High Evapotranspiration Rates Research Articles

Epidemiologia de doenças diarreicas de veiculação hídrica em uma região semiárida brasileira

Introdução: Na região semiárida do Nordeste do Brasil, com irregularidade de chuvas e altas taxas de evapotranspiração, são relatados graves problemas sobre qualidade e disponibilidade hídricas. Objetivo: Avaliar a ocorrência de doenças diarreicas agudas (DDA) em municípios do semiárido potiguar de 2009 a 2010. Métodos: O estudo é descritivo com abordagem quantitativa, utilizando dados do Sistema de Informação de Atenção Básica do Sistema Único de Saúde/Ministério da Saúde e da Secretaria de Saúde do Estado do Rio Grande do Norte. Resultados: O tratamento mais escolhido para o combate às doenças diarreicas foi o tipo A, não tendo havido registros de óbitos por doenças diarreicas na maioria dos municípios. A faixa etária que obteve a maior prevalência das doenças diarreicas está situada entre um e quatro anos. Conclusões: Os dados podem estar subestimados, e o quadro leva à necessidade do aprimoramento do Sistema de Monitoramento das DDA e realização de ações de Educação em Saúde, junto à população, no sentido de melhorar sua qualidade de vida e saúde.

Abiotic and biotic factors influencing the mobility of arsenic in groundwater of a through-flow island in the Okavango Delta, Botswana

Summary The Okavango Delta of Botswana is a large arid-zone wetland comprising 20,000 km2 of permanent and seasonal floodplains and over 100,000 islands. It has been shown that island groundwater can have very high dissolved arsenic (As) concentration, but the abiotic and biotic controls on As mobility are not well understood in this setting. At New Island, an island located in the seasonal swamp, dissolved As concentration increased from below detection limits in the surface water to 180 μg/L in groundwater, present as As(III) species. We investigated the relative importance of hydrologic, geochemical, and geomicrobial processes, as well as influences of recent extreme flooding events, in mobilizing and sequestering As in the shallow groundwater system under this island. Our results suggest that evapotranspiration and through-flow conditions control the location of the high arsenic zone. A combination of processes is hypothesized to control elevated As in the concentration zone of New Island: high evapotranspiration rates concentrate As and other solutes, more alkaline pH leads to desorption of arsenic or dissolution of arsenic sulfides, and formation of thioarsenic complexes acts to keep arsenic in solution. Evidence from X-ray absorption near-edge structure spectroscopy (XANES) and sulfate reducing bacteria (SRB) measurements further suggests that SRBs influence arsenic sequestration as orpiment (As2S3). Although dissolved organic matter (DOM) was not significantly correlated to dissolved As in the groundwater, our results suggest that DOM may serve as an electron donor for sulfate reduction or other microbial reactions that influence redox state and As mobility. These results have important implications for water management in the region and in other large wetland environments. The processes evaluated in this study are also relevant for arsenic removal in subsurface constructed wetland systems that may exhibit rapidly changing processes over small spatial scales.

Seasonal dynamics of CO2 balance and water consumption of C3 and C4-type cover crops compared to bare soil in a suitability study for their use in vineyards in Germany and Argentina

