Browsing by Author "Grigg, Neil S., committee member"

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Open Access
Analysis and evaluation of stormwater quantity and quality performance for three permeable pavement systems in Fort Collins, Colorado
(Colorado State University. Libraries, 2013) Gruber, Eli, author; Roesner, Larry A., advisor; Grigg, Neil S., committee member; Shuler, Scott, committee member
Urbanization and the subsequent increase of effective impervious area (EIA) result in an increase in storm runoff volumes, peak flow rates and pollutant concentrations. Stormwater management has recently shifted towards a focus on site level low impact development (LID) techniques that aim to reduce the total stormwater runoff volumes in addition to attenuating peak flows and removing pollutants at or near the source of runoff. Permeable pavement systems (PPS) are a subset of LID stormwater best management practices (BMPs) of particular interest in dense urban areas because they can be installed in parking areas and low traffic roadways where the availability of land space for more traditional BMPs is not available. However, few studies have documented the performance of PPS in terms of reducing runoff volume, peak flow and pollutant loads in semi-arid environments such as Colorado. Such information is necessary to improve the selection of BMP/LIDs for stormwater management. Three PPS in Fort Collins, Colorado were monitored between 2009 and 2011 to evaluate pollutant reduction, runoff volume reduction performance and surface infiltration rates. The Mountain and Walnut permeable inter-locking concrete paver (PICP) sites, referred to collectively as Mitchell Block, were each designed with differing "no-infiltration" sub-base designs to compare performance between a system with a sand filter layer (Walnut) and one with only gravel layers (Mountain). The third site, referred to as CTL, is a porous concrete (PC) parking lot that allows full infiltration, and was only monitored for water quality and surface infiltration rates. Mountain, Walnut and CTL all had lower effluent median event mean concentrations (EMCs) than those found at two Fort Collins stormwater outfalls for; total suspended solids (TSS), total recoverable zinc (TR Zn), total phosphorous (TP), total nitrogen (TN), total organic nitrogen (TON), total Kjeldahl nitrogen (TKN) and ammonia (NH3). EMCs for TR copper (Cu), nitrate (NO3) and total dissolved solids (TDS) at all three sites were elevated compared to the outfall sites. The TR Cu result EMCs at the three PPS were elevated compared to effluent PPS data from the International Stormwater BMP Database, which may indicate higher source concentrations in these study areas. CTL had elevated TR chromium (Cr) concentrations, which is likely a function of the portland cement in the PC itself, leaching Cr into the exfiltrate. Walnut had lower effluent median EMCs for 10 of the 13 water quality parameters analyzed, including significantly lower concentrations for TON, TKN and TR Cu. Recorded effluent volumes and estimated influent volumes to the PPS at the Mitchell Block sites were used to calculate runoff volume reduction on an event-based and long-term basis. Both sites provided runoff reduction for over 70% of the monitored events, with Mountain and Walnut reducing 45% and 35% of the total runoff volume monitored at each site, respectively. These results confirm that "no-infiltration" PPS designs are capable of reducing large volumes of storm runoff. Field capacity (water retention capacity) of the two sites was investigated with regard to runoff reduction. Runoff volume reduction at Mountain exceeded the field capacity for the two longest storms monitored. This suggests that runoff volume reduction potential can exceed field capacity given long intermittent rainfall events. An investigation of hydrologic storm parameters indicated a discernible trend between runoff volume reduction and antecedent dry time, showing increasing runoff volume reduction with increasing antecedent dry time. The runoff volume reduction performance at Mountain was greater than Walnut based on 23% greater median and average volume reduction per storm in addition to 25% greater total aggregate volume reduction for common monitored events at the two sites. This study did not investigate the design characteristics that allowed Mountain to provide greater runoff volume reduction. Surface infiltration rates at all three sites were estimated using a single infiltrometer field test. The results indicated that sections of all three sites are experiencing varying degrees of clogging. CTL had the highest degree of clogging, with two of the three tests indicating zero infiltration. Maintenance is recommended to reduce clogging for all three sites.
Open Access
Comparing multi-level and full spectrum detention design for urban stormwater detention facilities
(Colorado State University. Libraries, 2010) Zhang, Xiaoju, author; Roesner, Larry A., advisor; Willson, Bryan D., advisor; Grigg, Neil S., committee member; Kampf, Stephanie, committee member
Peak flow attenuation and water quality control are widely used in urban stormwater systems. Standard practice typically involves peak shaving of post-development flows to pre-development peak flow levels to control flood flows and best management practices (BMPs) for removing pollutants from runoff. Usually both practices are integrated by using Multi-level Detention ponds. Recently, Wulliman and Urbonas (2005 and 2007) have proposed the so-called Full Spectrum Detention approach to design detention facilities able to control runoff events. This method is based on the concept of capturing the Excess Urban Runoff Volume (EURV) that results from urbanization and releasing it over a period of 72 hours. This method has been tested successfully for the Denver region and excellent matching of post-development peak flows to pre-development peak flows has been achieved. However, these results have been obtained using discrete design storms and the model has not been studied using a continuous simulation approach. Continuous simulations are useful because they provide information about the long-term performance through peak flow exceedance frequency and flow duration curves. Moreover, these results can be used to define the stream erosion potential, a metric that characterizes the geomorphic stability of urban streams. Continuous simulation has been successfully used to characterize the performance of Multi-level Detention method, which uses combined peak shaving and extended detention practices, and protocols to reduce urbanization impacts in different locations have been demonstrated with it. This study compares the effectiveness and differences of the Multi-level Detention design approach with that of the Full Spectrum Detention approach through the use of design storms and 60-year continuous precipitation records in a conceptual watershed for two different climate regions in the United States. The US EPA Stormwater Management Model (SWMM) is used to simulate the response of a conceptual watershed using both design approaches. Sensitivity analysis of the land-use properties is performed in order to validate the assumptions of the Full Spectrum Detention method by using both Colorado Unit Hydrograph Procedure (CUHP) and SWMM models. The performances of these two design approaches are tested initially by comparing the post-development peak flows for different design storms with the pre-development conditions. Additionally, 60 years of hourly rainfall records are used to run continuous simulations and compute peak flow frequency exceedance curves, flow duration curves, the hydrologic metrics T0.5, and average boundary shear stress curves, which are used to compute the stream erosion potential. The differences of both design methods are assessed by comparing the post-development results with those obtained for the pre-development conditions.
