Norhan Abd Rahman

Multi-objective Assessment of Groundwater Quality in Madinah City, Saudi Arabia

In this research, a comprehensive assessment of groundwater quality in the city of Madinah, Saudi Arabia was carried out. The main objective was to evaluate whether the groundwater in the city is contaminated by leakage from different sources which will, in turn, give insight into the sources contributing to the shallow groundwater table rise (SWTR) that is observed in many locations in the city. In addition, the assessed groundwater quality helps in determining the most appropriate reuse of the excess water. Out of the 23 wells that were drilled in the study area for the purposes of this study, 20 wells were sampled for water quality analyses. Results showed that the groundwater in the study area is not contaminated by waste water or organic and inorganic compounds or by pesticides and herbicides from excess irrigation of agricultural areas. This suggests that the recent accelerated urban development in the city did not negatively impact the quality of groundwater and did not significantly contribute to SWTR in the city. Lithological description based on soil samples collected from drilled wells revealed the presence of impervious aquitard that extends over the aquifer in the city. This impervious aquitard has most likely played a role in protecting groundwater quality in the study area. Piper and Schoeller diagrams showed that the water type in the study area is a sodium-chloride type with a significant presence of sulfate. Results of this research give useful information about groundwater quality in Madinah city and will help authorities in planning the most appropriate reuse of excess water that may be pumped out to control SWTR.

Observation of Light Non-Aqueous Phase Liquid Migration in Aggregated Soil Using Image Analysis

Physical model experiments were conducted to observe the migration of light non-aqueous phase liquids (LNAPL) in a double-porosity soil medium. The double-porosity characteristics of the soil were simulated through aggregation of kaolin which resulted in well-defined intra-aggregate and inter-aggregate pores. Digital images were collected to monitor LNAPL (modeled by toluene) migration. A special experimental setup was developed to enable the instantaneous capture of the LNAPL migration around the whole soil column using a single digital camera. An image processing module was applied to the captured images and the results plotted using a surface mapping programme. Events observed during the duration of the experiments were discussed. It was found that the LNAPL flowed much faster in the aggregated soil as compared to a single-porosity soil. The wettability of the fluid and the capillary pressure characteristics were demonstrated to be influential factors in immiscible fluids migration when the soil fabric showed highly contrasting porosity values.

Laboratory Investigation of LNAPL Migration in Double-Porosity Soil Under Fractured Condition Using Digital Image Analysis

The issue of leakage and spillage of light non-aqueous phase liquid (LNAPL) contribute to groundwater contamination, resulting in groundwater pollution and rendering the quality of groundwater unsafe for drinking and agriculture. Therefore, the objective of this study was to investigate LNAPL migration in the double-porosity soil under vibration effect, which has become important for sustainability of groundwater utilization and a comprehensive understanding of the behaviour of liquid migration into the groundwater. A laboratory experiment was conducted to observe the phenomena and characteristics of soil structure, and the pattern of liquid migration in deformable double-porosity by using digital image processing technique. The experiments show that the simulated results were reasonably concise with the visual observations. The gradual increase in vibration table excitation frequency yielded different vibration responses from the respective soils. This indicated that the soil surface acceleration depended significantly on the soil conditions, soil water content, soil structure, and the pattern of soil crack. Faster migration occurred at the cracked soil surface condition compared to other locations on the soil surface that were not cracked. Comparison between soils with 25% and 30% moisture content showed that the downward migration of LNAPL is faster when the soil moisture content is higher. This occurs in soil with higher moisture content due to greater capillary pressure exerted by the liquids and the inter-aggregate pores. This study proved that the digital image processing technique is capable to provide detailed migration flow information to facilitate the researchers to better understand contaminate migration patterns and to ensure sustainability of groundwater resources.

Effect of Inflow and Infiltration in Sewerage System of Residential Area, Kuantan, Pahang

Inflow and infiltration is a phenomenon in sewerage systems that give negative effects on the environment and human health if not addressed properly. Collaboration has been made between Universiti Malaysia Pahang and Indah Water Konsortium Sdn. Bhd., where the purpose is to evaluate the amount of inflow infiltration happening in sewerage systems of residential areas in Kuantan. For this part of the study, one sewer pipeline was selected at the residential area of Bandar Putra, having a population equivalent of 1694. The method used in this research was the Flowrate method to tabulate data. ISCO 2150 and 4250 Area Velocity Flowmeters were used to measure flow rate data in the sewer pipeline, whereas ISCO 674 Rain Gauge was used to collect rainfall intensity data. The data were collected for 41 days with each measurement separated by an interval of five minutes. The result shows that the average percentage infiltration rate of Qpeak and Qave in this residential catchment were 6.0 and 19.4%, respectively. Inflow and infiltration is a real concern, more study is required to determine whether revision of the infiltration rate recommended in the Malaysian Standard is needed.

Sustainable Design of Compacted Laterite Soil Liner

Laterite soil, as one of the major groups of tropical residual soils, was investigated in application for engineered sanitary landfill liner. The laterite soil was used as a stand-alone material without any additives and subjected to different gradation to check its geotechnical potentiality as a sustainable material for liner. Specimens were prepared at different moulding water contents, i.e. optimum moisture content (OMC), dry of OMC and wet of OMC. Tests were carried out on natural soil 30, 40 and 50% fine content by dry weight of soil sample. The results showed that laterite soils should contain at least a minimum of 50% fine gradation to be used as liner. The outcome of this research is expected to serve as a sustainable guide to geotechnical/geo-environmental engineers in using laterite soil as a material in the construction of hydraulic barriers used for engineered sanitary landfill system in tropical countries of the world.

Evaluation of diversion channel capacity using flood hydrodynamic modeling

Flash flood in arid regions are rare but destructive, the capacity of Wadi Bathan ephemeral diversion channel with 10.3 km length in Madinah, Western Saudi Arabia is evaluated using coupled 1D/2D flood hydrodynamic modeling. InfoWorks Integrated Catchment Modeling (ICM) software is used and aerial LiDAR data with 4 points/m2 resolution is utilized for automatic extraction of 1D cross sections and 2D floodplain areas. The synthetic flood hydrograph for 100-year return period is computed using HEC-HMS software and used as inflow to the flood hydrodynamic model. Results of flood inundation mapping showed at least two flood prone areas, and more detailed flood characteristics are computed such as flood extent depth, and surface water profiles. This study showed the importance of flood hydrodynamic modeling and LiDAR data as powerful tools in flash flood simulation and ephemeral channel evaluation in arid regions.

SURFACE AND GROUNDWATER CONTAMINATION DUE TO MINING OF TIN AND IRON– A CASE STUDY IN JOHOR, MALAYSIA

Active and abandoned mines in Kota Tinggi, Johor, have raised environmental concern over heavy metal contamination. Arsenopyrite in tailing and ore body could be the source for acid water generation and subsequent acid mine drainage processes. According to the hydrochemistry facies classification, groundwater has Na-K-Ca, HCO3 character with trend toward sulfatic, near mining area. Two water quality indices have been used for groundwater and surface water assessment, which reveal low heavy metal dissolution, both in tailing and working sites. According to Ficklin diagram, surface water lies in near neutralhigh metal content boundary, that shows relatively high dissolved heavy elements in mining area. When compared to the INTERIM IIA/IIB standard for supply water in Malaysia, it shows that Cu is higher than the limit and As is almost reaching the threshold level.