Hierarchical object-based mapping of riverscape units and in-stream mesohabitats using LiDAR and VHR imagery

In this paper, we present a new, semi-automated methodology for mapping hydromorphological indicators of rivers at a regional scale using multisource remote sensing (RS) data. This novel approach is based on the integration of spectral and topographic information within a multilevel, geographic, object-based image analysis (GEOBIA). Different segmentation levels were generated based on the two sources of RS data, namely very-high spatial resolution, near-infrared imagery (VHR) and high-resolution LiDAR topography. At each level, different input object features were tested with Machine Learning classifiers for mapping riverscape units and in-stream mesohabitats. The GEOBIA approach proved to be a powerful tool for analyzing the river system at different levels of detail and for coupling spectral and topographic datasets, allowing for the delineation of the natural fluvial corridor with its primary riverscape units (e.g., water channel, unvegetated sediment bars, riparian densely-vegetated units, etc..) and in-stream mesohabitats with a high level of accuracy, respectively of K=0.91 and K=0.83. This method is flexible and can be adapted to different sources of data, with the potential to be implemented at regional scales in the future. The analyzed dataset, composed of VHR imagery and LiDAR data, is nowadays increasingly available at larger scales, notably through European Member States. At the same time, this methodology provides a tool for monitoring and characterizing the hydromorphological status of river systems continuously along the entire channel network and coherently through time, opening novel and significant perspectives to the river science and management, notably for planning and targeting actions.JRC.H.1-Water Resource

Controls on Sediment Connectivity in Fluvial Networks Impacted by Wildfire Across Utah

Flooding and sedimentation caused by wildfire are among the greatest threats to watersheds, fish populations and reservoirs in the western US. Burned landscapes are at risk for increased runoff and erosion and have the potential to transport sediment that may put downstream resources at risk. The ability of the channel to transport sediment downstream, known as the connectivity, is important for determining where impacts may occur. Sediment bottlenecks are locations within the watershed where local conditions produce a persistent decrease in downstream connectivity of sediment, resulting in increased sediment deposition and potentially a substantial modification of the local channel and floodplain. The primary objective of this research is to evaluate the volume, location, and amount of sediment bottlenecks in watersheds after wildfire. We identified and surveyed 86 sediment bottlenecks associated with 15 wildfires throughout Utah. The mechanisms responsible for these sediment bottlenecks were attributed to either the geometry of the channel and floodplain or physical obstructions, including large in-stream wood, beaver dams, debris flow deposits, and human infrastructure. We measured channel/floodplain geometry and land cover characteristics using GIS, which we then compared to the volume and location of these sediment bottlenecks. Additionally, we drew large wood and debris flow deposits in GIS at each site from aerial imagery, as both often increase considerably after wildfire and can significantly influence the amount of sediment bottlenecks. Our results indicate that the geometry of the channel and floodplain influences sediment bottlenecks in burned watersheds, directly causing sediment deposition in some locations and influencing occurrence of other physical obstructions on sediment deposition in other locations. Beyond local controls, several watershed attributes exert a significant influence on the recruitment and transport of sediment and wood. These findings will help refine sediment routing models, assist in identifying the magnitude and location of potential sedimentation risks, and better inform the management of infrastructure and aquatic habitat after wildfire

Assessing and managing urban riverscapes: integrating physical processes and social-ecological values