Cover crops are used in vineyards to maintain soil structure, minimise soil erosion and optimise vineyard mechanisation, yet few data are available on water consumption and carbon dioxide assimilation (CO2). Whereas cover crop use is common in the grape growing regions of Germany it is uncommon in Argentina. To obtain some information on the suitability of a selected number of species in terms of carbon gain and water expenditure under the climatic conditions of Germany and Argentina, we first quantified evapotranspiration (EvT), CO2 assimilation and water use efficiency of Trifolium repens L. (white clover) (TR), Festuca arundinacea Schreb (tall fescue) (FE), Sorghum sudanense (Piper) Stapf (Sudan grass) (SO), and Digitaria californica (Benth) Henr. (Arizona cotton top) (DI) in a field trial in Geisenheim, Germany. We then compared the performance of TR, FE and DI together with Sorghum halepense L. (Johnson grass) (SH) in a pot experiment under the warmer climatic conditions of Mendoza, Argentina, where water supply could be controlled. In all cases bare soil served as a reference for soil water loss. Gas-exchange of plants and soil were measured with customised open system canopy chambers and an infrared gas analyser and water dynamics in the soil with soil moisture probes (field) or gravimetrically (pots). SO and TR were the two species that reached the highest degree of soil coverage in Germany and substantially reduced soil moisture in the first 0.40m of depth. TR showed high EvT and CO2 assimilation rates in both climates when water supply was sufficient and maintained relative high rates when water status was reduced under cool conditions in Germany, yet performed poorly when high temperatures occurred concomitant to low water supply in Argentina. DI, being a C4 species from arid regions, had difficulties to get established in the cool conditions of Germany and there was no clear tendency for more efficient water use than the other cover crops. However under the warm condition of Argentina, especially when water supply was reduced, DI displayed higher WUE which was entirely related to the maintenance of higher assimilation rates at substantially reduced EvT. FE being common in German vineyards had low assimilation rates combined with high evapotranspiration rates under Argentinian conditions and was very sensitive to water deficit in combination with high temperature.

EXTRACTION PATTERN OF SOIL MOISTURE IN BARE SOIL, TEA PLANTATION AND SOIL COVERED WITH FOREST SPECIES (Alstonia macrophytla wall)

The present study conducted at the research farm, Faculty of Agriculture, University ofRuhuna, Mapalana and adjacent site of well established tea plantation from January toJuly 2003, to assess the moisture extraction patterns under tea (Camellia sinensis L.) andforest speices (Alostonia macrophylla wall) compared to bare soilDiviner 2000 is used to assess the soil moisture in different sites. The experiment wasconducted in two sites, viz well managed tea plantation and an experimental site whereAlstonia macrophylla wall is planted, and bare spots were kept randomlyThe soil under tea was loamy sand with bulk density of lBgcm" in surface layers whichincrease with the depth. The soil under forest species was silt loam with a bulk density of1.4gcm-3 in surface layers. Bulk density of bare soil was highly varied with an average of1.49gcm-3. A thick laterite layer was found in 40-5Ocm layer in tea soil and 50-60cmdepth in forest and bare soils. The results revealed that the water holding capacity of teasoil is high by about 16% compared to that of bare soil and water-holding capacity offorest soil is low by 8% compared to bare soil.According to the moisture extraction pattern of soils, somewhat highest retentioncapacity was in bare land followed by tea soil and then forest soil. The probable reasonfor this may be high evapotranspiration rate from tea plantation and forest species. Themoisture retention of the tea plantation is higher than the forest soil, due to the highevapotranspiration by forest speciesThe rate of moisture depletion is remarkably high in forest soil with an average of4.8mmlday constituting 60% increment over bare soil evaporation. Soil moisturedepletion rate of the soil under tea is about 4.2mmlday, which is 40% higher comparedthat to the bare soil evaporation. Well-established canopy cover of the tea plantationappeared to be a good barrier to reduce surface evaporationParameters like porosity, soil texture, soil temperature, rainfall, wind speed and rootdistribution pattern appeared to have an influence on the soil moisture depletion

Groundwater quality degradation of urban areas (case study: Tehran city, Iran)

Groundwater quality of Tehran city is considered in this study. Nine sampling stations were selected, and composite sampling campaign was performed in summer 2012. Groundwater sampled from northern stations appeared to have acceptable characteristics for agricultural and drinking uses. The southern station samples did not meet the required guidelines. Concentration of SO4 2−, Na+ and Cl− obey a sharp ascending trend southwards. Accordingly, the electrical conductivity of the last station at the very southern areas is more than fifteen times greater than that of the first northern station. Tehran city is located in a semi-arid climate and experiences long hot summers. High rates of evapo-transpiration within urban green spaces and agricultural lands facilitate the salinization phenomenon in root zones. As a result, excess irrigation water eases the consequent percolation into aquifers. Furthermore, saline water intrusion from salt marshes located down south of the city is an expected consequence of wells overpumping. Such case is especially remarkable in hot seasons when an increased urban water demand is observed. Remarkable sulfate concentrations in saline water are mainly justified by percolation of sulfate containing fertilizers which are broadly used by local farmers in an uncontrolled manner. Surface run-offs and municipal wastewater leakage may also trigger the salinization process.

