Hydrographic Basin Research Articles

The freshwater discharge into the Adriatic Sea revisited

The present study reconstructs the river discharge climatology and its respective historical series for all rivers of the Adriatic Sea with averaged climatological daily river discharge above 1 m3s−1, to reach a better representation of the Adriatic rivers in hydrodynamic models and, consequently, to develop a more realistic freshwater balance in the different regions of the hydrographic basin. Based on the European Flood Awareness System (EFAS) data set, a careful method of identification and selection of the Adriatic rivers, followed by a rigorous assessment against observational data, was developed to evaluate the current state of the Adriatic river discharges and their respective trends throughout several climate indicators from 1991 to 2022. Observational data are limited to 85% of the identified rivers, totaling 98% of the overall freshwater input into the Adriatic Sea. The results confirm that the Shallow Northern Adriatic receives the largest freshwater inputs with a daily average exceeding 2,400 m3s−1, which amounts to 61% of the overall Adriatic discharges. Consequently, this region guides the freshwater seasonal cycle of the Adriatic Sea, which presents a well-defined pattern of two flood peaks in late autumn and late spring, separated by a minimum discharge period at mid-summer. From the Central to the Southern Adriatic subregions, the absence of snow-melting effects prevents the secondary flood peak during the spring, shaping the seasonal cycle of river discharges from a single flood peak in late autumn to a drought period in August. The 32 years of continuous river discharge data reveal a negligible trend in the overall Adriatic Sea but a negative trend for the last decade (2013–2022). This decadal decrease is driven by the extreme drought that drastically pounded the northern Adriatic in 2022.

Water quality and sustainable solutions for drinking water supply in the Taquari-Antas watershed, RS, Brazil

Access to safe drinking water is a fundamental human right and a critical component of sustainable development. This study is conducted in the context of the Taquari-Antas Hydrographic Basin, Rio Grande do Sul, Brazil, and assesses the quality of drinking water in 101 rural properties, focusing on identifying problems of potability, especially regarding excessive fluoride concentration, which is a known problem for the water in this region. The study involves the collection of water samples from rural properties, a survey to understand water use and quality perception by users, and water quality analysis using established analytical methodologies. Results show that 58.4% of the investigated rural properties have potability issues, with excessive fluoride being the most prevalent concern, affecting 39.6% of properties. High fluoride levels have significant health implications, including dental and skeletal fluorosis, with global relevance. To address this issue, activated bone charcoal filtration systems were installed in ten properties, effectively reducing fluoride concentrations to within acceptable limits for human consumption. These defluoridation systems are characterized as sustainable, cost-effective, and scalable, offering a practical solution for regions facing similar challenges.
 Keywords: groundwater, rural properties, water stewardship.

Seasonal variation of the water quality in an intermittent river perennified by hydraulic work: a case study of the Terra Nova river basin, Northeast Brazil

The hydrographic basins inserted in the Brazilian semi-arid region tend to aridization and intermittency due to climatological and geological conditions, suffering great anthropic pressure and experiencing seasonal changes in water quality. The aim of this study was to analyze the seasonal variation of the water quality in an intermittent river perennified by hydraulic work: a case study of the Terra Nova river basin (TNRB), located in the state of Pernambuco, Brazil. Physical, chemical and biological parameters were analysed. Water samples were collected at eight sampling points in the TRNB, from 2009 to 2022, totaling 26 campaigns. The Water Quality Index (WQI) adapted by the Environmental Sanitation Technology Company of the State of São Paulo (CETESB) was applied. The results were evaluated spatially and temporally. It was observed that in most campaigns there was no water at the monitoring points, both in the rainy season (77.8%) and in the dry season (73.5%). During the sampling period the WQI ranged from Excellent (81) to Bad (24) in the TNRB. Point Q06 stood out from the others, presenting the only WQI classified as Excellent. With regard to seasonality, the dry season ranged from Excellent (81) to Bad (24), while in the rainy season it ranged from Good (78) to Bad (22). To improve water quality it is necessary to invest in basic sanitation in the TNRB municipalities, environmental recovery, environmental education and monitoring with the aim of mitigating conflicts and impacts.

