Hasil untuk "Hydraulic engineering"

Gabriel Jesús Montúfar Chiriboga

La regulación de los recursos naturales en proyectos de ingeniería civil constituye uno de sus principales pilares para el desarrollo sostenible, especialmente en aquellos espacios donde la extracción y uso de recursos como la arena, los sedimentos y los residuos de la construcción son capaces de propiciar altos impactos ambientales. Esta revisión sistemática indaga en investigaciones recientes en gobernanza sobre la extracción de arena, la economía circular de la construcción, las prácticas de dragado, las compras públicas ecológicas y las evaluaciones de impacto ambiental, con el objetivo de determinar alternativas que concilien el avance económico con la protección/conciencia ecológica. Se incorporan veintinueve artículos seleccionados en función de los criterios de inclusión criterios de idoneidad temáticas y robustez metodológica para regiones como Ghana, Malasia, Vietnam y otras partes del mundo. Los resultados destacan que la extracción ilegal de la arena degrada la fertilidad del suelo y las comunidades agrícolas; la economía circular genera menos desperdicio debido al reciclado de materiales; las políticas de compras públicas ecológicas extreman los criterios ambientales aplicados a las licitaciones; y la evaluación de impacto ambiental demanda simplificaciones de los modelos de forma coherente para no provocar un cierto retraso, pero, a la vez, sin limitar una cierta protección.

Taishi Yazawa, Kenn Joshua Geroy Rubite, Princess Eden Macabata-Rubite

This research conducted a citizen scientific field investigation and water quality assessment of nine major rivers using only on-site equipment and a smartphone in the Province of Antique, Philippines. Potential issues concerning water resources management in the province were discussed with local governors and citizens while conducting the water sampling and on-site measurement. The results of water quality assessments revealed that some of the rivers have experienced high turbidity, caused by anthropogenic activities such as embankment, sand mining, and dredging. In highly populated basins, such as the Sibalom and Malandog Rivers, a high biochemical oxygen demand level (>7 mg/L) was confirmed by the water quality analysis using an iPhone. Since high consumption of groundwater has already affected the lives of people in the province, surface water usage shifting from groundwater, involving the construction of a facility treating physical and chemical parameters, is needed. The citizen scientific approach employed in this research can provide more realistic insights into local environmental concerns, which would not be possible through quantitative measurements of water quality. HIGHLIGHTS The water quality of nine major rivers was assessed in the Province of Antique, Philippines.; Citizen scientific field investigation and water quality analysis used only an iPhone and an on-site water quality meter.; Some rivers have experienced siltation caused by anthropogenic activities.; A high biochemical oxygen demand level was confirmed in highly populated basins.; There is a need for a shift from groundwater to surface water usage.;

NIU Zihao 1, 2, ZHU Zhende 3, QUE Xiangcheng 3, XIE Xinghua 4, JIN Kai 1, 2

With the construction and commissioning of major hydropower projects represented by Baihetan of Jinsha River, it is of great significance to clarify the mechanical and seepage characteristics of engineering rock mass under complex stress environment with high confining pressure and high water pressure. Based on the field survey data and the structural characteristics of the columnar jointed basalt of dam foundation, two kinds of columnar joint similar material model samples with different dip angles β, quadrangular prisms and hexagonal prisms, are prepared, and the true triaxial stress-seepage coupling tests are carried out. The test results show that the columnar jointed rock mass with different cross-section characteristics has strong permeability anisotropy, and the permeability coefficient k is positively correlated with β at different loading stages. During the true triaxial loading process, the volume strain εV of the sample can be used as an effective characterization parameter of k. At the volume compression stage, k shows a low level, and at the volume expansion stage k shows a rapid growth trend. The final failure mode of the samples exhibits three typical forms, and the most dangerous failure mode is the structural failure dominated by the shear slip failure of the joint surface, which mainly occurs in the samples with β=45°, 60°. Correspondingly, the lateral support of this kind of rock mass should be strengthened in the construction design of surrounding rock of tunnels and rock mass of dam foundation.