Patterns and scaling properties of surface soil moisture in an agricultural landscape: An ecohydrological modeling study

• Validation of a dynamically coupled and process-based ecohydrological model. • Autocorrelation and scaling analysis of spatial surface soil moisture patterns. • Patterns depend on soil properties, precipitation and land use heterogeneity. • Evapotranspiration causes small scale patterns during growing season. • Scaling factor depends upon LAI and precipitation. Soil moisture is a key variable in hydrology, meteorology and agriculture. Soil moisture, and surface soil moisture in particular, is highly variable in space and time. Its spatial and temporal patterns in agricultural landscapes are affected by multiple natural (precipitation, soil, topography, etc.) and agro-economic (soil management, fertilization, etc.) factors, making it difficult to identify unequivocal cause and effect relationships between soil moisture and its driving variables. The goal of this study is to characterize and analyze the spatial and temporal patterns of surface soil moisture (top 20 cm) in an intensively used agricultural landscape (1100 km 2 northern part of the Rur catchment, Western Germany) and to determine the dominant factors and underlying processes controlling these patterns. A second goal is to analyze the scaling behavior of surface soil moisture patterns in order to investigate how spatial scale affects spatial patterns. To achieve these goals, a dynamically coupled, process-based and spatially distributed ecohydrological model was used to analyze the key processes as well as their interactions and feedbacks. The model was validated for two growing seasons for the three main crops in the investigation area: Winter wheat, sugar beet, and maize. This yielded RMSE values for surface soil moisture between 1.8 and 7.8 vol.% and average RMSE values for all three crops of 0.27 kg m −2 for total aboveground biomass and 0.93 for green LAI. Large deviations of measured and modeled soil moisture can be explained by a change of the infiltration properties towards the end of the growing season, especially in maize fields. The validated model was used to generate daily surface soil moisture maps, serving as a basis for an autocorrelation analysis of spatial patterns and scale. Outside of the growing season, surface soil moisture patterns at all spatial scales depend mainly upon soil properties. Within the main growing season, larger scale patterns that are induced by soil properties are superimposed by the small scale land use pattern and the resulting small scale variability of evapotranspiration. However, this influence decreases at larger spatial scales. Most precipitation events cause temporarily higher surface soil moisture autocorrelation lengths at all spatial scales for a short time even beyond the autocorrelation lengths induced by soil properties. The relation of daily spatial variance to the spatial scale of the analysis fits a power law scaling function, with negative values of the scaling exponent, indicating a decrease in spatial variability with increasing spatial resolution. High evapotranspiration rates cause an increase in the small scale soil moisture variability, thus leading to large negative values of the scaling exponent. Utilizing a multiple regression analysis, we found that 53% of the variance of the scaling exponent can be explained by a combination of an independent LAI parameter and the antecedent precipitation.

The groundwater recharge regime of some slightly metamorphosed neoproterozoic sedimentary rocks: an application of natural environmental tracers

