S. M. Shirazi

GIS-based DRASTIC method for groundwater vulnerability assessment: a review

Groundwater vulnerability is a burning issue all over the world due to the deterioration of groundwater level and increasing contamination which poses serious detrimental risk to the environment. To identify this risk, extensive research has been carried out to assess the groundwater vulnerability by using different methods. Generally, the process-based method, statistical method, and overlay & index methods are used in this regard. DRASTIC method is one type of overlay & index method for vulnerability assessment. This paper represents a comprehensive review of available literature on the applications of Geographic Information System (GIS)-based DRASTIC method for groundwater vulnerability assessment. Also, some other types of overlay & index methods are compared with the DRASTIC method. This study discusses the rescaling of rating ranges and modification of DRASTIC parameters, and shows the comparison of DRASTIC method with other vulnerability assessment methods. In addition, this study identifies some research gaps on the present state of groundwater vulnerability assessment and proposes some research needs for further studies. The findings of this study indicate that the combination of GIS and DRASTIC are more viable for groundwater vulnerability assessment. Furthermore, modified DRASTIC method can be used for agricultural, arid, semi-arid, and basaltic regions.

Storm runoff quality and pollutant loading from commercial, residential, and industrial catchments in the tropic

Information on the pollution level and the influence of hydrologic regime on the stormwater pollutant loading in tropical urban areas are still scarce. More local data are still required because rainfall and runoff generation processes in tropical environment are very different from the temperate regions. This study investigated the extent of urban runoff pollution in residential, commercial, and industrial catchments in the south of Peninsular Malaysia. Stormwater samples and flow rate data were collected from 51 storm events. Samples were analyzed for total suspended solids, 5-day biochemical oxygen demand, chemical oxygen demand, oil and grease (O&G), nitrate nitrogen (NO3-N), nitrite nitrogen, ammonia nitrogen, soluble reactive phosphorus, total phosphorus (TP), and zinc (Zn). It was found that the event mean concentrations (EMCs) of pollutants varied greatly between storm characteristics and land uses. The results revealed that site EMCs for residential catchment were lower than the published data but higher for the commercial and industrial catchments. All rainfall variables were negatively correlated with EMCs of most pollutants except for antecedent dry days (ADD). This study reinforced the earlier findings on the importance of ADD for causing greater EMC values with exceptions for O&G, NO3-N, TP, and Zn. In contrast, the pollutant loadings are influenced primarily by rainfall depth, mean intensity, and max 5-min intensity in all the three catchments. Overall, ADD is an important variable in multiple linear regression models for predicting the EMC values in the tropical urban catchments.

Sustainability of Rainwater Harvesting System in terms of Water Quality

Water is considered an everlasting free source that can be acquired naturally. Demand for processed supply water is growing higher due to an increasing population. Sustainable use of water could maintain a balance between its demand and supply. Rainwater harvesting (RWH) is the most traditional and sustainable method, which could be easily used for potable and nonpotable purposes both in residential and commercial buildings. This could reduce the pressure on processed supply water which enhances the green living. This paper ensures the sustainability of this system through assessing several water-quality parameters of collected rainwater with respect to allowable limits. A number of parameters were included in the analysis: pH, fecal coliform, total coliform, total dissolved solids, turbidity, NH3–N, lead, BOD5, and so forth. The study reveals that the overall quality of water is quite satisfactory as per Bangladesh standards. RWH system offers sufficient amount of water and energy savings through lower consumption. Moreover, considering the cost for installation and maintenance expenses, the system is effective and economical.

Experimental Study on Tsunami Risk Reduction on Coastal Building Fronted by Sea Wall

This experimental study was conducted to idealize the efficacy of sea wall in controlling the tsunami forces on onshore structures. Different types of sea walls were placed in front of the building model. The tsunami forces and the wave heights were measured with and without the sea wall conditions. Types of sea wall, wall height, and wall positions were varied simultaneously to quantify the force reductions. Maximum of 41% forces was reduced by higher sea wall, positioned closer proximity to the model whereas this reduction was about 27% when the wall height was half of the high wall. Experimental investigations revealed that wall with adequate height and placed closer to the structures enables a satisfactory predictor of the force reduction on onshore structures. Another set of tests were performed with perforated wall placing near the building model. Less construction cost makes the provision of perforated sea wall interesting. The overall results showed that the efficacy of perforated wall is almost similar to solid wall. Hence, it can be efficiently used instead of solid wall. Moreover, overtopped water that is stuck behind the wall is readily gone back to the sea through perforations releasing additional forces on the nearby structures.

Influence of Flow Shallowness on Scour Depth at Semi-Integral Bridge Piers

The paper presents the experimental study on the effect of flow shallowness on the scouring at semi-integral bridge piers. The experimental work was conducted in the Hydraulic Laboratory of University of Malaya. Out of 1020 data collected in the flow shallowness and time evolution experiments, 60 data were chosen at maximum scour depth to be analyzed. 30 data for sediment size of d50 = 0.8 mm and 30 data for d50 = 0.26 mm were taken at each side of the piers. The results showed that similar trend was produced for both sediment sizes, the depth of scour increased with the flow depth. Almost all of the data plotted gave the best correlation coefficient. The scour depth at the left and right side of the pier were almost averaged.