Huaixin LI, Changgen YAN, Jiale XIE et al.

Objective Pile-soil interaction plays a critical role in slope support engineering. Since the contact surface represents the weakest link in the system, analyzing the influence of the soil shear area on the mechanical properties and the constitutive model of the contact surface between soil and structure enhances the understanding of pile-soil interactions.Methods Three sets of ring-shaped samples are initially cast to evaluate the impact of the soil shear area on the interface strength characteristics between soil and structure. Each sample has a height of 1.00 cm, an outer diameter of 6.12 cm, and inner diameters of 0 cm, 3.50 cm, and 4.98 cm, respectively. Subsequently, corresponding segments of 300-mesh sandpaper are adhered to the sample surfaces using a robust adhesive. The remolded soil is then dried, pulverized, sieved through a 2 mm mesh, and adjusted to a moisture content of 20%. It is cured for 24 hours prior to sample preparation. Different soil-structure interface samples with varying soil shear areas are then fabricated using specially designed equipment, and shear tests are conducted using the electric ZLB-1 strain-controlled direct shear apparatus manufactured by Nanjing Soil Instrument Co., Ltd. The test employs the fast shear method, with a shear rate of 0.8 mm/min and a shear displacement of 7 mm. During the tests, the soil shear area ratio (<italic>ρ</italic>) at the interface between soil and structure is controlled at 0, 0.33, 0.66, and 1.00, with normal stresses of 100, 200, 300, and 400 kPa, respectively.Results and Discussions The peak strength of the soil-structure interface increases linearly with increasing normal stress and soil shear area ratio. The shear area ratio of soil significantly influences the stress-strain curve of the sample. When the soil shear area ratio is <italic>ρ</italic> = 0 or <italic>ρ</italic> = 1.00, the shear stress-displacement curve of the sample exhibits a hardening behavior. Conversely, when the shear area ratio is 0 &lt; <italic>ρ</italic> &lt; 1.00, the curve demonstrates a softening behavior. This primarily occurs because the soil strength exceeds the interface strength between the soil and the structure. Under various soil shear area conditions, the strength at the soil-structure interface initially derives from the soil itself. Once the soil’s shear strength reaches its maximum, the sample’s shear stress is substantially reduced, exhibiting a stress-softening phenomenon. As the soil shear area ratio at the soil-structure interface gradually increases, the shear strength at the interface approaches that of the soil. Consequently, the interface effect leads to a decrease in shear strength compared to that of the soil shear surface. The shear strength of the soil shear surface primarily arises from the interactions between soil particles, including rotation, interlocking, and biting. In contrast, the shear strength at the soil-structure interface comprises two components: one part is generated by the friction, interlocking, and biting between the soil particles and the structure’s surface, while the other arises from the interactions among soil particles near the shear zone on the structure’s surface. During the shear process of the specimen, the proportion of shear strength is contributed by inter-particle shear resistance within the soil, and the interface shear resistance undergoes dynamic changes, exhibiting variability in the shear strength mechanism at the soil-structure interface. The total damage to the soil shear surface results from loading damage, whereas the total damage at the soil-structure interface is divided into equivalent initial damage, loading damage, and coupling damage caused by the interaction of the two. The smaller the soil shear area ratio <italic>ρ</italic>, the greater the equivalent initial damage at the soil-structure interface. By establishing a damage evolution relationship between the soil shear surface and the soil-structure interface, the latter is equated to the soil shear surface with initial damage, describing the influence of soil shear area on the strength characteristics of the interface. Based on the assumption that the strength of both the soil-structure interface and the soil shear surface follows a two-parameter Weibull probability distribution during the shear process of the sample, a damage strength model of the soil-structure interface based on equivalent damage is proposed using statistical damage theory. This model primarily consists of the fitting parameter <italic>B</italic>, which controls peak strength, and the fitting parameter <italic>C</italic>, which controls softening characteristics. Compared to the soil shear plane, the pre-set interface leads to significant changes in pores and microcracks during the shear process of the soil-structure interface. Consequently, the total damage to the soil-structure interface is considerably higher than that of the soil shear plane initially, and the macroscopic performance is that the strength of the soil-structure interface is significantly lower than that of the soil shear plane. The proposed model is validated by comparing it with experimental data, demonstrating that it accurately represents both softening and hardening stress-strain behaviors at the soil-structure interface.Conclusions This study explores how the soil shear area influences the mechanical properties of the soil-structure interface and proposes a zero-thickness interface model to predict this behavior, supported by experimental evidence. This model effectively fits the nonlinear relationship at the soil-structure interface under different soil shear area ratios, making it suitable for programmed calculations in finite element software.

