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Cellulose in particular and phytomass in general are at the heart of our food system. They are also a central energy vector and a vital source of materials. In this article, a multiscale approach to the complex issue of lignocellulose sustainability is developed. Global thermodynamic concepts help to place current biomass exploitation in a global energetic context. In particular, the notion of entropy appears pivotal to understand energy and material fluxes at the scale of the planet and the limits of biomass production. Entropy is, however, best described at the microscopic scale, despite its large-scale consequences. Recent advances in entropy-driven colloid assembly parallel nature's choices and lignocellulose assembly at the nanometric scale. The functional concept of exergy is then developed and a few examples of its concrete use in photosynthesis and biorefinery research are given. In a subsequent part, an evaluation of the relative importance of biomass is performed with respect to non-renewable materials. This discussion helps to explain the interdependence of resources, including ores and fossil fuels. This interdependence has important consequences for current and future biomass uses. Some of these dependences are then quantitatively discussed using life cycle analysis (LCA) results from the literature. These results are of importance to different technological fields such as paper, biobased insulation, construction wood, information and communication technologies, and biobased textiles. A conclusion is then drawn that exposes the research tracks that are the most likely to be sustainable, including self-assembly, exergetically favourable options and low tech solutions. [ABSTRACT FROM AUTHOR]

In this study, mercerisation of native cellulose I was achieved in an aqueous sodium hydroxide solution at a concentration of only 1 wt% NaOH by processing at temperatures below 0 °C. This represents a tenfold reduction in the use of NaOH to accomplish this very common transformation. The cellulose sample was a form of hydrolysed cotton with a high crystallinity. The samples were mixed with aqueous sodium hydroxide at various concentrations and stored at −17 °C. The samples were then defrosted, neutralised and dried before being analysed by Fourier-transform infrared spectroscopy, wide-angle X-ray diffraction and field-emission scanning electron microscopy. In the route described here, transformation from cellulose I to cellulose II was possible without greatly affecting the crystallinity or the microstructure of the samples. [ABSTRACT FROM AUTHOR]

The dominant patterns of vegetation cover interannual variability over Morocco are isolated using rotated extended empirical orthogonal functions applied to AVHRR NDVI data (1982-2008). The three leading modes capture the NDVI signal at the vegetation peak for three distinct locations: mode 1 (18.7% of total variance) is located along the Atlantic coastline, mode 2 (13.1%) is southwest of the Riff Mountain whilst mode 3 (11.2%) is along the Mediterranean coastline. Correlations between the NDVI time coefficients for the modes 'Atlantic' and 'Mediterranean' dominated by annuals and precipitation amount during the early stage of the vegetation cycle (NDJ) are found. Significant fluctuations of NDVI time coefficients are isolated: a quasi-biennial signal is present in the three modes and an additional quasi-quadriennial (∼4.4 years) signal is identified for the 'Atlantic' mode only. Connection between vegetation activity and atmospheric and oceanic climate signals are sought using time-lag correlation analyses. The NAO during fall-beginning of winter (NDJ) is found to impact vegetation peak for the 'Atlantic' mode while the Scandinavian Pattern is related to NDVI peak over the 'Atlantic' and 'Riff' latter in the season (DJF). A significant connection is also found between vegetation over the 'Atlantic' mode and the 'Riff' and the 'Atlantic Niño' mode leading the SST variability in the equatorial Atlantic with a 6-months lag. Finally, linkages between NDVI and climate information are used to build a seasonal prediction model for NDVI using multiple linear regression. The NDVI anomalies during March-April may be predicted with a reasonable accuracy from January with 79% of explained variance, 60% and 72% for the 'Atlantic', the 'Riff' and the 'Mediterranean' regions, respectively. Results have (1) direct impacts for a better understanding of the role of large-scale climate signals on vegetation cover over Morocco and (2) contribute to the implementation of an agricultural early warning system. [ABSTRACT FROM AUTHOR]

