Estimating soil hydraulic properties
using remotely sensed soil moisture
and surface temperature

Peter Shellito, Geological Sciences, University of Colorado Boulder


Soil hydraulic properties are required by models that predict floods, droughts, and long-term climate change.


Project Goal

We will measure soil hydraulic properties (SHPs) at a continental scale using remotely-sensed data. Their importance and the need for this project are as follows:

(1)  Hydrologic land surface models that represent the coupled water-energy balance of the land surface depend on SHPs to partition precipitation into groundwater recharge, stream runoff, and evapotranspiration.

(2)  Research labs such as NOAA couple hydrologic models with atmospheric models to predict weather, floods, and droughts as well as longer-term climatic change.

(3)  Currently, SHPs are selected according to soil texture class, which is a poor predictor of SHPs due to issues of scale and variability.

(4)  Using remotely sensed data together with an inverse modeling procedure will provide estimates of SHPs that are independent of soil type. The improved SHP values will allow existing land and atmospheric models to make more accurate simulations.
Continental-scale modeling requires accurate SHPs estimates across the landscape




The relationship between soil tension and moisture

Water Retention Curves and Soil Hydraulic Properties

A water retention curve describes the drying process of a particular soil. It is a nonlinear, experimentally-determined relationship between the suction (or tension) exerted by a soil on the surrounding moisture and the soil’s relative water content or wetness. The suction is measured by a negative pressure, commonly centimeters of water, and the relative water content is a fraction of the saturated water volume. A variety of models have been developed to describe this nonlinear curve. The most common are the Campbell (Campbell, 1974), the Clapp and Hornberger (Clapp & Hornberger, 1978), and the van Genuchten (Van Genuchten, 1980) models. Each model has a set of curve-fitting parameters known as soil hydraulic properties (SHPs). SHPs are a combination of empirically and theoretically derived values, which include the saturated water content, the saturated hydraulic conductivity, and various coefficients and exponents unique to each model. More »




Private

Mailing Address

University of Colorado - Boulder
Department of Geological Sciences
Campus Box 399
2200 Colorado Ave.
Boulder, CO 80309-0399 USA

Phone/Email

Phone: (303) 735-5033
Fax: (303) 492-2606
eric.small@colorado.edu

Geological Sciences Homepage