Changes in the width of channels or rivers that have three-dimensional pool-riffle can affect the... more Changes in the width of channels or rivers that have three-dimensional pool-riffle can affect the key parameters of river engineering and flow resistance. Understanding the effect of width changes on flow structures helps to control erosion and sedimentation in coarse-bed rivers and better design ecological restoration projects. The present study investigates the effect of the sequential pool-riffle and its interaction with the bank narrowness on the turbulent flow characteristics. For this purpose, an experimental study was conducted in variable and fixed width flume with an aspect ratio greater than five. The results showed that when the flow decelerates (entrance of the pool), the negative and low longitudinal velocities expand as the flow depth increases. From both sides of the central axis, longitudinal velocities decreased when entering the middle part of the pool and reduced the flow width. The changes in the maximum turbulence intensity values, from the central axis towards ...
Wastewater treatment is a very energy-intensive process. The growing population, increased demand... more Wastewater treatment is a very energy-intensive process. The growing population, increased demands for energy and water, and rising pollution levels caused by fossil-fuel-based energy generation, warrants the transition from fossil fuels to renewable energy. This research explored the energy consumption offset of a satellite water reuse plant (WRP) by using solar photovoltaics (PVs) and anaerobic digestion. The analysis was performed for two types of WRPs: conventional (conventional activated sludge system (CAS) bioreactor with secondary clarifiers and dual media filtration) and advanced (bioreactor with membrane filtration (MBR)) treatment satellite WRPs. The associated greenhouse gas (GHG) emissions were also evaluated. For conventional treatment, it was found that 28% and 31.1% of the WRP’s total energy consumption and for advanced treatment, 14.7% and 5.9% of the WRP’s total energy consumption could be generated by anaerobic digestion and solar PVs, respectively. When both energ...
Urban irrigation is an essential process in land–atmosphere interactions. It is one of the uncert... more Urban irrigation is an essential process in land–atmosphere interactions. It is one of the uncertain parameters of urban hydrology due to various microclimates. This study investigated the microclimate effects and irrigation water requirements of three landscape types in an arid region of Phoenix, AZ. The microclimate effect encompassed surface temperature, air temperature, and wind speed. The simulations of the three landscapes were conducted using ENVI-met software for the hottest day of the year (23 June 2011). The simulated model was validated using ground data. Results show that the mesic landscape induced cooling effects, both in the daytime and nighttime, by reducing surface and air temperatures. However, the mesic landscape showed high-water consumption because of a high leaf area density. The oasis landscape showed 2 °C more daytime cooling than the mesic landscape, but the nighttime warming (surface temperature) was comparable to the xeric landscape. The potential irrigati...
IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, 2016
In order to simplify current fire simulation models for more wide-spread use, a Real-time Web-bas... more In order to simplify current fire simulation models for more wide-spread use, a Real-time Web-based Wildfire Simulation System (RWWSS) was developed. RWWSS is a web-based application that provides free access to exploring wildfire simulations. It was developed as an educational tool for the purpose of helping people understand the mechanism of fire propagation and its key impact factors, as well as for motivating fire prevention efforts. The model was implemented using the geography of the Lehman Creek watershed, Great Basin National Park, Nevada, USA. Through numerical simulation of fire propagation, the features of fire intensity, direction, and duration, based on the key factors of slope, wind, and vegetation type are estimated and presented on a 2D map. The user can change these key factors, making the application interactive. With improvements to the model RWWSS could be used for further research purposes.
Southern California’s Imperial Valley (IV) faces serious water management concerns due to its sem... more Southern California’s Imperial Valley (IV) faces serious water management concerns due to its semi-arid environment, water-intensive crops and limited water supply. Accurate and reliable irrigation system performance and water productivity information is required in order to assess and improve the current water management strategies. This study evaluates the spatially distributed irrigation equity, adequacy and crop water productivity (CWP) for two water-intensive crops, alfalfa and sugar beet, using remotely sensed data and a geographical information system for the 2018/2019 crop growing season. The actual crop evapotranspiration (ETa) was mapped in Google Earth Engine Evapotranspiration Flux, using the linear interpolation method in R version 4.0.2. The approx() function in the base R was used to produce daily ETa maps, and then totaled to compute the ETa for the whole season. The equity and adequacy were determined according to the ETa’s coefficient of variation (CV) and relative...