The objective of this study is to get a better understanding of radar signal over irrigated wheat fields and to assess the potentialities of radar observations for the monitoring of soil moisture. Emphasis is put on the use of high spatial and temporal resolution satellite data (Envisat/ASAR and Formosat-2). Time series of images were collected over the Yaqui irrigated area (Mexico) throughout one agricultural season from December 2007 to May 2008, together with measurements of soil and vegetation characteristics and agricultural practices. The comprehensive analysis of these data indicates that the sensitivity of the radar signal to vegetation is masked by the variability of soil conditions. On-going irrigated areas can be detected all over the wheat growing sea- son. The empirical algorithm developed for the retrieval of topsoil moisture from Envisat/ASAR images takes advantage of the Formosat-2 instrument capabilities to monitor the seasonality of wheat canopies. This monitoring is performed using dense time series of images acquired by Formosat-2 to set up the SAFY vegetation model. Topsoil moisture estimates are not reliable at the timing of plant emergence and during plant senescence. Estimates are accurate from tillering to grain filling stages with an absolute error about 9% (0.09m-³ m-3 , 35% in relative value). This result is attractive since topsoil moisture is estimated at a high spatial resolution (i.e. over subfields of about 5 ha) for a large range of biomass water content (from 5 and 65 t ha-1) independently from the viewing angle of ASAR acquisition (incidence angles IS1 to IS6). [ABSTRACT FROM AUTHOR]

The present paper proposes a method for the evaluation of soil evaporation, using soil moisture estimations based on radar satellite measurements. We present firstly an approach for the estimation and monitoring of soil moisture in a semi-arid region in North Africa, using ENVISAT ASAR images, over two types of vegetation covers. The first mapping process is dedicated solely to the monitoring of moisture variability related to rainfall events, over areas in the "non-irrigated olive tree" class of land use. The developed approach is based on a simple linear relationship between soil moisture and the backscattered radar signal normalised at a reference incidence angle. The second process is proposed over wheat fields, using an analysis of moisture variability due to both rainfall and irrigation. A semi-empirical model, based on the water-cloud model for vegetation correction, is used to retrieve soil moisture from the radar signal. Moisture mapping is carried out over wheat fields, showing high variability between irrigated and non-irrigated wheat covers. This analysis is based on a large database, including both ENVISAT ASAR and simultaneously acquired ground-truth measurements (moisture, vegetation, roughness), during the 2008-2009 vegetation cycle. Finally, a semi-empirical approach is proposed in order to relate surface moisture to the difference between soil evaporation and the climate demand, as defined by the potential evaporation. Mapping of the soil evaporation is proposed. [ABSTRACT FROM AUTHOR]

The present paper proposes an empirical approach for the modeling of vegetation development, using moisture measurements only. The study is based simply on the use of two databases: one containing soil moisture products derived from ERS scatterometer data over the period 1991-2006 and the other containing normalized difference vegetation indices (NDVI) derived from advanced very high resolution radiometer over the period 1991-2000. The study is applied over the Kairouan plain, the central semiarid region of Tunisia (North Africa). Soil moisture products were first validated on the basis of comparisons with Global Soil Wetness Project, Phase 2 Data, outputs and rainfall events. The soil moisture distribution during the rainy period between October and May is described and is found to be correlated with the vegetation dynamics estimated using the NDVI products. Finally, a semiempirical model is proposed, based on satellite moisture and NDVI products, which allows the NDVI value to be estimated for a period of 1 month during the rainy season as a function of the moisture profile estimations obtained during the previous months. This approach could prove very useful and provide a simple tool for the modeling of vegetation dynamics during rainy seasons in semiarid regions. [ABSTRACT FROM AUTHOR]

