Evapotranspiration measurements in the Brazilian Caatinga dry forest

2021 ◽  
Author(s):  
José Carlos de Araújo ◽  
Lucas Melo Vellame ◽  
Armin Raabe ◽  
Quirijn de Jong van Lier
Keyword(s):  
Water Availability ◽  
Global Radiation ◽  
Dry Season ◽  
Dry Forest ◽  
Actual Evapotranspiration ◽  
Semiarid Region ◽  
Application Site ◽  
Net Radiation ◽  
Simple Method ◽  
The North

<p>The Brazilian semiarid region (one million km²) is densely populated (25 million inhabitants), but its natural water availability is low. Despite the fact that evaporative processes are key to the regional water deficit, the actual evapotranspiration of natural environment has rarely been measured, especially in the native Caatinga dry forest. We hereby propose a simple method that demands the monitoring of five meteorological variables: relative humidity, global radiation, canopy and air temperature, as well as wind speed. These values are used to assess leaf energy balance, yielding net radiation (Rn) and actual evapotranspiration (LE). To estimate the actual Caatinga evapotranspiration under natural conditions and in different seasons, the proposed method was applied <em>in situ</em> during nine months. The application site was the Aiuaba Experimental Basin, situated in an environmental protection area in the North-eastern Brazil. The method provided consistent results when compared with independent measurements, such as atmospheric demand, leaf area, and soil water content variation. Results indicate that the daily average net radiation is 12 MJ m<sup>-</sup>². During the dry season, the actual evapotranspiration is very low, with negligible LE/Rn ratio. Contrastingly, in the rainy season, it raises to 6 mm per day, with average LE/Rn ratio equalling 0.89. The results show that the actual evapotranspiration in the Caatinga long-lasting dry season (up to nine months per year) is controlled by the water availability in the soil.</p>

scholarly journals A Thermodynamically Based Model for Actual Evapotranspiration of an Extensive Grass Field Close to FAO Reference, Suitable for Remote Sensing Application

2016 ◽  
Vol 17 (5) ◽  
pp. 1373-1382 ◽  
Author(s):  
H. A. R. de Bruin ◽  
I. F. Trigo ◽  
F. C. Bosveld ◽  
J. F. Meirink
Keyword(s):  
Global Radiation ◽  
Actual Evapotranspiration ◽  
Net Radiation ◽  
Reference Crop Evapotranspiration ◽  
In Situ Data ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
A Site ◽  
Reference Crop

Abstract A thermodynamically based model is presented to estimate daily actual evapotranspiration (ET) of a grass site closely resembling reference grass as defined by the Food and Agriculture Organization of the United Nations (FAO) under nonadvective conditions, from Meteosat Second Generation (MSG) imagery. The model presented here is derived from the thermodynamic theory by Schmidt combined with an atmospheric boundary layer model. Daily net radiation over the (reference) grass surface is parameterized as a function of global radiation, which can be estimated from MSG observations. It is then shown that ET over the grass area can be estimated using remotely sensed daily global radiation and air temperature as input only. The validation relied on observations gathered in Cabauw, a site closely resembling the reference grass, as defined by the FAO. The comparison with in situ data indicated a bias of 2.8 W m−2 and an RMSE of 7.7 W m−2. The possibility of using the approach developed here to provide reference crop evapotranspiration ETo is discussed. Because of the ambiguousness of ETo definition regarding local advection effects, it should be noted that explicitly advection-free conditions are dealt with. It is pointed out that in semiarid regions local advection cannot be ignored.

scholarly journals Spatial and temporal variations of aridity shape dung beetle assemblages towards the Sahara desert

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5210 ◽  
Author(s):  
Indradatta deCastro-Arrazola ◽  
Joaquín Hortal ◽  
Marco Moretti ◽  
Francisco Sánchez-Piñero
Keyword(s):  
Species Richness ◽  
Water Availability ◽  
Variation Partitioning ◽  
Dung Beetle ◽  
Mediterranean Coast ◽  
Dry Season ◽  
Semiarid Region ◽  
Wet Season ◽  
The Mediterranean ◽  
Linear Regressions