Open Access
Decision support systems for managing efficient irrigation water deliveries - a case study of irrigated agriculture in the Middle Rio Grande
(Colorado State University. Libraries, 2011) Manana, Nkosinathi David, author; Oad, Ramchand Naraindas, advisor; Grigg, Neil S., committee member; Myrick, Christopher A., committee member
Irrigation has been practiced for centuries in the Middle Rio Grande (MRG) Valley of New Mexico. Many of the practices governing irrigation in earlier times, both by Native Americans and by Spanish settlers, are continued into the present day. In recent years, considerable pressure has fallen on the Middle Rio Grande Conservancy District (MRGCD) to decrease its water diversions from the Rio Grande and to allow more water to remain in the river for ecological uses. This pressure has stemmed from increasing and competing water demands and interest in the preservation of natural habitat associated with the river, especially the endangered Rio Grande silvery minnow (Hybognathus amarus). The MRGCD has opted to modernize its physical infrastructure and improve water delivery practices to more efficiently utilize diversions from the Rio Grande, and meet farm demands with reduced river diversions. To reach this goal while still providing farmers with adequate supplies, the MRGCD has employed scheduled water delivery. Scheduled water delivery introduces significant management challenges that can be addressed using Decision Support iii Systems (DSS). The MRGCD DSS was successfully implemented in the Peralta Main service area during the year 2009. This thesis presents a hypothetical evaluation of the implementation of the Decision Support System (DSS) as a guiding tool for farmers to improve irrigation water scheduling management in the Albuquerque Division of the MRGCD. Specifically, this research evaluates the question of whether the use of the DSS for scheduling irrigation water deliveries would result in reduced river water diversion, efficiently improve irrigation water scheduling management, and identify required infrastructure improvements while still meeting all crop water requirements. The study verified the hypothesis that a DSS can proficiently and justifiably be utilized to manage scheduled water delivery operations in the Albuquerque Division of the MRGCD. A DSS combined with infrastructure improvement and SCADA inclusion can significantly reduce river diversion while still serving water users demands. Overall, the DSS can provide the MRGCD with a powerful tool that can be used to efficiently schedule water delivery, determine appropriate water use, improve reservoir operations and sustain irrigated agriculture in the face of future water management challenges.
Open Access
Development of a watershed modeling selection program and simple equations as an alternative to complex watershed modeling
(Colorado State University. Libraries, 2013) Cho, Yongdeok, author; Roesner, Larry A., advisor; Grigg, Neil S., committee member; Arabi, Mazdak, committee member; Stednick, John, committee member
Population pressures, land-use conversion and its resulting pollution consequences appear to be the major diffuse pollution problems of today. Research also indicates that the increase in imperviousness of land due to urbanization increases the volume, rate of stormwater runoff causing increased channel erosion and flooding downstream, water quality contamination, aquatic biota, and drinking water supplies. In the past, negative impacts were never seriously considered as urbanization increased, but the attitude of citizens and governments are changing and people now want to retain, restore or rehabilitate existing waterways, and manage future urban and rural development in order to improve environmental conditions. Water quality management in the contributing watersheds is vital to the management of water quality in the main stem rivers. Hence, policy makers should decide which places should be considered for restoration projects based on priority analyses. To carry out these evaluations in Korea, mathematical models are needed to forecast the environmental results after applying watershed restoration measures. However, the scope of sophisticated watershed modeling is very complicated, expensive and time consuming, and not really required for planning level decision making. Therefore, simpler evaluation methods should be applied, that can adequately discern for planning purposes the changes in aquatic environmental quality that can be expected in different watersheds after adapting restoration or protective measures. Thus, this research proposed to create a simple equation specifically for watershed planning. To create such a simple equation, three main tasks were undertaken. The tasks are as follows: (1) the creation of a selection program for available watershed models, (2) establish simple equations to be used instead of watershed models, and (3) verify the simple equations by comparing them with a physically based model (HSPF). In regards to the first task mentioned above, this dissertation presents a review of thirty three watershed models available for watershed planning and shows that these watershed models can not easily be applied to large-scale planning projects that are being undertaken by South Korea like the Four River Restoration Project. One of the main reasons for their inapplicability is that they require vast amounts of data and significant application effort to be used in a prioritization project involving many watersheds (Roesner, personal commucation). In addition, it is vital to select an appropriate watershed model that are realistically models a watershed's conditions and more specifically, to match users' needs. However a selection program has not yet developed, as well. Therefore, eight factors were selected for task 1 to examine the specific characteristics of each of the 33 watershed models in great detail. Based on the results of the 8 factors proposed, the selection program was developed to screen which will be most useful to a project. Based on these literature reviews of the 33 available watershed models but unrealistically complex models, it was determined that a simpler model utilizing accessible base data, such as land use type, is needed to evaluate and prioritize watersheds in the feasibility stage of a spatially large projectstudies for national based projects (i.e. National level). A correlation study between land use types and water quality parameters has been published (Tu, 2011, Mehaffey et al., 2005, Schoonover et al., 2005, etc.), however, the research examined the correlation between land usage and water quality in great detail, but did not address any correlations to implement real-based watersheds. Therefore, Task 2 is the development of simple equstions, for this task, two important sub-tasks were undertaken 1) Hydrology (rainfall), geology (slope), and land usage data were analyzed to verify their relationships with the water quality (BOD, COD, T-N, T-P) in the watershed, and 2) Simple Equations were constructed based on Statistical Methods (Excel Solver, Statistical Analysis Systems) and Data Mining (Model Tree, Artificial Neural Network, and Radial Based Function) in order to prove their accuracy. Thus, if the equations are accurate, they can be used to prioritize basins within a watershed with respect to their impact on water quality in the mainstem river. For the final task, task 3, Simple Equations were verified by comparing them with a physically based model, HSPF, based upon the real-based watersheds which are located in South Korea in order to prove the Simple Equations are capable of being a reliable alternative to physically based models. These simple equations could be used to allow management to identify and prioritize restoration and rehabilitation areas in a watershed even though sufficient data had yet been collected to satisfy the requirements of a physically based model.
Open Access
Enhancement of coupled surface / subsurface flow models in watersheds: analysis, model development, optimization, and user accessibility
(Colorado State University. Libraries, 2018) Park, Seonggyu, author; Bailey, Ryan T., advisor; Grigg, Neil S., committee member; Ronayne, Michael J., committee member; Sale, Thomas, committee member
To view the abstract, please see the full text of the document.