Analysis of environmental sustainability perception in Paraná Basin III residents via Item Response Theory

Environmental sustainability perception encompasses an individual’s ability to process and interpret sensory information related to the environment. This understanding guides them to consciously and actively protect and care for the environment through continuous learning. This article aims to analyze the environmental sustainability perception of residents of the Paraná Basin III using IRT models for polytomous items, relating it to socio-economic and location characteristics. The choice to conduct the research in this Brazilian territory is driven by the hydrographic basin’s substantial influence on the Itaipu hydroelectric power plant and its significance as a crucial water resource for the region. Results showed that: (1) 13.1% of residents have a low perception of sustainability, (2) there were significant differences in perception between cities, with Toledo having the lowest values, and (3) there was a positive relationship between remuneration and perception of sustainability. By analyzing the results presented, it becomes possible to develop effective public policies to improve the region’s perception of sustainability.

Application of the SMAP monthly model to the Piauitinga river basin located in the State of Sergipe, Brazil

The generation of flow data allows the assessment of the capacity to meet water demands, predict floods, and estimate the potential for hydraulic exploitation for electrical energy generation. In Brazil, precipitation data series, due to their ease of measurement, are more extensive compared to flow data series, enabling the use of hydrological models called rainfall-runoff models capable of estimating flows from precipitation data. Therefore, utilizing the Brazil Gridded Meteorological Data (BR-DWGD) database, this study aims to generate, calibrate, and validate flow data for the Piauitinga river basin located in the state of Sergipe, Brazil, using the monthly rainfall-runoff SMAP model. The soil parameters considered in the validation for the studied region showed a good fit to the observed data, achieving a Nash-Sutcliffe (NS) of 84% and log-Nash-Sutcliffe (NSLog) of 85% in calibration, and Nash-Sutcliffe (NS) of 70% and a log-Nash-Sutcliffe (NSLog) of 80% in validation. Therefore, since the rainfall-runoff model used exhibited good performance for the studied hydrographic basin, it becomes feasible to use the generated synthetic series to fill possible gaps in the historical series of monthly average flows.

HIDDEN ECOTOXICOLOGICAL DANGERS: INVESTIGATING PATHOGEN CIRCULATION AND NON-TOXIC RISKS HAZARDS IN A CRUCIAL BRAZILIAN WATERSHED

Numerous studies evaluate chemical contaminants released by human activities and their effects on biota and aquatic ecosystems. However, few of these studies address non-toxic agents and their potentially harmful effects, which, in a concealed manner, culminate in an increased ecotoxicological risk for aquatic life and public health. This study investigated the presence of toxic and non-toxic pollutants in one of the main watersheds in Northeast Brazil (Rio São Francisco) and proposed a model of dispersion and transfer of resistance among the analyzed bacteria, also assessing the health risks of individuals and aquatic organisms present there. The results are worrying because although most toxic parameters, including physical-chemical and chromatographic aspects, comply with Brazilian environmental standards, non-toxic (microbiological) parameters do not. This research reveals the circulation of pathogens in several points of this hydrographic basin, highlighting the hidden ecotoxicological potential of an aquatic environment considered unaffected by the usual patterns of toxic parameters.

Crecimiento exponencial de la contaminación del Río Moche

Pollution and at the same time water scarcity is considered one of the main concerns throughout the world. In Peru, most of its hydrographic basins are affected by pollution from productive and domestic activities. The present investigation sought to analyze the significant growth in pollution of the Moche River in the period 2010 to 2020; For this purpose, a descriptive study was carried out, using documentary analysis by recording data from the years 2010 - 2020 from entities such as the National Water Authority and other related studies; thereby determining that the pollution of the Moche River has not been reduced in the study period; On the contrary, the existence of chemicals, minerals and bacteria in water have increased exponentially in recent years. Faced with this, there are no encouraging prospects for a solution in the current decade; the political will of the authorities and greater participation and leadership of other representative organizations of the region and also raising citizen awareness through teaching in educational institutions and the media.

Estimation of erosion rate in a watershed of a deforestation area in the Brazilian Amazon, eastern of Mato Grosso

The central region of Brazil, geographically located in Mato Grosso, presents changes in land cover with replacement of the forest for soybean and cotton cultivation, intensifying soil losses in a hydrographic basin located in the tropical climate. The objective of the research is to estimate the loss of soil in the Curisevo River Basin, from the Universal Soil Loss Equation. The methodologies used were the elaboration of a cartographic base in the QGIS geographic information system, with the spatial information of slopes, soil types and land cover, of the Curisevo River Basin. The rainfall erosivity was estimated with rainfall data from the National Institute of Meteorology and the erodibility of the soils was estimated according to the indications of the State of Mato Grosso. The land cover of the Curisevo River Basin was analyzed based on remote sensing images with the vectorization of the areas of the agriculture, pasture and forest classes. The spatial data of slopes of the Curisevo River Basin were obtained from the Shuttle Radar Topography Mission base, with spatial analysis treatment in QGIS. In the basin with an area of 1.18 million hectares, an erosion rate of 134,526 t/ha/year was estimated, corresponding to 16 million tons of sediments. This study contributes to the geographical studies, and the indices used in the equation to estimate soil losses can be analyzed by climatic, pedological, geomorphological and landscape analysis studies in land cover changes in a watershed.

