Trend analysis of water discharge and sediment load during the past three decades of development in the Langat basin,Malaysia

Abstract

In this study, the trends of water discharge and sediment load from three hydrometric stations over the past 25 years of development in the state of Selangor, Peninsular Malaysia, were analysed using the Mann-Kendall and Pettitt tests. Landscape metrics for establishing the relationship between land-use changes and trends of hydrological time series were calculated. The hydrological trends were also studied in terms of rainfall variations and manmade features. The results indicate upward trends in water discharge in the Hulu Langat sub-basin and in sediment load in the Semenyih sub-basin. These increasing trends were mainly caused by rapid changes in land use. Upward trends of hydrological series in the Hulu Langat sub-basin matched its rainfall pattern. In the Lui sub-basin, however, trends of hydrological series, and variations in rainfall and land use were not statistically significant.

Editor Z.W. Kundzewicz; Associate editor K. Hamed

Citation Memarian, H., Balasundram, S.K., Talib, J.B., Sood, A.M., and Abbaspour, K.C., 2012. Trend analysis of water discharge and sediment load during the past three decades of development in the Langat basin, Malaysia. Hydrological Sciences Journal, 57 (6), 1207–1222.     

Deforestation effects on soil properties,runoff and erosion in northern Iran

Improper cultivation practices are seriously degrading native forest ecosystems in northern Iran. Hence, the objectives of this study are to compare selected soil properties, runoff amount, erosion and also introducing equations to predict the runoff and soil erosion in three types of land use (forest, garden and cultivated). A simple portable rainfall simulator has been set in 90 random points to create experimental rainfall. Result showed that changes in natural forest led to a significant clay, organic carbon of soil, total N and antecedent soil moisture decrease and sand, pH and bulk density increasing. The rainfall runoff experiments indicate that runoff content of the natural forest soils was 35 % and respectively 38.45 % higher than the garden and cultivated land soils .This result could be related to the higher antecedent soil moisture in natural forest compared with the other land uses. According to the obtained results, garden soil erosion and cultivated land was 1.351 and respectively 1.587 times higher than the forest. The correlation matrix revealed that runoff content was positively correlated with antecedent soil moisture, bulk density and silt, and negatively with soil organic carbon, total N and sand. Also, soil organic carbon, total N, clay and sand showed negative correlation with soil erosion, while there is a positive correlation between erosion and silt, bulk density, pH and antecedent soil moisture. The results of multiple linear regression showed that runoff in forest, garden and cultivated land can be predicted with correlation coefficient of 0.637, 0.547 and 0.624, respectively. The correlation coefficients of 0.798, 0.628 and 0.560 in equations indicate their moderate potential in simulating soil erosion.     

Fast direct sampling for multiple-point stochastic simulation

Multiple-point statistics simulation has recently attracted significant attention for the simulation of complex geological structures. In this paper, a fast direct sampling (FDS) algorithm is presented based on a fast gradient descent pattern matching strategy. The match is directly extracted from the training image (TI) and so the method does not require intensive preprocessing and database storage. The initial node of the search path is selected randomly but the following nodes are selected in a principled manner so that the path is conducted to the right match. Each node is selected based on the matching accuracy and the behavior of the TI in the previous node. A simple initialization strategy is presented in this paper which significantly accelerates the matching process at the expense of a very naïve preprocessing stage. The proposed simulation algorithm has several outstanding advantages: it needs no (or very limited) preprocessing, does not need any database storage, searches for the match directly in the TI, is not limited to fixed size patterns (the pattern size can be easily changed during simulation), is capable of handling both continuous and categorical data, is capable of handling multivariate data, and finally and more importantly, is a fast method while maintaining high standards for the matching quality. Experiments on different TIs reveal that the simulation results of FDS and DS are comparable in terms of pattern reproduction and connectivity while FDS is far faster than DS.     

Stochastic Modeling of Short Term Variations of Sea Level in Eastern Canada

Hourly sea level records from three stations in eastern Canada (Québec-Lauzon, Harrington-Harbour and Halifax) are analyzed both in frequency domain from 1970 to 1979 and in time domain during 1973. At the three stations, the deterministic model explains 90 to 96% of the total variability of sea level. The semidiurnal and diurnal tides contribute largely to its variations. The residual series, less than 10% of the initial variations of sea level, contain irregular values including extreme values of seiches and storm surges. Such random variations are analyzed and modeled following the method described by Box and Jenkins (1976). The long period variations (2 to 30 days) can be attributed to meteorological forcing (atmospheric pressure and winds). The short period variations (some hours to one day) can be attributed to longitudinal seiches, semidiurnal and diurnal atmospheric tides, and inertial oscillations. The water discharge from the St. Lawrence River contributes 29% of the monthly residual sea level at Qué     

Iron biomineralization by anaerobic neutrophilic iron-oxidizing bacteria

Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate-dependent iron-oxidizing bacterium Acidovorax sp. strain BoFeN1 in the presence of dissolved Fe(II) using electron microscopy and Scanning Transmission X-ray Microscopy (STXM). All detected minerals consisted mainly of amorphous iron phosphates, but based on their morphology and localization, three types of precipitates could be discriminated: (1) mineralized filaments at distance from the cells, (2) globules of 100 ± 25 nm in diameter, at the cell surface and (3) a 40-nm thick mineralized layer within the periplasm. All of those phases were shown to be intimately associated with organic molecules. Periplasmic encrustation was accompanied by an accumulation of protein moieties. In the same way, exopolysaccharides were associated with the extracellular mineralized filaments. The evolution of cell encrustation was followed by TEM over the time course of a culture: cell encrustation proceeded progressively, with rapid precipitation in the periplasm (in a few tens of minutes), followed by the formation of surface-bound globules. Moreover, we frequently observed an asymmetric mineral thickening at the cell poles. In parallel, the evolution of iron oxidation was quantified by STXM: iron both contained in the bacteria and in the extracellular precipitates reached complete oxidation within 6 days. While a progressive oxidation of Fe in the bacteria and in the medium could be observed, spatial redox (oxido-reduction state) heterogeneities were detected at the cell poles and in the extracellular precipitates after 1 day. All these findings provide new information to further the understanding of molecular processes involved in iron biomineralization by anaerobic iron-oxidizing bacteria and offer potential signatures of those metabolisms that can be looked for in the geological record.     

Phosphorylated nanocellulose papers for copper adsorption from aqueous solutions

Copper is a major problem in industrial wastewater streams, seriously affecting the quality of potential drinking water. Several approaches, including continuous membrane processes or batch-wise application of adsorbents, are in use to tackle this problem. Unfortunately, these processes suffer from their particular drawbacks, such as low permeance or disposal of saturated adsorbents. However, a combination of these processes could constitute a step towards a more efficient copper removal solution. Here, we present a nanopaper ion-exchanger prepared from cellulose nanofibrils produced from fibre sludge, a paper industry waste stream, for the efficient, continuous removal of copper from aqueous solutions. This nanopaper ion-exchanger comprises phosphorylated cellulose nanofibrils that were processed into nanopapers by papermaking. The performance of these phosphorylated nanopaper membranes was determined with respect to their rejection of copper and permeance. It was shown that this new type of nanopaper is capable of rejecting copper ions during a filtration process by adsorption. Results suggest that functional groups on the surface of the nanopapers contribute to the adsorption of copper ions to a greater extent than phosphate groups within the bulk of the nanopaper. Moreover, we demonstrated that those nanopaper ion-exchangers could be regenerated and reused and that in the presence of calcium ions, the adsorption capacity for copper was only slightly reduced.