Modeling and classifying variable width riparian zones utilizing digital elevation models, flood height data, digital soil data and national wetlands inventory : a new approach for riparian zone delineation

Riparian zones are dynamic, transitional ecosystems between aquatic and terrestrial ecosystems with well defined vegetation and soil characteristics. Development of an all-encompassing definition for riparian ecotones, because of their high variability, is challenging. However, there are two primary factors that all riparian ecotones are dependent on: the watercourse and its associated floodplain. Previous approaches to riparian boundary delineation have utilized fixed width buffers, but this methodology has proven to be inadequate as it only takes the watercourse into consideration and ignores critical geomorphology, associated vegetation and soil characteristics. Our approach offers advantages over other previously used methods by utilizing: the geospatial modeling capabilities of ArcMap GIS; a better sampling technique along the water course that can distinguish the 50-year flood plain, which is the optimal hydrologic descriptor of riparian ecotones; the Soil Survey Database (SSURGO) and National Wetland Inventory (NWI) databases to distinguish contiguous areas beyond the 50-year plain; and land use/cover characteristics associated with the delineated riparian zones. The model utilizes spatial data readily available from Federal and State agencies and geospatial clearinghouses. An accuracy assessment was performed to assess the impact of varying the 50-year flood height, changing the DEM spatial resolution (1, 3, 5 and 10m), and positional inaccuracies with the National Hydrography Dataset (NHD) streams layer on the boundary placement of the delineated variable width riparian ecotones area. The result of this study is a robust and automated GIS based model attached to ESRI ArcMap software to delineate and classify variable-width riparian ecotones

Downstream trends of alluvial sediment composition and channel adjustment in the Llano River watershed, Central Texas, USA : the roles of a highly variable flow regime and a complex lithology

textThis study investigates the downstream controls of alluvial sediment composition and river channel adjustment in the Llano River watershed, Central Texas, USA. The Llano River watershed is characterized by a highly variable, flood-prone flow regime and a complex lithology of Cretaceous carbonate rock, Paleozoic sedimentary rock, and Precambrian igneous and metamorphic rock. Sedimentary variables for this study include particle size, sorting, carbonate content, and magnetic susceptibility. Channel adjustment includes the planform dimension and cross-sectional dimensions of bankfull- and macro-channels. Nineteen sites along the Llano River and selected tributaries were visited to measure cross-sectional channel geometry and sample bed, bank, and overbank sediment. Laboratory analyses of sediment and hydraulic analyses of cross sections were accompanied by analyses of partial-duration flood frequency, flow resistance, hydrography, digital elevation models, and statistical correlation. Findings include: (1) channel-bed material reduces in size with downstream distance, despite increasing valley confinement and bedrock exposure; (2) the downstream decrease in particle size is more evident for channel-bar deposits than for low-flow-channel (thalweg) deposits; (3) an abrupt gravel-to-sand transition occurs about 20 kilometers downstream of the Paleozoic-Precambrian contact; (4) an abrupt coarse- to fine-gravel transition occurs between 75 and 90 kilometers downstream the North Llano and South Llano Rivers; (5) channel-bank material increases downstream, contrasting with decreases in bed material; (6) carbonate content and magnetic susceptibility of alluvial sediment are inversely related, with carbonate content peaking near Junction; (7) four general categories to classify reaches of the North Llano, South Llano, and Llano Rivers are based on hydrology, planform morphology, lithology, and valley confinement; (8) mean depth increasingly compensates for bankfull discharge in a downstream direction; (9) mean depth compensates more than width for macrochannels; and (10) the return periods for bankfull and macro-channels are about 1 to 2 years and greater than 10 years, respectively. The results of this study will contribute to fluvial geomorphic theory of downstream trends in sediment composition and channel adjustment; as well as inform applied efforts related to aquatic biology, flood hazards, infrastructure design, and riparian and water-resource management in the region.Geography and the Environmen