Tatyana D. Kartuzova, Natalya A. Shelestova, Alexander A. Tkachev et al.

Purpose: to solve the problem of conservation and reproduction of fish stocks of valuable commercial fish species in natural reservoirs, on the example of performing one of the tasks of developing a facility for regulating water regime of the ilmen part of the Volga delta. Using the well-known formulas of hydraulics, scientific developments of scientists in the field of hydraulic engineering and a priori information, it is necessary to determine the main parameters of a control structure located on a fishery reservoir in Astrakhan region. Materials and methods: a stage-by-stage hydraulic calculation of a tubular control structure that performs the functions of a water outlet was performed: the carrying capacity of the facility during operation in a pressure mode was determined; the main loads influencing the structure underground contour were determined by filtration calculation; a strength calculation of the floor for shear was performed. Results. A facility to regulate the water regime of the ilmen area of the Volga delta, ilmen, which are places of natural spawning grounds for commercial fish in Astrakhan region has been developed. The task of hydraulic calculation is to determine the conditions for the advancement of the filtration flow under the structure determining the pressure at characteristic points and to define the minimum dimensions of the floor that perceive stably the loads created by this flow. Conclusions. The calculation determined the main dimensions of the floor (length, width of the structure – 46.0; 4.65 m; length, thickness of the apron – 4.54; 0.3 m; length, thickness of the water apron – 4.8; 0.9 m; depth, water apron teeth width – 1.19; 0.40 m; length, thickness of the rear apron – 20.36; 0.6 m; length of the tubular part of the regulator – 16.3 m) taking into account the placement of gates, service and road bridges. The shear stability of the floor and the structure as a whole was determined.

Ao Sun, Qiuzhao Zhang, Zhangjun Yu et al.

The accuracy and integrity of structural deformation monitoring can be improved by the GNSS/accelerometer integrated system, and gross error detection is the key to further improving the reliability of GNSS/accelerometer monitoring. Traditional gross error detection methods assume that real-state information is known, and they need to establish state iterators, which leads to low computational efficiency. Meanwhile, in multi-sensor fusion, if the sampling rates are different, the change in the dimension of the observation matrix must be considered, and the calculation is complex. Based on state-domain consistency theory, this paper proposes the State-domain Robust Autonomous Integrity Monitoring by Extrapolation (SRAIME) method for identifying slow-growing gross errors for GNSS/accelerometer integrated deformation monitoring. Compared with the traditional gross error detection method, the proposed method constructs state test statistics based on the state estimated value and the state predicted value, and it directly performs gross error identification in the state domain. This paper deduces the feasibility of the proposed method theoretically and verifies that the proposed method does not need to consider the dimension change of the observation matrix in gross error detection. Meanwhile, in the excitation deformation experiments of the Suntuan River Bridge in Anhui and the Wilford Bridge in the United Kingdom, the slow gradient of the slope was added to the measurement domain, and the traditional AIME method and the method proposed in this paper were adopted for the gross error identification of the GNSS/accelerometer fusion process. The results demonstrate that both methods can effectively detect gross errors, but the proposed method does not need to consider the dimensional change in the observation matrix during the fusion process, which has better applicability to GNSS/accelerometer integrated deformation monitoring.

Satyam Panchal, Krishna Gudlanarva, Manh-Kien Tran et al.