2022 Summer.Includes bibliographical references.In the age of the Anthropocene, human influence has spread far and wide across our planet affecting the physical, chemical, and biological condition of the rivers, streams, and floodplains in the urban environment, our "urban riverscapes." The human connection to urban riverscapes includes both the built environment created and accessed by people and the intangible community values that humans place upon flowing water. The value of these benefits encourages stewardship of our waterways by integrating experiential, aesthetic, and cultural attributes that foster appreciation for streams as natural systems in the built environment. However, when poorly managed, human activities adversely impact our natural ecosystems, resulting in less resilient stream systems, poor aesthetics, and unsafe conditions. The research presented in this dissertation asks the following overarching research question: How can managers and practitioners apply multi-scale social-ecological, hydrologic, geomorphologic, and riparian ecological remote sensing and field data to advance urban riverscape management? Four chapters follow from this hypothesis: urban riverscape problems lie on a spectrum of complexity where solutions are often conceivable but difficult to implement. Integrating diverse perspectives and knowledge extends the scope of stakeholder perspectives so that social-ecological context is considered alongside the physical processes that typically characterize riverscapes. This approach entails leveraging existing and new methods to create frameworks that integrate the multi-scale assessment of physical conditions and social-ecological qualities underlying applied riverscape management. I explore the integration of diverse knowledge to enhance management outcomes through the concept of "wicked problems." I analyze the connections between diverse types of knowledge and practices through numerous case studies. My analysis shows how systematically characterizing project attributes, such as the prominence of local government and technical knowledge or the weakness of academia and indigenous knowledge, requires an approach that builds capacity and collaboration within transdisciplinary stakeholder groups. I find that the importance of integrating communities, including under-represented knowledge bases, into urban riverscape management can generate equitable and incremental solutions. To evaluate connections between social values, ecological conditions, and hydrogeomorphic processes, I outline a framework for urban riverscape assessment that advances the practice of managing urban riverscapes facing complex problems. The framework is based upon evaluation across four foundational categories, or facets, critical to the management of urban riverscapes: (1) human connections and values, (2) hydrologic processes and hydraulic characteristics, (3) geomorphic forms and processes, and (4) ecological structure and processes. I structure the framework around three tiers of actionable steps, which tackle the questions: Why are we assessing this riverscape (Tier 1)? What do we need to understand in and along this riverscape (Tier 2)? How will we assess the riverscape to develop that understanding (Tier 3)? I find that the answer to the first question is context-based and dependent upon integrating diverse types of knowledge, while the response to the second question involves examining the functions and values of urban riverscapes through the lens of the four facets and their inter-related processes. Answering the third question requires developing and testing a novel assessment method – the "Urban Riverscape conditions-Based Assessment for management Needs" (URBAN). I base URBAN on riverscape context and on integrating the assessment of facets at multiple scales. I apply the method to a test data set of publicly available and site-specific data across a study area in the Denver metropolitan region to illustrate its overall performance, including its ability to evaluate specific riverscape physical conditions and social-ecological qualities. I find reach typologies combined with urban riverscape characteristics provide tangible management strategies that managers can use to inform planning and decision making. The overarching conclusion of this dissertation is that managing urban riverscapes requires assessment methods that consider scale (spatial, temporal, and topical) and context (both physical and social characteristics), and the use of indicators and metrics that directly support decision-making among interdisciplinary stakeholders. It is possible to move toward this vision by using remote-sensed and field data that provides both social and physical information, to assess the relationship between physical condition and social-ecological values, and to use that information to determine where and how to prioritize management strategies for urban riverscapes

Basin-wide hydromorphological analysis of ephemeral streams using machine learning algorithms‡