Open Access
General framework for a water quality knowledge and information network
(Colorado State University. Libraries, 2010) Dalcanale, Fernanda, author; Fontane, Darrell G., advisor; Grigg, Neil S., committee member; Vlachos, Evan, committee member; Ferreira do Amaral Porto, Monica, committee member
The increasing pressure on water resources worldwide, due to growing demand, scarcity, and pollution, are leading to a shift from top-down models of management to interdisciplinary approaches and participatory processes, highlighting the need for collaborative work. As a result, the evolution in regulations and management practices and the forging of new partnerships are creating the need for unprecedented amounts of data and knowledge exchange, adding to the complexity of managing information on water resources. Regarding water quality management in particular, the interdependency with the land and the environment and the uncertainty around sources of contamination and chemical interactions can add to the problem. Furthermore, information and knowledge are produced by many different water quality management entities, and efficient means to communicate them are an important part of the process. Technology has provided some excellent tools for sharing information in all branches of science, including water resources. The latest developments go beyond static formats, allowing for the creation of online communities that can provide the necessary tools for information and knowledge exchange. In this project, a search for the available technology for collaboration, methods of community filtering, and community-based review was performed and the possible implementation of these tools to create a general framework for a collaborative “Water Quality Knowledge and Information Network” was evaluated. The main goals of the network are to advance water quality education and knowledge; encourage distribution and access to data; provide networking opportunities; allow public perceptions and concerns to be collected; promote exchange of ideas; and, give general, open, and free access to information. A reference implementation was made available online and received positive feedback from the community, which also suggested some possible improvements.
Open Access
Geospatial analysis of specific degradation in South Korea
(Colorado State University. Libraries, 2019) Kang, Woochul, author; Julien, Pierre Y., advisor; Grigg, Neil S., committee member; Morrison, Ryan, committee member; Kampf, Stephanie, committee member
South Korea experienced many local and concentrated sediment problems such as landslides, upland erosion, rills and valleys, aggradation/degradation, and flood plain sediment deposition. These problems vary in space and time, therefore a reliable and consistent approach to model sediment processes is desirable. In contrast to sediment yield at the basin scale, Specific Degradation (SD) is defined as the ratio of the sediment yield divided by the watershed area. Field measurements of discharge and sediment concentration are analyzed at 70 stations in South Korea. Half of the sampled river basins (35 stations) represent streams in mountain regions and the other half represent rivers. The Modified Einstein Procedure (MEP) was used to determine the total sediment load at all stations. The Flow Duration – Sediment Rating Curve (FD-SRC) method was used to determine the sediment yield and specific degradation for all gauging stations. The annual sediment yield of 70 rivers and streams in South Korea ranged from 10 to 1,000 tons/km2▪yr. The application of three existing models from the literature showed Root Mean Square Errors (RMSE) in excess of 1,400 tons/km2▪yr and gave negative values of the Nash-Sutcliffe Efficiency coefficient (NSE) for existing models, which indicates that the observed mean is a better predictor than the model. The main characteristics of each watershed were analyzed using GIS tools such as ArcGIS version 10.3.1. The data used for the analysis included: (1) daily precipitation data at 60 stations from the Korea Meteorological Administration (KMA); (2) a detailed soil map from the National Institute of Agriculture Sciences; (3) a 5m by 5m resolution Digital Elevation Model (DEM); and (4) land cover raster data at a 10 m resolution from the Ministry of Environment (ME). Seven regression models based on these watershed characteristics are proposed to estimate the mean annual sediment yield and specific degradation. In decreasing order of importance, the meaningful parameters are: (1) drainage area; (2) mean annual precipitation; (3) percentage of urbanized area; (4) percentage of sand of the surface soil (upper 50cm); (5) percentage of wetland and water; and (6) morphometric parameters such as watershed average slope and two parameters of the hypsometric curve. The RMSE for the newly developed models decreased to 90 tons/km2▪yr and the NSE increased from -50 to 0.5, which shows good agreement between the model and the measured sediment yield on these watersheds. The calculated specific degradation and mean annual soil loss of mountain streams were larger than alluvial rivers. Erosion loss mapping at 5m, 30m and 90m was also developed from the Revised Universal Soil Loss Equation (RUSLE). Satellite images and aerial photos were used to better represent geospatial features affecting erosion and sedimentation. Long-term reservoir sedimentation measurements were available to determine the Sediment Delivery Ratio (SDR). An important finding from this analysis is that the percentage of the area covered with wetland and water is well-correlated with the estimated sediment delivery ratios. It suggests that the transfer of sediment to the rivers is affected by wetlands located near alluvial rivers. The erosion maps at 5m resolution could clearly show unique erosion features (i.e. hill slopes, croplands, and construction sites) and locate areas for sediment deposition (i.e. wetlands and agricultural reservoirs). In comparison, the gross erosion rates at 90 m resolution were highly distorted and could not delineate the areas with high upland erosion rates. Sustainable sediment management with these methodologies could be helpful to solve various erosion and sedimentation problems.
Open Access
Hydraulic effects of biofilms on the design and operation of wastewater forcemains
(Colorado State University. Libraries, 2016) Michalos, Christopher T., author; Thornton, Christopher I., advisor; Grigg, Neil S., committee member; Julien, Pierre Y., committee member; Williams, John D., committee member
The impact of biofouling on wastewater forcemains is generally not accounted for in current design practice and little information is available in literature regarding the effect of wastewater biofilms on forcemain hydraulics. In practice, many engineers select a clean water, new pipe roughness factor, to perform hydraulic calculations which may lead to under-sizing wastewater lift station pumps. Forcemains have to cope with a particularly challenging task; they have to ensure that solids contained in the wastewater (sand, gravel, organics) are readily transported along with the wastewater. Forcemain design standards generally recommend a velocity of 2.0 ft/s (0.6 m/s) to prevent deposition of solids and a velocity of 3.5 ft/s (1.1 m/s) to re-suspend solids that may have settled. To further complicate forcemain design and operation; wastewater lift station pumps generally operate intermittently which requires remobilization of any material that may have settled while the pumps remain idle. Therefore, forcemains must be designed to be self-cleaning in order to prevent solids deposition which could cause increased sulfide production leading to corrosion and odor issues; loss of capacity through a reduction of cross sectional area; or even blockage at low points, or at the toe of an adversely sloped pipe leading to costly removal. The goal of this research is to identify short-comings in current forcemain design practice by 1) evaluating the hydraulic effect of biofilms on the absolute roughness (ks) of forcemains; 2) evaluating the hydraulic effect of biofilms on Hazen-Williams C factor; and 3) determine critical velocity required for sediment transport, air clearing, self-cleansing, and optimal diameter of forcemains, which are not identified in forcemain design standards. Operational data were collected and evaluated for 20 municipal wastewater forcemains located in the United States. Data from previous studies, academic research, reports, and published papers were used to supplement and support research findings. A total of 415 data points obtained from 68 forcemain systems ranging from 3- to 66 inches in diameter were evaluated as part of this research. Results of the hydraulic analysis determined that 44% of the systems evaluated were operating at velocities between 2- and 3.5 ft/s and 16% of systems were operating at velocities less than 2 ft/s; indicating that these systems are over designed and do not provide sufficient velocity to re-suspend solids promoting sedimentation. The hydraulic effect of biofilms on forcemain flow resistance was evaluated and determined that ks and C factor varied with forcemain velocity. Calculated values of ks ranged from approximately 35 mm to 0.01 mm, with larger values occurring at velocities less than 1 m/s (3.3 ft/s). The upper range of ks values are orders of magnitude larger than the standard clean water, new pipe ks value found in literature. C factor results ranged from approximately 30 to 150; approximately 60% of forcemain systems evaluated are operating at C factors less than 100, which is much lower than the recommended values of 130 – 150, depending on pipe material. Results suggest that biofilms effect forcemains in a similar manner regardless of pipe diameter, material, or age. Although velocity was determined to be the principle factor affecting ks and C factor; a comparison of the C factor results to ks results show that C factor is dependent upon both velocity and diameter. Equations were developed to estimate ks and C factor and should be utilized along with the Colebrook-White / Darcy-Weisbach and Hazen-Williams equations to estimate the friction headloss for forcemains. The required design velocity for self-cleansing, sediment transport, air clearing, and economical diameter ranges from approximately 4- to 11 ft/s, depending on diameter. Selecting a design velocity between 2 ft/s (0.6 m/s) and 3.5 ft/s (1.1 m/s) may not be appropriate and the minimum design velocity should be selected upon either the self-cleansing velocity or economical pipe sizing. Although each system should be evaluated to determine the correct minimum design velocity based upon the proposed system properties, these results indicate that the minimum forcemain design velocity should be at least 5 ft/s (1.5 m/s).