Flood hazard hydrology: interdisciplinary geospatial preparedness and policy

Thesis (Ph.D.) University of Alaska Fairbanks, 2017Floods rank as the deadliest and most frequently occurring natural hazard worldwide, and in 2013 floods in the United States ranked second only to wind storms in accounting for loss of life and damage to property. While flood disasters remain difficult to accurately predict, more precise forecasts and better understanding of the frequency, magnitude and timing of floods can help reduce the loss of life and costs associated with the impact of flood events. There is a common perception that 1) local-to-national-level decision makers do not have accurate, reliable and actionable data and knowledge they need in order to make informed flood-related decisions, and 2) because of science--policy disconnects, critical flood and scientific analyses and insights are failing to influence policymakers in national water resource and flood-related decisions that have significant local impact. This dissertation explores these perceived information gaps and disconnects, and seeks to answer the question of whether flood data can be accurately generated, transformed into useful actionable knowledge for local flood event decision makers, and then effectively communicated to influence policy. Utilizing an interdisciplinary mixed-methods research design approach, this thesis develops a methodological framework and interpretative lens for each of three distinct stages of flood-related information interaction: 1) data generation—using machine learning to estimate streamflow flood data for forecasting and response; 2) knowledge development and sharing—creating a geoanalytic visualization decision support system for flood events; and 3) knowledge actualization—using heuristic toolsets for translating scientific knowledge into policy action. Each stage is elaborated on in three distinct research papers, incorporated as chapters in this dissertation, that focus on developing practical data and methodologies that are useful to scientists, local flood event decision makers, and policymakers. Data and analytical results of this research indicate that, if certain conditions are met, it is possible to provide local decision makers and policy makers with the useful actionable knowledge they need to make timely and informed decisions

Development and Application of Hydraulic and Hydrogeologic Models to Better Inform Management Decisions

Water is one of the most important and limited resources in regions with little rainfall. As populations continue to grow, so does the need for water. Individuals in water management positions need to be well informed in order to avoid potential negative effects concerning the overall quality and amount of water available for both people and the environment. In order to provide better information for these individuals, computer models and mathematical relationships are commonly developed to estimate the outcome of different situations regarding surface water and groundwater. Along these lines, this study focused on two modeling studies that provide information to managers regarding either stream restoration techniques or the amount of groundwater available. The first study investigated the effects that beaver dams have on streams. In order to do this, a computer model was developed to represent a section of stream with beaver dams and a section without. The model provided information regarding changes in the average depth, width, and velocity of the stream as a result of having beaver dams. We also measured changes in sediment size distributions between the two stream sections to confirm that beaver dams additionally impact sediment movement and channel shape. Results indicated that only a few dams are actually needed to achieve many of the desired changes in stream restoration. The second study involved testing an equation that was used to predict how much precipitation would become groundwater in a Midwestern watershed. Variables in the equation included measurements of natural or developed land, movement of water through soil, the depth of the water table, and hillslope steepness. We tested the equation in two western watersheds to determine if variables used in the earlier study remain relevant when applied under different conditions. The independent application of the method to each western watershed stressed the importance of meeting simplifying assumptions and developing more complete datasets. We also found that the application of existing simplified empirical relationships may not be suitable in estimating groundwater recharge in mountain watersheds

Atlas of Hydrologic Characteristics of the Wolf River Basin

An atlas of the hydrologic characteristics of the WolfRiver basin in West Tennessee is derived by using a Geographic Information System (GIS) to simulate the watershed\u27s hydrologic response. A 30-meter digital elevation model (DEM), extracted from the National Elevation Dataset (NED) and managed by United States Geologic Survey (USGS), is used to develop the database of watershed characteristics. Arc Hydro, created by Environmental Systems Research Institute (ESRI), and the Geospatial Hydrologic Modeling System (HEC-GeoHMS) program, created by the United States Army Corps of Engineers’ Hydrologic Engineering Center (USACE-HEC), are used to delineate the watershed of the Wolf River basin and develop the hydrologic characteristics (physical parameters) of the main streams (creeks), such as length, slope, subbasin area, longest flow path, basin slope, centroid elevation, and centroidal flow path. These topographic characteristics were needed to analyze and evaluate every subbasin of the WolfRiver floodplain from its outlet to its headwaters. The development of an atlas that contains such information would be an invaluable source of information to municipalities and consultants in the design of storm water networks, the design of box culverts, the design of sanitary sewer systems and interceptors, the complete analysis of flood plains, and the development of a flood hydrograph for each subdivision