Urbanization increases the amount of impervious surfaces, making accurate information on spatial ... more Urbanization increases the amount of impervious surfaces, making accurate information on spatial and temporal expansion trends essential; the challenge is to develop a cost- and labor-effective technique that is compatible with the assessment of multiple geographical locations in developing countries. Several studies have identified the potential of remote sensing and multiple source information in impervious surface quantification. Therefore, this study aims to fuse datasets from the Sentinel 1 and 2 Satellites to map the impervious surfaces of nine Pakistani cities and estimate their growth rates from 2016 to 2020 utilizing the random forest algorithm. All bands in the optical and radar images were resampled to 10 m resolution, projected to same coordinate system and geometrically aligned to stack into a single product. The models were then trained, and classifications were validated with land cover samples from Google Earth’s high-resolution images. Overall accuracies of classifi...
Drinking water treatment, wastewater treatment, and water distribution are energy-intensive proce... more Drinking water treatment, wastewater treatment, and water distribution are energy-intensive processes. The goal of this study was to design the unit processes of an existing drinking water treatment plant (DWTP), evaluate the associated energy consumption, and then offset it using solar photovoltaics (PVs) to reduce carbon emissions. The selected DWTP, situated in the southwestern United States, utilizes coagulation, flocculation, sedimentation, filtration, and chlorination to treat 3.94 m3 of local river water per second. Based on the energy consumption determined for each unit process (validated using the plant’s data) and the plant’s available landholding, the DWTP was sized for solar PV (as a modeling study) using the system advisor model. Total operational energy consumption was estimated to be 56.3 MWh day−1 for the DWTP including water distribution pumps, whereas energy consumption for the DWTP excluding water distribution pumps was 2661 kWh day−1. The results showed that the...
With an ever-increasing world population and the resulting increase in industrialization and agri... more With an ever-increasing world population and the resulting increase in industrialization and agricultural practices, depletion of one of the world’s most important natural resources, water, is inevitable. Water reclamation and reuse is the key to protecting this natural resource. Water reclamation using smaller decentralized wastewater treatment plants, known as satellite water reuse plants (WRP), has become popular in the last decade. Reuse plants have stricter standards for effluent quality and require a smaller land footprint (i.e., real estate area). They also require additional treatment processes and advanced treatment technologies. This greatly increases the energy consumption of an already energy intensive process, accentuating even more the nexus between energy use and wastewater processing. With growing concerns over the use of nonrenewable energy sources and resulting greenhouse gas (GHG) emissions, WRPs are in need of energy evaluations. This paper contrasts the energy c...
One of the pressing issues currently faced by the water industry is incorporating sustainability ... more One of the pressing issues currently faced by the water industry is incorporating sustainability considerations into design practice and reducing the carbon emissions of energy-intensive processes. Water treatment, an indispensable step for safeguarding public health, is an energy-intensive process. The purpose of this study was to analyze the energy consumption of an existing drinking water treatment plant (DWTP), then conduct a modeling study for using photovoltaics (PVs) to offset that energy consumption, and thus reduce emissions. The selected plant, located in southwestern United States, treats 0.425 m3 of groundwater per second by utilizing the processes of coagulation, filtration, and disinfection. Based on the energy consumption individually determined for each unit process (validated using the DWTP’s data), the DWTP was sized for PVs (as a modeling study). The results showed that the dependency of a DWTP on the traditional electric grid could be greatly reduced by the use o...
Journal of Applied Meteorology and Climatology, 2019
This study evaluated the ability of phase 5 of the Coupled Model Intercomparison Project (CMIP5) ... more This study evaluated the ability of phase 5 of the Coupled Model Intercomparison Project (CMIP5) to capture observed trends under the influence of shifts and persistence in their data distributions. A total of 41 temperature and 25 precipitation CMIP5 simulation models across 22 grid cells (2.5° × 2.5° squares) within the Colorado River basin were analyzed and compared with the Climate Research Unit Time Series (CRU-TS) observed datasets over a study period of 104 years (from 1901 to 2004). Both the modeled simulations and observations were tested for shifts, and the time series before and after the shifts were analyzed separately for trend detection and quantification. Effects of several types of persistence were accounted for prior to both the trend and shift detection tests. The mean significant shift points (SPs) of the CMIP5 temperature models across the grid cells were found to be within a narrower range (between 1957 and 1968) relative to the CRU-TS observed SPs (between 1924...