BackgroundAssemblage responses to environmental gradients are key to understand the general principles behind the assembly and functioning of communities. The spatially and temporally uneven distribution of water availability in drylands creates strong aridity gradients. While the effects of spatial variations of aridity are relatively well known, the influence of the highly-unpredictable seasonal and inter-annual precipitations on dryland communities has been seldom addressed.AimsHere, we study the seasonal and inter-annual responses of dung beetle (Coleoptera, Scarabaeidae) communities to the variations of water availability along a semiarid region of the Mediterranean.MethodsWe surveyed a 400 km linear transect along a strong aridity gradient from the Mediterranean coast to the Sahara (Eastern Morocco), during four sampling campaigns: two in the wet season and two in the dry season. We measured species richness, abundance and evenness. Variations in community composition between sites, seasons and years were assessed through beta diversity partitioning of dissimiliarity metrics based on species occurrences and abundances. The effects of climate, soil, vegetation and dung availability were evaluated using Spearman-rank correlations, general linear regressions and partial least-squares generalized linear regressions for community structure, and non-metric multi-dimensional scaling, Permutational Analysis of Variance (PERMANOVA) and distance-based RDA variation partitioning for compositional variations.ResultsDung beetle abundance and species richness showed large seasonal variations, but remained relatively similar between years. Indeed, aridity and its interaction with season and year were the strongest correlates of variations in species richness and composition. Increasing aridity resulted in decreasing species richness and an ordered replacement of species, namely the substitution of the Mediterranean fauna by desert assemblages dominated by saprophagous and generalist species both in space towards the Sahara and in the dry season.DiscussionOur study shows that aridity determines composition in dung beetle communities, filtering species both in space and time. Besides the expected decrease in species richness, such environmental filtering promotes a shift towards generalist and saprophagous species in arid conditions, probably related to changes in resource quality along the transect and through the year. Our results highlight the importance of considering the effects of the highly-unpredictable seasonal and inter-annual variations in precipitation when studying dryland communities.

scholarly journals A 10-Year Dataset of Basic Meteorology and Soil Properties in Central Sudan

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jonas Ardö
Keyword(s):  
Soil Properties ◽  
Meteorological Data ◽  
Global Radiation ◽  
Semiarid Region ◽  
Net Radiation ◽  
Ecosystem Models ◽  
Central Sudan ◽  
General Data ◽  
A Site ◽  
Temperature Water

Meteorological data and soil data have been collected at a site in the central Sudan from 2002 to 2012. The site is a sparse savanna in the semiarid region of Sudan. In addition to basic meteorological variables, soil properties (temperature, water content, and heat flux) and radiation (global radiation, net radiation, and photosynthetic active radiation) were measured. The dataset has a temporal resolution of 30 minutes and provides general data for calibration and validation of ecosystem models and remote-sensing-based assessments, and it is relevant for studies of ecosystem properties and processes.

scholarly journals Soil Moisture Dynamics in Response to Precipitation and Thinning in a Semi-Dry Forest in Northern Mexico

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 105
Author(s):  
Argelia E. Rascón-Ramos ◽  
Martín Martínez-Salvador ◽  
Gabriel Sosa-Pérez ◽  
Federico Villarreal-Guerrero ◽  
Alfredo Pinedo-Alvarez ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Forest Management ◽  
Water Availability ◽  
Dry Forest ◽  
Rainfall Events ◽  
Rainfall Characteristics ◽  
Northern Mexico ◽  
The Difference ◽  
The Impact ◽  
Moisture Dynamics

Understanding soil moisture behavior in semi-dry forests is essential for evaluating the impact of forest management on water availability. The objective of the study was to analyze soil moisture based in storm observations in three micro-catchments (0.19, 0.20, and 0.27 ha) with similar tree densities, and subject to different thinning intensities in a semi-dry forest in Chihuahua, Mexico. Vegetation, soil characteristics, precipitation, and volumetric water content were measured before thinning (2018), and after 0%, 40%, and 80% thinning for each micro-catchment (2019). Soil moisture was low and relatively similar among the three micro-catchments in 2018 (mean = 8.5%), and only large rainfall events (>30 mm) increased soil moisture significantly (29–52%). After thinning, soil moisture was higher and significantly different among the micro-catchments only during small rainfall events (<10 mm), while a difference was not noted during large events. The difference before–after during small rainfall events was not significant for the control (0% thinning); whereas 40% and 80% thinning increased soil moisture significantly by 40% and 53%, respectively. Knowledge of the response of soil moisture as a result of thinning and rainfall characteristics has important implications, especially for evaluating the impact of forest management on water availability.

