion of the most pertinent drought drivers, and to the use of inade...

Urbanization can increase sheet, rill, gully, and channel erosion. We quantified the sediment budget of the Los Laureles Canyon watershed (LLCW), which is a mixed rural-urbanizing catchment in Northwestern Mexico, using the AnnAGNPS model and field measurements of channel geometry. The model was calibrated with five years of observed runoff and sed...

Land subsidence (LS) is among the most critical environmental problems, affecting both agricultural sustainability and urban infrastructure. Existing methods often use either simple regression models or complex hydraulic models to explain and predict LS. There are few studies that identify the risk factors and predict the risk of LS using machine l...

Land subsidence caused by land use change and overexploitation of groundwater is an example of mismanagement of natural resources, yet subsidence remains difficult to predict. In this study, the relationship between land subsidence features and geo-environmental factors is investigated by comparing two machine learning algorithms (MLA): maximum ent...

Excessive flooding and sedimentation threaten both ecosystems and human populations. On the US-Mexico border, urbanization has increased runoff and sedimentation loads. In the Tijuana-San Diego region, the Tijuana Estuary in the United States suffers from “excessive sedimentation”, and determining the source of the sediment and mitigating its produ...

We quantified effects of future climate warming on temperature and stability in a variably stratified, hypereutrophic reservoir with large fluctuations in water level by calibrating a 2-D model (CE-QUAL-W2, version 3.7.1, Portland State University, Portland, USA) of reservoir hydrodynamics using a time series (1992 to 2011) of inflow and air and wa...

Structure-from-Motion (SfM) photogrammetry is one of the most common approaches used to elaborate high-resolution Digital Elevation Models (DEMs) nowadays. Factors that influence the final error associated to the derived DEM are: camera-to-ground distance, camera-sensor system parameters, image network geometry, matching performance, terrain type,...

Structure-from-Motion (SfM) photogrammetry is one of the most common approaches used to elaborate high-resolution Digital Elevation Models (DEMs) nowadays. Factors that influence the final error associated to the derived DEM are: camera-to-ground distance, camera-sensor system parameters, image network geometry, matching performance, terrain type,...

Water circulation over coral reefs can determine the degree to which reef organisms are exposed to the overlying waters, so understanding circulation is necessary to interpret spatial patterns in coral health. Because coral reefs often have high geomorphic complexity, circulation patterns and the duration of exposure, or “local residence time” of a...

Both rural and urban development can lead to accelerated gully erosion. Quantify gully erosion is challenging in environments where gullies are rapidly repaired, and in urban areas where microtopographic complexity complicates the delineation of contributing areas. This study used Unmanned Aerial Systems (UASs) and Structure‐from‐Motion (SfM) photo...

Modelling gully erosion in urban areas is challenging due to difficulties with equifinality and parameter identification, which complicates quantification 0of management impacts on runoff and sediment production. We calibrated a model (AnnAGNPS) of an ephemeral gully network that formed on unpaved roads following a storm event in an urban watershed...

Hydrological models often perform poorly in simulating dry years in regions with large inter-annual variability in rainfall. We calibrated the Soil and Water Assessment Tool (SWAT) model to dry and wet years separately, using the semi-arid Barrett watershed on the west coast of USA as an example. We used hydrological and meteorological data from 19...

Urbanization can lead to accelerated stream channel erosion, especially in areas experiencing rapid population growth, unregulated urban development on erodible soils, and variable enforcement of environmental regulations. A combination of field surveys and Structure-from-Motion (SfM) photogrammetry techniques were used to document spatial patterns...

Upland soil erosion and sedimentation are the main threats for riparian and coastal reef ecosystems of watersheds, especially in Pacific islands. Due to small size and steep nature of the watersheds, the residence time of rainfall-runoff and its sediment yield is short. Fagaʹalu watershed, located on the island of Tutuila (American Samoa) was ident...

The 2010 BP Deepwater Horizon (DWH) oil spill damaged thousands of km² of intertidal marsh along shorelines that had been experiencing elevated rates of erosion for decades. Yet, the contribution of marsh oiling to landscape-scale degradation and subsequent land loss has been difficult to quantify. Here, we applied advanced remote sensing technique...

The numerous lakes on the Tibetan Plateau (TP) play an important role in the regional hydrological cycle and water resources, but systematic observations of the lake water balance are scarce on the TP. Here we present a detailed study on the water cycle of Cona Lake, at the headwater of Nujiang-Salween River, based on three years (2011-2013) of obs...

The surface energy balance algorithm for land (SEBAL) estimates land surface evapotranspiration (ET) from radiometric surface temperature (TR), but requires manual selection of calibration pixels, which can be impractical for mapping seasonal ET. Here, pixel selection is automated and SEBAL implemented using global climate grids and satellite image...

Suspended sediment concentrations (SSC) and yields (SSY) were measured during storm and non-storm periods from undisturbed and human-disturbed portions of a small (1.8 km2), mountainous watershed that drains to a sediment-stressed coral reef. Event-wise SSY (SSYEV) was calculated for 142 storms from measurements of water discharge (Q), turbidity (T...

Evapotranspiration (ET) is an important component of micro- and macro-scale climatic processes. In agriculture, estimates of ET are frequently used to monitor droughts, schedule irrigation, and assess crop water productivity over large areas. Currently, in situ measurements of ET are difficult to scale up for regional applications, so remote sensin...

Large numbers of lakes on the Tibetan Plateau (TP) play an important role in the regional hydrological cycle, and the river systems they occur in serve as important water resources for more than a billion people, but systematic observations of the lake water balance is scarce on the TP. Stable isotopes of water (δ18O and δD) can be used to understa...

Isotopes of oxygen and hydrogen in water from streams, snow, and lakes were used to model the ratio of evaporation to total inflow (E/I) of four high elevation lakes in closed basins in the Indian Himalaya. Air temperature and relative humidity (h) data from meteorological stations and global climate grids (GMAO-MERRA) were used as input to the mod...

Impervious surface cover is often associated with low socioeconomic status (SES) and vegetation with high SES in urban areas in both developed and developing countries. This study documents the relationships among land cover, number of years urbanized (YR), topographic slope, and socioeconomic indicators, including a socioeconomic marginality index...

Growing cities and their demand for water challenges the management of water resources and provides opportunities for wastewater use in irrigated agriculture. In the cases studied, large volumes of fresh water are extracted from sources often located increasingly further away from the city, while investments in wastewater disposal often lag behind....