Browsing by Subject "Water"

Sustainable water management is needed to ensure quality supplies of our vital water resources in the face of growing human demand for water, high levels of pollution, and increasing spatial and temporal variability associated with climate change. An integrated approach to water management is recommended to address current water challenges, which are often interrelated with other environmental, economic and social issues. Universities and colleges have missions, resources, and contexts that could enable them to lead the process of developing and applying sustainable and integrated water resource management (IWRM). The opportunity to exemplify integrated water management has grown as institutions of higher education have made progress towards incorporating environmental sustainability into teaching, research, and campus operations. This dissertation examines the issue of campus water management at institutions of higher education through a review of campus sustainability literature, a survey of sustainability and facilities managers, and case studies of three campus water-related projects.

Findings from the review of campus sustainability literature and websites suggests water is less of a campus management priority than issues such as energy and climate change; furthermore, where water is addressed, the focus is on water conservation, while water quality management is overlooked. IWRM is not explicitly discussed in the campus sustainability literature reviewed, though principles relevant to IWRM are included in some campus sustainability declarations and programs. Results from the survey substantiate the findings from literature review that water management is less of an institutional priority than energy management and water quality management is often underemphasized in campus management. According to the survey respondents, campus water management at the institutions represented was on average just adequately managed and institutions were minimally prepared to deal with several types of future water problems. Facilities managers tended to rate their institution's water management as slightly more effective compared to sustainability coordinators. Many campuses relied on top-down, engineering based water management approaches, rather than integrated and interdisciplinary water management. Individual initiatives, municipal codes and policies, campus community sustainability awareness, and campus environmental projects served as drivers for more sustainable water management, while budget constrains were a common barrier. Logistic regression analysis of the survey data revealed that institutions featuring stream and wetland restoration projects had greater odds of being described as having a developed watershed plan and taking into consideration multidisciplinary approaches to water management.

Case studies showed that wetland creation and restoration projects can serve as effective teaching and research laboratories for institutions of higher education, but that none of the studied cases fully exemplified IWRM in their operation. Of the three cases studied, the Stream and Wetland Assessment Management Park project at Duke University most closely demonstrated a campus project designed and developed to address water problems in the campus watershed, while also offering an effective outdoor teaching and research laboratory for hundreds of students, professionals, and researchers. The Olentangy River Wetland Research Park case at Ohio State University exemplified the potential for wetland creation and restoration projects to serve as a facility for educating thousands of students and visitors, training dozens of water experts, and influencing wetland and water resource management beyond the campus. The Radford University Stormwater Treatment Wetland Project case illustrated the potential for institutions with limited space and resources to establish effective outdoor teaching laboratories using environmental features already present or in development on campus.

Findings from the review, survey and case studies all point toward the need and opportunity for institutions of higher education to make greater efforts at implementing and promoting sustainable and integrated water resource management. Literature review and survey findings reveal that water is frequently overlooked as environmental resource at universities and colleges, while other environmental issues such as energy, climate change and recycling are prioritized in sustainability plans and efforts. Universities and colleges have made progress addressing water conservation, while water quality and stormwater need further attention and an integrated approach for more effective management.

Quantifying carbon fluxes and pools of forest ecosystems is an active research area in global climate study, particularly in the currently and projected increasing atmospheric carbon dioxide concentration environment. Forest carbon dynamics are closely linked to the water cycle through plant stomata which are regulated by environmental conditions associated with atmospheric and soil humidity, air temperature and light. Thus, it is imperative to study both carbon and water fluxes of a forest ecosystem to be able to assess the impact of environmental changes, including those resulting from climate change, on global carbon and hydrologic cycles. However, challenges hampering such global study lie in the spatial heterogeneity of and the temporal variability of fluxes in forests around the globe. Moreover, continuous, long-term monitoring and measurements of fluxes are not feasible at global forest scale. Therefore, the need to quantify carbon and water fluxes and to identify key variables controlling them at multiple stands and time scales is growing. Such analyses will benefit the upscaling of stand-level observations to large- or global-scale modelling approaches.

I performed a series of studies investigating carbon and water fluxes in pine forests of various site characteristics, conditions and latitudinal locations. The common techniques used in these studies largely involved sap flux sensors to measure tree-level water flow which is scaled up to stand-level transpiration and a process-based model which calculates canopy light absorption and carbon assimilation constrained by the sap-flux beased canopy stomatal conductance (called Canopy Conductance Constrained Carbon Assimilation or 4C-A model). I collected and analyzed sap flux data from pine forests of two major species: Pinus taeda in temperate (36 °N) and Pinus sylvestris in boreal (64 °N) climatic zones. These forests were of different stage-related canopy leaf area and some were under treatments for elevated atmospheric CO2 concentration or fertilization.

