Continental-scale high-resolution river geometry and real-time inundation mapping

Flooding is the most threatening natural disaster worldwide considering the fatalities and property damage it causes. Recent flood disasters have raised concerns for accurate and responsive inundation forecast due to the rapid spread and astonishing destructive power of these events. Although recent development in large scale hydrologic simulation has enabled the real-time streamflow simulation operating on millions of river reaches, a framework for converting the forecast discharge into corresponding water surface elevation and inundation maps at a continental-scale is absent to better support local flood response. To accurately map flood inundation extent, a comprehensive description of the geometry of the channel is indispensable. As such, this dissertation presents an innovative approach for estimating river geometry and conducting inundation mapping at a continental-scale with a high spatial resolution. This approach is based on the concept of Height Above Nearest Drainage (HAND). Advanced hydrologic terrain analysis workflows have been designed to derive channel hydraulic properties, stage-discharge rating curves, and inundation extents using HAND. After the mechanism being presented, the implementation of this approach across the contiguous United States has been demonstrated using the 10-meter National Elevation Dataset. The integrity of the outputs has been validated through the comparison with best available references at multiple test sites. Considering the increasingly availability of high-resolution topographic data derived from lidar technology, the dissertation further presents how advanced geomorphic feature extraction tools are integrated into the proposed approach to overcome the challenges associated with the enrichment of terrain details. At last, this dissertation presents how banklines, an essential piece of river geometry characteristic as the boundary differentiates channel zone from floodplain, is detected with enhanced geomorphic feature extraction tools for improving large-scale hydrologic simulation and inundation mapping accuracy.Civil, Architectural, and Environmental Engineerin

Quarterly literature review of the remote sensing of natural resources

The Technology Application Center reviewed abstracted literature sources, and selected document data and data gathering techniques which were performed or obtained remotely from space, aircraft or groundbased stations. All of the documentation was related to remote sensing sensors or the remote sensing of the natural resources. Sensors were primarily those operating within the 10 to the minus 8 power to 1 meter wavelength band. Included are NASA Tech Briefs, ARAC Industrial Applications Reports, U.S. Navy Technical Reports, U.S. Patent reports, and other technical articles and reports

Sediment Dynamics and Channel Connectivity on Hillslopes

The pattern, magnitude, and frequency of hillslope erosion and deposition are spatially varied under the influence of micro-topography and channel geometry. This research investigates the interrelationships between erosion/deposition, micro-topography, and channel connectivity on a hillslope in Loudon, Tennessee using the centimeter (cm) level temporal Digital Elevation Models collected using laser scanning. This research addressed (1) the effect of spatial resolution on the erosion/deposition quantification, and rill delineation; (2) the influences of micro-topographic factors (e.g. slope, roughness, aspect) on erosion and deposition; (3) the relationship between the structural connectivity -- depressions and confluence of rills -- and the sedimentological connectivity. I conducted (1) visual and quantitative assessments for the erosion and deposition, and the revised automated proximity and conformity analysis for the rill network; (2) quantile regression for micro-topographic factors using segmented rill basins; and (3) cross-correlation analysis using erosion and deposition series along the channels.Overall, rills are sedimentologically more dynamic than the interrill areas. A larger grid size reduces the detectable changes in both areal and volumetric quantities, and also decreases the total length and number of rills. The offset between delineated rills and the reference increases with larger grid sizes. A larger rill basin has higher erosion and deposition with the magnitude of erosion greater than deposition. The slope has a positive influence on erosion and a negative one on deposition; roughness has a positive influence on deposition and a negative one on erosion. Areas that are more north-facing experience higher erosion and lower deposition. Rill length explains 46% of the variability for erosion and 24% for deposition. The depressions are associated with higher erosion in the downslope direction. The correlations between the erosion and the confluence are positive; the correlation between the deposition and the sink is positive. Overall, the influence of structural connectivity on the sedimentological connectivity is within 25 cm in both upstream and downstream directions. This research contributes to the understanding in how the sediment movement on hillslopes is governed by topographic variations and channel connectivity, and future work may explore hillslope channels at broader geographical and temporal scales

A structural model for the Java Margin Subduction Zone, Indonesia, from multi-channel and wide-angle seismic data

