Surface Evaporation in Arid Regions: Insights From Lysimeter Decadal Record and Global Application of a Surface Evaporation Capacitor (SEC) Model

Lehmann, Peter; Berli, Markus; Koonce, Jeremy; Or, Dani

doi:10.1029/2019gl083932

Cited by 32 publications

(21 citation statements)

References 34 publications

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“…Figure 3 shows additional comparisons of BVG and PDI simulation results using measurements from depths of 25, 50, and 150 cm in the lysimeter soil from Day 320 to Day 365 (which is the same time period shown in Figure 2). These depths were chosen because 25 and 50 cm are the two depths (besides 10 cm) where most of the short‐term soil moisture changes occur because of precipitation and evaporation (Koonce, 2016; Lehmann, Berli, Koonce, & Or, 2019), and 150 cm is the center of the lysimeter soil profile. Four replicate soil moisture measurements were available per depth (25, 50, and 150 cm).…”

Section: Resultsmentioning

confidence: 99%

Modeling near‐surface water redistribution in a desert soil

Luo

Ghezzehei

et al. 2020

Vadose Zone Journal

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Despite the vast extent of desert soils on the earth's surface, our understanding of the moisture dynamics of near-surface desert soils (i.e., the top centimeters to few meters of the soil profile) remain limited. The goal of this study was to explore the use of the Peters-Durner-Iden (or PDI) instead of bimodal van Genuchten (or BVG) hydraulic functions to improve water redistribution simulations using HYDRUS-1D for drier soils in desert environments. The PDI hydraulic functions take capillary and film flow into account, whereas BVG hydraulic functions are limited to capillary flow. By comparing measured with simulated water content data, we found that moisture redistribution simulations were improved by using PDI instead of BVG soil water retention and hydraulic conductivity functions. Compared with the BVG simulations, the PDI simulations particularly improved for drier soil conditions (i.e., volumetric water contents ranging from 6 to 10%; suction heads between pF 2 and pF 3.8, and saturation degrees between 19 and 32%, respectively) for the studied sandy soil of Scaling Environmental Processes in Heterogeneous Arid Soils (SEPHAS) Lysimeter 1. For pF >3, the PDI functions predicted higher hydraulic conductivity than the BVG functions, which confirmed the hypothesis that a hydraulic conductivity function, which can capture film flow, may improve moisture distribution simulations for dry soils. For pF between 2 and 3, however, simulation results improved due to the difference in the water retention rather than the hydraulic conductivity function.

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Section: Resultsmentioning

confidence: 99%

Modeling near‐surface water redistribution in a desert soil

Luo

Ghezzehei

et al. 2020

Vadose Zone Journal

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“…Negative values were set to zero. Soil evaporation was calculated using the surface evaporative capacitance (SEC) concept (Lehmann et al, 2019; Or & Lehmann, 2019). The SEC is a one‐dimensional model for the water dynamics within the soil layer from where water can be extracted by evaporation.…”

Section: Methodsmentioning

confidence: 99%

Annual precipitation explains variability in dryland vegetation greenness globally but not locally

Ukkola

Kauwe

Roderick

et al. 2021

Global Change Biology

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Dryland vegetation productivity is strongly modulated by water availability. As precipitation patterns and variability are altered by climate change, there is a pressing need to better understand vegetation responses to precipitation variability in these ecologically fragile regions. Here we present a global analysis of dryland sensitivity to annual precipitation variations using long‐term records of normalized difference vegetation index (NDVI). We show that while precipitation explains 66% of spatial gradients in NDVI across dryland regions, precipitation only accounts for <26% of temporal NDVI variability over most (>75%) dryland regions. We observed this weaker temporal relative to spatial relationship between NDVI and precipitation across all global drylands. We confirmed this result using three alternative water availability metrics that account for water loss to evaporation, and growing season and precipitation timing. This suggests that predicting vegetation responses to future rainfall using space‐for‐time substitution will strongly overestimate precipitation control on interannual variability in aboveground growth. We explore multiple mechanisms to explain the discrepancy between spatial and temporal responses and find contributions from multiple factors including local‐scale vegetation characteristics, climate and soil properties. Earth system models (ESMs) from the latest Coupled Model Intercomparison Project overestimate the observed vegetation sensitivity to precipitation variability up to threefold, particularly during dry years. Given projections of increasing meteorological drought, ESMs are likely to overestimate the impacts of future drought on dryland vegetation with observations suggesting that dryland vegetation is more resistant to annual precipitation variations than ESMs project.

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“…Water applied to topsoil is lost via evaporation, transpiration, and percolation (Sutanto, 2012). High temperatures and dry winds in arid and semi-arid regions lead to substantial evaporative and transpiration losses (Al-Naizy, 2012, Balugani et al, 2017), whereas percolation is due to the poor water-holding capacity of sandy soils (Lehmann et al, 2019, Or and Lehmann, 2019). These water losses are compensated via irrigation that, due to the sheer size of agricultural operations, claims the lion’s share (approximately 80%) of global annual freshwater consumption (2500 km 3 /yr) (Shiklomanov, 2000, Hoekstra and Mekonnen, 2012).…”

Section: Introductionmentioning

confidence: 99%

Effects of Superhydrophobic Sand Mulching on Evapotranspiration and Phenotypic Responses in Tomatoes (Solanum lycopersicum) under Normal and Reduced Irrigation

Odokonyero

Gallo

Santos

et al. 2021

Preprint

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Irrigated agriculture in arid and semi-arid regions is a vital contributor to the global food supply; however, these regions endure massive evaporative losses that are compensated by unsustainable freshwater withdrawals. Plastic mulches have been used to curtail evaporation, improve water-use efficiency, and ensure food–water security, but they are non-biodegradable and their disposal is unsustainable. We recently developed superhydrophobic sand (SHS), which comprises sand grains with a nanoscale wax coating that could offer a more sustainable mulching solution. Here, the effects of adding a 1.0 cm-thick layer of SHS mulch on the evapotranspiration and phenotypic responses of tomato (Solanum lycopersicum) plants are studied under normal and reduced irrigation. Under both irrigation regimes, SHS mulching suppressed evaporation and enhanced transpiration by 78% and 17%, respectively relative to the bare soil. Overall, SHS mulching enhanced root xylem vessel diameter, stomatal aperture, stomatal conductance, and chlorophyll content index by 21%, 25%, 28%, and 23%, respectively. Total fruit yields, total dry mass, and harvest index increased in SHS-mulched plants by 33%, 20%, and 16%, respectively than in bare soil. These findings demonstrate the potential of SHS to boost irrigation efficiency in water-limited environments and provide mechanistic insights behind yield enhancement by SHS mulching.

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Surface Evaporation in Arid Regions: Insights From Lysimeter Decadal Record and Global Application of a Surface Evaporation Capacitor (SEC) Model

Cited by 32 publications

References 34 publications

Modeling near‐surface water redistribution in a desert soil

Modeling near‐surface water redistribution in a desert soil

Annual precipitation explains variability in dryland vegetation greenness globally but not locally

Effects of Superhydrophobic Sand Mulching on Evapotranspiration and Phenotypic Responses in Tomatoes (Solanum lycopersicum) under Normal and Reduced Irrigation

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