The aim of this study is to propose methods to improve crop and water management in Mediterranean regions. At landscape scale, there is a very large spatial variability of agricultural practices, particularly for grasslands irrigated by flooding. These grasslands are harvested three times per year and produce high quality hay, but their productions decreased significantly these last few years because of the water scarcity. It is therefore important to assess the real water requirement for crops in order to predict productions in the case of agricultural practice modifications. Until now, the spatial variability of agricultural practices was obtained through surveys from farmers, but this method was tedious to describe an entire region. Thus, the specific aim of the study is to propose a new approach based on: 1) the feasibility of using optical remote sensing data acquired at high spatio-temporal resolutions for agricultural practice monitoring and, 2) the evaluation of a crop model, forced with this data, for estimating water balance and crop yield. We developed a methodology based on the combined use of FORMOSAT-2 images and STICS crop model to estimate production, evapotranspiration and drainage of irrigated grasslands in "the Crau" region in the South Eastern France. Numerous surveys and ground measurements were performed during an experiment conducted in 2006. Simple algorithms were developed to retrieve the dynamic of Leaf Area Index (LAI) for each plot and the main agricultural practices such as mowing and irrigation dates. This information was then used to parameterize STICS, applied at region scale to estimate the spatial variability of water budget associated with the biomass productions. Results are displayed at the farm scale. Satisfactory results were obtained when compared to ground measurements. The method for extrapolation to other regions or crops is discussed as regard to data available. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study is to present a new application of optical and radar remote sensing with high spatial (∼10m) and temporal (a few days) resolutions for the detection of tillage and irrigation operations. The analysis was performed for irrigated wheat crops in the semi-arid Tensift/Marrakech plain (Central Morocco) using three FORMOSAT-2 images and two ASAR images acquired within one week at the beginning of the 2005/2006 agricultural season. The approach we developed uses simple mapping algorithms (band thresholding and decision tree) for the characterisation of soil surface states. The first images acquired by FORMOSAT and ASAR were processed to classify fields into three main categories: ploughed (in depth), prepared to be sown (harrowed), and not ploughed-not harrowed. This information was combined with a change detection analysis based on multitemporal images to identify harrowing and irrigation operations which occurred between two satellite observations. The performance of the algorithm was evaluated using data related to land use and agricultural practices collected on 124 fields. The analysis shows that drastic changes of surface states caused by ploughing or irrigation are detected without ambiguity (consistency index of 96%). This study provided evidence that optical and radar data contain complementary information for the detection of agricultural operations at the beginning of agricultural season. This information could be useful in regional decision support systems to refine crop calendars and to improve prediction of crop water needs over large areas. [Copyright &y& Elsevier]

Earth Observing Systems designed to provide both high spatial resolution (10 m) and high capacity of time revisit (a few days) offer strong opportunities for the management of agricultural water resources. The FORMOSAT-2 satellite is the first and only satellite with the ability to provide daily high-resolution images over a particular area with constant viewing angles. As part of the SudMed project, one of the first time series of FORMOSAT-2 images has been acquired over the semi-arid Tensift-Marrakech plain. Along with these acquisitions, an experimental data set has been collected to monitor land-cover/land-use, soil characteristics, vegetation dynamics and surface fluxes. This paper presents a first analysis of the potential of these data for agrometerological study of semi-arid areas. [ABSTRACT FROM AUTHOR]

Recent efforts have been concentrated in the development of models to understand and predict the impact of environmental changes on hydrological cycle and water resources in arid and semi-arid regions. In this context, remote sensing data have been widely used to initialize, to force, or to control the simulations of these models. However, for several reasons, including the difficulty in establishing relationships between observational and model variables, the potential offered by satellite data has not been fully used. As a matter of fact, a few hydrological studies that use remote sensing data emanating from different sources (sensors, platforms) have been performed. In this context, the SUDMED programme has been designed in 2002 to address the issue of improving our understanding about the hydrological functioning of the Tensift basin, which is a semi-arid basin situated in central Morocco. The first goal is model development and/or refinement, for investigating the hydrological responses to future scenario about climate change and human pressure. The second aim is the effective use of remote sensing observations in conjunction with process models, to provide operational prognostics for improving water-resource management. The objective of this paper is to present the SUDMED programme, its objectives, and its thrust areas, and to provide an overview of the results obtained in the first phase of the programme (2002-2006). Finally, the lessons learned, future objectives, and unsolved issues are presented. [ABSTRACT FROM AUTHOR]

A time series of eight high-resolution Landsat TM images, ranging over the crop season, has been acquired over an irrigated area in central Morocco. From this time series, a Normalized Difference Vegetation Index (NDVI) profile was generated for each pixel. In order to get significant profiles, the images were radiometrically corrected, first, using invariant objects located on the scene, based on visual observation of the images, and second, using the reflectance of these objects, estimated from a previously corrected image. In the following step, these NDVI profiles were used to identify four main crop types - bare soil, annual crops, trees on bare soil and trees on annual understory - using a decision tree algorithm. The resulting land cover map and the associated NDVI profiles were then used for an evapotranspiration estimate over the whole area, using the Food and Agriculture Organization (FAO) model. Daily outputs of the Moroccan meteorological model Aire Limitée Adaptation Dynamique développement International (ALADIN) were used to generate reference evapotranspiration (ET0) maps and K c estimates were determined using the NDVI profiles. [ABSTRACT FROM AUTHOR]