Modeling of Soil Water Distribution in a Small Mid-Latitude Watershed on the British Isle for Short Term Landslide and Flood Risk Assessment

The R-TopModel hydrological model coupled with two landslide and flood probability distribution models was applied to simulate the daily hydrological conditions of a small catchment in the Midlands of the British Isles, throughout 2017. Originally, the methodology was applied to a risk area in the tropical region. In this work, the application was extended to mid-latitude watersheds. The hydrographic basin around the Carsington Water dam (located in the Midlands of the Great Britain) is chosen because it presents risks. The model Nash-Sutcliffe Efficiency for the upstream discharge from the Carsington Water dam reached 50% with a correlation coefficient of the order of 70%, an acceptable value considering the seasonal effects of the dam on evapotranspiration and higher soil permeability. Modeling the distribution of soil moisture and excess surface water allowed obtaining the spatial distribution of the maximum conditional probability of landslides and floods in the Carsington Water catchment. These probability maps obtained are consistent with long-term susceptibility maps for Great Britain.

Characterization and Proposal of Technologies for The Treatment of Domestic Sewage in Ilha Grande Bay – RJ

Objective: To characterize the situation of sanitary wastewater discharge in the hydrographic basins draining into the Baía da Ilha Grande (BIG) and to propose wastewater treatment alternatives based on the literature on decentralized solutions.
  
 Theoretical framework: The BIG has been experiencing negative environmental impacts due to the urbanization process in the region, mainly due to the irregular discharge of domestic wastewater into the environment.
  
 Method: The methodology was developed in two stages, with stage 1 involving data collection from available data in the 2017 Wastewater Atlas, and stage 2 focusing on identifying the most appropriate treatment technologies for this study from the fifteen options evaluated.
  
 Results and conclusion: The characterization revealed that municipalities within the BIG are already using decentralized solutions for domestic wastewater treatment, albeit below the national average coverage rates (18-54%). The five most promising technologies identified were Septic Tanks, Compact UASB, Biodigesters, Compartmentalized Anaerobic Reactors, and Integrated Biosystems. It is concluded that the communities have a sanitation deficit and show potential for implementing decentralized solutions.
  
 Implications of the research: The study helped develop strategies for decision-makers to select the most appropriate wastewater treatment technologies to meet local needs. It also served as a model for scientific studies in other locations.
  
 Originality/value: This study aligns with the Sustainable Development Goals (SDGs), particularly SDG 6, by presenting decentralized solutions as a promising pathway to universalizing household wastewater treatment in developing countries.

Application of bathymetry in water bodies in urban areas of the five Brazilian regions

Application of bathymetry in water bodies in urban areas of the five Brazilian regions

History of geographical research in the field of tourism within the Dniester hydrographic basin (sector of the Republic of Moldova)

The geographical research in the field of tourism within the Nistru Hydrographic Basin on the territory of the Republic of Moldova can be found in several geographical, economic, military, medical works, most of them having a fragmentary character and addressing only some aspects of the tourism resources and infrastructure. The purpose of the present study consists in the chronological analysis of the geographical research in the field of tourism related to the Nistru Hydrographic Basin within the limits of the Republic of Moldova. The main objectives of this study are: the identification and analysis, chronologically and by research fields, of the main works on the tourism resources of the study region; the assessment of the contribution of the analyzed studies in the development of domestic tourism, including in the Nistru Hydrographic Basin; the identification of the strengths and gaps of previous research in the field; the development of a complex geographic study of the tourist phenomenon at the hydrographic basin level. Studies on the spatial distribution of natural and anthropogenic tourism resources were highlighted, particularly protected natural, bioclimatic areas, estate parks, monuments, etc.

Description of a new species of Aegla (Decapoda, Anomura) from the Paran 3 hydrographic basin, Brazil.