Open Access
Hydrologic modeling of a small ungauged basin in the Sahel: unique calibration and results
(Colorado State University. Libraries, 2014) Warms, Mikell, author; Ramirez, Jorge A., advisor; Grigg, Neil S., committee member; Kampf, Stephanie, committee member
The Sahelian region of Africa is a geographic belt directly south of the Sahara, connecting the desert to the wetter Sudanian and Guinean savannas to the South. The region is semi-arid, receiving only 300-600 mm of precipitation on average annually. In addition, the Sahel experiences severe dry seasons (7-9 months) with little to no rain. Measurement stations in the region are scarce and reliable data is often difficult to obtain. It is common for drainage basins throughout many parts of the world to be ungauged or gauged but deteriorating. Conventional hydrologic modeling techniques to calibrate and verify basin parameters are rarely applicable in these cases. This problem is exacerbated when human-induced changes to the land surface and climate change impacts lead to increased uncertainty. A recent hydrologic regime shift in parts of the Sahel has been observed and is the basis for this study. Traditionally, a lack of perennial water sources in the region limited settlement, and only seasonal grazing was commonplace. However, many of the previously ephemeral lakes in the region have become perennial or less drastically ephemeral, and settlements have begun to appear in these locations. Hypotheses of how this regime shift occurred, or whether this trend will continue were tested with a calibrated hydrologic model. This study will: (1) address briefly the difficulty in calibrating hydrologic models in ungauged basins; (2) share the results of a unique calibration procedure; and (3) test project hypotheses using the calibrated hydrologic model in a case study of a small lake basin in Northern Mali.
Open Access
Improvements in GRACE-based terrestrial water storage anomalies for groundwater depletion and ecohydrological analyses
(Colorado State University. Libraries, 2022) Ukasha, Muhammad, author; Niemann, Jeffrey D., advisor; Grigg, Neil S., committee member; Bailey, Ryan T., committee member; Ronayne, Michael J., committee member
To view the abstract, please see the full text of the document.
Open Access
Improving hydrologic modeling of runoff processes using data-driven models
(Colorado State University. Libraries, 2021) Han, Heechan, author; Morrison, Ryan, advisor; Grigg, Neil S., committee member; Bailey, Ryan T., committee member; Kampf, Stephanie, committee member
Accurate rainfall–runoff simulation is essential for responding to natural disasters, such as floods and droughts, and for proper water resources management in a wide variety of fields, including hydrology, agriculture, and environmental studies. A hydrologic model aims to analyze the nonlinear and complex relationship between rainfall and runoff based on empirical equations and multiple parameters. To obtain reliable results of runoff simulations, it is necessary to consider three tasks, namely, reasonably diagnosing the modeling performance, managing the uncertainties in the modeling outcome, and simulating runoff considering various conditions. Recently, with the advancement of computing systems, technology, resources, and information, data-driven models are widely used in various fields such as language translation, image classification, and time-series analysis. In addition, as spatial and temporal resolutions of observations are improved, the applicability of data-driven models, which require massive amounts of datasets, is rapidly increasing. In hydrology, rainfall–runoff simulation requires various datasets including meteorological, topographical, and soil properties with multiple time steps from sub-hourly to monthly. This research investigates whether data-driven approaches can be effectively applied for runoff analysis. In particular, this research aims to explore if data-driven models can 1) reasonably evaluate hydrologic models, 2) improve the modeling performance, and 3) predict hourly runoff using distributed forcing datasets. The details of these three research aspects are as follows: First, this research developed a hydrologic assessment tool using a hybrid framework, which combines two data-driven models, to evaluate the performance of a hydrologic model for runoff simulation. The National Water Model, which is a fully distributed hydrologic model, was used as the physical-based model. The developed assessment tool aims to provide easy-to-understand performance ratings for the simulated hydrograph components, namely, the rising and recession limbs, as well as for the entire hydrograph, against observed runoff data. In this research, four performance ratings were used. This is the first research that tries to apply data-driven models for evaluating the performance of the National Water Model and the results are expected to reasonably diagnose the model's ability for runoff simulations based on a short-term time step. Second, correction of errors inherent in the predicted runoff is essential for efficient water management. Hydrologic models include various parameters that cannot be measured directly, but they can be adjusted to improve the predictive performance. However, even a calibrated model still has obvious errors in predicting runoff. In this research, a data-driven model was applied to correct errors in the predicted runoff from the National Water Model and improve its predictive performance. The proposed method uses historic errors in runoff to predict new errors as a post-processor. This research shows that data-driven models, which can build algorithms based on the relationships between datasets, have strong potential for correcting errors and improving the predictive performance of hydrologic models. Finally, to simulate rainfall-runoff accurately, it is essential to consider various factors such as precipitation, soil property, and runoff coming from upstream regions. With improvements in observation systems and resources, various types of forcing datasets, including remote-sensing based data and data-assimilation system products, are available for hydrologic analysis. In this research, various data-driven models with distributed forcing datasets were applied to perform hourly runoff predictions. The forcing datasets included different hydrologic factors such as soil moisture, precipitation, land surface temperature, and base flow, which were obtained from a data assimilation system. The predicted results were evaluated in terms of seasonal and event-based performances and compared with those of the National Water Model. The results demonstrated that data-driven models for hourly runoff forecasting are effective and useful for short-term runoff prediction and developing flood warning system during wet season.