Land surface emissivity in the thermal infrared usually increases when the vegetation amount increases, reaching values that are larger than 0.98. During an experiment in Morocco over dry barley crops, it was found that emissivity may be significantly lower than 0.98 at full cover and that in some situations, it might decrease with increasing amount of vegetation, which was unexpected. Older data acquired in Barrax, Spain, over senescent barley also exhibited emissivity values lower than 0.98. The decrease of emissivity was also observed by means of simulations done with our land surface emissivity model developed earlier. The main reason for such behavior might be found in low leaf emissivity due to leaf dryness. This letter also stresses that knowledge on leaf and canopy emissivities and on their variation as a function of water content is still very limited [ABSTRACT FROM PUBLISHER]

The rationale of this research is to investigate approaches based on modelling and remote sensing data for estimating the spatial distribution of yield and irrigation of wheat in semi-arid areas. The specific objective is to compare the performances of two approaches to test the STICS crop model using remotely sensed estimates of leaf area index (LAI). An experimental study of phenology, yield and water balance of irrigated wheat was made in the Marrakech-Haouz plain during year 2003. Experimental data was allowed to run STICS using two approaches: (1) Calibration of the parameters that control the time course of LAI; (2) driving from LAI time series interpolated with a simple model. The results show the accuracy of STICS to simulate actual evapotranspiration and yield for both approaches. Finally, the two approaches were compared using remotely sensed estimates of LAI upon four scenarios of satellite time revisit frequency. The simulations we obtained always show acceptable results. However, differences appear between the variables, between the approaches and between the frequencies. [ABSTRACT FROM AUTHOR]

Abstract: The monitoring of crop production and irrigation at a regional scale can be based on the use of ecosystem process models and remote sensing data. The former simulate the time courses of the main biophysical variables which affect crop photosynthesis and water consumption at a fine time step (hourly or daily); the latter allows to provide the spatial distribution of these variables over a region of interest at a time span from 10 days to a month. In this context, this study investigates the feasibility of using the normalised difference vegetation index (NDVI) derived from remote sensing data to provide indirect estimates of: (1) the leaf area index (LAI), which is a key-variable of many crop process models; and (2) crop coefficients, which represent the ratio of actual (AET) to reference (ET0) evapotranspiration. A first analysis is performed based on a dataset collected at field in an irrigated area of the Haouz plain (region of Marrakesh, Central Morocco) during the 2002–2003 agricultural season. The seasonal courses of NDVI, LAI, AET and ET0 have been compared, then crop coefficients have been calculated using a method that allows roughly to separate soil evaporation from plant transpiration. This allows to compute the crop basal coefficient (K cb) restricted to the plant transpiration process. Finally, three relationships have been established. The relationships between LAI and NDVI as well as between LAI and K cb were found both exponential, with associated errors of 30% and 15%, respectively. Because the NDVI saturates at high LAI values (>4), the use of remotely-sensed data results in poor accuracy of LAI estimates for well-developed canopies. However, this inaccuracy was not found critical for transpiration estimates since AET appears limited to ET0 for well-developed canopies. As a consequence, the relationship between NDVI and K cb was found linear and of good accuracy (15%). Based on these relationships, maps of LAI and transpiration requirements have been derived from two Landsat7-ETM+ images acquired at the beginning and the middle of the agricultural season. These maps show the space and time variability in crop development and water requirements over a 3km×3km irrigated area that surrounds the fields of study. They may give an indication on how the water should be distributed over the area of interest in order to improve the efficiency of irrigation. The availability, in the near future, of Earth Observation Systems designed to provide both high spatial resolution (10m) and frequent revisit (day) would make it feasible to set up such approaches for the operational monitoring of crop phenology and irrigation at a regional scale. [Copyright &y& Elsevier]

