MODWT-ANN hybrid models for daily precipitation estimates with time-delayed entries in Amazon region.

Hydrological analyses based on precipitation records in the Amazon are essential due to their importance in climate regulation and regional and global atmospheric circulation. However, there are limitations related to data series with short periods and many gaps and failures at the daily scale. Thus, a hybrid model was developed based on an artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) coupled with the maximum overlap discrete wavelet (MODWT) method to obtain precipitation estimates. Six rainfall gauge stations located in different biomes within the studied region were adopted, and satellite data (CMORPH) were used. The interval of data that was have used is 1998-2016. The precipitation data were evaluated by seasonal (wet and dry) periods. The results obtained demonstrated the good capacity of the MODWT-ANFIS model to simulate the daily precipitation. In this case, data entries lagged by 4 days and 5 days performed better, with Nash values close to 1.0 and mean square errors (MSE) below 0.1.

Modeling of land use and land cover change dynamics for future projection of the Amazon number curve.

The hydrological parameter Curve Number (CN) was projected in the future in a 30 m spatial resolution grid for the Amazon. Through the DINAMICA EGO platform, Land Use and Land Cover (LULC) were calibrated, simulated, validated, and projected for 2049 in a five-year time frame from 2009. The reclassified LULCs of 2009, 2014, and 2019 of the MapBiomas 5.0 project were used as input to DINAMICA EGO. Calibration was prepared using the 2009 and 2014 maps and the 2014 simulated map; the validation was carried out using the 2014 map, 2019, and 2019 simulated. In the calibration, the multiple window similarity values were all above 50% for the models of each basin, except for the Tapajós which was 40% in spatial resolution of 255 m. Validation values ranged between 36% and 76% at a spatial resolution of 255 m. Concerning the future projection of CN, the average CN of the Amazon region is equal to 77. The highest values of CN were found in the southern regions of the basins of the Xingu, Tapajós, Madeira, and throughout the basins of the Araguaia and Tocantins. In this Amazon region, in 2049, the areas of high CN will increase due to forest conversion to pasture/agriculture, implying larger runoff and flooding, including the urban areas, which will also expand. These floods will be intensified concerning those that already occur in the Amazon.

Estimation of suspended sediment concentration in Guamá River in the Amazon region.

Monitoring of the suspended sediment concentration (SSC) is important for the analysis of morphological processes in watersheds and rivers, river habitats, and human activities associated with river management. Acoustic Doppler current profilers (ADCP) are used for measurements of flow and velocity in rivers through acoustic waves, which can also be converted into sediment concentrations. In this context, the objective is to verify the applicability of the use of ADCPs (Sontek YSI, model M9 River Surveyor) as an alternative for SSC estimates, this being a recent application of the equipment, mainly in rivers in the Amazon region rich in sediments in suspension. Thus, the Gartner method was used, calibrating its equation with the concentrations obtained by the point sampling method, collected with a bottle of Van Dorn in the Guamá River, Amazon, Brazil. The method used to obtain the SSC with data measured via ADCP resulted in a satisfactory estimate of the concentrations. The correlations between the measured and estimated sediment concentrations had R2 = 0.6827 for point sampling method and R2 = 0.8103 for vertically averaged SSC. These satisfactory results demonstrate the potential of using ADCP to estimate sediments suspended in Amazon basin.

Modelagem Sísmica via métodos das diferenças finitas: caso da bacia do Amazonas / Seismic Modeling by finites difference method: case of Amazon basin

Este trabalho tem por objetivo apresentar os resultados da modelagem sísmica em meios com fortes descontinuidades de propriedades físicas, com ênfase na existência de difrações e múltiplas reflexões, tendo a Bacia do Amazonas como referência à modelagem. As condições de estabilidade e de fronteiras utilizadas no cálculo do campo de ondas sísmicas foram analisadas numericamente pelo método das diferenças finitas, visando melhor compreensão e controle da interpretação de dados sísmicos. A geologia da Bacia do Amazonas é constituída por rochas sedimentares depositadas desde o Ordoviciano até o Recente que atingem espessuras da ordem de 5 km. Os corpos de diabásio, presentes entre os sedimentos paleozóicos, estão dispostos na forma de soleiras, alcançam espessuras de centenas de metros e perfazem um volume total de aproximadamente 90000 Km³. A ocorrência de tais estruturas é responsável pela existência de reflexões múltiplas durante a propagação da onda sísmica o que impossibilita melhor interpretação dos horizontes refletores que se encontram abaixo destas soleiras. Para representar situações geológicas desse tipo foram usados um modelo (sintético) acústico de velocidades e um código computacional elaborado via método das diferenças finitas com aproximação de quarta ordem no espaço e no tempo da equação da onda. A aplicação dos métodos de diferenças finitas para o estudo de propagação de ondas sísmicas melhorou a compreensão sobre a propagação em meios onde existem heterogeneidades significativas, tendo como resultado boa resolução na interpretação dos eventos de reflexão sísmica em áreas de interesse. Como resultado dos experimentos numéricos realizados em meio de geologia complexa, foi observada a influência significativa das reflexões múltiplas devido à camada de alta velocidade, isto provocou maior perda de energia e dificultou a interpretação dos alvos. Por esta razão recomenda-se a integração de dados de superfície com os de poço...

This paper discusses the seismic modeling in medium with strong discontinuities in its physical properties. The approach takes in consideration the existences diffractions and multiple reflections in the analyzed medium, which, at that case, is the Amazon Basin. The stability and boundary conditions of modeling were analyzed by the method of the finite differences. Sedimentary rocks deposited since the Ordovician to the present, reaching depth up to 5 Km. The bodies of diabasic between the paleozoic sediments are layers reaching thickness of hundred meters, which add to 90.000 km3, form the geology of the Amazon Basin. The occurrence of these structures is responsible for multiple reflections during the propagation of the seismic waves, which become impossible a better imaging of horizons located bellow the layers. The representation this geological situation was performed an (synthetic) acoustic velocity model. The numerical discretization scheme is based in a fourth order approximation of the acoustic wave equation in space and time The understanding of the wave propagation heterogeneous medium has improved for the application of the finite difference method. The method achieves a good resolution in the interpretation of seismic reflection events. The numerical results discusses in this paper have allowed to observed the influence of the multiple reflection in a high velocity layer. It increase a loss of energy and difficult the interpretation of the target. For this reason the integration of surface data with the well data is recommended, with the objective to get one better image of the targets below of the diabasic layer.