HR: 1330h
AN: B52A-1031    [PDF]
TI: A Stable Isotope Study of Runoff Processes in a Semi-arid Shrubland
AU: * Huang, Y
EM: yunh@tamu.edu
AF: Department of Rangeland Ecology and Management, Texas A&M University, College Station, TX 77843 United States
AU: Wilcox, B P
EM: bwilcox@tamu.edu
AF: Department of Rangeland Ecology and Management, Texas A&M University, College Station, TX 77843 United States
AU: Stern, L
EM: lstern@mail.utexas.edu
AF: Department of Geological Sciences Department of Geological Sciences Department of Geological Sciences Department of Geological Science, The University of Texas at Austin, Austin, TX 78712 United States
AB: The most direct effects that woody plant encroachment may have on local and regional hydrology include altering evapotranspiration rates; modifying runoff processes and creating different microclimate and regional climate. Over the last one hundred years, western Texas has experienced significant woody plant encroachment. Shrub control is now commonly viewed as a viable way to increase catchment water yield. However, there are few process-based studies evaluating brush removal and related water yield. The catchment water yield, recharge processes and runoff processes are directly interrelated. This project on the Texas Parks \& Wildlife Department's Honey Creek State Natural Area, in conjunction with other NRCS and USGS projects, is aimed at providing insight into runoff processes over the Edwards Aquifer contributing zone on the Edward's Plateau of Texas. Field observation of runoff processes from Honey Creek Experimental Watershed led us to hypothesize that the majority of the storm runoff from that catchment is precipitation event water and overland flow dominates during the event. The isotopically-based hydrograph separation of event hydrograph indicates that an appreciable amount of pre-event water contributed to the event hydrograph. This demonstrates the importance of subsurface flow in the runoff generation in this catchment. The study site geomorphology and topography preclude the flood wave effect and saturation overland flow mixing mechanism proposed by similar studies for large amount of pre-event water discharge during the storms. However, the riparian zone and water table responses can explain such phenomenon in our study site. The results show that groundwater-surface water dynamics must be considered in water balance studies in the catchment, whether the groundwater is transient saturation, perched aquifer or water table aquifer. Groundwater-surface water dynamics should also be considered when designing a brush control project or evaluating long term brush control effects.
DE: 0400 Biogeosciences
DE: 1860 Runoff and streamflow
SC: Biogeosciences [B]
MN: 2003 Fall Meeting