Recycling of Greywater (GW) through Natural Adsorbents

2018 ◽  
Vol 7 (3.12) ◽  
pp. 1140 ◽  
Author(s):  
Mukesh Chandra Kestwal ◽  
Ravi Kumar Patel ◽  
Benoit Teychene ◽  
Prasenjit Mondal ◽  
Sukdeb Pal ◽  
...  
Keyword(s):  
Water Availability ◽  
Water Scarcity ◽  
Secondary Treatment ◽  
Valuable Resource ◽  
Simple Method ◽  
Household Level ◽  
Natural Adsorbent ◽  
Minimum Change ◽  
Natural Adsorbents ◽  
Individual Household

Reuse of water has been a popular choice toward balancing water scarcity and managing water availability in defined areas.  GW which can be defined as the wastewater that comprises water from baths, showers etc, when managed and treated properly could be valuable resource for sectors like agricultural and horticultural. GW is one of the best option if treated and if not, it will mix with the sewage stream. It is possible to intercept this GW at the household level using minimum change in design, and with the primary and secondary treatment it can be recycled for garden washing, flushing and many purposes. In the present work, GW from student accommodation were collected, characterized and treated through series of natural adsorbent. Various parameters such as TDS, pH, Turbidity, BOD,COD, amount of nitrate and phosphorus were measured and it was found that most of the parameters were considerably in range after treatment.  A simple method has been proposed that may be applied at individual household level. 

scholarly journals Analysing surface energy balance closure and partitioning over a semi-arid savanna FLUXNET site in Skukuza, Kruger National Park, South Africa

2017 ◽  
Vol 21 (7) ◽  
pp. 3401-3415 ◽  
Author(s):  
Nobuhle P. Majozi ◽  
Chris M. Mannaerts ◽  
Abel Ramoelo ◽  
Renaud Mathieu ◽  
Alecia Nickless ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Latent Heat ◽  
Surface Energy Balance ◽  
Sensible Heat Flux ◽  
Dry Season ◽  
Energy Balance Closure ◽  
Net Radiation ◽  
Wet Season

Abstract. Flux towers provide essential terrestrial climate, water, and radiation budget information needed for environmental monitoring and evaluation of climate change impacts on ecosystems and society in general. They are also intended for calibration and validation of satellite-based Earth observation and monitoring efforts, such as assessment of evapotranspiration from land and vegetation surfaces using surface energy balance approaches. In this paper, 15 years of Skukuza eddy covariance data, i.e. from 2000 to 2014, were analysed for surface energy balance closure (EBC) and partitioning. The surface energy balance closure was evaluated using the ordinary least squares regression (OLS) of turbulent energy fluxes (sensible (H) and latent heat (LE)) against available energy (net radiation (Rn) less soil heat (G)), and the energy balance ratio (EBR). Partitioning of the surface energy during the wet and dry seasons was also investigated, as well as how it is affected by atmospheric vapour pressure deficit (VPD), and net radiation. After filtering years with low-quality data (2004–2008), our results show an overall mean EBR of 0.93. Seasonal variations of EBR also showed the wet season with 1.17 and spring (1.02) being closest to unity, with the dry season (0.70) having the highest imbalance. Nocturnal surface energy closure was very low at 0.26, and this was linked to low friction velocity during night-time, with results showing an increase in closure with increase in friction velocity. The energy partition analysis showed that sensible heat flux is the dominant portion of net radiation, especially between March and October, followed by latent heat flux, and lastly the soil heat flux, and during the wet season where latent heat flux dominated sensible heat flux. An increase in net radiation was characterized by an increase in both LE and H, with LE showing a higher rate of increase than H in the wet season, and the reverse happening during the dry season. An increase in VPD is correlated with a decrease in LE and increase in H during the wet season, and an increase in both fluxes during the dry season.