In this paper, an analogous study of the velocity and temperature profiles inside microchannel cooling plates (with hydraulic diameter of 6 mm), placed on a large pouch-type LiFePO₄ battery, is presented using both the laboratory and simulation techniques. For this, we used reverse engineering (RE), computed tomography (CT) scanning, Detroit Engineering Products (DEP) MeshWorks 8.0 for surface meshing of the cold plate, and STAR CCM+ for steady-state simulation. The numerical study was conducted for 20 A (1C) and 40 A (2C) and different operating temperatures. For experimental work, three heat flux sensors were used and were intentionally pasted at distributed locations, out of which one was situated near the negative tab (anode) and the other was near the positive tab (cathode), because the heat production is high near electrodes and the one near the mid body. Moreover, the realizable <i>k</i>-ε turbulence model in STAR CCM+ is used for simulation of the stream in a microchannel cooling plate, and the computational fluid dynamics (CFD) simulations under constant current (CC) discharge load cases are studied. Later, the validation is conducted with the lab data to ensure sufficient cooling occurs for the required range of temperature. The outcome of this research work shows that as C-rates and ambient temperature increase, the temperature contours of the cooling plates also increase.

Jingkai Xie, Yue-Ping Xu, Yuxue Guo et al.

Quantifying the contributions of climatic variables to runoff variance is still a great challenge to water resource management. This study adopted an extended Budyko framework to investigate the effects of terrestrial water storage changes (ΔS) on runoff variance across the source region of the Yellow River, China, during the period of 2003–2014. A new decomposition framework based on the extended Budyko framework was proposed to effectively quantify the contributions of different climatic variables including precipitation, PET and ΔS to runoff variance. The results demonstrated that the extended Budyko framework showed a better performance in presenting the water and energy balance than the original Budyko framework, especially at fine time scales. Meanwhile, the variance in runoff estimated by the new decomposition framework was close to that of runoff observations, indicating that this framework can effectively capture the variation in runoff during 2003–2014. It was also found that precipitation was the most important factor that contributed to runoff changes, while PET made a slightly smaller contribution compared to precipitation. Notably, the results also emphasized the important effects of ΔS on runoff variance at fine time scales, which was useful to better understand the interactions between atmospheric and hydrological processes for regions. HIGHLIGHTS A new decomposition framework was proposed to effectively quantify the contributions of different climatic variables to runoff variance.; Precipitation was the most important factor that contributed to runoff changes, while PET made a slightly smaller contribution compared to precipitation.; The important effects of ΔS on runoff variance at fine time scales can not be neglected.;

WANG Xiaofan, WU Yong, ZHANG ZHONG Lili et al.

【Background and Objective】 Magnetizing the water prior to irrigation is a new technology developed over the past decades in China. The objective of this paper is to investigate how different irrigation water sources alter the effects of the magnetization on photosynthesis, physiological and biochemical characteristics, as well as the yield of lettuce. 【Method】 The experiment was conducted in a solar greenhouse with the Italian lettuce taken as the model plant. It consisted of non-magnetization (M0) and magnetization (M1); added to these are three irrigation water sources: fresh water (T1), reclaimed water (T2) and saline water (T3). Overall, there were six treatments which were arranged in the greenhouse by a randomized block design. For each treatment, we measured the net photosynthetic rate, transpiration rate, antioxidant enzyme activity, mineral element, yield and water use efficiency of the lettuce. 【Result】 Effects of the three water sources after magnetization on crop growth were different. For a given water source, there was no significant difference in the net photosynthetic rate between magnetization and non-magnetization in the early and late growth stage, but in the middle growth stage the magnetized fresh water and the reclaimed water increased the net photosynthetic rate of the crop by 11.16% and 14.73%, respectively. Saline water irrigation reduced the net photosynthetic rate at significant level, and there was no significant difference in net photosynthetic rate between the fresh water and reclaimed water irrigation. Magnetizing the fresh water, reclaimed and saline water increased the transpiration rate, despite not at significant, but they significantly boosted the activities of SOD by 18.08%, 12.77% and 14.68% respectively, the activities of POD by 20.97%, 18.14% and 16.99% respectively, and the activities of CAT by 22.54%, 23.09% and 18.55% respectively. In the meantime, magnetizing the fresh water and the reclaimed water increased the total nitrogen in the lettuce leaves by 7.71% and 6.83%, respectively. Magnetization also altered the content of P, Ca, Mg, Na and K in the leaves, with the alterations varying with water sources. For yield, magnetizing the fresh and the reclaimed water increased the yield by 9.42% and 10.15% at significant level, respectively, magnetizing the saline water did not lead to a noticeable change in the yield. M1T1 was most effective in improving yield and the above-ground dry mass, whereas M0T3 was the least effective. Compared with M0T3, M1T1 increased the yield and the above-ground dry mass by 33.44% and 31.29%, respectively. Depending on water sources, magnetization could also increase water use efficiency by 5.03%~11.65%. 【Conclusion】 Magnetizing the water in irrigating lettuce was beneficial to its physiological and biochemical activities such as photosynthesis and antioxidant enzyme activity, thereby increasing yield and water use efficiency. But the improvement depends on water sources. In our study, magnetizing the fresh water and the reclaimed water was more effective than the saline water.

