Modeling landscape fluxes for land management and hazard prevention

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Modeling landscape fluxes for land management and
hazard prevention Helena
Mitasova Dept. of Marine, Earth and Atmospheric
Sciences, NCSU, Raleigh L. Mitas, J. Hofierka,
R. McLaughlin http//www.skagit.meas.ncsu.edu/hel
ena/
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GIS and Land Management
Goal sustainable land use, hazard prevention and
mitigation, ...
Monitoring modern mapping technologies LIDAR,
IFSARE, multispectral imagery, RTK-GPS, automated
sensors Analysis and risk assessment
integration of data from multiple sources,
spatial analysis, visualization identifying the
problem areas, trends, risks Prediction of
impacts spatially distributed numerical modeling,
simulations Planning and decision support
information and tools for management of natural
and socio-economic resources
H. Mitasova
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Modeling of mass flows over complex terrain
Fundamental task for land management flood
hazard prevention, erosion and sediment control,
debris flow risk management, protection of
natural resources (water, soil, ecosystems)
Animation illustrates a simple, kinematic wave
overland water flow simulation for uniform
rainfall, soil and cover conditions. Created by
customized version of r.flow by writing output
flowline densities after passing given number of
cells. Depressions are handled as sinks.
Geometry-based flow analysis tools are solutions
of water flow equations for special cases (e.g.,
uniform flow velocity)
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Sediment flow at transport capacity
Combines series of kinematic wave overland flow
surfaces with slope using r.mapcalc to illustrate
simulation of sediment flow
H. Mitasova
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Water flow modeling
Shallow overland flow - St. Venant equation
dynamic kinematic wave
steady state approx. diffusive wave
h - water depth, ie - rainfall excess, v -
velocity given by Mannings eq.,
kinematic wave
kinematic wave with predefined channel in the
depression
approximate diffusive wave
H. Mitasova
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Water flow over complex terrainapproximate
diffusive wave
Water flow depth simulated by approximate
diffusive wave using path sampling
H. Mitasova
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Path sampling method
- based on duality between particle and field
representation - path
samples represent water or sediment evolving
according to the shallow-water
bivariate continuity equation
- solved by
operator inversion Green's function
representing short time propagation of the
sample points (drift diffusion)
Land cover red - disturbed areas green - forest
Water depth particles continuous
fieldparticle density
Rainfall excess, land cover and topography are
spatially variable
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Sediment transport
Sediment transport and net erosion/deposition
model is based on 2D generalization of a 1D
hillslope erosion model used in the WEPP model
new generation USDA erosion model .
where D (r) ? (r)T (r)-qs(r) is
sources-sinks term and D (r)/Dc(r)
qs(r)/T (r)1 (Foster and Meyer, 1972)
c - sediment concentration, qs sediment flow,
T - transport capacity, Dc- detachment
capacity, ? first order reaction coef.
Net erosion and deposition is computed as a
divergence of sediment flow.
Used along with GeoWEPP in our study areas
possible link is being discussed with Chris
Renschler UB
GeoWEPP GIS and Internet supported WEPP. WEPP
continuous time simulations with weather
generator, plant growth, crop rotation,
watershed and hillslope version, etc.
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Sediment flow for different soils
sand ? ? 1
clay ? ? 0.1
detachment capacity limited case DCL
transport capacity limited case TCL
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Path sampling method properties
- robust and flexible based on stochastic
representation - multi-dimensional - scalable
accuracy determined by the number of samples,
ideal for distributed computing
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Multiscale simulations
Simulation of overland water flow 10m
resolution combined with 2m resolution
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Implementation in GRASS and Applications
Original FORTRAN program SIMWE was implemented in
GRASS as r.sim.water r.sim.sediment New
capabilities added preferential flow,
semipermeable barriers (e.g. checkdams),
infiltration in buffers Research work on
sedimentation basins with baffles, bank erosion
Applications focus on spatial pattern of water
and sediment flow and net erosion/deposition
under spatially variable conditions studies of
land use change impact, design of conservation
measures.
H. Mitasova
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Water flow with depressions application to
drainage planning
Spatial distribution of water depth after 1 hour
rainfall. Based on 6m resolution DEM derived from
RTK-GPS survey
Spatial distribution of water depth 24 hours
after rainfall with and without drainage
Important for mobility, construction, ecosystem
management, etc.