I found that (Chapter 2) the 17-year long free-air CO2 enrichment (FACE) had little effect on canopy transpiration of a mixed forest with the dominant P. taeda and other broadleaved species as the understory in North Carolina, USA (Duke FACE). The result was due to the compensation of elevated [CO2]-induced increase of canopy leaf area for the reduction of mean canopy stomatal conductance. My next theoretical study (Chapter 3), comparing P. taeda (native at 36 °N in North Carolina), P. sylvestris (native at 64 °N in norther Sweden) and Pinus contorta (native at 58 °N in British Columbia, Canada) canopies, revealed that the interaction between crown architecture and solar elevation associated with site latitude of pine canopies affected the distribution and total amount of canopy light absorption and potentially photosynthesis such that the latitudinally prescribed needle organization of a pine canopy is optimal for light interception and survival in its native location. Then, I quantified and analyzed water fluxes in four pine forests: one composed of P. taeda in North Carolina and three containing P. sylvestris in northern Sweden (Chapter 4). The latter forests consisted of various stage-related canopy leaf area and nutrient status. Combining my estimates with other published results from forests of various types and latitudinal locations, I derived an approach to estimate daily canopy transpiration during the growing season based on a few environmental variables including atmospheric and soil humidity and canopy leaf area. Moreover, based on a water budget analysis, I discovered that the intra-annual variation of precipitation in a forest has a small effect on evapotranspiration and primarily affecting outflow; however, variation of precipitation across latitudes proportionally influences anuual evapotranspiration and outflow. Furthermore, the hydrologic analyses implied the `disequilibrium' of forest water cycling during the growing season when forests may use less and more water in dry and wet regions, respectively, than the incoming precipitation. Nevertherless, at annual timescale, most forests became in `equilibrium' by using similar proportion of incoming precipitation. Finally, (Chapter 5) I estimated and analyzed the temporal and spatial variabilities of carbon fluxes of the same four forests measured in Chapter 4 using the 4C-A computational approach and analyzed their resource-use efficiencies. I concluded that, based on my results and others as available, despite the differences in species clumping and latitudes which influence growing season length and solar elevation, the gross primary productivity can be conservatively linearly related to the canopy light absorption. However, based on previous findings from a global study, different allocation of the acquired carbon to the above- and belowground is regulated by soil nutrient status.

Overall, the findings in this dissertation offer new insights into the impacts of environmental changes on carbon and water dynamics in forests across multiple sites and temporal scales which will be useful for larger-scale analyses such as those pertaining to global climate projection.

An abstract of a dissertation: As humans increasingly alter the surface geomorphology of the Earth, a multitude of artificial aquatic systems have appeared, both deliberately and accidentally. Human modifications to the hydroscape range from alteration of existing waterbodies to construction of new ones. The extent and ecosystem services of these systems are underexplored, but likely substantial and changing. Instead of simply accepting that artificial ecosystems have intrinsically low values, environmental scientists should determine what combination of factors, including setting, planning and construction, subsequent management and policy, and time, impact the condition of these systems. Scientists, social scientists, and policymakers should more thoroughly evaluate whether current study and management of artificial aquatic systems is based on the actual ecological condition of these systems, or judged differently, due to artificiality, and consider resultant possible changes in goals for these systems. The emerging recognition and study of artificial aquatic systems presents an exciting and important opportunity for science and society.

Irrigation ditches are ubiquitous features of water networks in rural and urban settings in drylands, and are thus potentially important habitats within the modern hydroscape. The habitat value of ditches and other artificial systems depends on whether these systems respond to local and watershed-scale land use in similar ways to natural features, or whether artificial origin inherently constrains a system's ecological condition. The ditches and creeks of Bishop, California are fed by water from the same minimally developed watershed on the Eastern slope of the Sierra Nevada Mountains, and so served to test whether artificial and natural waters in the same watershed setting and with shared water can provide similar habitat. We sampled benthic macroinvertebrates at 52 sites within the town, stratified by substrate and season. Communities varied by substrate and season as expected, but did not differ significantly between artificial and natural streams. Instead, both types of streams changed as water flowed from undeveloped desert through town, suggesting that irrigation ditches respond to local urbanization in much the same way that natural streams do. Differences in finer-scale spatial structure of community similarity suggest that community assembly processes may differ between natural and artificial channels, but potential mechanisms for these differences are unclear. This study demonstrates that artificial aquatic systems may have substantial ecological value, and suggests that the poor condition of many artificial aquatic systems may reflect stressful watershed settings rather than something intrinsic to their artificiality.

The drainage ditches of the North Carolina Coastal Plain do not merely degrade wetlands; they themselves have ecological structural characteristics of wetlands. We surveyed 32 agricultural, freeway, and forested ditch reaches across this region for hydrologic indicators, soil organic matter, and plants. All showed some hydrologic indicators and had some soil organic matter, with easterly, swampy forests having the most, though with substantial variation across all and few significant differences between types. All had hydrophytic herbaceous plant communities in the sense of at least half their percent cover belonging to obligate, facultative wetland, or facultative taxa. These herbaceous communities differed significantly across site types (F=3.25, d.f.= 2, p=0.001), and responded to both landscape-level factors like nearby development coverage and local-level factors like apparent mowing. Sample sites were not well mapped in well-used federal aquatic databases; the National Hydrography Dataset only included one on a “CanalDitch” flow line, and the National Wetlands Inventory only included two within “partially drained/ditched” areas, and none as individual “excavated” features. Others were mis-categorized, but neither database included any highway sampling sites. Despite this limited information about extent, variation and management impact suggests that human potential to impact wetland structure of these manmade aquatic ecosystems throughout the North Carolina Coastal Plain, and beyond, could be large.

Artificial lakes are a dominant aquatic ecosystem type, but the processes controlling their condition are under-explored. Here we use structural equations modeling to compare the formation of algal blooms and associated water quality issues in 1,045 artificial and 870 natural lakes in the United States using the U.S. Environmental Protection Agency’s National Lakes Assessment data. We compare chemical and physical measurements associated with water quality and the relationships between them, and find that the processes are significantly different between natural and artificial lakes, in a way that suggests impacts of interference with thermal stratification through dam management in reservoirs. However, both the overall processes and the distributions of the data are roughly similar between the two origin types, and between 2007 and 2012 sample years. Artificial lakes are lakes, and process-based explorations of their behavior can help us better know management options.

Taken together, this dissertation examines an artificial version of each of the major aquatic ecosystem types: stream, wetland, and lake. It examines the processes controlling their ecological condition with increasing intricacy with each chapter, and finds ways that artificial aquatic ecosystems are both similar to and different from natural ones. This dissertation provides a new way of looking at the constraints and opportunities that artificial waterbodies afford those in charge of them and interested in their conservation potential.