Análise de atributos limnológicos em reservatórios do semiárido nordestino

Este trabalho objetiva investigar os parâmetros limnológicos: condutividade, sólidos totais, turbidez, pH, e clorofila-A, de quatro reservatórios multiuso do semiárido nordestino, sendo estes: Barreiras, Bocaina, Estreito e Piaus. Durante os anos de 2018 a 2019, tais reservatório sofreram impactos decorrentes da seca resultando em volumes inferiores a 30% da capacidade total desses reservatórios. Ao longo do período estudado, foram comparados valores obtidos in situ aos valores estabelecidos na resolução CONAMA n° 357/2005 para águas doces de classe II. A correlação linear foi aplicada para verificar as relações entre os parâmetros estudados e fatores naturais como temperatura média e precipitação. A caracterização climática, volumétrica e a ocorrência de seca, foram fatores importantes na discussão dos atributos limnológicos. Os resultados demostram que a ocorrência da seca tem relação com a redução dos volumes dos reservatórios, impactando negativamente na qualidade da água. Os sólidos em suspensão na água foram apontados como determinantes na variação de outros parâmetros, principalmente, da turbidez, da condutividade e do pH. A clorofila-A, variável de grande importância para a qualidade da água, apresentou correlação significativa positiva com precipitação e temperatura. Quanto os valores determinados pelo CONAMA, observou-se que o pH, sólidos totais, e clorofila-A encontram-se com valores superiores ao que é recomendado. A turbidez foi o único parâmetro que se enquadrou dentro do limite de aceitabilidade desta resolução. Os reservatórios Barreiras e Estreito apresentaram os piores valores médios para os parâmetros analisados. Analysis of limnological attributes in northeastern semi-arid reservoirs A B S T R A C TThis work investigates the limnological parameters: conductivity, total solids, turbidity, pH, and chlorophyll-A, from four multipurpose reservoirs in the northeastern semi-arid region of Brazil, namely: Barreiras, Bocaina, Estreito, and Piaus. During the years 2018 to 2019, these reservoirs suffered impacts due to droughts, resulting in volumes below 30% of the reservoirs' full capacity. Over the study period, values obtained in situ were compared to the values established in CONAMA resolution n° 357/2005 for class II freshwater. A linear correlation was applied to verify the relationships between the studied parameters and natural factors such as average temperature and precipitation. Climatic and volumetric characterization and the occurrence of drought were essential factors in the discussion of limnological attributes. The results show that droughts' occurrence is related to the reduction of reservoir volumes, negatively impacting water quality. Suspended solids in water were identified as determining the variation of other parameters, mainly turbidity, conductivity, and pH. Chlorophyll-A, a variable of great importance for water quality, showed a significant positive correlation with precipitation and temperature. Regarding the values determined by CONAMA, it was observed that the pH, total solids, and chlorophyll-A are higher than what is recommended. Turbidity was the only parameter that fell within the acceptability limit of this resolution. The Barreiras and Estreito reservoirs had the worst average values for the analyzed parameters.Keywords: water quality, CONAMA resolution n° 357/2005, drought, semi-arid.

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Impacts of inter-basin water transfer on the water quality of receiving reservoirs in a tropical semi-arid region

Hydrobiologia ◽

10.1007/s10750-020-04471-z ◽

2021 ◽

Author(s):

José Etham de Lucena Barbosa ◽

Juliana dos Santos Severiano ◽

Hérika Cavalcante ◽

Daniely de Lucena-Silva ◽

Camila Ferreira Mendes ◽

...

Keyword(s):

Water Quality ◽

Arid Region ◽

Water Transfer ◽

Basin Water ◽

Semi Arid Region ◽

Semi Arid

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Hydrochemistry, δD and δ18O to explain the distribution of water quality in a karst setting in the semi-arid region of Northeast Mexico

Environmental Earth Sciences ◽

10.1007/s12665-020-09310-x ◽

2021 ◽

Vol 80 (1) ◽

Author(s):

René Ventura-Houle ◽

Oscar Guevara-Mansilla ◽

Glenda Requena-Lara ◽

Elizabeth Andrade-Limas ◽

Elisenda López-Altarriba

Keyword(s):

Water Quality ◽

Arid Region ◽

Semi Arid Region ◽

Δd And Δ18o ◽

Semi Arid

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Temporal Variation of Chlorophyll-a Concentrations in Highly Dynamic Waters from Unattended Sensors and Remote Sensing Observations

Sensors ◽

10.3390/s18082699 ◽

2018 ◽

Vol 18 (8) ◽

pp. 2699 ◽

Cited By ~ 2

Author(s):

Jian Li ◽

Liqiao Tian ◽

Qingjun Song ◽

Zhaohua Sun ◽

Hongjing Yu ◽

...