Wei Lu, Xiaosheng Qin

Urban areas are becoming increasingly vulnerable to extreme storms and flash floods, which could be more damaging under climate change. This study presented an integrated framework for assessing climate change impact on extreme rainfall and urban drainage systems by incorporating a number of statistical and modelling techniques. Starting from synthetic future climate data generated by the stochastic weather generator, the simple scaling method and the Huff rainfall design were adopted for rainfall disaggregation and rainfall design. After having obtained 3-min level designed rainfall information, the urban hydrological model (i.e., Storm Water Management Model) was used to carry out the runoff analysis. A case study in a tropical city was used to demonstrate the proposed framework. Particularly, the impact of selecting different general circulation models and Huff distributions on future 1-h extreme rainfall and the performance of the urban drainage system were investigated. It was revealed that the proposed framework is flexible and easy to implement in generating temporally high-resolution rainfall data under climate model projections and offers a parsimonious way of assessing urban flood risks considering the uncertainty arising from climate change model projections, downscaling and rainfall design.

Paloma Mara de Lima Ferreira, Adriano Rolim da Paz, Juan Martín Bravo

ABSTRACT Hydrological models (HMs) can be applied for different purposes, and a key step is model calibration using objective functions (OF) to quantify the agreement between observed and calculated discharges. Fully understanding the OF is important to properly take advantage of model calibration and interpret the results. This study evaluates 36 OF proposed in the literature, considering two watersheds of different hydrological regimes. Daily simulated streamflow time-series, using a distributed hydrological model (MGB-IPH), and ten daily streamflow synthetic time-series, generated from the observed and calculated streamflows, were used in the analysis of each watershed. These synthetic data were used to evaluate how does each metric evaluate hypothetical cases that present isolated very well known error behaviors. Despite of all NSE-derived (Nash-Sutcliffe efficiency) metrics that use the square of the residuals in their formulation have shown higher sensitivity to errors in high flows, the ones that use daily and monthly averages of flow rates in absolute terms were more stringent than the others to assess HMs performance. Low flow errors were better evaluated by metrics that use the flow logarithm. The constant presence of zero flow rates deteriorate them significantly, with the exception of the metrics TRMSE (Transformed root mean square error) did not demonstrate this problem. An observed limitation of the formulations of some metrics was that the errors of overestimation or underestimation are compensated. Our results reassert that each metric should be interpreted specifically thinking about the aspects it has been proposed for, and simultaneously taking into account a set of metrics would lead to a broader evaluation of HM ability (e.g. multiobjective model evaluation). We recommend that the use of synthetic time series as those proposed in this work could be useful as an auxiliary step towards better understanding the evaluation of a calibrated hydrological model for each study case, taking into account model capabilities and observed hydrologic regime characteristics.