Embargo
Investigating the impact of irrigation and water storage practices on hydrologic fluxes under climate change in a highly managed river basin
(Colorado State University. Libraries, 2024) Almahawis, Mohammed K., author; Bailey, Ryan T., advisor; Grigg, Neil S., committee member; Scalia, Joseph, IV, committee member; Sanford, William E., committee member
Irrigation practices and sources can have significant impacts on water resources and the hydrologic fluxes that control these resources. To better manage water resources and future water supply, the influence of irrigation practices and management on these hydrologic fluxes should be quantified in time and space at varying scales, under potential irrigation management practices. To fulfill this objective, a surface-subsurface modeling approach was applied to simulate watershed-scale hydrologic processes in the Cache la Poudre River Basin, Colorado, USA (4,824 km2), in which both surface water irrigation and groundwater irrigation are prevalent. The model chosen for this study is the watershed model SWAT+, using the spatially distributed, physically based groundwater module gwflow, in which unconfined groundwater storage, flows, and interaction with land surface features are simulated using a collection of grid cells that represent control volumes of the aquifer. Major groundwater inflows and outflows include pumping, recharge, groundwater-channel exchange, groundwater-lake exchange, and tile drainage outflow. To investigate the impact of irrigation practices, detailed surface and groundwater irrigation routines and canal-aquifer interactions were added to the SWAT+ source code, requiring information of irrigation sources and irrigation canal locations throughout the river basin. Model calibration and testing was performed using monthly stream discharge and groundwater head. The calibrated model is used to quantify the impact of surface water and groundwater irrigation scenarios on water availability and hydrologic fluxes within the river basin. A total of 22 scenarios were conducted and grouped into five main groups: irrigation source, irrigation amount, irrigation type, canal bed thickness, and partial or full sealing of earthen irrigation canals. Using groundwater as the only irrigation source decreases groundwater discharge to streams (by 14%) due to lowering groundwater levels; converting flood irrigation to sprinkler irrigation throughout the basin decreases surface runoff by 22%; and sealing earthen canals leads to a lowering of groundwater levels, which decreases groundwater discharge to streams by 9%, leading to an overall decrease in streamflow in the Cache la Poudre River and changes to temporal patterns in streamflow. Overall, irrigation amount and type and canal sealing have a small impact on total groundwater storage, compared to changes in the percent of fields irrigated by groundwater pumping. The potential impacts of climate change on water resources and hydrologic fluxes were analyzed in this study. The calibrated SWAT+gwflow model is run under five different CMIP5 climate models downscaled by MACA, each representing two different climate emission scenarios, RCP4.5 and RCP8.5. Except for the CGCM3 (Warm) model, all climate models and emission scenarios predict an increase in the yearly average temperature. The projected variation in precipitation (that is, snow and rain) depends on the climate model used. However, the average annual precipitation across the entire basin is expected to increase by 6.1% under the RCP8.5 scenario for the NorESM1-M (Mild) model. On the other hand, the IPSL-CM5A-MR (Dry) model shows a maximum decrease rate of 6% from the average climate conditions under the RCP8.5 scenario. The analysis reveals that the IPSL-CM5A-MR-8.5 climate model in the CLP is the most severe, as it combines two climatic stressors: less precipitation and increased temperature. Runoff is observed to be reduced by 47.6%, groundwater recharge to drop by 11%, and a 0.5% reduction in groundwater storage under this climate scenario. Although the climate conditions in the past have been inconsistent, the transboundary water source that flows into the watershed has consistently maintained a stable discharge throughout the investigated historical period. This indicates the existence of regulated water management methods and agreements, irrespective of the impact of climate change. The potential effects of constructing a new reservoir were also assessed in this study, specifically focusing on the influence on streamflow and hydrologic fluxes under changing climatic conditions. The calibrated SWAT+gwflow model was run using two different CMIP5 climate models downscaled by MACA, CNRM-CM5 (Wet) and IPSL-CM5A-MR (Dry) under RCP8.5 emission scenario. The analysis revealed that the CNRM-CM5 (Wet) climate scenario had a higher average monthly diversion rate from the CLP river to the Glade Reservoir during operation months (2.1 m3/s) compared to the IPSL-CM5A-MR (Dry) scenario (1.6 m3/s). Both climate models show a consistent reduction in the average annual streamflow of the CLP river when the reservoir is present. The largest reduction in the average monthly streamflow in CLP river was observed under the IPSL-CM5A-MR (Dry) RCP8.5 with reservoir scenario for the month of June, showing a 78% decrease from the historical average streamflow. The reduction in streamflow, under the reservoir scenario, for both future climate models led to a 13% and 24% reduction in surface water irrigation for the wet and dry climate scenarios, respectively, compared to historical values. Results are helpful for informed decision-making in agriculture water management and can lead to sustainable, efficient, and equitable use of water resources, helping to address the challenges posed by water scarcity and environmental conservation.
Open Access
Key complex issues impacting public private partnerships for transportation renewal projects in the United States
(Colorado State University. Libraries, 2014) Chhun, Sereyrithy, author; Strong, Kelly C., advisor; Ozbek, Mehmet E., committee member; Grigg, Neil S., committee member
Highways have become a symbol of modern America (Levinson, 2004), and infrastructure investment plays a pivotal role both in short-term and long-term economic growth and in job creation. In the US, it represents 16% of the gross national product, and every dollar of public investment in highways has a net rate of return of 22 cents, and every billion dollars of federal highway investment generates 47,500 jobs (AASHTO 2003). In response to the inabilities to raise government revenues in the US, aging infrastructure systems, and high construction and O/M costs, infrastructure development has steadily become a collaboration work between the public and private sector. In liberalized infrastructure markets, various governance structures are being tested for application of public-private partnerships (PPPs or P3s) strategies in infrastructure development (Estache, 2004). This thesis aims to review the key complex PPP issues in transportation renewal projects in the US that adopt PPPs. While PPPs can be applied to a range of agreements, the PPP projects to be studied and analyzed in this paper will be limited to those involving complex financing, design, construction and long-term operation and maintenance of transportation infrastructure of at least 10 years. These issues are examined in the context of six case studies in six different state across the US by means of interview and archival record. Findings resulting from this work suggested that PPPs have been increasingly implemented by departments of transportation in the US as a mean to tape into private resources. In addition, this research identified four key complex PPP issues in transportation projects as such Economic issue, Procurement issue, Risk Issue, and Governance issue. States have established a dedicated organizational unit to facilitate the use of PPPs, for example High Performance Enterprise (HPTE) in Colorado and Innovative Project Delivery Division in Virginia, but there exist no standards or best practices in the United States for procurement, concession terms, or risk-sharing.