Keyword(s):

Remote Sensing ◽

Water Quality ◽

Chlorophyll Fluorescence ◽

Chlorophyll A ◽

Temporal Variations ◽

Lake Area ◽

Short Term ◽

Chl A ◽

Spatio Temporal

Monitoring of water quality changes in highly dynamic inland lakes is frequently impeded by insufficient spatial and temporal coverage, for both field surveys and remote sensing methods. To track short-term variations of chlorophyll fluorescence and chlorophyll-a concentrations in Poyang Lake, the largest freshwater lake in China, high-frequency, in-situ, measurements were collected from two fixed stations. The K-mean clustering method was also applied to identify clusters with similar spatio-temporal variations, using remote sensing Chl-a data products from the MERIS satellite, taken from 2003 to 2012. Four lake area classes were obtained with distinct spatio-temporal patterns, two of which were selected for in situ measurement. Distinct daily periodic variations were observed, with peaks at approximately 3:00 PM and troughs at night or early morning. Short-term variations of chlorophyll fluorescence and Chl-a levels were revealed, with a maximum intra-diurnal ratio of 5.1 and inter-diurnal ratio of 7.4, respectively. Using geostatistical analysis, the temporal range of chlorophyll fluorescence and corresponding Chl-a variations was determined to be 9.6 h, which indicates that there is a temporal discrepancy between Chl-a variations and the sampling frequency of current satellite missions. An analysis of the optimal sampling strategies demonstrated that the influence of the sampling time on the mean Chl-a concentrations observed was higher than 25%, and the uncertainty of any single Terra/MODIS or Aqua/MODIS observation was approximately 15%. Therefore, sampling twice a day is essential to resolve Chl-a variations with a bias level of 10% or less. The results highlight short-term variations of critical water quality parameters in freshwater, and they help identify specific design requirements for geostationary earth observation missions, so that they can better address the challenges of monitoring complex coastal and inland environments around the world.

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Surface water quality assessment in semi-arid region (El Hodna watershed, Algeria) based on water quality index (WQI)

Studia Universitatis Babeș-Bolyai Chemia ◽

10.24193/subbchem.2021.01.10 ◽

2021 ◽

Vol 66 (1) ◽

pp. 127-142

Author(s):

Amel Ferahtia ◽

◽

Mohammed Tahar Halilat ◽

Fateh Mimeche ◽

Ettayib Bensaci ◽

...

Keyword(s):

Water Quality ◽

Surface Water ◽

Quality Assessment ◽

Water Quality Index ◽

Arid Region ◽

Quality Index ◽

Surface Water Quality ◽

Water Quality Assessment ◽

Semi Arid Region ◽

Semi Arid

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Field Spectroscopy as a Tool for Enhancing Water Quality Monitoring in the ACE Basin, SC

The Journal of South Carolina Water Resources ◽

10.34068/jscwr.04.04 ◽

2017 ◽

pp. 41-55 ◽

Cited By ~ 1

Author(s):

Caitlyn C. Mayer ◽

Khalid A. Ali

Keyword(s):

Water Quality ◽

South Carolina ◽

Chlorophyll A ◽

Algal Species ◽

Water Quality Monitoring ◽

Water Systems ◽

Quality Monitoring ◽

Least Squares Regression ◽

Monitoring Methods

The Ashepoo, Combahee, Edisto (ACE) Basin in South Carolina is one of the largest undeveloped estuaries in the Southeastern United States. This system is monitored and protected by several government agencies to ensure its health and preservation. However, as populations in surrounding cities rapidly expand and land is urbanized, the surrounding water systems may decline from an influx of contaminants, leading to hypoxia, fish kills, and eutrophication. Conventional in situ water quality monitoring methods are timely and costly. Satellite remote sensing methods are used globally to monitor water systems and can produce an instantaneous synopsis of color-producing agents (CPAs), including chlorophyll-a, suspended matter (TSM), and colored-dissolved organic matter by applying bio-optical models. In this study, field, laboratory, and historical land use land cover (LULC) data were collected during the summers of 2002, 2011, 2015, and 2016. The results indicated higher levels of chlorophyll, ranging from 2.94 to 12.19 μg/L, and TSM values were from 60.4 to 155.2 mg/L between field seasons, with values increasing with time. A model was developed using multivariate, partial least squares regression (PLSR) to identify wavelengths that are more sensitive to chlorophyll-a (R2 = 0.49; RMSE = 1.8 μg/L) and TSM (R2 = 0.40; RMSE = 12.9 mg/L). The imbrication of absorption and reflectance features characterizing sediments and algal species in ACE Basin waters make it difficult for remote sensors to distinguish variations among in situ concentrations. The results from this study provide a strong foundation for the future of water quality monitoring and for the protection of biodiversity in the ACE basin.