The influence of El Niño Southern Oscillation (ENSO) on the north Indian temperature, precipitati... more The influence of El Niño Southern Oscillation (ENSO) on the north Indian temperature, precipitation, and potential evapotranspiration (PET) change patterns were evaluated during the monsoon season across the last century. Trends and shifts in 146 districts were assessed using nonparametric statistical tests. To quantify their temporal variation, the concept of apportionment entropy was applied to both the annual and seasonal scales. Results suggest that the El Niño years played a greater role in causing hydro-climatological changes compared to the La Niña or neutral years. El Niño was more influential in causing shifts compared to trends. For certain districts, a phase change in ENSO reversed the trend/shift direction. The century-wide analysis suggested that the vast majority of the districts experienced significant decreasing trends/shifts in temperature and PET. However, precipitation experienced both increasing and decreasing trends/shifts based on the location of the districts....
Transient flows result in unbalanced forces and high pressure in pipelines. Under these condition... more Transient flows result in unbalanced forces and high pressure in pipelines. Under these conditions, the combined effects of flow-induced forces along with sudden pipe displacements can create cracks in the pipeline, especially at the junctions. This situation consequently results in water leakage and reduced operational efficiency of the pipeline. In this study, displacements and stresses in a buried pressurized water transmission pipe installed by pipe jacking method are investigated using numerical modeling and considering interactions between fluid, pipe, and soil. The analyses were performed consecutively under no-flow, steady flow, and transient flow conditions, in order to investigate the effects of flow conditions on displacements and stresses in the system. Analyses of the results show that displacements and stresses in the jointed concrete pipes are significant under transient flow conditions. Moreover, because of pressure transient effects, maximum tensile stresses exceed ...
Changes in the width of channels or rivers that have three-dimensional pool-riffle can affect the... more Changes in the width of channels or rivers that have three-dimensional pool-riffle can affect the key parameters of river engineering and flow resistance. Understanding the effect of width changes on flow structures helps to control erosion and sedimentation in coarse-bed rivers and better design ecological restoration projects. The present study investigates the effect of the sequential pool-riffle and its interaction with the bank narrowness on the turbulent flow characteristics. For this purpose, an experimental study was conducted in variable and fixed width flume with an aspect ratio greater than five. The results showed that when the flow decelerates (entrance of the pool), the negative and low longitudinal velocities expand as the flow depth increases. From both sides of the central axis, longitudinal velocities decreased when entering the middle part of the pool and reduced the flow width. The changes in the maximum turbulence intensity values, from the central axis towards ...
Wastewater treatment is a very energy-intensive process. The growing population, increased demand... more Wastewater treatment is a very energy-intensive process. The growing population, increased demands for energy and water, and rising pollution levels caused by fossil-fuel-based energy generation, warrants the transition from fossil fuels to renewable energy. This research explored the energy consumption offset of a satellite water reuse plant (WRP) by using solar photovoltaics (PVs) and anaerobic digestion. The analysis was performed for two types of WRPs: conventional (conventional activated sludge system (CAS) bioreactor with secondary clarifiers and dual media filtration) and advanced (bioreactor with membrane filtration (MBR)) treatment satellite WRPs. The associated greenhouse gas (GHG) emissions were also evaluated. For conventional treatment, it was found that 28% and 31.1% of the WRP’s total energy consumption and for advanced treatment, 14.7% and 5.9% of the WRP’s total energy consumption could be generated by anaerobic digestion and solar PVs, respectively. When both energ...
