Publications by authors named "Iran E Lima Neto"

Eutrophication is a recurrent problem in water bodies, especially in tropical semiarid reservoirs. The trophic state index (TSI) is an important tool for the environmental management of aquatic systems. However, determining the TSI involves uncertainties that can affect decision-making.

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This paper investigated whether rainfall promotes dilution or increase in nutrient concentrations and which land use indicators are the main predictors of nutrients in intermittent rivers in a large Brazilian semiarid region. The total phosphorus (TP) and total inorganic nitrogen (TIN) were monitored between 2013 and 2018 at 92 river water quality monitoring sites. The monthly rainfall (Rn) was obtained from 575 rain gauges.

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In arid and semiarid environments, evaporation is responsible for significant water losses from reservoirs. This condition is of special concern in the Brazilian Northeast region, as this is one of the most populous semiarid areas in the planet. The present study aims to assess the spatio-temporal variability of evaporation rates on the water surface of Pentecoste reservoir, located in the Brazilian semiarid region, by using both the hydrodynamic model Delft3D and a remote sensing technique (RS).

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The dissolved oxygen (DO) level in the hypolimnion of lakes and reservoirs can reach anoxic conditions, which favor the release of phosphorus from the sediment bed to the water column. However, to estimate nutrient release from sediment is extremely important to quantify the duration of anoxia. In low latitude regions, the water-sediment layer is warmer than in temperate regions and eutrophication is usually more severe, potentially accelerating oxygen depletion and extending the anoxia period.

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Climate variability and change, associated with increasing water demands, can have significant implications for water availability. In the Brazilian semi-arid, eutrophication in reservoirs raises the risk of water scarcity. The reservoirs have also a high seasonal and annual variability of water level and volume, which can have important effects on chlorophyll-a concentration (Chla).

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This study investigated the relationships between physical, limnological and climatic drivers with the internal total phosphorus (TP) loading produced over the dry period in 30 water supply reservoirs of the Brazilian semiarid. Improvements in the understanding of sedimentary TP fluxes in reservoirs of dryland regions are pressing as they usually have serious water quality related issues, remaining mostly eutrophic especially under frequent drought events. Gross daily fluxes and net seasonal average release rates were calculated from mass balance and regression equations considering water and sediment TP concentrations, anoxic duration, water temperature and fish contribution.

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Nutrient accumulation in man-made reservoirs has been documented worldwide. Therefore, quantifying phosphorus loading and understanding its temporal dynamics in reservoirs is mandatory for sustainable water management. In this study, the Vollenweider's complete-mix phosphorus budget model was adapted to account for high water level variations, which are a common feature in tropical reservoirs, and for internal phosphorus loads.

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The dynamics of total phosphorus (TP) in 18 strategic reservoirs of the high-density reservoir network of the Brazilian semiarid was evaluated during the wet and dry periods for the past 12 years. Seasonal overlying concentrations presented no significant differences for about 90% of the reservoirs (p>0.05).

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Hydrological data and total phosphorus (TP) concentration at reservoirs' outlet were combined in a transient complete-mix model to obtain mean input loads and inlet concentration-flow relationships. This approach was designed to investigate the issue of phosphorus pollution in semiarid regions with intermittent rivers. The methodology was applied for twenty reservoirs in the State of Ceará, Brazilian semiarid.

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This study investigated experimentally the air entrainment and pressure drop in low-cost ejectors composed of two pieces shaped from PVC bars inserted in a 25 mm T-junction of the same material. The hydraulic behavior was very similar for the different ejector designs, and linear relationships between the water and air flow rates were fitted. However, when a rotameter was installed at the air line, the head losses resulted in a pronounced decrease (3-fold) in the air entrainment rate.

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Eutrophication of lakes has affected society in many regions, particularly in water scarce environments where: i) low runoff reduces the self-purification potential of water bodies; ii) water supply relies on surface reservoirs, which are susceptible to nutrient enrichment. This work presents an assessment of the impact of the silted sediment management on the trophic status of a tropical surface reservoir with intense temporal variability of water storage. A complete mixing model describing the total phosphorus budget in the water and sediments was used, based on semi-empirical formulations.

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This study investigated phosphorus (P) dynamics in the sediment-water interface of three distinct reservoirs located in a tropical semiarid region. Sequential chemical fractioning of the P content in the sediment and controlled experiments of the sediment-water interface were performed to understand and model the effect of the different P fractions on the exchange dynamics under anoxic and oxic scenarios. The results revealed that the older the reservoir, the higher the amount of iron and aluminum-bound P in the sediment, and that this fraction was responsible for a 10-fold increase in P concentration in the water during anoxic conditions.

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Field surveys and integral modelling were carried out to study the effect of bubble plumes on the flow hydrodynamics and the time-evolution of water temperature profiles in a shallow lake with maximum depth of about 4 m. Then, model simulations were performed to verify the feasibility of destratification of ten water-supply reservoirs with capacities of 10-2,000 hm3. Finally, hydrological modelling was conducted to assess the impact of destratification on evaporation suppression and its effects on reservoir yield.

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This paper investigates phosphorus dynamics in a highly polluted system composed of a drainage channel followed by a shallow reservoir in the city of Fortaleza, Brazilian semiarid. During the dry season, significant non-point source loads of total phosphorus originated from residences unconnected to sewers were identified along the channel, resulting in an increasing flow rate of untreated sewage towards the reservoir. During the rainy season, as a consequence of dilution, phosphorus concentrations decreased by about 5-fold.

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This paper presents an integral model to evaluate the impact of gas transfer on the hydrodynamics of bubble plumes. The model is based on the Gaussian type self-similarity and functional relationships for the entrainment coefficient and factor of momentum amplification due to turbulence. The impact of mass transfer on bubble plume hydrodynamics is investigated considering different bubble sizes, gas flow rates and water depths.

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