Dynamics of snow in semi-arid mountains are poorly investigated despite the fact that snow may represent an important source of water for downstream populations especially in the spring and early summer. Data acquired by space-borne optical sensors (i.e. reflectance and derived snow indices) may be suitable for spatial and temporal monitoring of snow cover. However, due to prevailing terrain and climatic conditions, the use of satellite sensor data to monitor snow dynamics is not trivial over such regions. Snowfall as well as precipitation are characterized by strong space-time variability. Indeed snow can fall and melt within one week. Under such conditions, appropriate monitoring of snow dynamics requires space instruments that provide data with high spatial and high temporal resolutions. In this context we developed a new approach based on the combination of two types of instruments: low spatial and high temporal resolution (Systéme Pour l'Observation de la Terre (SPOT)-VEGETATION) and high spatial and low temporal resolution (Landsat Thematic Mapper). This new approach improves the relationship between snow index and snow area. The method is validated against snow maps derived from classification of high spatial resolution data on the Atlas range, in Morocco. It is then applied to a one-year series of SPOT-4 VEGETATION images allowing to derive a temporal snow cover profile at 1 km spatial resolution over the entire Atlas, The yearly snow profile obtained is of great interest for hydrological modelling. [ABSTRACT FROM AUTHOR]

For a regional assessment of water needs and consumption in semiarid agricultural zones, one needs robust and simple tools that provide space-time estimates of evaporation losses. Most operational evaporation estimates rely on semiempirical relationships that are not generally applicable. Several authors have proposed physically based simple expressions to model the 'energy-limited' (stage-one) and the 'supply-limited' (stage-two) evaporation rates during a dry down. They use the time compression approximation (TCA) to relate stage-one and stage-two drying. Two asymptotic approximations of the TCA corresponding to the diffusion-dominated and the drainage-dominated flows have been proposed in the literature. In this study a full analytical solution of the TCA is presented. The derived 'supply-limited' evaporation rate is evaluated for a wide range of soil conditions and vegetation cover against a physically based complex soil-vegetation-atmosphere transfer model, the Simple Soil-Plant-Atmosphere Transfer scheme (SiSPAT). SiSPAT solves the differential equations of water flow in a vertical soil column and computes estimates of soil evaporation and transpiration. SiSPAT is used to evaluate the performance of the full solution as well as the two existing asymptotic approximations for the case of sparse to dense vegetation in a semiarid environment. The full analytical solution gives accurate predictions of first- to second-stage evaporation time series for the bare soil and vegetated cover conditions with a leaf area index of 3 or higher. The results of the full solution are closer to the evaporation rate time series simulated by SISPAT than the asymptotic approximations. [ABSTRACT FROM AUTHOR]

The VEGETATION instrument is the starting point of a European Earth monitoring system that was developed jointly by France, the European Commission, Belgium, Italy and Sweden. Since April 1998, VEGETATION has provided a high quality global monitoring of the day-to-day land cover dynamics at 1 km resolution. The whole dataset is now available free of charge to the broad range of potential users and applications. The quality of delivered products in terms of radiometry, geometry and additional processing for directional and atmospheric effects stands VEGETATION as an excellent tool for the monitoring of surface hydrology, crops, forest and land cover. Surface reflectances that are delivered by the operational VEGETATION system are corrected for molecular and aerosol scattering, for water vapour, ozone and other gas absorption. So far, the only well known Maximum Value Composite (MVC) technique was used in the construction of 10-day synthesis. An additional enhanced composite product is now available, which evaluates the atmospheric optical depth and normalizes angular Sun-target-sensor variations. After presenting the VEGETATION instrument and products, this paper introduces the new compositing schemes ( Duchemin and Maisongrande 2002, Duchemin et al. 2002 ) and presents samples of the new products. [ABSTRACT FROM AUTHOR]

We focussed on the potential and limits of NOAA-AVHRR 5-day composite data for monitoring the phenology and the fluxes of temperate forests at regional scale. The spatio-temporal variability ofkm2 Normalised Difference Vegetation Index (NDVI) was large, and primary varied with the deciduous/ coniferous mixture. It could provide the phenological cycle of deciduous ecosystems. For the large coniferous Landes forest, it characterised the different ecotypes, and was sensitive to land use (age of the pine stands) and understorey vegetation. Relationships between NDVI, TS and rainfall confirmed the ability of km2 thermal infrared data to infer the water status of this forest. [ABSTRACT FROM AUTHOR]