Sustainable river management now encompasses a much wider concept that includes hydromorphological and fluvial habitat studies. In ephemeral streams, the geomorphological characterization of channels is complex due to episodic flows and riparian vegetation dynamics. Stream channel survey and classification at the watershed scale provide the basis for geomorphological conservation, process interpretation, assessing sensitivity to disturbance, and identifying reaches that supply and store sediment. Here, we present a stream classification based on a two-step approach: (1) automatic river segmentation based on spatial variability in channel/valley morphology from topographic measurements (LiDAR, light, detection and ranging), and (2) fluvial landform and vegetation density mapping derived from multispectral open-source satellite images (Sentinel-2) using support vector machine (SVM) and Random Forest (RF) algorithms. These analyses provide continuous, quantitative spatial values of geometric (channel/valley width, slope gradient, and route distance), landform (active channel and gravel bars with five densities of vegetation cover), and hydraulic (specific stream power) variables. Four stream types were identified in the Rambla de la Viuda catchment (~1500 km2), an ephemeral gravel-bed river in eastern Spain. The spatial distribution of channel types is explained by differences in geometry (active channel width, valley width, and slope gradient) and a hydraulic parameter (specific stream power). The landforms/vegetation patterns provided insight on causal relationships between erosion and deposition processes during high flow periods and the time since the most recent large disruptive flood event. Channel type distribution provided first-order predictions about the location of reaches that supply and store sediment and thus information on sediment continuity along the river. Dam effects on downstream reaches resulted in geomorphological disequilibrium, producing narrowing of the active channel, slope reduction, and a decrease of gravel bar areal extension. The proposed catchment scale analysis provides a comprehensive and replicable methodology for environmental planning in Mediterranean ephemeral streams to guide further hydromorphological surveys at the reach scale.</p

GIS Data and Geoprocess Modeling for Hydrologic Network Conservation Analysis in a Green Infrastructure Plan

As urban sprawl swallows the areas around cities, planners are looking for alternative methods of development that help to protect and preserve the environment, enhance the lives of residents, and help reduce the skyrocketing costs of maintaining sprawling infrastructure. Green Infrastructure (GI) planning principles have gained in popularity due to their holistic nature and ability to balance preservation and development. A GI plan seeks to identify the critical “green” infrastructure in an area (the environmental resources that we rely on for clean air and water) and proposes complementary development strategies. One plan component of particular interest is the analysis of the hydrologic network, since it is water quality that drives many ecological and environmental planning issues. Over the last 30 years, riparian buffering has emerged as an accepted best practice for the protection and restoration of sensitive hydrologic features. When creating a GI plan, the power of geographic information systems (GIS) is leveraged to help organize, analyze, and display the large datasets needed to synthesize the plan components. The plan components can be quite complex, and the need for solid, well-defined methodologies is great. In response, this thesis proposes a data model that defines the database structure and attributes needed for hydrologic network conservation analysis, based on research conducted during the creation of the Beaver Creek Watershed Green Infrastructure Plan in Knox County, Tennessee. The analysis methodology and some common hydrologic feature buffer practices are described. The specific methods chosen for this project are detailed and a geoprocessing model that generates the datasets necessary to visualize the hydrologic network buffers is presented

Proceedings of 2006 Kentucky Water Resources Annual Symposium

This symposium was funded in part by the U.S. Environmental Protection Agency, with Clean Water Act, Section 319(h) grant money through the Kentucky Division of Water and the Kentucky Waterways Alliance, #C9994861-00. Planning for this conference was conducted as part of the state water resources research annual program with the support and collaboration of the Department of Interior, U.S. Geological Survey and the University of Kentucky Research Foundation, under Grant Agreement No. 01HQGR0133. The views and conclusions contained in this document are those of the abstract authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government or other symposium organizers and sponsors

Geomorphic analysis of river character and behaviour in three semi-arid, mountainous catchments in the Eastern Cape, South Africa

>Magister Scientiae - MScThe analysis of what controls why rivers are the way they are, and how and why they change is crucial in predicting river dynamics and deriving classification systems that can assist management. A variety of factors control the pattern of fluvial styles in a river system across spatial scales. The geomorphic response of a river to an individual control, such as stream power for example, will vary due to a combination of other contributing factors such as geology and climate

Proceedings of 2018 Kentucky Water Resources Annual Symposium

This symposium was planned and conducted as a part of the state water resources research institute annual program that is supported by Grant/Cooperative Agreement Number G16AP00055 from the United States Geological Survey. The contents of this proceedings document and the views and conclusions presented at the symposium are solely the responsibility of the individual authors and presenters and do not necessarily represent the official views of the USGS or of the symposium organizers and sponsors. This publication is produced with the understanding that the United States Government is authorized to reproduce and distribute reprints for government purposes. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey