Page Banner

United States Department of Agriculture

Agricultural Research Service

headline bar

Great Plains Agroclimate and Natural Resources Research Unit



To quantify interactive effects of land use, agricultural management, climate, and the water cycle on agricultural and hydrologic systems; and to develop planning tools to evaluate and manage environmental and economic risks under variable climate, energy, and market conditions.


Scientific Staff

Jurgen Garbrecht        Hydraulic Engineer

Daniel Moriasi             Hydrologist

Jeanne Schneider        Meteorologist

Jean Steiner               Soil Scientist, RL

Patrick Starks             Soil Scientist

Xunchang Zhang         Hydrologist


Research Objectives

••         Quantify environmental impacts of conservation practices in Oklahoma watersheds, in collaboration with the nation-wide Conservation Effects Assessment Project.

••         Evaluate and adapt seasonal climate forecasts and develop risk-based decision support tools for agricultural and natural resource management.

••         Identify multi-year climate variations, quantify their impacts on watershed hydrology, and develop risk-based climate information in support of agricultural decision making, conservation efforts, watershed management, and environmental stewardship.

••         Quantify interactive effects of land use, management, and variable climate on soil compaction, infiltration, sediment and nutrient movement, surface water supplies, ground water recharge and return flows.

••         Integrate remote sensing estimates with other data to monitor and predict root zone soil water content at regional scales.

••         In collaboration with the Forage & Livestock Production Research Unit, develop a remote sensing technology for rapid determination of forage quality in the field.


Research Projects

••    Climate variability, climate forecasts, and risk-based decision information.


Research Assets and Facilities





••         Expertise in field observations using in situ and remote sensing data acquisition and analysis systems, Geographic Information Systems (GIS) applications, climate and seasonal forecast analysis, and hydrologic modeling; equipment for in-field remote sensing, extraction of soil cores, in-stream water quality sampling, and drilling monitoring wells; laboratories for water, soil, and forage quality analyses.

••         Little Washita River Experimental Watershed, a 236 mi2 mixed land-use watershed in Central Oklahoma, with 50 flood retarding structures, 20 automated weather stations, an automated ground water monitoring well, and 7 USGS
stream gauges.

••         Fort Cobb Lake Experimental Watershed, a 313 mi2 agricultural watershed that drains into a multiple-use reservoir, with 15 automated weather stations and 4 USGS stream gauges.

••         Eight grazed 4-acre watersheds, planted in contrasting vegetation, with automated flumes to collect water samples.

••         Fort Reno Cooperative Flux Stations

••        Large Scale Experiments


Data, Products and Information



Recent Research Accomplishments

••   Remotely sensed estimates of surface soil water content were demonstrated to improve simulated root-zone water content over time.

••    Analyses of precipitation revealed an unprecedented period of high precipitation and an absence of severe, extended drought in the Great Plains during the last two decades of the 20th century.  This "wet" period ended with the new millennium.

••    Field and computer studies demonstrated that stream flow is sensitive to decade-scale precipitation cycles:  periods with 20% lower annual precipitation may produce only half the stream flow, potentially resulting in water shortages.

••   Analysis of flood retarding structures in the Little Washita Watershed demonstrated that maximum daily flows that occur on average every 5 to 10 years were reduced by about 40%, thereby reducing flooding; unfortunately, low flows during drought are also reduced.

••    Computer simulation indicated that conversion of only 2.5% of wheat, sorghum-wheat, and peanut-wheat cropping systems to Bermuda grass in a tributary of the Fort Cobb Watershed could result in respective erosion reductions of 15%, 10%, and 7%. 

••    NOAA's seasonal precipitation forecasts have greater potential utility from California through the Desert Southwest to Florida than in the rest of the contiguous United States because of more forecasts with stronger deviation from normal and more frequent observation of deviations that match the forecast direction.

••     A new method to downscale 3-month precipitation forecasts to monthly and daily amounts for use in agricultural management and conservation planning has been developed.

••     Grazed pastures had 3 to 7 times more runoff than un-grazed pastures due to soil surface compaction, and runoff from wheat pastures was reduced if a legume cover crop was grown during the summer period between wheat crops.


Last Modified: 8/13/2016
Footer Content Back to Top of Page