Open Access
Low impact development modeling to manage urban storm water runoff and restore predevelopment site hydrology
(Colorado State University. Libraries, 2010) Simpson, Matthew G., author; Roesner, Larry A., advisor; Grigg, Neil S., committee member; Glick, Scott, committee member
The hydrologic effects of urban development have been documented for some time. Urban streams experience dramatic changes to their natural flow regime, which is mostly due to the increased rate and volume of runoff. Conventional stormwater management focuses on peak rate control through the use of detention and retention basins while paying little attention to the increased volume of urban runoff. Low Impact Development (LID) is a land planning and stormwater management approach that seeks to control runoff as close as possible to its source. LID practices take advantage of natural processes, such as infiltration, to reduce the rate and volume of runoff while improving water quality at the same time. It is hypothesized that LID can be used to restore the predevelopment hydrology to a site. This thesis investigates if LID can be used exclusively to meet stormwater requirements and secondly whether LID can maintain the predevelopment site hydrology. In order to examine if LID can restore predevelopment site hydrology, an EPA SWMM model was created based upon a proposed development in Fort Collins, CO. Several different scenarios were evaluated including: rainfall from Fort Collins, CO and Atlanta, GA; a high and a low infiltration soil; and BMPs with partial infiltration (with underdrain) and with full infiltration (without underdrain). The amount of LID in each model was increased until predevelopment peak flow rates and water balance were met; this was accomplished using design storm simulations. Each model was then analyzed with a continuous simulation using historic rainfall data from both locations. The LID BMPs that were modeled include grassed swales, rain gardens, infiltration trenches, and permeable pavement. Finally, a cost review of the LID designs was performed to explore the financial practicality of LID. The results show that LID can restore predevelopment site hydrology, but the amount of LID required is substantial. However, the cost review shows that the extra LID expense could be recovered in certain locations through development of the detention pond land which is no longer needed.
Open Access
Methodologies for transforming data to information and advancing the understanding of water resources systems towards integrated water resources management
(Colorado State University. Libraries, 2017) Oikonomou, Panagiotis D., author; Fontane, Darrell G., advisor; Waskom, Reagan M., advisor; Grigg, Neil S., committee member; Karavitis, Christos A., committee member; Anderson, Charles W., committee member
The majority of river basins in the world, have undergone a great deal of transformations in terms of infrastructure and water management practices in order to meet increasing water needs due to population growth and socio-economic development. Surface water and groundwater systems are interwoven with environmental and socio-economic ones. The systems' dynamic nature, their complex interlinkages and interdependencies are inducing challenges for integrated water resources management. Informed decision-making process in water resources is deriving from a systematic analysis of the available data with the utilization of tools and models, by examining viable alternatives and their associated tradeoffs under the prism of a set of prudent priorities and expert knowledge. In an era of increasing volume and variety of data about natural and anthropogenic systems, opportunities arise for further enhancing data integration in problem-solving approaches and thus support decision-making for water resources planning and management. Although there is a plethora of variables monitored in various spatial and temporal scales, particularly in the United States, in real life, for water resources applications there are rarely, if ever, perfect data. Developing more systematic procedures to integrate the available data and harness their full potential of generating information, will improve the understanding of water resources systems and assist at the same time integrated water resources management efforts. The overarching objective of this study is to develop tools and approaches to overcome data obstacles in water resources management. This required the development of methodologies that utilize a wide range of water and environmental datasets in order to transform them into reliable and valuable information, which would address unanswered questions about water systems and water management practices, contributing to implementable efforts of integrated water resources management. More specifically, the objectives of this research are targeted in three complementary topics: drought, water demand, and groundwater supply. In this regard, their unified thread is the common quest for integrated river basin management (IRBM) under changing water resources conditions. All proposed methodologies have a common area of application namely the South Platte basin, located within Colorado. The area is characterized by limited water resources with frequent drought intervals. A system's vulnerability to drought due to the different manifestations of the phenomenon (meteorological, agricultural, hydrological, socio-economic and ecological) and the plethora of factors affecting it (precipitation patterns, the supply and demand trends, the socioeconomic background etc.) necessitates an integrated approach for delineating its magnitude and spatiotemporal extent and impacts. Thus, the first objective was to develop an implementable drought management policy tool based on the standardized drought vulnerability index framework and expanding it in order to capture more of drought's multifaceted effects. This study illustrated the advantages of a more transparent data rigorous methodology, which minimizes the need for qualitative information replacing it with a more quantitative one. It is believed that such approach may convey drought information to decision makers in a holistic manner and at the same time avoid the existing practices of broken linkages and fragmentation of reported drought impacts. Secondly, a multi-scale (well, HUC-12, and county level) comparative analysis framework was developed to identify the characteristics of the emergent water demand for unconventional oil and gas development. This effort revealed the importance of local conditions in well development patterns that influence water demand, the magnitude of water consumption in local scales in comparison to other water uses, the strategies of handling flowback water, and the need for additional data, and improved data collection methods for a detailed water life-cycle analysis including the associated tradeoffs. Finally, a novel, easy to implement, and computationally low cost methodology was developed for filling gaps in groundwater level time series. The proposed framework consists of four main components, namely: groundwater level time series; data (groundwater level, recharge and pumping) from a regional physically-based groundwater flow model; autoregressive integrated moving average with external inputs modeling; and the Ensemble Smoother (ES) technique. The methodology's efficacy to predict accurately groundwater levels was tested by conducting three numerical experiments at eighteen alluvial wells. The results suggest that the framework could serve as a valuable tool in gaining further insight of alluvium aquifer dynamics by filling missing groundwater level data in an intermittent or continuous (with relative short span) fashion. Overall, it is believed that this research has important implications in water resources decision making by developing implementable frameworks which advance further the understanding of water systems and may aid in integrated river basin management efforts.