This paper presents a new method developed for the atmospheric correction of the images that will be acquired by the Venμs satellite after its launch expected in early 2010. Every two days, the Venμs mission will provide 10 m resolution images of 50 sites, in 12 narrow spectral bands ranging from 415 nm to 910 nm. The sun-synchronous Venμs orbit will have a 2-day repeat cycle, and the images of a given site will always be acquired from the same place, at the same local hour, with constant observation angles. Thanks to these characteristics, the directional effects will be considerably reduced since only the solar angles will slowly vary with time. The algorithm that will be implemented for the atmospheric correction of Venμs data is being developed using both radiative transfer simulations and the actual data acquired by the Formosat-2 satellite. Because of its one-day sun-synchronous repeat cycle, Formosat-2 acquires images with a sun-viewing geometry close to the one Venμs will offer. With this geometry, reflectance time series are free from directional effects on the short term, a feature which reduces the number of unknowns to retrieve. The atmospheric corrections algorithm exploits this feature and the two following assumptions: [–] Aerosol optical properties vary quickly with time but slowly with location. [–] Surface reflectances vary quickly with location but slowly with time. Consequently, the top of atmosphere reflectance short term variations (10 to 15 days) are mainly due to the variations of aerosol optical properties, and it is thus possible to use these variations to characterise the atmospheric aerosols and to retrieve surface reflectances. This paper first describes the aerosol inversion method we developed and its results when applied to simulations. In the second part, we show the first tests of the method against three data sets acquired by Formosat-2 images with constant observation angles. Aeronet sun photometers measurements were available on all sites. Formosat-2 estimates of optical thickness compare favourably with Aeronet in situ measurements, leading to a noticeable improvement of the smoothness of time series of surface reflectances after atmospheric correction. [Copyright &y& Elsevier]

Abstract: The aim of this study is to use the FAO-56-based single crop coefficient approach to estimate actual evapotranspiration (AET) of an olive (Olea europaea L.) orchard in the Mediterranean semi arid region of Tensift-basin (central Morocco) during two consecutive growing seasons (2003 and 2004). The results showed that using crop coefficients K c suggested by FAO-56 method yielded an AET overestimation by about 18% when compared against eddy covariance measurements. Therefore, the determination of appropriate K c values is required to accurately estimate crop water requirement of olive orchards in such water scarce area. In this study, after applying the K c values derived over olive orchard in Spain by Pastor and Orgaz [Pastor, M., Orgaz, F., 1994. Riego deficitario del olivar: los programas de recorte de riego en olivar. Agricultura 746, 768–776 (in Spanish)], a better agreement was observed between measured and simulated AET. The root mean square error (RMSE) was reduced by about 28%, from 0.80 to 0.61mm/day for 2003 and from 0.93 to 0.69mm/day for 2004. The used K c values of olives at three crop growth stages (initial, mid-season and maturity) were 0.65, 0.45, and 0.65, respectively, the mid-season stage value being considerably lower than that suggested by the FAO-56. Despite these improvements in the performance of AET simulations, some discrepancies between measured and simulated AET remained, especially when water stress occurred. These discrepancies were ascribed to the estimation of the stress coefficient K c To overcome this problem, we assimilated into FAO-56 single source model estimates of AET derived from a simple energy balance model along with thermal infrared observations. The latter were collected with the ASTER sensor in 2003 and from ground-based measurements in 2004. The results showed a clear improvement for FAO-56 performances after assimilation: for 2003 and 2004, the RMSE values between observations and simulations, respectively, dropped down from 0.61 to 0.52 and from 0.69 to 0.46 (corresponding to relative reductions of 15 and 40%, respectively). [Copyright &y& Elsevier]