The plate margin offshore Java and the Lesser Sunda islands are located in the eastern portion of the Sunda plate margin, which starts from Burma in the northwest to the Banda arc in the southeast. Different geological configurations in the Sunda plate margin vary enormously from the west to the east due to the variations in sediment supply and the different nature of the oceanic plates along the convergent plate boundary. The Sunda arc hosts earthquakes spanning from moderate magnitude ones to some of the largest earthquakes on Earth. In order to understand the current tectonic structure, the oceanic crust relief, and the temporal evolution of the large volume accretionary mass of the eastern Java and Lesser Sunda margins, we use MCS streamer data and OBS data collected by BGR and GEOMAR to image the plate interface reflection, the upper plate tectonic structure, and velocity attributes of the convergent plates. In this study, we incorporate an innovative seismic processing approach called the Non-Rigid Matching technique applied to the reflection tomography and the pre-stack depth migration and retrieve the structural image of the forearc wedge and the geometry of the plate interface. The depth migrated seismic sections and the bathymetry reveal different scales and shapes of the oceanic relief. By comparing the observed subducting seamount location with the 1994 tsunami earthquake epicentre, the co-seismic slip model, and the aftershock focal mechanisms, we conclude that the seamount acts as an earthquake barrier in the 1994 rupture's propagation process and is weakly coupled in the inter-seismic period before the co-seismic rupture

Scale dependence of hydrological effects from different climatic conditions on glacierized catchments

The high altitude environments are particularly sensitive to climate change and very rapid and intense effects are affecting the Alpine cryosphere. Knowledge of the hydrological responses of high-altitude watershed is critical to manage water resources, especially in the context of current climate change, resulting in a lower percentage of solid precipitation, temporal redistribution and quantitative variations in precipitation inputs, higher temperatures, and more persistent drought conditions during the summer. Although the remaining glacial masses are still able to secure sufficient water supplies, the rate of reduction of the glaciers, however, is now very rapid. Mountain glaciers have generally experienced worldwide retreat since the second half of XIX Century, and for example in the Alps they lost about two/thirds of the initial area, with area loss rates accelerating since 2003. At this pace, the hydrological buffering effect of the glaciers will run out quickly. Several years in the last decades, which have been particularly warm and dry, have shown that glaciers can compensate scarce rainfall with a significant contribution to the runoff of rather large basins, especially in summer. The aim of this work was to understand how different climatic and glacier cover conditions can modify the hydrological response of glacierized catchments, and to analyze the scale dependency of the hydrological response and the resulting impacts on fresh water availability. The investigations were carried out in the Noce catchment, a 1050 km2 watershed located in the Eastern Italian Alps, and in three sub-catchments of the same basin, with area ranging from 8 to 385 km2 and different percent glacierization. Valuable information on past and current evolution of climate and glaciers exist in this study area. In particular, precious data series of high-altitude meteorological and hydrometric data, reconstructions of glacier fluctuations since the Little Ice Age, and measurements of glacier mass balance were available. Based on this availability, and considering the high uncertainties affecting model studies that use future projections of climate and glaciers, we decided to do a sensitivity analysis based on past observations. This approach has the advantage of analyzing the sensitivity of the glacio-hydrological system of the study area under actually observed climatic and glacier cover conditions, likely reducing the main source of error caused by model approaches based on future projections. Moreover using real observations has the potential of increasing the internal consistency of the glacio-hydrological model employed in this sensitivity analysis, during calibration and validation. A drawback of this method is that it does not take into consideration future change in climate and glacier cover. For this reason, we analyzed also a condition with complete absence of glaciers, and recent ‘extreme’ years, like 2003, that has been frequently referred to as a possible example of future climatic conditions during summer in the Alps. The results of this study confirm previous research that indicate a progressive transition from a glacial to a nival hydrological regime in the analyzed catchments, with a tendency to a strong decrease in runoff after the seasonal snow has melted, in the second half of summer. The runoff peak tends to shift from mid- to early summer. Different glacier cover scenarios (LIA, current and absence of glaciers) have highest impacts in August runoff, during periods of glacier wastage as in the 1940s and in the 2000s, and in the smaller catchments with high percent glacierization. Compared to the absence of glaciers, current glaciers still ensure higher runoff during summer, in all climatic conditions considered. However, this glacier damping effect is largely decreased if compared to the LIA conditions, and this decrease is directly related to catchment area. If smaller and highly glacierized catchment still preserves ~50% of the initial damping effect in August, the larger catchments keep only 25-30% of it. The glacier contribution to late summer runoff decreases obviously from headwater to lower and larger catchments. However, the decreasing rate tends to flatten for catchment area larger than 80 km2, and for the larger analyzed catchment it still reaches 26%. Most importantly, the current glacier contribution to late summer runoff in the larger catchment reaches ~60% in extremely warm and dry summers, like in 2003. However, increased runoff due to glacier wastage in 2003 occurred only in the headwater and most glacierized catchment, whereas using the LIA glacier cover would have ensured increased runoff in all analyzed catchments. This suggests that the expected peak in runoff under warming climate, attributable to glacier melt, has already passed in the study area