scholarly journals Interplay of riparian forest and groundwater in the hillslope hydrology of Sudanian West Africa (northern Benin)

2013 ◽  
Vol 17 (12) ◽  
pp. 5079-5096 ◽  
Author(s):  
A. Richard ◽  
S. Galle ◽  
M. Descloitres ◽  
J.-M. Cohard ◽  
J.-P. Vandervaere ◽  
...  
Keyword(s):  
West Africa ◽  
Transpiration Rate ◽  
Riparian Forest ◽  
Dry Season ◽  
Groundwater Table ◽  
Actual Evapotranspiration ◽  
Virtual Experiment ◽  
Deep Groundwater ◽  
Riparian Area ◽  
Study Results

Abstract. Forests are thought to play an important role in the regional dynamics of the West African monsoon, through their capacity to extract water from a permanent and deep groundwater table to the atmosphere even during the dry season. It should be the case for riparian forests too, as these streambank forests are key landscape elements in Sudanian West Africa. The interplay of riparian forest and groundwater in the local hydrodynamics was investigated, by quantifying their contribution to the water balance. Field observations from a comprehensively instrumented hillslope in northern Benin were used. Particular attention was paid to measurements of actual evapotranspiration, soil water and deep groundwater levels. A vertical 2-D hydrological modelling approach using the Hydrus software was used as a testing tool to understand the interactions between the riparian area and the groundwater. The model was calibrated and evaluated using a multi-criteria approach (reference simulation). A virtual experiment, including three other simulations, was designed (no forest, no groundwater, neither forest nor groundwater). The model correctly simulated the hydrodynamics of the hillslope regarding vadose zone dynamics, deep groundwater fluctuation and actual evapotranspiration dynamics. The virtual experiment showed that the riparian forest transpiration depleted the deep groundwater table level and disconnected it from the river, which is consistent with the observations. The riparian forest and the deep groundwater table actually form an interacting transpiration system: the high transpiration rate in the riparian area was shown to be due to the existence of the water table, supplied by downslope lateral water flows within the hillslope soil layer. The simulated riparian transpiration rate was practically steady all year long, around 7.6 mm d−1. This rate lies within high-end values of similar study results. The riparian forest as simulated here contributes to 37% of the annual hillslope transpiration, and reaches 57% in the dry season, whereas it only covers 5% of the hillslope area.

scholarly journals Thermal performance and concentration of gases in facilities for pigs in semiarid region from State of Paraiba - Brazil

2012 ◽  
Vol 32 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Dermeval A. Furtado ◽  
Daniele Amancio ◽  
José W. B. do Nascimento ◽  
Josivanda P. Gomes ◽  
Rafael C. Silva
Keyword(s):  
Carbon Monoxide ◽  
Thermal Comfort ◽  
Rainy Season ◽  
Dry Season ◽  
International Standards ◽  
Semiarid Region ◽  
Thermal Discomfort ◽  
Rainy Period ◽  
Globe Temperature ◽  
The Times

The study was conducted in a facility for pigs during the nursery and finishing in the town of 'Montadas', in the semiarid of the state of Paraiba, Brazil, in the rainy and dry season, aiming to evaluate the concentration of oxygen, methane, carbon monoxide and ammonia, and the bioclimatic indexes: ambient temperature (AT), relative humidity (RH) and the index of black globe temperature and humidity (IBGTH). These indexes differed significantly (P>0.05) between the periods and times. The AT in the rainy season was in the thermal comfort zone(TCZ) in most of the times in the nursery; for the finishing phase, thermal discomfort occurred; during the dry season, there was thermal comfort in the nursery phase; in the finishing phase the thermal discomfort occurred at all times. In the rainy season, the IBGTH was in TCZ; in the dry season, it was above the TCZ. The RH in the rainy period was in the TCZ; in the dry season, in most of the times, below the range of the TCZ. The concentration of gases showed no differences (P > 0.05) between periods and between the times, and the carbon monoxide, hydrogen sulfide and methane were below 1.0 ppm, and the ammonia showed a mean of 5.2 ppm. None of the analyzed gases exceeded the limits established by Brazilian and international standards for animals and workers.

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