Sajjad Ahmad

Sajjad Ahmad
University of Nevada, Las Vegas | UNLV · Department of Civil and Environmental Engineering and Construction

PhD

About

253
Publications
75,902
Reads
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7,115
Citations
Introduction
My work is focused on application of systems approach to understand and manage complex water and environmental systems. Goal is to provide decision support to policy makers for sustainable management of resources.
Additional affiliations
August 2006 - present
University of Nevada, Las Vegas
Position
  • Professor
December 2004 - July 2006
University of Miami
Position
  • Research Assistant Professor
March 2002 - November 2004
University of California, Irvine
Position
  • Specialist

Publications

Publications (253)
Chapter
Available water and environmental resources are facing high scarcity due to population growth, urban development, and the rapid growth of industrial and agricultural projects. It is necessary to apply appropriate methods to achieve accurate policies and decisions for sustainable water and environmental development in such circumstances. With an inc...
Chapter
The focus of this chapter is some general knowledge and application of Genetic Programming (GP) especially in water and environmental science. A brief introduction and literature review of the GP and Genetic Algorithm (GA) are presented. Then the natural process, the basic GP algorithm iteration procedure, and the computational steps of GP algorith...
Chapter
In this chapter most common knowledge of the Ant Colony Optimization Algorithm (ACO) is presented especially in water and environmental science. A brief introduction and literature review of the ACO and its application are demonstrated in detail. Then the process and the basic pseudo-code of ACO are introduced as well. Additionally, the Antlion Opt...
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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 tem...
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Urbanization creates new development in open spaces and agricultural fields, synonymous with increasing impervious surfaces. Such surfaces restrain the natural infiltration of water, and directly affect the non-point source pollution. Thus, consequential events like flooding and surface water degradation require spatial and quantitative information...
Article
Urban surfaces affect the surface energy budget, which plays a defining role in outdoor water requirements changing an area's evapotranspiration. They also affect thermal comfort levels for humans, animals, and vegetation by causing the surface temperature to vary. This study analyzes the effects of land use change on the surface albedo, land surfa...
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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 o...
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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 eva...
Article
Urban landscapes, made of unique buildings, pavements, and vegetation, create complex influences on the atmosphere. These influences induce increased nighttime warming and daytime cooling, especially in arid regions. This study compared three types of surfaces, including rooftop, turfgrass, and canyons, in terms of surface temperature and surface e...
Chapter
The world is currently facing extremely high water scarcity, due to the limitation of available water resources, droughts, and increasing water demand follows population growth and changing consumption patterns. In such circumstances, it is necessary to determine the optimal and sustainable operational policies of this vital source. In addition, co...
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Study region Sixteen different sites from two provinces (Lorestan and Illam) in the western part of Iran were considered for the field data measurement of cumulative infiltration, infiltration rate, and other effective variables that affect infiltration process. Study focus Soil infiltration is recognized as a fundamental process of the hydrologic...
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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)...
Article
Hormesis is an intriguing phenomenon characterized by low-dose stimulation and high-dose inhibition. The hormetic phenomena have been frequently reported in the past decades, but the researches on the biphasic responses of soil enzymes are still limited. The main objective of this study is to explore dose response of alkaline phosphatase (ALP) to C...
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Levee breaches are some of the most common hazards in the world and cause the loss of lives, livelihoods, and property destruction. During the 2010 flood in Pakistan, the most devastating breach occurred at Tori Levee on the right bank of the Indus River, downstream of the Guddu Barrage, which caused residual floods in northern Sindh and the adjoin...
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The Sacramento River Basin (SRB) and the San Joaquin River Basin (JRB) have a history of recurring droughts. Both are important for California, being the crucial source of water supply. The available instrumental records may not depict the long-term hydrologic variability encompassing the duration and frequency of the historic low flow events. Thus...
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Urban Evapotranspiration (ET) plays a crucial role in controlling irrigation water demand. The estimation of urban ET is difficult because of high spatial variability of urban surfaces. This paper reviews the two most commonly used approaches pertaining to advancements, limitations, and opportunities in arid regions. The two approaches include the...