Urban irrigation is an essential process in land–atmosphere interactions. It is one of the uncert... more Urban irrigation is an essential process in land–atmosphere interactions. It is one of the uncertain parameters of urban hydrology due to various microclimates. This study investigated the microclimate effects and irrigation water requirements of three landscape types in an arid region of Phoenix, AZ. The microclimate effect encompassed surface temperature, air temperature, and wind speed. The simulations of the three landscapes were conducted using ENVI-met software for the hottest day of the year (23 June 2011). The simulated model was validated using ground data. Results show that the mesic landscape induced cooling effects, both in the daytime and nighttime, by reducing surface and air temperatures. However, the mesic landscape showed high-water consumption because of a high leaf area density. The oasis landscape showed 2 °C more daytime cooling than the mesic landscape, but the nighttime warming (surface temperature) was comparable to the xeric landscape. The potential irrigati...
IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, 2016
In order to simplify current fire simulation models for more wide-spread use, a Real-time Web-bas... more In order to simplify current fire simulation models for more wide-spread use, a Real-time Web-based Wildfire Simulation System (RWWSS) was developed. RWWSS is a web-based application that provides free access to exploring wildfire simulations. It was developed as an educational tool for the purpose of helping people understand the mechanism of fire propagation and its key impact factors, as well as for motivating fire prevention efforts. The model was implemented using the geography of the Lehman Creek watershed, Great Basin National Park, Nevada, USA. Through numerical simulation of fire propagation, the features of fire intensity, direction, and duration, based on the key factors of slope, wind, and vegetation type are estimated and presented on a 2D map. The user can change these key factors, making the application interactive. With improvements to the model RWWSS could be used for further research purposes.
Southern California’s Imperial Valley (IV) faces serious water management concerns due to its sem... more Southern California’s Imperial Valley (IV) faces serious water management concerns due to its semi-arid environment, water-intensive crops and limited water supply. Accurate and reliable irrigation system performance and water productivity information is required in order to assess and improve the current water management strategies. This study evaluates the spatially distributed irrigation equity, adequacy and crop water productivity (CWP) for two water-intensive crops, alfalfa and sugar beet, using remotely sensed data and a geographical information system for the 2018/2019 crop growing season. The actual crop evapotranspiration (ETa) was mapped in Google Earth Engine Evapotranspiration Flux, using the linear interpolation method in R version 4.0.2. The approx() function in the base R was used to produce daily ETa maps, and then totaled to compute the ETa for the whole season. The equity and adequacy were determined according to the ETa’s coefficient of variation (CV) and relative...
Urbanization increases the amount of impervious surfaces, making accurate information on spatial ... more Urbanization increases the amount of impervious surfaces, making accurate information on spatial and temporal expansion trends essential; the challenge is to develop a cost- and labor-effective technique that is compatible with the assessment of multiple geographical locations in developing countries. Several studies have identified the potential of remote sensing and multiple source information in impervious surface quantification. Therefore, this study aims to fuse datasets from the Sentinel 1 and 2 Satellites to map the impervious surfaces of nine Pakistani cities and estimate their growth rates from 2016 to 2020 utilizing the random forest algorithm. All bands in the optical and radar images were resampled to 10 m resolution, projected to same coordinate system and geometrically aligned to stack into a single product. The models were then trained, and classifications were validated with land cover samples from Google Earth’s high-resolution images. Overall accuracies of classifi...
Drinking water treatment, wastewater treatment, and water distribution are energy-intensive proce... more Drinking water treatment, wastewater treatment, and water distribution are energy-intensive processes. The goal of this study was to design the unit processes of an existing drinking water treatment plant (DWTP), evaluate the associated energy consumption, and then offset it using solar photovoltaics (PVs) to reduce carbon emissions. The selected DWTP, situated in the southwestern United States, utilizes coagulation, flocculation, sedimentation, filtration, and chlorination to treat 3.94 m3 of local river water per second. Based on the energy consumption determined for each unit process (validated using the plant’s data) and the plant’s available landholding, the DWTP was sized for solar PV (as a modeling study) using the system advisor model. Total operational energy consumption was estimated to be 56.3 MWh day−1 for the DWTP including water distribution pumps, whereas energy consumption for the DWTP excluding water distribution pumps was 2661 kWh day−1. The results showed that the...