Spar platform at deep water region in Malaysian sea

Exploration of oil and gas resources has been accelerated towards deeper waters due to depletion of their reserve in shallow water depth. Malaysian sedimentary basins signpost the existence of these energy sources below its sea-bed. In deep sea depth, traditional fixed types of offshore structures to explore these resources have become incongruous and they have resorted to new configurations. Spar platform is treated as a cost-effective and efficient compliant floating platform in this locale for drilling, production, processing and storage of ocean deposits. This study deals with the oil and gas eminence in Malaysian sea along with structural response behaviors of spar platform subjected to hydrodynamic loading. A single model of spar-mooring line combination has been developed. Coupled conduct has been computed under unidirectional wave loading where all non-linearities are incorporated. Solution in time domain approach follows Newmark-beta integration technique. It is seen that the continental shelf offshore of Malaysian waters is divided into seven sedimentary basins, out of which three basins have major ongoing oil and gas exploration and production activity, namely the Malay basin in West Malaysia off Terengganu and the Sabah and Sarawak basins off the two East Malaysian states of Sabah and Sarawak, respectively. Surge, heave, pitch motion response of spar hull and tension in mooring line tension have been evaluated. Spar platform indicates itself as advanced and competent offshore structures to enhance the oil and gas exploration from all the Malaysian sedimentary basins in the deep water region.

Runoff Potentiality of a Watershed through SCS and Functional Data Analysis Technique

Runoff potentiality of a watershed was assessed based on identifying curve number (CN), soil conservation service (SCS), and functional data analysis (FDA) techniques. Daily discrete rainfall data were collected from weather stations in the study area and analyzed through lowess method for smoothing curve. As runoff data represents a periodic pattern in each watershed, Fourier series was introduced to fit the smooth curve of eight watersheds. Seven terms of Fourier series were introduced for the watersheds 5 and 8, while 8 terms of Fourier series were used for the rest of the watersheds for the best fit of data. Bootstrapping smooth curve analysis reveals that watersheds 1, 2, 3, 6, 7, and 8 are with monthly mean runoffs of 29, 24, 22, 23, 26, and 27 mm, respectively, and these watersheds would likely contribute to surface runoff in the study area. The purpose of this study was to transform runoff data into a smooth curve for representing the surface runoff pattern and mean runoff of each watershed through statistical method. This study provides information of runoff potentiality of each watershed and also provides input data for hydrological modeling.

Arsenic contamination of groundwater in Bangladesh: A review

The groundwater arsenic contamination in Bangladesh is known as the largest natural calamity in the world in terms of the affected population. The millions of tube-wells that had been sunk for drinking water supply are now dispensing poisonous arsenic. Consequently, about 80 million people are at risk and another 30 million are potentially exposed to arsenic poisoning. Most of the recognized stages of arsenic poisoning such as melanosis, keratosis, and hyper-keratosis have been identified in Bangladesh. In addition to the health crisis, the arsenic poisoning is affecting the agricultural crops and causing many social problems. The present study is an overview of the groundwater arsenic contamination in Bangladesh. The severity, sources, and causes of arsenic contamination are discussed in this paper. The health, agricultural, and social effects of the arsenic poisoning are highlighted. In addition, a number of urgent needs are given for combating the arsenic disaster.

RANKING OF SKUDAI RIVER SUB-WATERSHEDS FROM SUSTAINABILITY INDICES - APPLICATION OF PROMETHEE METHOD

In this study, ranking of sub-watersheds in the Skudai River watershed was developed from the sustainability index. The watershed sustainability index (WSI) was developed by considering two important parameters such as potential flood damages (PFD) and potential water quality deterioration (PWQD) parameters. Preference Ranking Organization Method (PROMETHEE), a multicriteria decision making (MCDM) method, was used and WSI scores for 25 Skudai River sub-watersheds were produced. Based on the WSI score, a ranking of sub-watersheds was developed to locate the more problematic areas in the Skudai River watershed. The middle and lower parts of the Skudai River watershed were found to have considerably low sustainability score which suggested the degradation of sub-watersheds from water quality and flood damage parameters. The ranking of sub-watersheds in this study will assist planners and decision makers to identify the problematic areas within the watershed so that priority interventions can be built before the problem gets worse and affects other areas of the Skudai River watershed.

Groundwater quality and hydrogeological characteristics of Malacca state in Malaysia

Abstract Groundwater quality and aquifer productivity of Malacca catchment in Peninsular Malaysia are presented in this article. Pumping test data were collected from 210 shallow and 17 deep boreholes to get well inventory information. Data analysis confirmed that the aquifers consisting of schist, sand, limestone and volcanic rocks were the most productive aquifers for groundwater in Malacca state. GIS-based aquifer productivity map was generated based on bedrock and discharge capacity of the aquifers. Aquifer productivity map is classified into three classes, namely high, moderate and low based on discharge capacity. Groundwater potential of the study area is 35, 57 and 8% of low, moderate and high class respectively. Fifty two shallow and 14 deep aquifer groundwater samples were analyzed for water quality. In some cases, groundwater quality analysis indicated that the turbidity, total dissolved solids, iron, chloride and cadmium concentrations exceeded the limit of drinking water quality standards.