Abstract: This study was performed to test three methods based on the FAO-56 “dual” crop coefficient approach to estimate actual evapotranspiration (AET) for winter wheat under different irrigation treatments in the semi-arid region of Tensift Al Haouz, Marrakech (center of Morocco). The three methods differ in the calculation of the basal crop coefficient (K cb) and the fraction of soil surface covered by vegetation (f c). The first approach strictly follows the FAO-56 procedure, with K cb given in the FAO-56 tables and f c calculated from K cb (No-Calibration method). The second method uses local K cb and f c values estimated from field measurements (Local-Calibration method) and the last approach uses a remotely-sensed vegetation index to estimate K cb and f c (NDVI-Calibration method). The analysis was performed on three fields using actual (AET) measured by Eddy Correlation systems. It was shown that the Local-Calibration approach gave best results. Accurate estimates of K cb and f c were necessary for FAO-56 “dual” crop coefficient application. The locally derived K cb for winter wheat taken at initial, mid-season, and maturity crop growth were 0.15, 0.90 and 0.23, respectively. The K cb value at the mid-season stage was found to be considerably less than that suggested by the FAO-56. Similarity between the seasonal pattern of normalized difference vegetation index (NDVI) and K cb showed potential for modelling NDVI into a K cb. The obtained relationships between K cb and NDVI, and between f c and NDVI could be easily incorporated within the FAO-56 “dual” crop coefficient model and, thereby, provide a means to apply remotely sensed observation for real-time wheat irrigation scheduling. The results obtained were very acceptable especially when the soil evaporation is negligible. Therefore, the K cb–NDVI relationship employed in the FAO-56 “dual” crop coefficient model holds great potential for estimating crop water requirements on an operational basis and consumption at a regional scale. [Copyright &y& Elsevier]

Abstract: Global temporal composites of surface reflectances are among the most commonly used products of wide field-of-view satellite-borne instruments such as the Advanced Very High Resolution Radiometer (AVHRR), the MODerate resolution Imaging Spectroradiometer (MODIS) and VEGETATION. The multi-temporal and spatial consistencies of these composites are key elements for their usefulness. In this paper, we use two different criteria to evaluate the quality of existing and new temporal composite products in SPOT–VEGETATION imagery. The first criterion, based on variograms, analyses the spatial characteristics of composite images, and the second one evaluates the quality of the time series based on the analysis of simultaneous imagery from VEGETATION 1 and VEGETATION 2. Thanks to these criteria, we show that the standard deviation of the errors that affect the surface reflectances of current composite products can be reduced by a factor greater than 2 using improved algorithms detailed in this paper. Finally, we produce multi-instrument composites by integrating images from both VEGETATION instruments to further improve the composite products. [Copyright &y& Elsevier]

Encapsulation revolutionizes industries through enhanced stability, controlled release, and targeted performance of active ingredients. The novel aspect of this study explores the impact of the wall material-to-active (WM:A) ratio on the stability of ascorbic acid (AA) encapsulated in a maltodextrin (MD) and gum arabic (GA) blend (2:1 w/w ). Microparticles were spray-dried and analyzed using SEM, TGA, DSC, thermal stability, and antioxidant activity assessments. Stability tests under different conditions revealed that a higher WM:A ratio (7:1) improved the active stability and antioxidant activity during storage, highlighting its importance in the encapsulation process. SEM analysis confirmed particles with no cracks, and the particles demonstrated excellent thermal stability up to 200 °C with minimal degradation. These findings underscore the critical role of the WM:A ratio in determining the stability of encapsulated AA within a carbohydrate matrix, offering valuable insights for advancing encapsulation technologies.

Hypothesis: The temperature dependence of the static contact angle could a priori be predicted by using surface tension partitioning. An original model based on the transition state theory is also introduced. This model considers thermocapillary fluctuations on the droplet surface near the triple line and the self-affine pinning of this triple line against a solid substrate modeled with a pseudo-periodic distribution of adsorption sites., Experiments: The temperature dependence of the static contact angle was studied for a representative range of liquids with different polarities and on a wide array of solid substrates for temperatures ranging from 25 to 240 °C. Atomic force microscopy (AFM) was also used to quantify the surface roughness of the solid substrates., Findings: Whereas the surface tension partitioning failed to bring consistent results above room temperature, the transition state model proved very useful, thereby opening a way to yield predictive contact angle values with temperature variations. The introduction of a topological dimension in the equations yields a unified model that covers normal wetting (perfectly bonded liquids on smooth surfaces) but also the onset of Cassie-Baxter and Wenzel states on real surfaces. Moreover, the model encompasses the transition to complete wetting., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

