Assessment of check dams’ role in flood hazard mapping in a semi-arid environment

This study aimed to examine flood hazard zoning and assess the role of check dams as effective hydraulic structures in reducing flood hazards. To this end, factors associated with topographic, hydrologic and human characteristics were used to develop indices for flood mapping and assessment. These indices and their components were weighed for flood hazard zoning using two methods: (i) a multi-criterion decision-making model in fuzzy logic and (ii) entropy weight. After preparing the flood hazard map by using the above indices and methods, the characteristics of the change‐point were used to assess the role of the check dams in reducing flood risk. The method was used in the Ilanlu catchment, located in the northwest of Hamadan province, Iran, where it is prone to frequent flood events. The results showed that the area of ‘very low’, ‘low’ and ‘moderate’ flood hazard zones increased from about 2.2% to 7.3%, 8.6% to 19.6% and 22.7% to 31.2% after the construction of check dams, respectively. Moreover, the area of ‘high’ and ‘very high’ flood hazard zones decreased from 39.8% to 29.6%, and 26.7% to 12.2%, respectively

Evaluating river cross section geometry for a hydraulic river routing model : Guadalupe and San Antonio river basins

textA new methodology is presented to construct reliable river channel cross section approximations. These approximations are based on the idea of downstream hydraulic geometry as well as supported by the information collected by the USGS streamflow measurement stations across the study area. A hydraulic river routing model (SPRNT) is run with the newly constructed cross section approximations. Initial conditions for the simulation are estimated based on the steady state solution for the model. Boundary conditions or lateral inflows for the river network are estimated based on the outputs of a Land Surface model: Noah, which provides surface and sub-surface runoff for every catchment area in the San Antonio and Guadalupe river basins. Simulations are compared with observed measurements from the USGS stations.Civil, Architectural, and Environmental Engineerin

Morphologic characterization of urban watersheds and its use in quantifying hydrologic response

2009 Summer.Covers not scanned.Includes bibliographical references.Print version deaccessioned 2022.Current methods for hydrologic characterization of urban watersheds and analysis of the impacts of urbanization are primarily based on the description of imperviousness and how changes in this characteristic affect storage, infiltration, and runoff generation. The morphology of urban watersheds and the effects of urbanization on the structure of the drainage system have been much less studied. The overarching objectives of this study are to develop methodologies to characterize the morphology of urban drainage systems including the hillslopes, streets, pipes, and channels and to use this characterization to model the hydrologic response of the watershed. These objectives are accomplished through: (a) an exploration of potential applications of morphologic theories in the characterization of urban watersheds and the impacts of urbanization; (b) the development and testing of a methodology to generate urban terrains (i.e. a raster representation of the topography) in which the effects of conduits typically observed in urban areas are represented; and (c) the development and testing of a new rainfall-runoff model called the U-McIUH (Urban Morpho-climatic Instantaneous Unit Hydrograph). The model is based on the morpho-climatic instantaneous unit hydrograph theory, in which the hydrologic response is identified from the spatial structure of the watershed and the properties of the storm event. The morphologic approach adopted reveals significant impacts of urbanization on the internal structure of natural watersheds at a wide range of scales. This finding is relevant when building stormwater models intended to simulate and compare the pre- and post-development catchment response. The morphologic impacts should be incorporated into stormwater models through the redefinition of model parameters that characterize both the channelized and unchannelized portions of the catchment when the urbanized scenario is simulated. This research also shows the importance of incorporating artificial conduits into urban terrain for hydrologic modeling. A new method to incorporate the artificial conduits into the DEM based on the real elevation of these conduits proved to be superior to other previously available methods because it better represents the flow directions and flow paths. Finally, the new rainfall-runoff model developed in this study fills an existing gap in the field of distributed stormwater modeling. It provides a more thorough treatment of the flows in minor conduits and unchannelized portions of the watershed, which enhances the simulations of runoff accumulation that are traditionally used in conceptual models. The model is parsimonious and uses a simplification of kinematic wave routing that considers the dependence of the unit hydrograph on rainfall intensity and the effect of upstream contribution on the travel times without explicitly solving the flow equation at each cell for each time step. This simplification reduces the complexity of the model computations while still producing reasonable model performance

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

Response of river channel morphology to urbanization: the case of Highland Creek, Toronto, Ontario, 1954-2005

Current studies of urban channel form attempt to understand channel response to major changes in prevailing controlling conditions, mainly discharge. But very few studies actually track channel adjustment over the course of urbanization, ignoring the complexity of channel adjustment to other factors such as large floods and/or engineering. Seldom have these changes been analyzed in terms of expected adjustment from regime theory and the actual processes o f adjustment. Highland Creek in Toronto, Ontario has undergone a rapid transformation from mainly rural to almost completely urban land-use (85% of the drainage area) from 1954 to 2005. It has had a pronounced hydrological response with peak flows reaching up to nine times the pre-urban maximum. Channel form was measured from a series of 5 sets of air photos (1954, 1965, 1978, 2002, and 2005) encompassing the entire development period. The results of this analysis in general indicate that the Creek has become wider and sinuosity has decreased, but variability exists temporally and spatially. Comparison with predicted channel widths using regime theory shows that much of the channel length has ‘under-adjusted’ compared to expectations. It is apparent that this resulted from extensive channel engineering, preventing channel adjustment

A reach, catchment and multiple catchment scale assessment of the patterns and controls of historic upland river planform adjustments