AbstractIsotope data of precipitation and groundwater in parts of the Voltaian Basin in Northern Ghana were used to explain the groundwater recharge regime in the area. Groundwater recharge is an important parameter in the development of a decision support system for the management and efficient utilization of groundwater resources in the area. It is therefore important to establish the processes and sources of groundwater recharge. δ18O and δ2H data for local precipitation suggest enrichment relative to the Global Meteoric Water Line (GMWL) and indicate that precipitation takes place at a relative humidity less than 100%. The groundwater data plot on an evaporation line with a slope of 5, suggesting a high degree of evaporative enrichment of the precipitation in the process of vertical infiltration and percolation through the unsaturated zone into the saturated zone. This finding is consistent with the observation of high evapotranspiration rates in the area and ties in with the fact that significant clay fraction in the unsaturated zone limits vertical percolation and thus exposes the percolating rainwater to the effects of high temperatures and low humidities resulting in high evapotranspiration rates. Groundwater recharge estimates from the chloride mass balance, CMB, method suggest recharge in the range of 1.8–32% of the annual average precipitation in the form of rainfall. The highest rates are associated with areas where open wells encourage significant amount of groundwater recharge from precipitation in the area. In the northern parts of the study area, groundwater recharge is lower than 12%. The recharge so computed through the application of the CMB methodology takes on a spatial distribution akin to the converse of the spatial pattern of both δ18O and δ2H in the area. As such, the locations of the highest recharge are associated with the most depleted values of the two isotopes. This observation is consistent with the assertion that low vertical hydraulic conductivities slow down vertical percolation of precipitation down to the groundwater water. The percolating precipitation water thus gets enriched in the heavier isotopes through high evapotranspiration rates. At the same time, the amount of water that finally reaches the water table is considerably reduced. Copyright © 2013 John Wiley & Sons, Ltd.

A critical assessment of the JULES land surface model hydrology for humid tropical environments

Abstract. Global land surface models (LSMs) such as the Joint UK Land Environment Simulator (JULES) are originally developed to provide surface boundary conditions for climate models. They are increasingly used for hydrological simulation, for instance to simulate the impacts of land use changes and other perturbations on the water cycle. This study investigates how well such models represent the major hydrological fluxes at the relevant spatial and temporal scales – an important question for reliable model applications in poorly understood, data-scarce environments. The JULES-LSM is implemented in a 360 000 km2 humid tropical mountain basin of the Peruvian Andes–Amazon at 12-km grid resolution, forced with daily satellite and climate reanalysis data. The simulations are evaluated using conventional discharge-based evaluation methods, and by further comparing the magnitude and internal variability of the basin surface fluxes such as evapotranspiration, throughfall, and surface and subsurface runoff of the model with those observed in similar environments elsewhere. We find reasonably positive model efficiencies and high correlations between the simulated and observed streamflows, but high root-mean-square errors affecting the performance in smaller, upper sub-basins. We attribute this to errors in the water balance and JULES-LSM's inability to model baseflow. We also found a tendency to under-represent the high evapotranspiration rates of the region. We conclude that strategies to improve the representation of tropical systems to be (1) addressing errors in the forcing and (2) incorporating local wetland and regional floodplain in the subsurface representation.

Impact of direct drilling and conventional tillage on seasonal changes of soil water content in Chromic Haploxerert (south-west Spain)

A continuous monitoring of spatial and temporal variability of soil water content was studied under two soil management systems: direct drilling (DD) and conventional tillage (CT), during four consecutive seasons. The soil water content was read at different soil depths using multisensor capacitance probes in each soil-management treatment. During the first season (2003–2004), soil water content dynamics for both treatments were similar during the rainy season, although the DD plot was able to retain more water in the soil profile, and during the maximum evapotranspirative period faster soil water depletion took place in the CT plot. The 2004–2005 season registered a high evapotranspiration rate (1741 mm) with low rainfall (228 mm), promoting a low soil water recharge for both treatments. The 2005–2006 season registered an increase in rainfall, promoting a greater recovery of the soil water reserve in DD than CC plot. Finally, during the 2006–2007 season with an evapotranspiration rate ET0 and rainfall of 1504 and 560 mm, respectively, DD retained more soil water content, mainly in the deeper zones, with progressive soil water depletion during the maximum evapotranspirative period in comparison to CT. Thus, DD was demonstrated to be a promising soil management technique for improving the soil water content.

Impact of plant assemblages on nutrient removal in constructed wetlands

Four different mesocosm scale constructed wetlands – monoculture (Carexstipata), self-designed (passive) community, mixed planted monoculturepassive community and a non-vegetated control were compared to assess the effects of plant community composition on the removal of inorganic nutrients from agricultural runoff (synthetic tile water). The mixed and self-designed systems consistently produced effl uent NO3–N concentrations signifi cantly below 10 mg/L, and had higher rates of evapotranspiration. Results indicate the type and composition of the plant community can impact the performance of constructed wetlands. Therefore, self-design of the plant community through the existing seed bank may increase the effectiveness of wetlands in treating agricultural runoff.