A cotransport study of heavy metals and kaolinite particles in sand column with and without flax geotextiles was carried out. The objectives were to evaluate the potential role of kaolinite in heavy metals transfer and to analyse the influence of flax geotextiles on the transfer of these pollutants. The adsorption rates of heavy metals on the kaolinite particles were, respectively, 53%, 65% and 25% for copper, lead, and zinc. The injection of kaolinite with heavy metals resulted in a significant decrease in the retention efficiency of copper and lead in the filter. The presence of kaolinite in the injected solution has virtually no influence on the effectiveness of zinc fixation in the filter. The retention of heavy metals is in the order of Zn > Cu > Pb with a significant drop of retention efficiency of 34% for copper, 67% for lead, and less than 1% for zinc. The presence of kaolinite in the injected solution reversed the retention order of heavy metals when metals solution was injected alone. Flax geotextiles increase the ability of the filter to retain soluble and attached heavy metals. It improves the sand retention capacity and it retains soluble and attached metals in its structure.

To overcome water scarcity issues in arid and semi-arid regions, Managed Aquifer Recharge (MAR) remains a viable and suitable solution to manage and restore aquifers. However, clogging represents a major issue that can affect the durability and efficiency of MAR structures. The aim of this study was to evaluate the extent of clogging in MAR sites (Berrechid, Morocco). To achieve this objective, two field-based studies were undertaken: the first one consists of implantation of sand-filled columns in the recharge sites to evaluate the surface and subsurface clogging. The second one consists of the implantation of pickets over a 750 m 2 area in each recharge site to measure the extent of deposit thickness on the surface of the wadi bed. Results show that, despite the low rainfall (<1.4 mm/day) and the short period (91 days) of the study, the deposits thickness exceeds 3 cm in a large part of the MAR. The suspended solids concentrations measured in recharge sites ranged from 1.1 to 1.4 g/L. Due to the particles retention, the estimation of the saturated hydraulic conductivity (k) of the sand declines over 90% in the immediate entrance of the columns. The k values measured in situ during the drying period ranged from 10 -5 to 10 -6  m/s. The k values of the cake formed, without cracks, was about 10 -8  m/s. The presence of cracks drives the entire infiltration. However, due to the high plasticity index of the MAR soil, a slight reduction of cracks opening during wetting cycles is observed. In addition, particles deposited in these cracks, would contribute actively to the reduction of infiltration. The results of this study clearly showed the MAR sites vulnerability in semi-arid regions due to physical clogging., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Filtration tests were carried out in laboratory columns filled with crushed sand with and without flax geotextiles to study the transfer and retention of soluble heavy metals. Divalent cations of copper, zinc and lead were simultaneously and continuously injected in filtration columns. Results show that, when geotextiles discs are present the retention of metals in sand is favoured and retention profiles are modified. In addition, and unlike synthetic geotextiles, flax fibres geotextiles contribute to the retention of a significant fraction of the cationic metal pollutants in their own structure. The overall metals retention efficiency of the filter is improved. Competition between cationic metals for adsorption on retention sites occurs in the column in the order Pb > Cu > Zn. Most of the lead is retained in the inlet of the column while copper and even more zinc migrate deeper in the column.

In this work, the properties of cellulose (CE)/xyloglucan (XG) biopolymer blends are investigated, taking inspiration from the outstanding mechanical properties of plant cell walls. CE and XG were first co-solubilized in an ionic liquid, 1-ethyl-3-methylimidazolium acetate, in order to blend these biopolymers with a varying CE:XG ratio. The biopolymers were then regenerated together using water to produce solid blends in the form of films. Water-soluble XG persisted in the films following regeneration in water, indicating an attractive interaction between the CE and XG. The final CE:XG ratio of the blends was close to the initial value in solutions, further suggesting that intimate mixing takes place between CE and XG. The resulting CE/XG films were found to be free of ionic liquid, transparent and with no evidence of phase separation at the micron scale. The mechanical properties of the blend with a CE:XG ratio close to one revealed a synergistic effect for which a maximum in the elongation and stress at break was observed in combination with a high elastic modulus. Atomic force microscopy indicates a co-continuous nanostructure for this composition. It is proposed that the non-monotonous variation of the mechanical performance of the films with XG content is due to this observed nanostructuration., (Copyright © 2017 Elsevier Ltd. All rights reserved.)