costs and human tragedy inflicted by flooding are felt on an almost daily basis across various parts of the US and the world.
Currently, a serious
dearth of accurate elevation data exists to measure the shape of the land surface which is critical in determining the direction,
velocity, and depth of flood waters. In the US, most of the publicly available elevation data, the U.S. Geological Survey's
National Elevation Dataset, is more than 35 years old. Digital floodplain maps have been prepared for about 1 million miles
of the nation's 4.2 million miles of rivers and streams, but only 247,000 miles have been mapped using high-resolution
elevation data such as LIDAR.
Urban expansion and land development have significantly altered the earth surface. New roads and flood drainage structures
affect expected floodwater depths, and land subsidence can be significant in coastal areas. As a result, flood disasters over
the past years have created an increasing demand for precise, accurate and actual data of the earth’s surface.
Aerial LIDAR is the accepted
method of measuring surface elevation for the creation of high-accuracy elevation data. However, the information and operational benefits accrued
by the simultaneous collection of multispectral imagery along with LIDAR far outweighs the sum of its parts. The fusion of
data from diverse sensors can provide information for the creation of higher-value products and services such as development
of intelligent 3-D urban/natural geospatial databases which are critical for flood management.
Geospatial elements such as building footprint, height
and structural characteristics; vegetation type, height and density; and, natural and cultural land-use and cover information,
provide a powerful toolkit to enable intelligent data analysis.
This “Intelligent Data” is derived by the simultaneous acquisition of LIDAR and multispectral
data such as that generated by the TopoSys line of aerial LIDAR/Imaging systems. The turnkey line of LIDAR/Imaging systems comes totally integrated with GPS, IMU, data storage, flight planning, LIDAR and RGB/NIR camera providing the ability to collect high-resolution, multispectral imagery and high-density, precise LIDAR datasets. The system is complimented with TopPIT, the pre-and-post processing software that streamlines the entire workflow from pre-flight
planning to complete final deliverables.
LIDAR = XYZ
LIDAR+(RGB/NIR) = 3-D Urban/Natural Geospatial Intelligence
The time and cost benefits accrued by collecting
multiple datasets simultaneously are multiplied by the value-added products that can be created by the fused data. Acquiring
imagery simultaneously with the surface data can save up to 50% in acquisition costs. But, the real value is that each surface
point possesses an accurate spectral signature assigned to its location, allowing the creation of true digital orthos and the accurate classification of features such as urban terrain, forested terrain, agricultural lands, mountains, cliffs,
ravines, pervious/impervious surfaces; vegetation type; wetlands; and agricultural classes. In addition, it provides vastly
improved bare-earth surfaces.
The 3D geospatial information derived from the fusion of multiple sensors is ideal for flood and coastal applications.
The simulation of high water scenarios can be calculated using different types of elevation models: Digital Surface Models
(DSM): which detail roofs, treetops, power lines, etc.; Digital Elevation Models (DEM): with building and
vegetation; Digital Terrain Models (DTM): bare-earth excluding buildings and vegetation.
For hydraulic simulation, DTM’s with buildings and
vegetation removed are used while multispectral imagery acquired with LIDAR are used for the classification of land-use and
land-cover to define roughness parameters for hydraulic simulation models. Complex hydraulic simulations can be done for 2D
and 3D simulations using the terrain data.
This 3D geospatial information can be beneficial for environmental protection and restoration of floodplains
by the acquisition of drainage channels and monitoring of dikes, levees and other infrastructure. Simulation of water flows
and floodplains helps support plans for disaster prevention, flood protection, and definition of potential flood regions.
LIDAR and multispectral
imagery are useful for the monitoring and protection of coastal zones by creating an inventory of coastal zones and islands,
determining drainage channels, potential flood regions, and the simulation of tidal water levels. It can provide the localization
and calculation of volumes of erosion and accumulation, documentation of erosion, and destruction of cliffs and beaches. 3D
geospatial data facilitates the creation of coastal information systems for the planning, construction, and maintaining of
dikes, levees and coastlines; disaster prevention, mitigation and environmental protection.
For more information on the benefits of acquiring
LIDAR and multispectral imagery simultaneously for flood or other applications, please contact:
TopoSys North America, Inc.
4600 South Ulster Street
Denver, CO 80237