J. R. Santillan, J. R. Santillan, A. M. Amora et al.

Changes in land cover can have negative impacts on the hydrological and hydraulic processes in river basins and watersheds such as increase in surface runoff and peak flows, and greater incidence, risk and vulnerability of flooding. In this study, the impacts of land-cover changes to the hydrologic and hydraulic behaviours of the Agusan River Basin (ARB), the third largest river basin in the Philippines, was analysed using an integrated approach involving Remote Sensing (RS), Geographic Information System (GIS), and hydrologic and hydraulic models. Different land-cover classes in the ARB for the years 1995 and 2017 were mapped using Landsat 5 TM and Landsat 8 OLI images. Using a post-classification change detection approach, changes in land-cover were then determined. The impacts of these changes in land-cover to the to the basin discharge were then estimated using a calibrated hydrologic model based on the Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS) under different extreme rainfall conditions. The impact of the changes in land-cover to flood depth and extent was also determined using a hydraulic model based on the HEC-RAS (River Analysis System). Land cover classification results revealed that the ARB is 67.7% forest in 1995 but have decreased to 62.8% in 2017. Agricultural areas in the basin were also found to have increased from 12.2% to 15.5% in the same period. Other notable land cover changes detected include the increase in built-up lands and range lands, and decrease in barren lands. HEC HMS and HEC RAS model simulation results showed that there was an increase in discharge, flood depth, and flood extents between 1995 and 2017, implying that that the detected changes in land cover have negative impacts to hydrologic and hydraulic behaviours of the ARB.

Gustavo López, Miriam M. García, Luis A. Gameros et al.

En la región noroeste de la república mexicana, zona fronteriza entre México y Estados Unidos (EE.UU.), se está evaluando una posible problemática de la escasa cantidad de agua que México recibe de su vecino del norte, proveniente del Río Colorado (RC). En ocasiones, México recibe agua contaminada por agroquímicos debido a que ese recurso hídrico proviene del lavado de tierras estadounidenses. Además, Estados Unidos propuso revestir el Canal Todo Americano (CTA), lo que ha generado una disminución en los mantos acuíferos del valle de Mexicali, generando preocupación en autoridades y la población. Esto ha conllevado a deteriorar ecosistemas y con ello presentarse cambios de clima que incrementan los niveles de humedad relativa (HR) y temperatura, que genera corrosión y pérdidas económicas, y reducción de la competitividad en la industria electrónica de la región.

نسترن چیت ساز, محمد ابراهیم بنی حبیب

استفاده از مدل‌های تصمیم‌گیری چندمعیاره به‌عنوان یک سیستم تصمیم‌گیری در مدیریت سیلاب، تأثیر بسزایی دارد. در این مقاله به‌منظور مدیریت سیلاب در رودخانۀ گرگانرود، از مدل تصمیم‌گیری چند‌معیارۀ شباهت به گزینۀ ایده‌آل، در رتبه‌بندی هفت گزینۀ مدیریت سیلاب شامل حفظ شرایط طبیعی، بهره‌برداری از سد گلستان، احداث گوره، احداث کانال انحراف، سامانۀ پیش‌بینی و هشدار سیل، استفاده از بیمۀ‌ سیل و سامانۀ پیش‌بینی و هشدار سیل همراه با بیمۀ‌ سیل استفاده شده‌ است. به‌منظور ارزیابی گزینه‌ها علاوه بر ارزش کمی معیارهای اجتماعی، فنی، اقتصادی و زیست‌محیطی، از وزن معیارها نیز استفاده شده‌ است. این داده‌ها بر اساس قضاوت کارشناسی به‌دست آمده‌ است. به‌دلیل محدودیت‌های مدل شباهت به گزینۀ ایده‌آل، از مدل اصلاحی آن استفاده شده و نتایج آنها با یکدیگر مقایسه شده‌ است. نتایج نشان داد که مدل اصلاحی هم در رتبه‌بندی و هم در تحلیل حساسیت وزن معیار، بهتر از مدل قبلی آن عمل کرده‌ است. این مدل اهمیت بیشتری به معیارهای اجتماعی و زیست‌محیطی می‌دهد و برای رتبه‌بندی گزینه‌های مدیریت سیلاب در این مقاله توصیه شده‌ است.