Open Access
Modeling artificial groundwater recharge and low-head hydroelectric production: a case study of southern Pakistan
(Colorado State University. Libraries, 2016) Siddiqui, Rafey Ahmed, author; Bailey, Ryan T., advisor; Grigg, Neil S., committee member; Sale, Thomas, committee member; Sanford, William, committee member
DHA City Karachi (DCK), a city designed for approximately one million people, is envisaged to become a satellite city to the second largest city in the world, Karachi, which has a population of 25 million. The upcoming city is located 21 miles north of main metropolitan Karachi in the arid southern part of Pakistan. The region receives little rainfall with an annual average of 217 mm and temperatures ranging from an average of 88°F in the summers to 68°F in the winters. The town has a projected water demand in the fully developed stage of 45 Million Gallons per Day (MGD) and 500 Mega Watts (MW) of electricity. Since water and electricity are prized and expensive commodities in the region, alternate and renewable sources of both need to be explored for DCK to meet its goal of sustainability and conservation. Two options for these sources, artificial recharge and hydroelectric product, are explored in this study. Artificial recharge to replenish groundwater resources is becoming more common in arid areas. In this thesis, the capacity of small lakes to produce significant seepage and recharge to the underlying aquifer within city limits is explored for DCK. The lakes are fed by treated effluent from Sewage Treatment Plants (STP), which then ponds and creates downward seepage to the water table. Artificial recharge and resulting groundwater flow within the aquifer is simulated using a three-dimensional groundwater flow model (MODFLOW). A variety of pumping scenarios are explored to determine the quantity of groundwater that can be pumped for water supply. An optimal placement of 50 pumps throughout the city also is determined, with drawdown used as the variable to be minimized so as to minimize pumping costs. In the fully developed stage of artificial recharge, the lakes feed almost 7.9 MGD of water to the aquifer, out of which 6.6 MGD can be pumped out and consumed sustainably on a daily basis through the 50 planned wells. Since DCK is to be developed and inhabited in 3 phases, analysis revealed that quantities of 1.4 and 3.5 MGD can be pumped out sustainably for the short and mid-term developmental plans. A sustainable hydroelectric system was also designed for using the hydraulic structures of the small lakes. System control was introduced by application of Artificial Neural Networks (ANN) and Model Predictive Control (MPC) to maintain the hydroelectric potential and constant head against variation in flow as delivered from the STPs. The results show an output of 13.92 MW of green and sustainable hydroelectricity which can be produced at a very low cost. A cost-benefit analysis projects a savings of $11,550 and $60,000 per day due to the artificial groundwater recharge and hydroelectric production respectively, with the cost of construction of these projects being paid off within 5 and 2 years at this rate, including the cost of operation and maintenance. Results, however, should be used with caution due to the preliminary nature of the models and calculations.
Open Access
Modeling in a three-dimensional world: whitewater park hydraulics and their impact on aquatic habitat in Colorado
(Colorado State University. Libraries, 2013) Kolden, Eleanor, author; Bledsoe, Brian P., advisor; Wohl, Ellen, committee member; Grigg, Neil S., committee member
Whitewater parks (WWPs) are becoming more popular in Colorado rivers and streams, but the effects of WWPs on aquatic habitat and fish passage are poorly understood. This study investigated the use of a three-dimensional (3-D) hydrodynamic model (FLOW-3D®) for assessing effects of WWPs on aquatic habitat. The objective of this study was to compare modeled habitat quality to actual fish biomass and to examine the utility of 3-D modeling (vs. two-dimensional (2-D) modeling) in this hydraulically-complex system. Two sections of a small river in Colorado were modeled: one natural section, and one section containing a WWP with three engineered drop structures. A 2-D habitat suitability analysis for juvenile and adult brown and rainbow trout, longnose dace, and longnose sucker predicted higher habitat quality in the WWPs than the natural reaches for adult brown and rainbow trout at some flow rates, while in-stream surveys showed higher fish biomass per volume in the natural pools. All hydraulic metrics (depth, depth-averaged velocity, turbulent kinetic energy (TKE), 2-D vorticity, and 3-D vorticity) had higher magnitudes in the WWP pools than in the natural pools. In the WWP pools, 2-D model results did not describe the spatial distribution of flow characteristics or the magnitude of variables as well as 3-D results. This thesis supports the use of 3-D modeling for complex flow found in WWPs, but other projects should be evaluated case-by-case to determine if the simplified 2-D rendering of flow characteristics is acceptable. For 3-D modeling to be widely useful, improved understanding of linkages between 3-D aquatic habitat quality and hydraulic descriptors such as TKE, vorticity, and velocity is needed.
Open Access
Modeling nonpoint-source uranium pollution in an irrigated stream-aquifer system: calibration and simulation
(Colorado State University. Libraries, 2024) Qurban, Ibraheem A., author; Gates, Timothy K., advisor; Bailey, Ryan T., committee member; Grigg, Neil S., committee member; Ippolito, James A., committee member
The Lower Arkansas River Valley (LARV) in southeastern Colorado has been a source of significant agricultural productivity for well over a century, primarily due to extensive irrigation practices. Mirroring trends seen in other semi-arid irrigated areas globally, however, irrigated agriculture in the LARV has resulted in several challenges for the region. In addition to the emergence of waterlogging and soil salinization, leading to decreased crop yields, elevated levels of nutrients and trace elements have appeared in the soil and water. Among these constituents, uranium (U), along with co-contaminants selenium (Se) and nitrate (NO3), has shown particularly high concentrations in groundwater, surface water, and soils. These heightened concentrations pose environmental concerns, impacting human health and the well-being of aquatic life such as fish and waterfowl. Careful monitoring and management practices are crucial to prevent potential harm to water resources. The main goal of this research is to develop a comprehensive numerical model for assessing U pollution in a stream-aquifer system within a large irrigated area. To achieve this, a computational model is built and tested that can predict with reasonable accuracy how U, along with Se and NO3, are mobilized and move within a coupled system of streams and groundwater. The approach combines two key modeling components: a MODFLOW package, which handles the simulation of groundwater and stream flow dynamics, and an RT3D package, which addresses the reactive transport of U, Se, and nitrogen (N) species in both groundwater and interconnected streams. RT3D relies on the simulated flows generated by MODFLOW to track the movement of U, Se, and N species between streams and the aquifer in the irrigated landscape, updating daily to adequately capture changes over time. This integrated model provides an understanding of how these contaminants behave and interact within the stream-aquifer system, aiding in effective pollution assessment and providing insights valuable to the planning of management strategies. The coupled MODFLOW-RT3D flow and reactive transport model is applied to a 550 km² area within the LARV, stretching from Lamar, Colorado, to the Colorado-Kansas border and spanning a period of 14 years. The flow package is compared with observations of groundwater hydraulic head and stream flow, along with estimates of return flow along the Arkansas River. The reactive transport package is assessed by comparing predicted U, Se, and NO3 concentrations against data collected from groundwater monitoring wells and stream sampling sites along with estimates of solute mass loads to the river. To calibrate and