Groundwater Simulation System Study on Physical and Climatic properties on Kuwait Group Aquifer

In Kuwait natural resources of fresh water are very limited. Kuwait is situated in an arid coastal region characterized by high temperatures, low humidity, sparse precipitation rates, and high evaporation and evapotranspiration rates with no rivers or lakes. Therefore, Kuwait has always relied on other sources to secure freshwater to meet its growing demands. The aim of this study was to design a conceptual system to provide a sustainable water source at a feasible cost. The conceptual design system was developed to address the problem of water scarcity and sustainability in general, and specifically to represent the Kuwaiti water quality and quantity limitation problem.The conceptual design system consists primarily of utilizing brackish groundwater in conjunction with treated wastewater augmentation and a reverse osmosis unit for plant production, the simulation was chosen to represent the quasi-Kuwaiti environment data.The study considered two types of simulation models for the conceptual design system approach. These models are the lump model approach and the areal distribution model approach. The lump model approach was carried out through the construction of a simplified model approach utilizing the Visual Basic model. On the other hand, the areal distribution model approach was carried out through the utilization of the Visual MODFLOW and MT3D simulation model approach. This paper present a part of the study that directed to test the physical and climatic performance, and the durability of the conceptual design system, Visual basic, lump, model simulation approach was simulated for different ranges of hydrologic, hydrogeologic, and climatic parameters to determine the total power and treated wastewater consumption. From the performance test results, the increase in evapotranspiration had the highest increase effect on the system total power consumption per unit area and the highest increase effect on the treated wastewater consumption per unit area. On the other hand, the increase in the aquifer porosity had the least increase effect on both the total power consumption and the treated wastewater consumption by the system. In contrast, the hydraulic conductivity increase had no direct effect on either the total power consumption or on the treated wastewater consumption per unit area.

English

  The effects of dust storm were investigated in three wild plants named Ficus nitida, Datura stramonium and Plumeria acutifolia by means of chlorophyll fluorescence measurements, as well as, net photosynthetic rate and stomatal conductance after progressive dust deposition extended for 6 days. In the two months leading up to the storm, severe drought conditions in Riyadh, plus above average maximum temperatures resulted in high potential evapo-transpiration rates, producing severe soil moisture deficits. Exposure to dust resulted in a drastic effect on some physiological parameters including the loss of chlorophyll a and b contents, inhibition of net photosynthetic rate (PN) and significant decrease of stomatal conductance (gs). Carotenoids content and carotenoids/total chlorophyll ratio of dust stressed plants were significantly increased parallel with the progressive deposition of the dust in comparison with control plants. The maximum efficiency of photosystem II photochemistry (Fv/Fm, PSII efficiency) varied among plants collected from the same site. Our results evidenced that dust deposition decreased overall plant performance through its severe effect on photosynthesis and resulted in a significant inhibition of PSII efficiency throughout this study period.   Key words: Chlorophyll fluorescence, dust storm, photosynthesis, Saudi Arabia. &nbsp

Dryness is accelerating degradation of vulnerable shrublands in semiarid Mediterranean environments

Semiarid Mediterranean regions are highly susceptible to desertification processes. This study investigated the influence of increasing climate aridity in explaining the decline in vegetation cover in highly vulnerable gypsum semiarid shrublands of the Mediterranean region. For this purpose, we have used time series of percent cover of vegetation obtained from remote sensing imagery (Landsat satellites). We found a dominant trend toward decreased vegetation cover, mainly in summer and in areas affected by the most severe water stress conditions (low precipitation, higher evapotranspiration rates, and sun‐exposed slopes). We show that past human management and current climate trends interact with local environmental conditions to determine the occurrence of vegetation degradation processes. The results suggest that degradation could be a consequence of the past overexploitation that has characterized this area (and many others in the Mediterranean region), but increased aridity, mainly related to global warming, may be triggering and/or accelerating the degradation processes. The observed pattern may be an early warning of processes potentially affecting more areas of the Mediterranean, according to the most up‐to‐date climate change models for the 21st century.