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Optimizing conservation measures
Original LU
sediment flow
net erosion/deposition Optimized
LU
Prevention of high sediment flows hazard on
roads, mobility issues, water quality, soil
conservation, ecosystem protection, pollution
prevention
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Conservation measures impact of hedges
Observed slope change
big difference in roughness small diff.
in rougness, large diffusion, small diff. in
roughness, small diffusion
Seth M. Dabney et al. 1999 Landscape Benching
from Tillage Erosion Between Grass Hedges
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Evolution of hedge slope without tillage
Change in erosion and deposition pattern
Tillage or other type of maintenance is
crucial. Optimal distances, widths, properties
can be explored by combining computer aided
design with interactive manipulation
Seth M. Dabney et al. 1999 Lansdcape Benching
from Tillage Erosion Between Grass Hedges
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Change in land use SW Cent. Campus
1993
2001
construction
future
2001
Models are created by combining the GIS and
CAD data
future
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Pre-development 1993 overland flow and location
of sediment control structures
constructed wetland
future school location
check dam
detention area
H. Mitasova
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Overland flow current, construction, future
1hr rainfall 43mm/hr intensity (at 60mm/hr check
dams overflow)
H. Mitasova
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Overland flow and net erosion/deposition
The biggest impact of disturbance will be on bank
erosion
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Sediment flow and erosion/deposition
Current
0.002m3/s
0.001kg/ms
erosion87kg/s
Construction
0.69
0.01-6.0kg/ms
erosion968kg/s
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Control measures
Check dams and buffers
future
"Rolling disturbance"
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Impact of extended buffers
cft/s 0.02 0.2 2.0 20
Added grass
Erosion
359kg/s
Added forest
Deposition
142kg/s
Buffers must have excellent infiltration , they
protect well against erosion from sheet flow but
are ineffective for concentrated flow
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Impact of terrain and land use change on water
depthwith possible consequences for ecosystems
pre-and post-development
pre- and during construction
redistribution of water flow increase from C,
decrease from A,B for small events, spikes for
extreme events
increase in water depth on construction site and
within the stream buffer
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Charlotte beltline construction DOT
Monitoring and modeling impact of construction on
sediment transport and evaluation of
effectiveness of sediment control measures
15 real-time monitoring stations providing data
over the Internet rapid response to sediment
problems
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Proposed test area SECREF and surrounding
experimental farms
Data 1993 2ft contours 2m resolution DEM, 2001
lidar, CYREX? Sediment control training facility
demonstration site for control measures
ponds, wetlands, spreaders, forested buffers,
hedges, fences...
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SECREF and surrounding experimental farms
Data series of high resolution orthophotos,
frequent land cover change
Test dam break at different locations and designs
that will minimize the damage. Release of
pollutant (accidental or malignant) and explore
designs that will enable fast containment.
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Open source GIS GRASS
http//grass.itc.it/
General purpose GIS for raster, vector, site and
image data processing, analysis, modeling and
visualization. Developed at US Army CERL
(1982-1995). General Public License (GPL) in 1999
free to run, modify, distribute, and release
(but it cannot be modified and released as a
proprietary system)
Coordination Markus Neteler, ITC-Trento
council type approach automated web-based
infrastructure supported by Intevation GmbH,
Free GIS Project
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GRASS linked to other Free Software
Interoperability and data accessibility
Map production
(Geo)statistics
Online data dissemination
vis5d, povray
PROJ
Databases
Markus Neteler
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Conclusions I
Mapping and monitoring - new generation of
georeferenced data (lidar, imagery) high
spatial and temporal resolution, massive data
sets - new methods for processing and
analysis Modeling - new generation of
spatially distributed, process-based models
(USACE, ARO major contributors to advancements
in the development) - coupling with GIS -
increasing importance of stochastic techniques,
path sampling very promising - multi-scale,
multi-model approaches
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Conclusions II
Linking Illuminated Clay concept with GIS and
simulation tools can provide environment for
real-time human interaction with simulations to
support land design, management, hazard
prevention and mitigation and facilitate
communication during decision making. Main
tasks link with GIS and simulation tools to
support work with georeferenced data, link with
real-time monitoring explore two way interaction
between the GIS data/simulation results and the
clay model support computer controled terrain
modification along the with manual
design. explore the multi-scale, multi-interface
and multi-model approaches
H. Mitasova
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Funding by the NRC/ARO fellowship andNorth
Carolina sediment control commission for erosion
and sediment control is gratefully acknowledged
SG3d
Solar radiation during summer and winter
solstice, computed by r.sun draped as dynamic
color map over a DEM.