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Meeting the healthy nutrition needs of the increasing population in the arid and semi-arid climates of the different regions of the world such as Iran has become very important for the agriculture ministry and water resources managers. In this study, the system dynamics approach was used in the Vensim software environment to allocate the water of t...
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Urmia Lake, as the largest lake in Iran borders, has a special role in the ecosystem of the region. The water level in this lake declines in recent year remarkably, so monitoring the lake water quality is important from an environmental view. In this research, the changes in the qualitative variables of the lake water (including electrical conducti...
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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 D...
Conference Paper
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Estimation of urban outdoor water demand is challenging due to variability in the irrigation of heterogeneous vegetated surfaces. Urban shade can cause fluctuations in irrigation water demand due to changes in air temperature subsequently affecting evapotranspiration (ET). This study analyzes the effect of urban shade on landscape ET. The shade is...
Conference Paper
Treated wastewater is a viable alternative to conventional irrigation water, particularly in arid areas, but it is imperative to understand potential environmental or public health risks associated with this practice, e.g., accumulation of trace organic compounds (TOrCs) in the edible portions of food crops. This study monitors the concentrations o...
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This study analyzes the effects and financial viability of retrofitting the low impact developments on runoff and pollutant loads for different land use. A105-acre area in the city of North Miami was considered for study. Two priority pollutants, total suspended solids (TSS) and total Kleijdal nitrogen (TKN), were analyzed. Three scenarios were cre...
Article
Sustainability of energy and water are inextricably linked with each other. Over-utilization/degradation of these resources may occur due to changing climate, growing population, and increasing pollution including carbon emissions due to the burning of fossil fuels. Drinking water treatment is essential for safeguarding public health; however, it i...
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Due to the complexity and heterogeneity inherent to the hydrologic cycle, the modeling of physical water processes has historically and inevitably been characterized by a broad spectrum of disciplines including data management, visualization, and statistical analyses. This is further complicated by the sub-disciplines within the water science commu...
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Study region: Sacramento San Joaquin River Basin, California. Study focus: The study forecasts the streamflow at a regional scale within SSJ river basin with largescale climate variables. The proposed approach eliminates the bias resulting from predefined indices at regional scale. The study was performed for eight unimpaired streamflow stations f...
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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 pl...
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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 ener...
Article
Due to the complex physics of both snow and snowmelt, particularly in mountainous topographic regions, studying the dynamics and variations of snow cover (SC) has been a very challenging task, and therefore, its relationship with snowline elevation (SLE) mobility has not been well documented. The spatiotemporal dynamics of SC in the Haraz Watershed...
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Full-text available
The total phosphorus (TP) concentration, as the primary limiting eutrophication factor in the Mahabad Dam reservoir in Iran, was studied, considering the combined impacts of climate change, as well as the scenarios on changes in upstream TP loadings and downstream dam water allocations. Downscaled daily projected climate data were obtained from the...
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Full-text available
This study describes the results of a dynamic quantitative microbial risk assessment (QMRA) for norovirus (NoV) that was used to evaluate the relative significance of foodborne, person-to-person, and person-to-sewage-to-person transmission pathways. This last pathway was incorporated into simulated potable reuse systems to evaluate the adequacy of...
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This paper studies how to improve the accuracy of hydrologic models using machine-learning models as post-processors and presents possibilities to reduce the workload to create an accurate hydrologic model by removing the calibration step. It is often challenging to develop an accurate hydrologic model due to the time-consuming model calibration pr...
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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...
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Water shortages in Pakistan are among the most severe in the world, and its water resources are decreasing significantly due to the prevailing hydro-meteorological conditions. We assessed variations in meteorological and hydrological variables using innovative trend analysis (ITA) and traditional trend analysis methods at a practical significance l...
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This case study presents a framework for evaluating the sustainability of indirect potable reuse (IPR) and direct potable reuse (DPR) in Las Vegas, Nevada. A system dynamics model was developed to simulate population growth, water supply, water quality, energy costs, net present worth (NPW), and greenhouse gas (GHG) emissions. The model confirmed t...