MODELING AND MANAGEMENT OF WATER QUANTITY AND QUALITY IN COLD-CLIMATE PRAIRIE WATERSHEDS

Saskatchewan’s surface and ground water sources are vital to life in the province, not only as the supply of safe drinking water for the residents, but also as a key driver of economic activity. The Qu'Appelle and Assiniboine River Basins are among the highly valued water resources in the province as they supply water for more than one-third of the population of Saskatchewan and contain a chain of eight lakes that are major recreational and economically valued resources in the region. The health of several watersheds within these highly valued river basins is being degraded by intensive agricultural and other developmental activities. The decision making processes for sustainable water management in these watersheds is stunted by limited observed field data. As a result, for Saskatchewan watersheds in general, and the Qu’Appelle and Assiniboine River Basins in particular, a better understanding is required of the type, extent and sources of pollutant loadings, and effects of potential alternative management practices may have to mitigate water quality problems. Modeling approaches that have the capacity to analyze the quantity and quality of water resources, identify existing and potential watershed stressors, and the relative importance of best management options are therefore needed. With the intention of helping decision makers in the province, this thesis focuses on developing an eco-hydrological model, which is suitable for Canadian prairie watersheds and capable of simulating the long term effects of management practices. Following a review of several models, the Soil and Water Assessment Tool (SWAT) has been selected for this study. In order achieve the objectives, the SWAT model has been modified to suit site specific characteristics of the Canadian prairies. The first such modification was to incorporate the numerous landscape depressions that vary in storage capacity into SWAT. This was done by representing depression storage heterogeneity using a probability distribution using an algorithm called “Probability Distributed Landscape Depressions (PDLD)”. The modified model, called SWAT-PDLD, was tested over two prairie watersheds: the Assiniboine and Moose Jaw watersheds. An improved simulation for streamflow was achieved for both case study watersheds as compared to the original SWAT lumped storage approach. The other modification to SWAT was the incorporation of seasonally varying soil erodibility due to the cold climate conditions. This was done using a sediment module with a time variant soil erodibility factor that allows the value of soil erodibility to vary between seasons. The modified SWAT-PDLD along with seasonally varying soil erodibility was tested for sediment export simulation for the same two case study watersheds: the Assiniboine and Moose Jaw watersheds. Results show an improved sediment simulation for both case study watersheds when seasonally varying soil erodibility factors are considered as compared to the original SWAT model sediment module, which uses annual values of soil erodibility. The modified model was also used to simulate phosphorous and nitrogen export from the Assiniboine watershed and a satisfactorily model performance was obtained. In addition, the developed model was used to assess the impacts of three different management practices on the export of pollutants for the Assiniboine watershed. The scenarios considered were conservation tillage, a cover crop, and filter strips. Model results show that both the filter strips and cover crops decreased sediment, phosphorous, and nitrogen export, while conservation tillage increased phosphorous export in the study watershed. Finally, the study investigated the different sources of modeling uncertainty for the developed model. Parameter as well as precipitation, observed discharge, and model structure uncertainty of the SWAT-PDLD model was evaluated. Parameter uncertainty was quantified using three different techniques that include GLUE, ParaSol, and SUFI-2. Model structure uncertainty was assessed using a framework that combines the Bayesian Model Averaging (BMA) and Shuffled Complex Evolution (SCE). Results suggest that ignoring either input error or model structure uncertainty will lead to unrealistic model simulations and incorrect uncertainty bounds. The study also shows that prediction uncertainty bounds, posterior parameter distribution, and final parameter values vary between methods

A propensity index for surface runoff on a karst plateau

Karst aquifers are an important water resource, but are particularly vulnerable to pollution due to the typically short residence times. As the rainwater runs off on the surface it may collect contamination from faeces and other sources, before infiltrating the surface. It is therefore important to understand the spatial distribution of the frequency of surface runoff in karst areas. This paper proposes a new field-mapping method for the ability of the landscape to produce and convey surface runoff. The mapping method is based on (i) prior spatial information (e.g. geological map, terrain model), (ii) a visual assessment from a distance at the landscape scale (e.g. traces of surface runoff) and (iii) local data collection in the field (e.g. soil moisture, grain size distribution). The focus on variables that can be assessed from a distance in the landscape makes the method suitable for mapping larger areas than traditional field mapping. The mapping method is developed and tested for the 60&thinsp;km2 Hochschwab area in Austria. The field mapping is used to specify a surface runoff propensity index which is tested against the spatial distribution of observed sink holes in the area. The mapping indicates that, in the study region, runoff occurs much more frequently in the poorly karstified dolomitic areas than in the limestone areas that are highly karstified. On dolomites, low permeable soils or debris prevail, often resulting in a permanent surface drainage network. On karstified limestone, sometimes overlaid by debris, surface runoff only occurs through infiltration excess at high rainfall intensities. Overall the analyses suggest that the mapping method is suitable for efficiently and reliably identifying spatial patterns of the ability of the landscape to produce and convey surface runoff in karst areas.</p