Norbert Hüsers, Jochen Großmann, Holger Weiß et al.

Matthias Gross

Whereas different types of risk assessments are important, real world decision making in processes of restoring contaminated land often necessitates an open acknowledgement that ignorance cannot be avoided. In this presentation a sociological reconstruction of different examples of real world decision making is offered to discuss some of the strategies used to cope with ongoing situations involving ignorance in the remediation of areas containing multiple contaminant sources. Analysis of these processes of dealing with the unknown indicates that planning and policy making benefit when limits to knowledge are openly acknowledged and communicated and when scientific‐technical risk assessments are calibrated with these limits in mind. If ignorance is taken as unavoidable, the allocation of blame radically changes its meaning. Such processes can be seen as a lynchpin of successful planning and acting in face of unknowns during remediation processes on contaminated land.

Enrique González-Sosa, Carlos A. Mastachi-Loza, J. Bernardo Rivera-Vázquez et al.

La composición anual de la evaporación en la cuenca del lago de Pátzcuaro se integró por la evapotranspiración de la vegetación, las pérdidas por intercepción, la evaporación del cuerpo de agua y la evapotranspiración de la vegetación hidrófita. La evapotranspiración de la vegetación se estimó con los registros de seis estaciones climatológicas clásicas y siete evaporímetros ETgage. La evaporación del lago se midió con el método BREB. La evaporación por la intercepción de la vegetación fue calculada con relaciones lineales en función de la precipitación para diversos tipos de vegetación y la transpiración de la vegetación hidrófita a partir de mediciones puntuales con una cámara de circuito abierto. La evapotranspiración resultó de 308 mm < ETR < 503 mm (± 60), la evaporación del lago de 1 179 mm, la evapotranspiración de la vegetación hidrófita (ETH) de 1 824 mm y la correspondiente a la intercepción entre 102 mm < EI < 227 mm (± 51). En el contexto del balance hídrico, en el nivel subcuenca se encontró un déficit de 12 mm en la de Ajuno y más del 65% en la propia cuenca del lago. En el resto de las subcuencas, el balance del residuo fue positivo para la generación de escurrimientos superficiales e infiltración, y/o percolación profunda, entre 18 mm < (P-ET) < 156 mm (± 53). Los resultados encontrados muestran la importancia de la vegetación y el lago en la distribución de la evaporación de la cuenca.

XIE Cheng-yu

Clóvia M. Mistura, Gisieli G. Portela

No Brasil a água subterrânea vem sendo utilizada desde os primórdios, nos tempos coloniais tanto para o abastecimento da população quanto na agricultura, a água subterrânea tem se tornado uma fonte alternativa de abastecimento de água para o consumo humano, devido à escassez e a poluição das águas superficiais ou pela falta de redes de abastecimento. Na zona rural do Município de Marau, RS, não há abastecimento público. O controle da potabilidade da água e o cadastro das fontes alternativas comunitárias são realizados pela Prefeitura Municipal, o que possibilita uma visão da quantidade e qualidade da água captada e distribuída. O fato da água subterrânea ser captada por poços tubulares profundos sem possuírem outorga de uso, torna esta captação irregular perante a legislação, somada ao fato de não se ter controle da quantidade de água retirada do aqüífero aliada ao desconhecimento dos sistemas de cloração e fluoretação existentes, causa uma grande preocupação. A água retirada destes poços tubulares profundos não recebe nenhum tratamento antes do consumo, podendo estar contaminada e assim provocar danos à saúde dos usuários. Ainda há a preocupação de contaminação do aqüífero através destes poços, já que muitos deles não possuem o perímetro de segurança sanitária recomendado.