Freshwater crustaceans of the genus Aegla are endemic to southern South America, and present greater richness in the river basins of the state of Rio Grande do Sul, Brazil. However, recent studies have shown the enormous potential for discovering new species of Aegla in the state of Paran. In the last six year the number of species recorded has almost doubled, increasing from 9 to 16. In the present work, we expand the current knowledge about the diversity of Aegla in a set of poorly explored drainage basins in the western region of the state and describe a new species, Aegla urussanga n. sp., based on morphological and molecular evidence. A combination of morphological characters supports the new species: orbital spine absent, non-elevated epigastric prominences, robust protogastric lobes with scales, anterior dorsal margin of epimeron 2 armed and with pronounced concavity, sub-rectangular palmar crest of chelipeds, internal margin of the ventral face of the ischium of the cheliped with a proximal stout spine, a distal stout spine, and up to three tubercles with spiniform scales. The molecular data, based on partial COI sequences, also support the distinction of the new species from others that occur in adjacent river basins. The species with the smallest genetic distance from A. urussanga n. sp. is Aegla castro Schmitt, 1942 which occurs in the Iguau River basin. The new species occurs in distinct streams, probably interconnected in the past and currently isolated by the Itaipu reservoir and is the second species of Aegla described from the complex of drainage basins called Paran 3 basin.

Effects of hydrological dynamics in controlling phosphorus bioavailability in intermittent rivers and implications for estuaries

Several studies on intermittent rivers and ephemeral streams (IRES) have focused on the ecology of populations and communities, and very few explored the biogeochemistry and bioavailability of key elements, such as phosphorus (P) and nitrogen (N). In this study, we aimed to explore the role of environmental seasonality on P bioavailability in an intermittent river in Northeastern Brazil and the implications for nutrient dynamics to downstream ecosystems, such as the estuaries. The study was performed at the Cruxati River, located in the Litoral Hydrographic Basin on the coast of Ceará State, Brazil. We sampled riverine sediments during three hydroperiods (i.e., dry, rewetting, and flow) according to the theoretical model for research in intermittent rivers. We performed a geochemical fractionation of different P forms and determined the physicochemical parameters, particle size distribution, mineralogy, and total organic carbon of the sediments. Mean values were compared using the Kruskal–Wallis non-parametric statistical test (p-value < 0.05) and by discriminant function analysis. We observed that the predominant fractions of P were associated with Fe-oxides, silicates, and refractory organic matter, but there were no statistical differences among these fractions for all hydroperiods. The exchangeable-P form was higher in the dry and flow periods than in the rewetting period. On the opposite side, P associated with humic acids and carbonates was lower in the dry and flow periods but higher in the rewetting period. We concluded that seasonality influences the bioavailability of P in intermittent rivers, being strongly influenced by the organic fraction, including the humic acid fraction and the refractory organic matter, which are important sources of P in the aquatic system. Furthermore, the IRES may act as a source or a sink of nutrients throughout the cycles of wetting and drying, which may release P from the sediments to the aquatic environment. Hence, IRES plays an important role in transporting nutrients to estuaries and maintaining their ecosystem services.

Evidence of water surface and flow reduction in the main hydrographic basin of the Brazilian savannah (Cerrado biome): the Araguaia river

Evidence of water surface and flow reduction in the main hydrographic basin of the Brazilian savannah (Cerrado biome): the Araguaia river

The use of integrative tools and multiple models for aquatic environmental quality assessment: a case study of the Mirim Lagoon, Southern Brazil.

This study performed toxicity assays with microalgae, microcrustaceans, and fish as well as evaluated biochemical and behavioral biomarkers in fish and microcrustaceans to assess the quality of the surface water of Mirim Lagoon, which belongs to one of the largest hydrographic basins in the world, located in southern Brazil. Three distinct sampling periods were chosen (January, March, and June 2022) based on the rice plantation dynamics which is the main activity surrounding the lagoon. In January, the plantation is irrigated; in March, the water is drained into the Mirim Lagoon, and July is the off-season. Concerning toxicity tests, there was significant inhibition in microalgae growth when exposed to water collected in March, but no mortality was observed for Ceriodaphia dubia, Daphnia magna, and Danio rerio. Regarding biomarkers, behavioral variables contributed more to the higher values of the Integrated Biomarker Response (IBR) index for both D. magna and D. rerio, in March. The Redundancy Analysis (RDA) indicated a correlation between the biomarkers for both organisms and abiotic parameters, mainly nutrients (total phosphorus and total nitrogen), thermotolerant coliforms, total solids, and turbidity. Spatially, there was no difference during monitoring, but the most significant ecotoxicological effects were observed in March. Multivariate analysis and the IBR index proved to be useful tools for monitoring of water bodies such as Mirim Lagoon.