Drought sensitivity of three co-occurring conifers within a dry inner Alpine environment

We applied dendroclimatological techniques to determine long-term stationarity of climate-growth relationships and recent growth trends of three widespread coniferous tree species of the central Austrian Alps, which grow intermixed at dry-mesic sites within a dry inner Alpine environment (750 m asl). Time series of annual increments were developed from > 120 mature trees of Picea abies, Larix decidua and Pinus sylvestris. Calculation of response functions for the period 1911 - 2009 revealed significant differences among species in response to climate variables. While precipitation in May - June favoured radial growth of Picea abies and Larix decidua, Pinus sylvestris growth mainly depended on April - May precipitation. P. abies growth was most sensitive to May - June temperature (inverse relationship). Moving response function coefficients indicated increasing drought sensitivity of all species in recent decades, which is related to a decline in soil moisture availability due to increasing stand density and tree size and higher evapotranspiration rates in a warmer climate. While recent trend in basal area increment (BAI) of L. decidua distinctly declined implying high vulnerability to drought stress, moderately shade-tolerant P. abies showed steadily increasing BAI and quite constant BAI was maintained in drought adapted P. sylvestris, although at lowest level of all species. We conclude that synergistic effects of stand dynamics and climate warming increased drought sensitivity, which changed competitive strength of co-occurring conifers due to differences in inherent adaptive capacity.

Groundwater Recharge, Evapotranspiration and Surface Runoff Estimation Using WetSpass Modeling Method in Illala Catchment, Northern Ethiopia

Hydrometeorological information is important in planning and management of natural resources. The northern Ethiopia in general and Illala sub-basin in particular is lacking reliable information with regard to groundwater recharge, evapotranspiration and surface runoff. The main objective of the study is to estimate the distributed groundwater recharge, surface runoff and evapotranspiration amount of Illala sub basin using WetSpass modeling method. Long term mean hydrometeorological data and physical characteristics of the catchment such as land use/land cover, soil type, topography, groundwater level and slope are used as an input to the model. The mean annual groundwater recharge, evapotranspiration and runoff were found to be 66, 440 and 40mm respectively. Accordingly, recharge accounts for 12% of the precipitation while the rest 81% and 7% becomes evapotranspiration and surface runoff respectively. The study area is characterized by low groundwater recharge due to the presence of high evapotranspiration rate associated with high temperature, dry wind, low rainfall and relative humidity though it is a little bit large compared to some parts of the northern Ethiopia. Keywords : Groundwater, WetSpass, Recharge, Illala, Catchment, Tigray, Ethiopia

Ecohydrological feedbacks between permafrost and vegetation dynamics

The presence of forest vegetation can aid in preserving the permafrost layer by maintaining lower soil temperatures via the accretion of an organic layer at the surface. This layer has a low bulk density and low thermal conductivity (due also to high evapotranspiration rates by forest vegetation), which insulates ice-rich permafrost. Forest removal can lead to significant increases in the summer soil temperature, which increases the thickness of the active layer (i.e., the surficial layer above permafrost which thaws during summer and freezes again in winter) and causes a rise in the active layer towards the surface. When vegetation is sensitive to saturated soil conditions, a rise in the active layer can lead to the conversion of forested areas to wetlands. In this manuscript, we develop a modeling framework to relate vegetation–permafrost feedbacks to the emergence of multiple stable ecosystem states. Factors related to soil temperature and hydrologic characteristics of the system were examined to see how they affect the location of the stable and unstable states. This model was also used to examine how an increase in precipitation would affect the temporal dynamics of the active layer and vegetation. Results show that the presence of forest vegetation can enhance the resilience of the system in that it is less prone to state shifts following a disturbance. Understanding these dynamics is important given, (i) the rapid rate at which these systems can shift between states, (ii) the projected climatic changes for forested areas underlain by permafrost and (iii) the high rates of forest loss in these areas.