The supply, transfer and deposition of sediment from channel headwaters to lowland valleys and lakes, along the upland sediment cascade, is a fundamental process in upland catchment geomorphology. The continuity of the sediment cascade coupled with local geomorphic controls can be partly understood by quantifying river planform adjustments both in space and over time. However, few studies have adopted rigorous quantitative assessments of sediment continuity and planform adjustment beyond the reach scale over historical time periods or considered key controls governing the stability of upland river channels (e.g. climate, anthropogenic activity). This research presents an assessment of the patterns and geomorphic variables of upland river planform adjustment and stability over the past 150 years. A nested sampling strategy is adopted exploring sediment continuity and planform adjustment at the reach, catchment and multiple catchment (regional) scales in the Lake District upland region, north-west England. In total, 270 rivers and streams (total length: 597 km) were studied across 17 catchments in the upland region (total area: 1250 km2) for six dates from 1860s – 2010. Reach scale investigations focused on exploring the impact of the extreme Storm Desmond (December 2015) flood event on St John’s Beck in the Bassenthwaite catchment. A total of 29,832 stable and adjusting reaches were mapped in the Lake District upland region. Over the full period of analysis (1860s – 2010), 21 % (128 km) of rivers and streams studied were classified as adjusting. Regionally, the highest percentage of river and stream lengths mapped as adjusting between 1860s – 2010 were observed in the Ennerdale (37 %), Wasdale (32 %) and Calder (29 %) catchments (Western Lake District). These catchments showed persistent adjustment and active zones of sedimentation in high order channels over the last 150 years. This is attributed to a high supply of sediment to the fluvial system, greater accommodation space for lateral planform adjustment, and 57 % of the river and stream lengths were anthropogenically modified via reinforced banks and flood embankments restricting planform adjustment. At the reach scale, the influence of a low frequency, high magnitude flood event (Storm Desmond) on river planform adjustment was quantified. However, with increasing spatial and temporal scale the correlation between high magnitude flood events and planform adjustments are harder to define. Anthropogenic activity (e.g. channel engineering, or mining) had a significant influence on river planform adjustment and stability at the reach scale. Regional patterns of geology and the legacy of glacial processes help condition sediment supply, channel slope, and valley bottom width (confinement) thereby setting the general environmental template in which channels adjust in the Lake District. Valley bottom width was found to be an important variable determining the accommodation space for lateral planform adjustment and sedimentation. Planform adjustments occurred in reaches with a mean valley bottom width of 120 ± 190 m. This research has demonstrated the importance of considering planform stability in a sediment continuity framework across all scales of the stream and river network. The methodology developed provides a quantitative assessment of planform adjustment patterns and geomorphic controls, which aids understanding of historic river behaviour and provides context for current and future river management and restoration strategies

The SLIM (Social learning for the integrated management and sustainable use of water at catchment scale) Final Report

Background: SLIM stands for 'Socuak Learning for the Integrated Management and Sustainable Use of Water at Catchment Scale'. It is a multi-country research project funded by the European Commission (DG RESEARCH - 5th Framework Programme for research and technological development, 1998-2002). Its main theme is the investigation of the socio-economic aspects of the sustainable use of water. Within this theme, its main focus of interest lies in understanding the application of social learning as a conceptual framework, an operational principle, a policy instrument and a process of systemic change

MK3: On optimizing the management of cascades or systems of reservoirs at catchment level

This project is about scaling up to the catchment level the results obtained from optimizing the management of individual reservoirs. As such, it draws on results from MKs 1 and 2. It seeks to understand at the catchment scale the cumulative upstream and downstream consequences of management decisions taken for multiple reservoirs. It includes the study of land degradation and reservoir siltation processes

TWINLATIN: Twinning European and Latin-American river basins for research enabling sustainable water resources management. Combined Report D3.1 Hydrological modelling report and D3.2 Evaluation report

Water use has almost tripled over the past 50 years and in some regions the water demand already exceeds supply (Vorosmarty et al., 2000). The world is facing a “global water crisis”; in many countries, current levels of water use are unsustainable, with systems vulnerable to collapse from even small changes in water availability. The need for a scientifically-based assessment of the potential impacts on water resources of future changes, as a basis for society to adapt to such changes, is strong for most parts of the world. Although the focus of such assessments has tended to be climate change, socio-economic changes can have as significant an impact on water availability across the four main use sectors i.e. domestic, agricultural, industrial (including energy) and environmental. Withdrawal and consumption of water is expected to continue to grow substantially over the next 20-50 years (Cosgrove & Rijsberman, 2002), and consequent changes in availability may drastically affect society and economies. One of the most needed improvements in Latin American river basin management is a higher level of detail in hydrological modelling and erosion risk assessment, as a basis for identification and analysis of mitigation actions, as well as for analysis of global change scenarios. Flow measurements are too costly to be realised at more than a few locations, which means that modelled data are required for the rest of the basin. Hence, TWINLATIN Work Package 3 “Hydrological modelling and extremes” was formulated to provide methods and tools to be used by other WPs, in particular WP6 on “Pollution pressure and impact analysis” and WP8 on “Change effects and vulnerability assessment”. With an emphasis on high and low flows and their impacts, WP3 was originally called “Hydrological modelling, flooding, erosion, water scarcity and water abstraction”. However, at the TWINLATIN kick-off meeting it was agreed that some of these issues resided more appropriately in WP6 and WP8, and so WP3 was renamed to focus on hydrological modelling and hydrological extremes. The specific objectives of WP3 as set out in the Description of Work are