Article
Open Access Link: https://doi.org/10.1016/j.mran.2019.06.003 Due to rapid growth in the potable reuse industry, there is a need to better characterize the associated pathogenrisks and degree of attenuation achieved by various treatment trains. It is also important to understand howemerging treatment frameworks compare to the historical practice o...
Conference Paper
Full-text available
Construction of impervious surface by replacing natural vegetation increases surface runoff and is traditionally managed by channeling storm water to an outlet. However, traditional methods create problems such as downstream erosion and flooding, reduction in ground water storage, and increase in pollutant loads. This study presents an analysis on...
Conference Paper
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Sediment is one of the major contributing factors that affect the river morphology of the United States. During the construction of hydraulic structures like a dam, irrigation channel, or even to utilize the stream for navigation purpose, one of the major concerns for the design engineer would be the characteristics of sediment transported within r...
Conference Paper
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Rainfall-runoff simulation is an essential step in analyzing the impacts of extreme flood events. This can aid in water resource management and planning. In areas that are prone to floods, it becomes necessary to perform an extensive hydrological study. Cache River watershed is one of the flood prone watersheds in Illinois, mainly due to the conflu...
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This study evaluated the trends and shifts of the ambient air quality standards of the most polluted states and cities of India with respect to air quality parameters, e.g., nitrogen dioxide (NO2), sulfur dioxide (SO2), suspended particulate matter (SPM), and respirable suspended particulate matter (RSPM). The choice of air quality parameters was b...
Conference Paper
ABSTARCT The urban area of Las Vegas expanded rapidly between 1990 and 2010 covering large areas of native desert landscape with urban materials. These alterations to the surfaces change the thermal processes in the immediate region. In this research, we study the relation between air temperature and surface temperature in Las Vegas by comparing gr...
Conference Paper
Full-text available
Las Vegas have undergone significant development in the past two decades in the form of pavements and buildings. Surface energy of the city has changed due to urbanization that plays crucial role in urban heat island effect and in altering the energy for evaporation and transpiration. It indirectly contributes to the urban hydrological cycle. Role...
Conference Paper
The estimation of crop water requirement (CWR) is an important aspect in efficient usage of water, especially in regions where water is scarce. This study estimates the change in agricultural land of major crops in Gujranwala District due to urbanization using remote sensing. The irrigation water demand (IWD) and irrigation cost are computed for th...
Conference Paper
Full-text available
Freshwater natural wetlands are under threat of environmental degradation due to the anthropogenic and natural activities. In some cases, wetlands are transformed into manmade water reservoirs which have resulted in waterlogged and salinity problems in the nearby areas. Conversion of Chotiari natural wetland into the off canal manmade Chotiari Rese...
Conference Paper
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Being one of the largest crop producers district in Punjab, Rahim Yar Khan, is currently going through a severe water crisis. The increased abstraction of the groundwater reserves for agriculture and anthropogenic use has resulted in the reserves turning saline along with decrease in the depth of water table. Therefore, this study focuses on identi...
Conference Paper
Full-text available
Drinking water treatment, integral for ensuring public health is an energy-intensive process. Increasing population and pollution levels compel water sector to incorporate design practices that help achieve sustainability of water operations. Incorporating renewables such as wind and solar energy into a drinking water treatment plant (DWTP) operati...
Conference Paper
Full-text available
The uncertainties in the hydrology allied with the climate and land change have been a research topic of recent scientific and engineering communities. Texas Trinity River Basin (TRB) of an area about 46,620 square kilometres comprises the river system with maximum water storage as compared to the other river systems of Texas. TRB also includes hyd...
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Full-text available
The study attempts to investigate the significant spatiotemporal variations in the continental United States’ streamflow as a response to large-scale climate signals across multiple spectral bands (SBs). Using non-parametric (long-term) trend and (abrupt) shift detection tests, coupled with discrete wavelet transform, 237 unimpaired streamflow stat...
Article
Snowmelt from the Tianshan Mountains (TS) is a major contributor to the water resources of the Central Asian region. Thus, changes in snow phenology over the TS have significant implications for regional water supplies and ecosystem services. However, the characteristics of changes in snow phenology and their influences on the climate are poorly un...
Article
Full-text available
The total phosphorus (TP) concentration, as the primary limiting eutrophication factor in the Mahabad Dam reservoir in Iran, was studied, considering the combined impacts of climate change, as well as the scenarios on changes in upstream TP loadings and downstream dam water allocations. Downscaled daily projected climate data were obtained from the...