Predicting suspended sediment load in Peninsular Malaysia using support vector machine and deep learning algorithms

High loads of suspended sediments in rivers are known to cause detrimental effects to potable water sources, river water quality, irrigation activities, and dam or reservoir operations. For this reason, the study of suspended sediment load (SSL) prediction is important for monitoring and damage mitigation purposes. The present study tests and develops machine learning (ML) models, based on the support vector machine (SVM), artificial neural network (ANN) and long short-term memory (LSTM) algorithms, to predict SSL based on 11 different river data sets comprising of streamflow (SF) and SSL data obtained from the Malaysian Department of Irrigation and Drainage. The main objective of the present study is to propose a single model that is capable of accurately predicting SSLs for any river data set within Peninsular Malaysia. The ANN3 model, based on the ANN algorithm and input scenario 3 (inputs consisting of current-day SF, previous-day SF, and previous-day SSL), is determined as the best model in the present study as it produced the best predictive performance for 5 out of 11 of the tested data sets and obtained the highest average RM with a score of 2.64 when compared to the other tested models, indicating that it has the highest reliability to produce relatively high-accuracy SSL predictions for different data sets. Therefore, the ANN3 model is proposed as a universal model for the prediction of SSL within Peninsular Malaysia.

CONTROL AND METHODOLOGY OF MODELING HYDROLOGICAL PROCESSES IN THE DESIGN OF HYDRAULIC STRUCTURES IN THE ESTUARIES OF RIVERS

The article presents the methodology of hydrological modeling of water flows for constructing flow plans in the design of hydraulic structures. On the basis of these calculations, both the specific costs of bottom and suspended sediments in each flow stream and the deformation of the riverbed at various points in time can be determined. The results of experiments with spatial models of river sections are considered. The developed technique makes it possible to calculate the deformation of the bottom and shores and form a flow organization scheme, which, due to an increase in velocities in some section of the channel, ensures sediment transport to more remote areas of the seashore, up to the open sea.

Sediment Flow Characteristics in The Upper Slope of Volcanic Landscapes With Dryland Agriculture

Increasing population densities and food demands are major factors contributing to the widespread use of agricultural drylands in upper volcanic slope areas. This phenomenon poses a high risk of severe erosional events that are environmentally hazardous. Therefore, this study aims to analyze the sediment flow characteristics, based on the relationship between sediment flow and water level as well as the sediment discharge rate and soil loss. Field surveys were conducted to determine the soil measurement, slope morphology and dryland cover characteristics. The sediment flow was evaluated at the gully outlet, where 169 suspension data pairs for the modeling and 130 suspension data pairs for the validation, as well as the bed load, water level, rainfall and water flow characteristics were obtained. Tables and figures were subsequently used to represent the measurement data and analysis results for the correlation between the flow rate effects, sediment and soil loss on the water surface. The results showed that the sediment flow in volcanic landscape slopes with dryland agriculture were possibly characterized by the polynomial relationship, using the suspension discharge model, Qs=0.0322Q2+6.0625Q–1.2658. Under this condition, the average rate of soil loss in the form of sediment load and erosion rate of the catchment area occurred at 953.53 and ​​1,657.94 ton/ha/yr, respectively. Furthermore, the sediment sources in the soil loss were believed to originate from 83% of the suspended sediments and 17% bed loads. Keywords: Discharge; Dryland; Landscape; Sediment; Volcano Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License

Variation entry of sediment, organic matter and different forms of phosphorus and nitrogen in flood and normal events in the Anzali wetland

Phosphorus (P), nitrogen (N) and organic component are released from the soil into surface bodies by runoff and erosion, causing the pollution and eutrophication of water resources. This study was aimed to investigate the seasonal changes in loads of N and P components, and organic matter (OM) in the Pasikhan River in flood and normal conditions. Sampling was performed monthly during normal flow conditions and for five flood events. The concentrations of P and N components were measured in the samples. The OM of the suspended sediments was determined by the combustion method. Under the normal flows, the maximum loads of total P and OM were about 0.553 mg l−1 (STD = 0.11) (November) and 3.41% (STD = 1.17) (November) in the autumn, respectively. The total N concentration of 0.533 mg l−1 (STD = 0.12) was observed in the winter. In the flood events, the TP, TN and OM ranged from 0.48 to 3.5 mg l−1, 0.28 to 0.79 mg l−1 and 1.24 to 4.11%, respectively. The results indicated a high risk of eutrophication in the Pasikhan River. Also, the study revealed that in a severe flood event, some 113.9 tons h−1 of OM can be released from the river watershed. Furthermore, there was a high correlation between the amount of P and OM losses with the concentration of suspended sediments in different flood events. Finally, it is concluded that if the floods are not controlled, they not only cause a rapid loss of soil nutrients and OM but also lead to severe eutrophication in the Anzali wetland.

Multiple anthropogenic stressors have inconsistent cumulative effects across a large spatial gradient

Biodiversity is declining, typically because of multiple anthropogenic stressors. Cumulative effects of multiple stressors are classified as additive, when cumulative effects are as expected from the stressor’s singular effects, synergistic when greater than additive or antagonistic when less than additive. Less attention has been given to the consistency of cumulative effects. We analysed stream insects, Ephemeroptera, Plecoptera and Trichoptera (EPT) data from two habitats spanning a 3,600 km latitudinal (S11◦-S43◦) gradient in eastern Australia. We found that the cumulative effect of salinity and suspended sediments on EPT family richness was inconsistent with additive, synergistic or antagonistic effects, and the reduction EPT family richness from increasing both stressors varied (48-70%) depending on habitat (riffle vs. edge), water temperature and terrain slope. Studies of cumulative effects of multiple stressors at one location risk not describing cumulative effects elsewhere and ecologists should consider the spatial consistency of multiple stressors.