Ghazi Al-Rawas

Effects of urban form on wadi flow frequency analysis in the Wadi Aday watershed in Muscat, Oman

The effect of urban form on Curve Number (CN) use in rainfall-runoff modelling is explored in an arid wadi watershed in Oman. The standard hydrologic CN used in the Soil Conservation Service method may not be appropriate to use in urbanized arid wadi regions since the land-use characteristics are different than those for which the CN method was developed for. In this paper a new method is described to develop regional CN for arid wadi regions. The modified CN are then used to predict peak-flow and time-to-peak in a wadi watershed and are compared to results from the standard CN method. The regional values produce higher peak-flow (an increase of 19% or 7.4 m3/s, on average) with shorter time-to-peak (a decrease of 16% or 86 minutes, on average), mimicking the flash-floods seen in the region. In addition, the regional CN were used to model the change in hydrology caused by urbanization.

Development of ground-shaking maps for the Sultanate of Oman

This study presents research toward the development of ground-shaking maps after a real earthquake, or for scenario earthquakes originating from seismic sources within and around the Sultanate of Oman. Major important earthquake sources that are important for the Sultanate of Oman are the Makran zone, the Zagros zone, the Zendan-Minab system, the Oman Mountain zone, the Owen fracture zone and the Gulf of Aden zone. The earthquakes that take place on these zones, particularly those from Makran, already resulted and are likely to result in ground-shaking levels that may be significant for the country. The hazard module of software package ELER was customized for use in the development of shake maps in the Sultanate of Oman. For this purpose, (1) major active faults and systems within and around Oman were defined and implemented; (2) ground-motion prediction equations suitable for use and representative of tectonic conditions in Oman were identified and implemented; (3) the effect of local site conditions in resulting ground-shaking levels was attended by implementing the Vs30 maps into ELER methodology; and (4) scripts were developed for the consideration of ground-motion data coming from strong motion stations and from seismometers in and around Oman. They were used in the adjustment of ground-motion distribution maps, such as peak ground acceleration, peak ground velocity and spectral acceleration maps produced using ground-motion prediction equations. Example runs of different scenarios reflecting the use of newly adopted information are presented.

Assessment of greenhouse CO2 emissions associated with the cement manufacturing process

ABSTRACT The goal of the present work was to identify the impact of carbon dioxide (CO2) emissions on a cement plants workplace environment and its surrounding area. The concentration levels of CO2 over the study domain were investigated by means of the Weather Research and Forecasting/California Puff Model (WRF/CALPUFF) integrated modeling system (TRC Environmental Corporation, Windsor, CT, USA). Two sources were modeled for the current study: CO2 resulting from the calcination of raw materials and fuel consumption in three kilns and power plant emissions, which were treated as point sources, and vehicular-based CO2 emissions, emitted during the transportation of raw materials from the quarry to the crusher, which was modeled as a line source and calculated using the activity data collected from the cement plant and the emission factors as described by various environmental agencies. A comparison between the predicted results and the allowable limits of CO2 were made to investigate the environmental quality in the study area. The results of the study revealed that the CO2 contributions due to line source emissions were higher within and outside the plant than those from the point sources during the selected winter days. On the other hand, the individual contributions made by the point sources in the selected summer days exceeded the line source contributions, even though the combined contribution of CO2 (from both types of sources in the workplace and nearby areas) was at its height during the chosen winter days. Furthermore, maximum average concentrations, as predicted by CALPUFF for a standard period of 1 hr, were at higher than permissible levels during the selected days in both winter and summer. Within an average 24-hr period, the maximum modeled concentrations of CO2 were at the higher end of allowable limits during the designated winter days and at the lower end throughout the summer days.

Modelling the trends of vehicle-emitted pollutants in Salalah, Sultanate of Oman, over a 10-year period

From 2004 to 2014, a significant increase in the number of vehicles in Salalah, Oman, has been observed and is related to the fact that the city has become a more popular tourist destination. Due to this rise in the number of vehicles, traffic jams have become a serious problem in Salalah. Therefore, this study aims to assess carbon monoxide (CO), nitrogen oxides (NOx), and carbon dioxide (CO2) from 2004 to 2014 for the Salalah region using the CALPUFF modelling system. Although the number of vehicles gradually increased in the area, the pollutant concentration levels fluctuated. CALPUFF results illustrated that CO levels were within the allowable concentrations assigned by the U.S. Environmental Protection Agency (EPA) standards, but NOx and CO2 concentrations were higher than the criterion limits set by the EPA and the Ontario Ministry of the Environment and Climate Change’s emission standards. Since Salalah is a coastal city, wind blowing toward the land from the sea significantly affects the dispersion of pollutants. Additionally, most of the maximum concentrations of the three pollutants were located near the centers of the streets. Replacing roundabouts with flyovers might significantly reduce traffic jams and vehicle-emitted pollutants in Salalah.

Simulating thermal pollution caused by a hypothetical groundwater heat pump system under different climate, operation and hydrogeological conditions

Thermal–hydraulic analysis was conducted to examine the propagation of temperature anomalies under different climatic, subsurface and operation conditions. A series of scenarios simulated by numerical modeling indicate that the injection rate, injection depth and anisotropy of the aquifer are important parameters that need to be properly estimated to avoid critical thermal interference in shallow subsurface areas. The potential impact due to climate change is predominant only in shallow subsurface areas, but the situation may become severe if thermal anomalies that propagate upward due to injection of warm water mix with climate change anomalies that penetrate downward. Groundwater recharge and horizontal groundwater flows retard upward migration of temperature anomalies. Therefore, a proper analysis of groundwater flow in the area would facilitate harvesting a large amount of geothermal energy while limiting its impact to acceptable levels. Furthermore, a set of type curves was developed to select operational conditions with a reasonable accuracy while maintaining thermal pollution in an acceptable range.