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OPTMIZATION OF BIO-OPTICAL MODEL PARAMETERS FOR TURBID LAKE WATER QUALITY ESTIMATION USING LANDSAT 8 AND WASI-2D

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-3-w11-67-2020 ◽

2020 ◽

Vol XLII-3/W11 ◽

pp. 67-72

Author(s):

A. Manuel ◽

A. C. Blanco ◽

A. M. Tamondong ◽

R. Jalbuena ◽

O. Cabrera ◽

...

Keyword(s):

Water Quality ◽

Chlorophyll A ◽

The Philippines ◽

Quality Data ◽

Model Parameters ◽

Landsat 8 ◽

Water Quality Data ◽

Chlorophyll A Concentration ◽

In Situ Data

Abstract. Laguna Lake, the Philippines’ largest freshwater lake, has always been historically, economically, and ecologically significant to the people living near it. However, as it lies at the center of urban development in Metro Manila, it suffers from water quality degradation. Water quality sampling by current field methods is not enough to assess the spatial and temporal variations of water quality in the lake. Regular water quality monitoring is advised, and remote sensing addresses the need for a synchronized and frequent observation and provides an efficient way to obtain bio-optical water quality parameters. Optimization of bio-optical models is done as local parameters change regionally and seasonally, thus requiring calibration. Field spectral measurements and in-situ water quality data taken during simultaneous satellite overpass were used to calibrate the bio-optical modelling tool WASI-2D to get estimates of chlorophyll-a concentration from the corresponding Landsat-8 images. The initial output values for chlorophyll-a concentration, which ranges from 10–40 μg/L, has an RMSE of up to 10 μg/L when compared with in situ data. Further refinements in the initial and constant parameters of the model resulted in an improved chlorophyll-a concentration retrieval from the Landsat-8 images. The outputs provided a chlorophyll-a concentration range from 5–12 μg/L, well within the usual range of measured values in the lake, with an RMSE of 2.28 μg/L compared to in situ data.

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Households’ Adaptation to Climate Change Hazards in Semi-Arid Region of Mopani, South Africa

10.5772/intechopen.94759 ◽

2021 ◽

Author(s):

Musa Yusuf Jimoh ◽

Peter Bikam ◽

Hector Chikoore ◽

James Chakwizira ◽

Emaculate Ingwani

Keyword(s):

Climate Change ◽

South Africa ◽

Climate Change Adaptation ◽

Urban Areas ◽

Arid Region ◽

Adaptive Systems ◽

Adaptation To Climate Change ◽

Temperature And Precipitation ◽

Semi Arid Region ◽

Semi Arid

New climate change realities are no longer a doubtful phenomenon, but realities to adapt and live with. Its cogent impacts and implications’ dispositions pervade all sectors and geographic scales, making no sector or geographic area immune, nor any human endeavor spared from the associated adversities. The consequences of this emerging climate order are already manifesting, with narratives written beyond the alterations in temperature and precipitation, particularly in urban areas of semi-arid region of South Africa. The need to better understand and respond to the new climate change realities is particularly acute in this region. Thus, this chapter highlights the concept of adaptation as a fundamental component of managing climate change vulnerability, through identifying and providing insight in respect of some available climate change adaptation models and how these models fit within the premises and programmes of sustainable adaptation in semi-arid region with gaps identification. The efforts of governments within the global context are examined with households’ individual adaptation strategies to climate change hazards in Mopani District. The factors hindering the success of sustainable urban climate change adaptation strategic framework and urban households’ adaptive systems are also subjects of debate and constitute the concluding remarks to the chapter.

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MARINE-EO project: Monitoring and forecast of eutrophication around fish farms, a Maliakos Gulf case (Eastern Mediterranean).