With an ever-increasing world population and the resulting increase in industrialization and agri... more With an ever-increasing world population and the resulting increase in industrialization and agricultural practices, depletion of one of the world’s most important natural resources, water, is inevitable. Water reclamation and reuse is the key to protecting this natural resource. Water reclamation using smaller decentralized wastewater treatment plants, known as satellite water reuse plants (WRP), has become popular in the last decade. Reuse plants have stricter standards for effluent quality and require a smaller land footprint (i.e., real estate area). They also require additional treatment processes and advanced treatment technologies. This greatly increases the energy consumption of an already energy intensive process, accentuating even more the nexus between energy use and wastewater processing. With growing concerns over the use of nonrenewable energy sources and resulting greenhouse gas (GHG) emissions, WRPs are in need of energy evaluations. This paper contrasts the energy c...
One of the pressing issues currently faced by the water industry is incorporating sustainability ... more One of the pressing issues currently faced by the water industry is incorporating sustainability considerations into design practice and reducing the carbon emissions of energy-intensive processes. Water treatment, an indispensable step for safeguarding public health, is an energy-intensive process. The purpose of this study was to analyze the energy consumption of an existing drinking water treatment plant (DWTP), then conduct a modeling study for using photovoltaics (PVs) to offset that energy consumption, and thus reduce emissions. The selected plant, located in southwestern United States, treats 0.425 m3 of groundwater per second by utilizing the processes of coagulation, filtration, and disinfection. Based on the energy consumption individually determined for each unit process (validated using the DWTP’s data), the DWTP was sized for PVs (as a modeling study). The results showed that the dependency of a DWTP on the traditional electric grid could be greatly reduced by the use o...
Journal of Applied Meteorology and Climatology, 2019
This study evaluated the ability of phase 5 of the Coupled Model Intercomparison Project (CMIP5) ... more This study evaluated the ability of phase 5 of the Coupled Model Intercomparison Project (CMIP5) to capture observed trends under the influence of shifts and persistence in their data distributions. A total of 41 temperature and 25 precipitation CMIP5 simulation models across 22 grid cells (2.5° × 2.5° squares) within the Colorado River basin were analyzed and compared with the Climate Research Unit Time Series (CRU-TS) observed datasets over a study period of 104 years (from 1901 to 2004). Both the modeled simulations and observations were tested for shifts, and the time series before and after the shifts were analyzed separately for trend detection and quantification. Effects of several types of persistence were accounted for prior to both the trend and shift detection tests. The mean significant shift points (SPs) of the CMIP5 temperature models across the grid cells were found to be within a narrower range (between 1957 and 1968) relative to the CRU-TS observed SPs (between 1924...
The influence of El Niño Southern Oscillation (ENSO) on the north Indian temperature, precipitati... more The influence of El Niño Southern Oscillation (ENSO) on the north Indian temperature, precipitation, and potential evapotranspiration (PET) change patterns were evaluated during the monsoon season across the last century. Trends and shifts in 146 districts were assessed using nonparametric statistical tests. To quantify their temporal variation, the concept of apportionment entropy was applied to both the annual and seasonal scales. Results suggest that the El Niño years played a greater role in causing hydro-climatological changes compared to the La Niña or neutral years. El Niño was more influential in causing shifts compared to trends. For certain districts, a phase change in ENSO reversed the trend/shift direction. The century-wide analysis suggested that the vast majority of the districts experienced significant decreasing trends/shifts in temperature and PET. However, precipitation experienced both increasing and decreasing trends/shifts based on the location of the districts....
Transient flows result in unbalanced forces and high pressure in pipelines. Under these condition... more Transient flows result in unbalanced forces and high pressure in pipelines. Under these conditions, the combined effects of flow-induced forces along with sudden pipe displacements can create cracks in the pipeline, especially at the junctions. This situation consequently results in water leakage and reduced operational efficiency of the pipeline. In this study, displacements and stresses in a buried pressurized water transmission pipe installed by pipe jacking method are investigated using numerical modeling and considering interactions between fluid, pipe, and soil. The analyses were performed consecutively under no-flow, steady flow, and transient flow conditions, in order to investigate the effects of flow conditions on displacements and stresses in the system. Analyses of the results show that displacements and stresses in the jointed concrete pipes are significant under transient flow conditions. Moreover, because of pressure transient effects, maximum tensile stresses exceed ...
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Papers by Sajjad Ahmad