refine the model, the PESTPP-iES iterative ensemble smoother (iES) software is employed. This calibration process is dedicated to enhancing the model's accuracy in predicting both flow and transport dynamics. PESTPP-iES addresses calibration uncertainty by establishing prior frequency distributions for key model parameters based on data and expertise, then iteratively adjusts these parameters during calibration to align model predictions with observed data. Post-calibration, posterior distributions reflect updated parameter values and reduced uncertainties. Demonstrating a strong alignment with concentrations of CNO3, CSe, and CU values found in groundwater, streams, and the mass loading entering the Arkansas River, outcomes of the model-based simulations reveal a substantial violation of the Colorado chronic standard (85th percentile = 30 μg/L) for CU throughout the study region. On average, simulated CNO3, CSe, and CU values for groundwater in non-riparian areas in the region are 3.6 mg/L, 41 µg/L, and 126 µg/L, compared to respective averages of 4 mg/L, 53 µg/L, and 112 µg/L observed in monitoring wells. When considering the 85th percentile of simulated CNO3, CSe, and CU values, the figures for non-riparian groundwater are 6 mg/L, 50 µg/L, and 218 µg/L, respectively. Groundwater in riparian areas shows lower average simulated CNO3, CSe, and CU values of 3 mg/L, 26 µg/L, and 72 µg/L, respectively, and 85th percentile values of 5 mg/L, 41 µg/L, and 152 µg/L. Additionally, simulated average mass loading rates for NO3, Se, and U along the river are 8.8 kg/day per km, 0.05 kg/day per km, and 0.27 kg/day/km respectively, compared to stochastic mass balance estimates of 9.2 kg/day per km , 0.06 kg/day per km , and 0.23 kg/day per km. The simulated 85th percentile CNO3, CSe, and CU values in the Arkansas River are 1 mg/L, 11 μg/L, and 87 μg/L, respectively. Notably, the simulated U levels in groundwater exceed the chronic standard across 44% of the region. Along the Arkansas River, concentrations consistently surpass the chronic standard, averaging 2.9 times higher. Predicted Se concentrations also show significant exceedances of the chronic standard, while NO3 violations are slight to moderate. The varying pollutant levels across the region highlight specific areas of concern that require targeted attention, indicating potential contributing factors to these hotspots. Findings outline how serious and widespread the problem is in the LARV, providing a starting point for comparing potential pollution reduction from alternative water and land best management strategies (BMPs) to be explored in future applications of the calibrated model.
Open Access
Modeling the impact of climate change on water resources case study: Arkansas River Basin in Colorado
(Colorado State University. Libraries, 2012) Nasr Azadani, Fariborz, author; Fontane, Darrell G., advisor; Grigg, Neil S., committee member; Fitzhorn, Patrick A., committee member
There is mounting evidence that amount of carbon dioxide is being increased which can lead to changing the global climate drastically during this century. Climate change can have important effect on the water resources and water demand like urban and agriculture uses. The effects of climate change have been explored in the Arkansas River Basin in Colorado which is one of the major rivers in Colorado that provides water for 650,000 people a year and irrigates around 280,600 acres of agriculture areas. The aim of this research is to project precipitation and temperature in smaller temporal and spatial scale by MAGICC/SCENGEN tool and model the impact of climate change on the water resources by water Evaluation and Planning (WEAP) software to provide results for the water managers and policy makers. Two climate scenarios (A2 and B2) and a 550 ppm policy were used to project future temperature and precipitation in the Arkansas River Basin for the period of 2013 to 2040. Based on the results from the two climate scenarios, a warmer and drier climate is anticipated for the region. Three adaptation scenarios (new irrigation technology scenario, new irrigation technology along with crop change scenario, and new irrigation technology along with reducing crop area scenario) were analyzed to consider their effects to mitigate the negative impact of climate change in the Arkansas River Basin. The results of the simulation of these scenarios showed that all three have a relatively short term impact. This indicates that globe warming is a potentially very serious problem for water management in the Arkansas River Basin.
Open Access
Multi-criteria decision-making approach for building maintenance in facility management
(Colorado State University. Libraries, 2021) Besiktepe, Deniz, author; Ozbek, Mehmet E., advisor; Atadero, Rebecca A., advisor; Grigg, Neil S., committee member; Bradley, Thomas H., committee member; Valdes-Vasquez, Rodolfo, committee member
Facility Management (FM) encompasses multi-disciplinary processes to ensure the built environment functions properly for its intended use and service. Maintenance practices are critical to sustaining the longevity of the built environment. As buildings continue to age, there is an increasing need for effective maintenance practices and strategies. In addition, cost and financial constraints require enhanced processes in building maintenance decision-making to assure the resources are allocated efficiently to get the best possible outcome. Building maintenance decisions present challenges to FM professionals. These challenges arise from the complexity of building systems as well as the participation of multiple stakeholders in the process, such as the property owner, facility manager, engineer, project supervisors, technicians, and occupants. The overarching goal of this dissertation is to develop a systematic and structured multi-criteria decision-making (MCDM) approach for building maintenance practices in a resource-constrained environment. To do so, this dissertation includes three separate but related studies; each focusing on the essential pieces of the MCDM approach. The first study identified the set of fundamental criteria needed for constructing an MCDM model for FM decision-making utilizing the results of a nationwide survey conducted with the members of the International Facility Management Association (IFMA) and the Leadership in Educational Facilities (APPA) in the United States, two globally recognized FM organizations. The first study also has an exploratory aspect and tries to establish the decision-making and condition assessment practices currently used in FM practices. The second study focused on developing a resource-efficient and quantitative condition assessment (CA) framework to establish a condition rating value. Condition information is essential in the decision-making process of building maintenance; however, financial challenges limit the practice of CA, which currently is mostly based on visual inspections and likely to generate a subjective outcome. Fuzzy sets theory is utilized to obtain a quantitative condition rating value that would be less subjective than that obtained through visual inspections, as fuzzy sets theory deals with imprecise, uncertain, and ambiguous judgments with the membership relations. In the third study, an MCDM method, Choosing by Advantages (CBA), is used to develop a structured and systematic decision-making approach in building maintenance and FM. CBA allows the identification of the most-value generating alternative in the absence of cost and financial constraints, which helps to eliminate the dominancy of financial considerations in the decision-making process. In addition, CBA provides a practical framework to decision-makers in FM with various backgrounds, allowing the participation of multiple stakeholders in the process. This study contributes to the body of knowledge in the FM domain by identifying criteria in the building-maintenance decision-making process, developing a less subjective and quantitative CA framework, and demonstrating an MCDM method for a systematic approach in building-maintenance decision-making. Additionally, this study will benefit FM professionals and decision-makers at all levels by helping to prioritize maintenance activities, justify maintenance budget requests, and support strategic planning.