10.5194/egusphere-egu21-9961 ◽

2021 ◽

Author(s):

Amandine Declerck ◽

Matthias Delpey ◽

Thibaut Voirand ◽

Ioanna Varkitzi

Keyword(s):

Water Quality ◽

High Resolution ◽

Real Time ◽

Chlorophyll A ◽

Satellite Observation ◽

Risk Level ◽

Fish Farms ◽

Ocean Modelling ◽

Monitoring And Forecasting

Keywords: eutrophication; high resolution ocean modeling ; Chla satellite data ; biogeochemistryMaliakos Gulf corresponds to mesotrophic waters that can reach eutrophic conditions and are occasionally subject to Harmful Algal Blooms (HAB) (Varkitzi et al. 2018). At the same time, it is an important fish farming and aquaculture production area. A large issue is thus related to the monitoring and forecasting of the risk of occurrence of algae blooms in the Gulf. For this purpose, the present study couples predictions from a high-resolution numerical ocean model with satellite observation to improve the monitoring and anticipation of threats for the local fish farms induced by occasional eutrophication.This solution is developed in the frame of the MARINE-EO project (https://marine-eo.eu/). It combines satellite observation with high-resolution ocean modelling to provide detailed information as a support to fish farms management and operations. It is implemented in an operational platform, which provides continuous information in real time as well as short term predictions. The deployed solution uses CMEMS physical products as an input data and offers to refine this solution in order to provide a local information on site using a downscaling strategy. High resolution satellite products and ocean modelling allow to include the impact of local coastal processes on currents and water quality parameters to provide a proper monitoring and forecasting solution at the scale of a specific fish farm.To model specific eutrophication processes, a NPZD (Nutrients-Phytoplankton-Zooplankton-Detritus) biogeochemical model is used. Included in the MOHID Water modelling system, the water quality module (Mateus, 2006) considering 18 properties: nutrients and organic matter (nitrogen, phosphorus and silica biogeochemical cycles), oxygen and organisms (phytoplankton and zooplankton) was deployed in the western Aegean Sea. The simulated chlorophyll a concentrations are used to compute a risk level for the eutrophication occurrence. To complete this indicator, another risk level was based on the eutrophication variation following Primpas et al. (2010) formulation. In addition to model forecasts, ocean color observations from the Sentinel-2 MSI and Landsat-8 OLI sensors are used to provide high resolution chlorophyll a concentrations maps in case of bloom events. The processing chain uses the sixth version of the Quasi-Analytical Algorithm initially developed by Lee et al. (2002) and an empirical relation based on a database built using the HydroLight software to compute chlorophyll a concentration.Two past eutrophication events monitored in situ (Varkitzi et al. 2018) were studied to assess the accuracy of the developed tool. Although few in situ data were available on environmental input (as rivers flow and nutrient concentrations), it was possible using statistics to reproduce qualitatively these blooms. Finally, an operational demonstration was conducted during 2 months of the 2020 autumn season, to showcase real time monitoring and predictive perspectives.

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Impacts of drying and reflooding on water quality of a tropical semi-arid reservoir during an extended drought event

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x6918 ◽

2019 ◽

Vol 31 ◽

Author(s):

Jéssica Nayara de Carvalho Leite ◽

Vanessa Becker

Keyword(s):

Water Quality ◽

Electrical Conductivity ◽

Chlorophyll A ◽

Total Phosphorus ◽

Algal Biomass ◽

Soluble Reactive Phosphorus ◽

Drought Event ◽

Reactive Phosphorus ◽

Semi Arid

Abstract Aim The aim of this study was to analyze the water quality of a tropical, semi-arid reservoir after a reflooding. In terms of impact on water quality after a drought event, it is expected that there will be improvements with the reflooding. Less algal biomass, increased water transparency, decreased turbidity and low nutrient concentration. Methods This study was performed in a tropical, semi-arid man-made lake (Dourado Reservoir), during an extended drought period. This study consisted of a comparison of three distinct periods determined by water accumulation. The limnological variables, including water transparency, turbidity, electrical conductivity, pH, total phosphorus, soluble reactive phosphorus, and chlorophyll-a were analyzed. A principal component analysis (PCA) was also performed to verify the patterns of the variables in relation to the sample units in the studied periods. Results After water renewal, there was an expressive reduction in chlorophyll-a. Electrical conductivity, pH, and turbidity variables also reduced after the reflooding, indicating an improvement in water quality. There was no reduction in total phosphorus and soluble reactive phosphorus after the reflooding compared to the previous periods. Conclusions The significant reduction in algal biomass after reflooding in Dourado indicates water quality improvement in terms of eutrophication due to the change of the trophic state from eutrophic to mesotrophic.

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