<p>Topography is one of the primary drivers of
physical processes in the rivers and floodplains. Advances in remote-sensing
and survey techniques have provided high-resolution representation of the
floodplains but information regarding the 3D representation of river channels
(commonly known as river bathymetry) is sparsely available. Field surveys along
an entire river network in a watershed remains infeasible and algorithms for
estimating simple but effective characterization of river channel geometry are
hindered by an incomplete understanding of the role of river bathymetry in
surface and subsurface processes. </p>
<p> The
first objective of this dissertation develops an automated framework – System
for Producing RIver Network Geometry (SPRING) for improving the geospatial
descriptors of a river network. The tool takes as input the DEM and erroneous
river centerline to produce spatially consistent river centerlines, banks, and
an improved representation of river channel geometry. SPRING can process entire
river networks and is not limited single reach applications. The proposed
framework is flexible in terms of data requirements, resolution of output
datasets and user preferences. It has a user-friendly graphic user interface
(GUI) and is appropriate for large-scale applications since it requires minimal
user input.</p>
<p> A
better understanding of the role of bathymetric characteristics in surface-subsurface hydrology and hydrodynamics can
facilitate an efficient incorporation of river bathymetry in large river
networks. The second objective explores the level of bathymetric detail
required for accurately simulating surface and subsurface processes by developing
four bathymetric representations using SPRING with reducing level of detail.
These bathymetric configurations are simulated using a physically based tightly
coupled hydrologic and hydrodynamic model to estimate surface and subsurface
fluxes in the floodplains. Comparison of fluxes for the four bathymetric
configurations show that the impact of river bathymetry extends beyond surface
routing to surface water – groundwater interactions. Channel conveyance
capacity and thalweg elevation are the most important characteristics
controlling these interactions followed by channel side slope and channel
asymmetry. </p>
<p> The
final objective aims to develop benchmarks for bathymetric characteristics for
accurately simulating flooding related physical processes. The sensitivity of
surface and subsurface fluxes to error in channel conveyance capacity is
investigated across reaches with varying geomorphological characteristics. SPRING
is used to create six bathymetric configurations with varying range of error in
channel conveyance capacity (ranging from 25% to 300%). They are simulated
using a tightly coupled physically distributed model for a flood event and the
estimates of water surface elevation, infiltration and lateral seepage are compared.
Results show that incorporating channel conveyance capacity with an error of
within 25% significantly improves the estimates of surface and subsurface
fluxes as compared to those not having any bathymetric correction. For certain
reaches, such as those with high drainage area (>1000km<sup>2</sup>) or low
sinuosity (< 1.25), errors of up to 100% in channel conveyance capacity can still
improve H&H modeling.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/17136473 |
| Date | 19 December 2021 |
| Creators | Sayan Dey (7444328) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/ENABLING_LARGE-SCALE_HYDROLOGIC_AND_HYDRAULIC_MODELING_THROUGH_IMPROVED_TOPOGRAPHIC_REPRESENTATION/17136473 |
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