What is the height above the nearest drainage model?
The height above the nearest drainage model is a drainage normalized version of a digital elevation model. The z axis variable of the HAND model is the normalized local height, defined as the vertical distance from a hillslope surface cell to a respective outlet-to-the-drainage cell, i.e., the difference in level between such cells that belong
How is height above nearest drainage calculated in ArcGIS?
In 2011 I created an ArcGIS Toolbox called the “Riparian Topography Toolbox” and added a tool to calculate HAND. Height Above Nearest Drainage differs “Height Above River”, which is calculated as the difference in elevation between a grid cell and a weighted average of grid cells within a stream.
How is nearest drainage based on vertical distance?
Furthermore, HAND results depict nearest drainage maps that are based on the vertical distance of each unit cell/pixel (each cell contains a value representing information such as elevation) to the nearest stream cell it drains into. A flowchart for the HAND model (courtesy of Xing Zheng, a PhD student) is provided in the Appendix (Figure A3).
How tall is the drainage system in Houston?
In terms of data resources, NHDPlus flowlines at medium and high resolution as well as national elevation datasets of Houston at 10-meter and 3-meter were provided by Yan Liu and Dr. Maidment. Additionally, a HAND raster file of Houston (using 3-meter NED and high resolution NHD flowlines) was already generated by Yan Liu (Appendix, Figure A1).
How does the hand model of drainage work?
The HAND model normalizes topography according to the local relative heights found along the drainage network, and in this way, presents the topology of the relative soil gravitational potentials, or local draining potentials.
How are normalized draining potentials related to drainage?
Normalized draining potentials can be classified according to the relative vertical flowpath-distances to the nearest drainages, defining classes of soil water environments.
How is the hand model used in hydrology?
The HAND model and the derived soil water maps can help to advance physically based hydrological models and be applied to a host of disciplines that focus on soil moisture and ground water dynamics.