LC-FLD Determination of Glyphosate, AMPA and Glufosinate in Surface Water from the Paraná River Basin

Natural waters from the Paraná River hydrographic basin in the Brazil-Paraguay cross-border region were analyzed by liquid chromatography coupled to a fluorescence detector (LC-FLD) after extraction of the analytes in anion exchange resin IRA-900. The method allowed good recovery (91 to 113%) of the studied species (glyphosate, (aminomethyl)phosphonic acid (AMPA) and glufosinate) precision compatible with the requirements of the National Metrology Institute (relative standard deviation < 18%) and limit of quantification (LOQ) values between 0.2 and 0.8 mg L-1. In most of the samples collected between January and September 2022, it was impossible to detect the presence of herbicides, even in regions of intense agricultural activity, probably due to the high adsorption capacity of the soils of the region and due to the higher LOQ of the method. Under these conditions, the main transport route is estimated to be associated with surface runoff, which is only favored by heavy rainfall events.

Hydrological modeling for the discharge production in an experimental area of the Guayas river basin, Ecuador

Hydrological simulation is a vital issue within the comprehensive management of hydrographic basins, with estimates being an input for decision-making by territorial managers. The objective of the current study is to conduct the hydrological modeling of an experimental basin of the Guayas River, where the discharge of the Baba River will be simulated using the HEC-HMS hydrological modeler. Hereby, the morphometric and hydrological modeling of the basin was performed from a global DEM (ASTER GDEM) in an environment of Geographic Information Systems (GIS) complemented with the analysis of thematic coverage of land types and uses as well as of precipitation data for the sector. The simulation of the discharge of the experimental basin determined that twenty percent of the precipitation that fell in the time window of analysis generated direct runoff and the residual eighty percent is attributed to abstractions. This is a condition that is given by the presence of agricultural crops corresponding to seventy percent forest masses, native forest and shrubby vegetation, as well as by the interception processes as well as water catchment systems in the urban area. The adequate results obtained in the application of the HEC - HMS model are based on the previous work of physical and hydrological characterization of the basin expressed through the physiographic structure of the basin and the valorization of the parameters that characterize the hydrological processes. This research tends to be useful for small hydrographic basins in Ecuador that play an important role in the ecosystem and lack of hydrometeorological information.

STUDY ON THE ANALYSIS OF PEDOCLIMATIC AND HYDROGRAPHIC CONDITIONS IN ORDER TO INTRODUCE IRRIGATION IN AN AGRICULTURAL FARM IN THE HILLY AREA

The observations made through this paper aim to analyse local conditions and identify optimal solutions for introducing irrigation in an agricultural farm in a hill area, located in the north of Oltenia region, Romania, more precisely Ghioroiu, Valcea County. The relief of the area is characteristic of the hill area with numerous plateaus and valleys, valleys made over the years by the hydrographic network and from the runoff from the slopes. In such areas apparently several sources of water are available, but only part of them can be used for irrigation.Water sources available in the area have been identified, namely groundwater, surface springs and surface waters (Olteț River belonging to the Olt River hydrographic basin). These sources were analysed if they can be used for agriculture through irrigation, and the result was that the Olteț River can be used in crop irrigation.The areas of agricultural land that are exploited by the respective agricultural farm were also analysed to determine which areas can be irrigated and by what method of watering.

Hazard Assessment of Soil Contamination resulting from Solid Waste Trench Landfill Systems

Contamination due to the inadequate disposal of solid waste can cause irreversible environmental damage and public health risks. In the state of São Paulo (Brazil), legislation allows small municipalities to license landfills adopting the trench model. In most cases, it is not mandatory to carry out environmental protection works such as waterproof lining and the drainage of leachate and gases. The aim of this research was to evaluate soil contamination hazards resulting from Solid Waste Trench Landfill Systems (SWTLS). An consultation with experts was carried out in which a Hazard Level (HL) score was applied that considered factors such as geology, pedology, geomorphology, hydrography, groundwater, environmental protection, land use, composition and gravimetric demographic densities. A resource management unit, UGRHI 16 - Tietê Batalha Hydrographic Basin, was defined as the study area, where hazard level was identified to the trench landfill. It was also found that all the municipalities studied are exempt from installing linings in their landfills, in accordance with Brazilian standards, as water surpluses, analyzed in terms of local rainfall, comply with the limits established by regulation. However, the evaluation carried out as part of the present research considered other important factors, through which the existence of risks at different levels for all the municipalities evaluated in relation to the adoption of small SWTLS was noted. The study concluded that the factors adopted for the research are relevant to decision making in terms of system design and the definition of criteria regarding the need for protective lining.