Tracking Multi-Decadal Lake Dynamics using Optical Imagery, Digital Elevation Models, and Bathymetric Datasets

The goal of this research is to review the current state of long-term, multi-decadal lake dynamic monitoring and develop novel techniques for scalable analysis at local, regional, and global levels. This dissertation is comprised of three chapters formatted as journal manuscripts with each chapter progressively addressing some key limitation in current lake dynamic monitoring methodologies. Chapter 1 tracks lake dynamics (surface elevation, surface area, volume, and volume change) for a single water body, Lake McConaughy, which is the largest lake and reservoir in the state of Nebraska, using the cloud-based geospatial analysis platform Google Earth Engine. Lake dynamics were estimated using bathymetric survey data, the Shuttle Radar Topography Mission 30-meter digital elevation model, and Landsat 5 image composites for 100 time periods between 1984 and 2009. Water surface elevation was estimated and assessed for 5,994 different combinations of water indices, segmentation thresholds, water boundaries, and statistics and produced elevations as accurate as 0.768 m CI95% [0.657, 0.885] root-mean-square-error. The method also detected seasonal and long-term trends which would have major implications for regional agriculture, recreation, and water quality. Chapter 1 was published as an article in the peer-reviewed journal Water Resources Research in October 2019. Chapter 2 expands and improves upon the techniques explored in Chapter 1 in multiple ways. First, the techniques were improved to remove image contamination sources such as snow, ice, cloud cover, shadow, and sensor error for individual images using the Pixel Quality Assurance (QA) band available as a part of the Landsat 4, 5, 7, and 8 Top-of-Atmosphere Tier-1 Collection-1 archives. Using the Pixel QA band information, image contamination was removed from each image between August 1982 and December 2017 and water surface elevation was estimated with the remaining visible water boundary extents overlaying merged National Elevation Dataset digital elevation model and bathymetric survey data resampled to 30-meters which resulted in enhanced temporal resolution compared to the techniques used in Chapter 1. Second, the analysis was expanded from a single water body to fifty-two lakes/reservoirs to provide a better understanding of how the techniques generalize to imagery and water bodies encompassing a wide range of ecotypes, geologies, climates, and management strategies. A variety of common water indices, such as the Modified Normalized Difference Water Index, naïve and dynamic water indices, water boundary types, and filtering strategies were tested and individual lake accuracies are as low as 0.191m RMSE CI95%[0.129, 0.243], and 45 of the 52 lakes produced sub-meter root-mean-squared-error accuracies. Furthermore, accuracy of surface elevation estimates is highly correlated with the mean slope of surrounding terrain with low-slope shorelines having greater accuracy than high-slope shorelines such as those in canyon-filled reservoirs or in mountainous regions. Overall, the improved techniques extend our ability to track long-term lake dynamics to lakes with bathymetric datasets while lacking in-situ hydrological stations, provide a framework for scale-able analysis in Google Earth Engine, and balance a need between high-accuracy estimates and maximum temporal resolution. Bathymetric survey data, such as that used in Chapters 1 and 2 is, unfortunately, not available for most water bodies at regional and global scales. Chapter 3 introduces a method of tracking long-term lake dynamics without bathymetry data and only using available digital elevation models such as Shuttle Radar Topography Mission, the National Elevation Dataset, and Advanced Land Observing Satellite. In digital elevation models, the water surface is often, but not always, hydroflattened producing a flat surface approximating the surface of the water at the time of the data capture which precludes using water boundaries like those in Chapter 1 and Chapter 2 to estimate water level when it is lower than the hydroflattened surface in the digital elevation model. However, using hypsometric relationships developed from the digital elevation models, subsurface water dynamics can still be estimated by extrapolating the low water levels using regression, albeit with increased uncertainty compared to levels above the hydroflattened surface. Using multiple digital elevation models, the lowest hydroflattened surface can be identified for each water body which reduces uncertainty for low water levels by reducing the extrapolation distance to those values while simultaneously increasing the number of above hydroflattened surface estimates. In addition to low-level uncertainty, hypsometric techniques are highly impacted by image contamination such as cloud, cloud shadow, snow, ice, and sensor error which reduces the observable water surface area resulting in erroneous surface elevation, volume, and volume change estimates. To help alleviate this issue, a technique of using proportional hypsometry was developed to remove contamination effects. Together, using the lowest hydroflattened surface and proportional hypsometry, this research produced 12,680 additional water surface elevation estimates for 46 lakes in comparison to traditional hypsometric techniques, reduced the number of sub-hydroflattened water surface estimates by 549 or more compared to individually using any of the three digital elevation models assessed, and lays the groundwork for regional and global scale surface water dynamic research without bathymetric survey data