Stream Dynamics in the Headwaters of Post-Glacial Watershed Systems

This dissertation summarizes research examining watershed processes across Northern New England, with an emphasis on the Central and Coastal regions of Maine. The research presented here focuses on the linkages between watershed geomorphic conditions, climate, and surface flow regimes driving stream channel hydraulic conditions and bed dynamics governing channel geometry. The geologic and human history of the landscape provides the context in which earth surface processes are examined within the dominant physiographic settings in Maine to describe vulnerabilities to climate change. Results are summarized to support the development of sustainability solutions for forecasted watershed management problems by natural resource management agencies and communities. The research components of this dissertation were developed through stakeholder engagement to identify regional water resource sustainability problems. Physical watershed processes affecting stream flow and sediment transport conditions are fundamental to stakeholder concerns. This research examines the influence from human activities, climate, and earth surface processes associated with erosion from ice and water flows on modern surface hydrology and fluvial geomorphology in the region. Research targets are organized relative to scientific principles and contemporary watershed management approaches relevant to stakeholder interests related to water quality, aquatic habitat, recreation, and coastal fisheries. This research is framed by geo-spatial analyses organized to examine Northern New England landscape conditions linked to patterns of surface water flow. The approach uses dominant geologic, soil, topographic, and land cover conditions as independent variables, providing a tool for scaling observations in reference watersheds and evaluating the transferability of information guiding selection of watershed management practices across the region. River discharge measurement data within representative assemblages are analyzed to evaluate the implications of varied landscape conditions to surface water flow regimes. Stream channel hydraulic geometry is quantified to relate surface flows, stream channel conditions, and the history of glaciation and human activities affecting watershed processes. Flow regime responses to forecasted climate change in varied landscape settings are estimated using numerical watershed hydrologic simulations. Modeling results suggest that changes to annual snow pack conditions will have the most substantial influence on surface flows. Base, mid-range, and peak flows have varied responses governed by surface water storage, snow pack dynamics, and rainfall patterns. The impact of the predicted surface flow changes on stream channel sedimentary environments are quantified by coupling simulated flow time series with a sediment transport model. Results indicate that changes to sediment dynamics affecting stream hydraulics and channel stability may result from forecasted climate changes in the region. Research objectives and outcomes are framed to support the development of sustainability solutions to watershed management challenges related to public safety, water quality, and aquatic habitat conservation. The process of designing the project approach with input from stakeholders and evaluating outcomes from quantitative analyses improves understanding of how multiple factors governing earth surface processes operating over varied time scales combine to create varied hydrologic and geomorphic responses to watershed land use and climate changes in the Northern New England region. The prediction of measurable alterations to streams in evaluated settings provide rationale for development of watershed management strategies in response to future land use and climate changes. Varied vulnerabilities to changes suggest that customized management approaches will be necessary as some stream systems will be more responsive than others. The development of an approach for parsing the landscape into Geomorphic Response Units (GRUs) demonstrated by this research provides a basis for designing a statewide approach for implementing strategies for watershed management that considers varied vulnerabilities to land use and climate changes in the region. This work provides tools for the stakeholder community to evaluate the applicability of management techniques across the region and knowledge of water resource vulnerabilities as they relate to landscape conditions and climate

Workshop on computer applications in water management: proceedings of the 1995 workshop

Compiled and edited by L. Ahuja, J. Leppert, K. Rojas, E. Seely.Also published as: Great Plains Agricultural Council publication, no. 154.Includes bibliographical references.Presented at the Workshop on computer applications in water management: proceedings of the 1995 workshop held on May 23-25, 1995 at Colorado State University in Fort Collins, Colorado