Project Title: Modeling and field experimentation to determine the impacts of terraces and small reservoirs on water supplies and hydrological balances in the Republican River Basin

Project PIs: Derrel Martin, James Koelliker (Kansas State University), Ayse Irmak, Dean Eisenhauer

Granting Agency Name: US Bureau of Reclamation

Grant Period: 06/01/2004 - 06/01/2009

Addendums:

Presentation at ASABE meeting. Modeling the effects of terracing on water supplies in the Medicine Creek, Nebraska. 2006 ASABE Annual International Meetings. Portland, Oregon.

ASABE Paper #:062291

Presentation at Water Colloquium. October 27, 2006. Lincoln, Nebraska

Research objectives: A provision in the settlement of the litigation on the Republican River requires a study to determine the impact of field terraces and non-federal reservoirs on streamflow depletion in the Republican basin. The objective of this research is to determine the impact of field terraces and non-federal reservoirs on streamflow depletion on the Republican River. In particularly, we are interested in to quantify the impact of terracing on percolation, runoff, and ET parameters. The project has two components: hydrologic modeling and field experimentation. The POTYLDR (Potential Yield Revised), a physically based, continuous time scale, modeling tool is used for predicting the effects of terraces on water balance parameters. Other models, such as CROPSIM, and SWAT have been developed to simulate some watershed processes and contain components that are more robust than some procedures in POTYLD. We are using important relationships from such models to improve POTYLD to better account for the effects of terraces and ponds and evapotranspiration.

The sketch in Figure 1 shows the characteristics of terraced land. A berm is constructed at intervals within the field. The soil used to form the berm is removed from the channel just upstream of the berm. The contributing slope portion of the terraced land has the same slope as before completion of the terraces. Water that runs off of the contributing slope region is retained for a period of time within the channel.