The effects of human-induced watershed changes on streamflows

The aim of the study was to establish the effects of human-induced watershed changes on strearnflows. The research hypothesised that land use change influences base flows. Enjoro river in Kenya was used as the case study. In the 1940s, the watershed was characterised with a sparse population, forestry and large scale conservative agriculture. The river regime was naturally perennial. Between 1960 and 1990 land subdivision, intensive cultivation, urbanisation, and deforestation changed such stable ecosystem Several approaches were used to evaluate the perceived cause-effect relations in the watershed. The time series of the flows, rainfall, and other climatic records were used to infer effects of changed physical characteristics in the watershed. Quantitative evaluation of the changes was accomplished by simple graphs, homogeneity tests, satellite imagery and model simulations of hydrologic variables. Analysis of the data series before and after the presumed changes provided an understanding of the variability masked in the hydrologic system. These comparisons allowed for the determination of the period in which the watershed changes influenced the river regime. The combinede ffect of humana nd natural factors decreasedth e river basef lows. A 30% increase in deforestation, 20% in agriculture and 10.4% in urbanisation was observed- Water availability decreased from a runoff coefficient of 22% in the 1960s, 10% in the 1970s and 8% in the 1980s. This progressive decline in runoff developed into hydrologic drought regime in the 1980s. Normalized difference vegetation index (NDVI) predicted well the flow changes in the watershed. Simulations of rainfall and flow supported the changes observed in the hydrologic variables. The optimised parameters with HYRROM showed 'store' parameters (SS, RDEL, GDEL) to be sensitive to changes in vegetation cover especially during the dry years of 1965,1973 and 1984. The model simulated some parameters in the watershed which could be used to infer changes in strearnflows due changes in land use. It was however, difficult to estimate and to validate long-term model parameters because of limited data and the contrasting geography of the region which induced hydrologic variability. The model did not isolate effects of specific land uses, although it predicted the observed flows. There is evidently, a need for future research on the problem. The investigation demonstrated the difficulty in identifying differences in strearnflows from watersheds undergoing simultaneous physical changes and human interventions. Since a specific effect of a particular land use change could not be isolated independently, continued research on the development of an integrating watershed coefficient is recommended. Remote sensing techniques should be incorporated in the development of integrating watershed coefficients

Proceedings of the 1st WSEAS International Conference on "Environmental and Geological Science and Engineering (EG'08)"

This book contains the proceedings of the 1st WSEAS International Conference on Environmental and Geological Science and Engineering (EG'08) which was held in Malta, September 11-13, 2008. This conference aims to disseminate the latest research and applications in Renewable Energy, Mineral Resources, Natural Hazards and Risks, Environmental Impact Assessment, Urban and Regional Planning Issues, Remote Sensing and GIS, and other relevant topics and applications. The friendliness and openness of the WSEAS conferences, adds to their ability to grow by constantly attracting young researchers. The WSEAS Conferences attract a large number of well-established and leading researchers in various areas of Science and Engineering as you can see from http://www.wseas.org/reports. Your feedback encourages the society to go ahead as you can see in http://www.worldses.org/feedback.htm The contents of this Book are also published in the CD-ROM Proceedings of the Conference. Both will be sent to the WSEAS collaborating indices after the conference: www.worldses.org/indexes In addition, papers of this book are permanently available to all the scientific community via the WSEAS E-Library. Expanded and enhanced versions of papers published in this conference proceedings are also going to be considered for possible publication in one of the WSEAS journals that participate in the major International Scientific Indices (Elsevier, Scopus, EI, ACM, Compendex, INSPEC, CSA .... see: www.worldses.org/indexes) these papers must be of high-quality (break-through work) and a new round of a very strict review will follow. (No additional fee will be required for the publication of the extended version in a journal). WSEAS has also collaboration with several other international publishers and all these excellent papers of this volume could be further improved, could be extended and could be enhanced for possible additional evaluation in one of the editions of these international publishers. Finally, we cordially thank all the people of WSEAS for their efforts to maintain the high scientific level of conferences, proceedings and journals

Effects of Complementary use of Organic and Inorganic fertilizers on the growth and yield of Cucumber (Cucumu sativus. L.) on an ultisol

A field study was conducted in 2008 and 2009 early cropping seasons to assess the response of cucumber (Cucumus sativus L.) to complementary use of organic and inorganic fertilizers in Uyo agro-ecology. The fertilizer treatments were: NPK (15:15:15) at 100 and 200 kgha-1, poultry manure (PM) at 5 and 10 tha-1 , and complementary application of 100 kgha-1 of NPK + 5 tha-1 of PM, 100 kgha-1 of NPK + 10 tha-1 of PM, 200 kgha1 of NPK +5 tha-1 of PM ,200 kgha-1 of NPK +10 tha-1 of PM and control (no fertilizer). Results showed significant differences (P<0.05) in all the growth and yield parameters considered in both cropping seasons. The combined application of 200 kgha-1 of NPK and 10 tha-1 of PM performed better than sole application of either organic or inorganic fertilizer, with fresh fruit yield of 14.63 and 14.92 tha-1 in 2008 and 2009, respectively and exceeded other treatments by 1 -76% and 1-73% in 2009 and 2010, respectively. This indicates strongly the synergistic benefits of using both organic and inorganic fertilizers even at lower rates