Hydrology of the Walker River Basin

Imagery

In 2004, the USGS, in cooperation with the Bureau of Reclamation (BOR), began a multiyear program studying hydrology of the Walker River Basin and consequences of water management alternatives on Walker Lake, Nevada. One requirement is to obtain current, basic information of high spatial resolution elevation and image data. The data will be used to, but not limited to, mapping land cover, drainage networks, and diversion canals.

Map showing the boundaries of the multi-spectral imagery and LIDAR

Using the Geography Disipline's Cartographic Services Contract, orthorectified, multispectral imagery at 1-meter resolution was acquired. Orthorectified imagery has a horizontal positional accuracy less then 4-meter error at 90% confidence. Simply put, it is very accurate positionally. The data will be able to display natural color and color-infrared images. One use of this data will be to map evapotranspiration (ET) units. An ET unit is an area of similar vegetation and soil conditions. ET is a major source of discharge in the area so it is important to accurately map ET units.

The USGS and NASA entered an agreement to share research involving USGS hydrologic studies of evapotranspiration and surface-water modeling and NASA development of the Experimental Advanced Airborne Research Lidar (EAARL) system. NASA will fly the EAARL system over an area of the Walker River Basin and provide the USGS with the resulting EAARL dataset which can be processed by NASA’s Airborne Lidar Processing System (ALPS) software. The EAARL dataset includes laser transmit and backscattered waveforms, precision GPS trajectories, and other ancillary data. NASA is developing their ALPS software to be used to produce basic high resolution and high accuracy topographic survey data. Vegetation biomass parameters will be determined and collected. The USGS and NASA will jointly use this information to refine processing algorithms for vegetation characterization and improve the accuracy of bare earth elevation.

Additional Links
Lidar	Imagery