Rubber plantations act as water pumps in tropical China

[1] Whether rubber plantations have the role of water pumps in tropical Southeast Asia is under active debate. Fifteen years (1994–2008) of paired catchments water observation data and one year paired eddy covariance water flux data in primary tropical rain forest and tropical rubber plantation was used to clarify how rubber plantation affects local water resources of Xishuangbanna, China. Both catchment water observations and direct eddy covariance estimates indicates that more water was evapotranspired from rubber plantation (1137 mm based on catchment water balance, 1125 mm based on eddy covariance) than from the rain forest (969 mm based on catchment water balance, 927 mm based on eddy covariance). Soil water storage during the rainy season is not sufficient to maintain such high evapotranspiration rates, resulting in zero flow and water shortages during the dry season in the rubber plantation. Therefore, this study supports the idea that rubber plantations act as water pumps as suggested by local inhabitants.

Evapotranspiration of deforested areas in central and southwestern Amazonia

Considering the high rates of evapotranspiration of Amazonian forests, understanding the impacts of deforestation on water loss rates is important for assessing those impacts on a regional and global scale. This paper quantifies evapotranspiration rates in two different pasture sites in Amazonia and evaluates the differences between the sites. In both places, measured evapotranspiration varies seasonally, decreasing during the dry season. The decrease is higher at the southwestern Amazonia site, while at the central Amazonia site, the decrease is less pronounced. During the dry season, average values of evapotranspiration are around 2.2 ± 0.6 mm day−1 in central Amazonia and 2.4 ± 0.6 mm day−1 in southwestern Amazonia, while during the wet season, those values are 2.1 ± 0.6 mm day−1 in central Amazonia and 3.5 ± 0.8 mm day−1 in southwestern Amazonia. On an annual basis, the pasture in southwestern Amazonia has higher evapotranspiration than in central Amazonia. We conclude that the main reason for this difference is the lower available energy in the wet season at the central Amazonian site, combined with a lower leaf area index at this site during the whole year. Still, the evapotranspiration is significantly controlled by the vegetation, which is well coupled with the local moisture conditions in the dry season.

Willow vegetation filters for wastewater treatment and soil remediation combined with biomass production

Vegetation filters of fast-growing trees such as willows and poplars are becoming important as an alternative to conventional treatment of wastewater and landfill leachate. Short-rotation willow coppice is a non-edible crop and has many of the requirements for a suitable vegetation filter. The filtering capacity (e.g., of nitrogen) is very high, and the crop promotes denitrification in the root zone. It has a highly selective uptake of heavy metals, especially cadmium, which enables remediation of contaminated soils. In addition, willows have a high evapotranspiration rate facilitating high loads, e.g., of polluted landfill leachate. Because of the pathogens present in municipal wastewater and sludge, special attention must be paid to storage and distribution of wastewater. In many cases vegetation fdters are more cost-effective than conventional treatment methods and also facilitate recycling of valuable resources in society.

Analysis of variability of climatic indexes for the state of the Paraíba - PB

This work had as main objective the study of spatial variation of meteorological variables (DEF, EXC, Ia, Iu and Ih) according to the available water capacity (AWC) levels of 75, 100, 125 and 150 mm obtained from water balance proposed by THORNTHWAITE (1948) in the State of Paraiba. In the execution of the water balance it was used rainfall data available at the Academic Unit of Atmospheric Sciences, Federal University of Campina Grande and an estimation of air temperature for a specified series from 1970 to 2000 based on 54 rain gauge stations located throughout the state. In the mapping of meteorological variables it was used the tools of Geostatistics for the construction of contour maps, using the technique of Kriging to obtain the homogeneous areas that enable a planning of the use and a differential agricultural management of the area. Through this analysis it was verified that it occurred small variations of these variables according to the slides studied, proven by the low rainfall coupled with high rate of potential evapotranspiration for most of that state.