HR: 1330h
AN: B52A-1029    [PDF]
TI: Rainfall Simulation at the Hillslope Scale: A Technique for Understanding the Role of Shrubs in the Water Cycle
AU: * Wilcox, B P
EM: bwilcox@tamu.edu
AF: Rangeland Ecology and Management, Texas A&M University, College Station, TX 77843 United States
AU: Munster, C
EM: c-munster@tamu.edu
AF: Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843 United States
AU: Owens, K
EM: m-ownes@tamu.edu
AF: Texas Agricultural Experiment Station, 1619 Garner Field Road, Uvalde, TX 78801 United States
AU: Mohanty, B
EM: bmohanty@cora.tamu.edu
AF: Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843 United States
AU: Jackson, R B
EM: jackson@duke.edu
AF: Department of Biology, Box 90340 Duke University, Durham, NC 27708 United States
AU: Stern, L
EM: lstern@mail.utexas.edu
AF: Geological Sciences Department, The University of Texas 1 University Station, #C1100, Austin, TX 78712 United States
AU: Banner, J
EM: banner@mail.utexas.edu
AF: Geological Sciences Department, The University of Texas 1 University Station, #C1100, Austin, TX 78712 United States
AB: Reducing woody vegetation cover may be an effective way of increasing water supplies in semiarid landscapes. Using public monies to subsidize the control of woody vegetation for this purpose has broad support among the public. In Texas, around 30 million dollars has been spent or appropriated for this purpose. Unfortunately, there is remarkably little scientific evidence for the efficacy of brush management for increasing water supplies. In an effort to better understand the influence of woody plants on the water cycle, we have established several hillslope-scale rainfall simulation studies. Water is applied from above the tree canopies, at various rainfall intensities, onto sloped plots measuring approximately 7 x 15 m (slope $<$ 3%); the parameters measured and recorded are transpiration, interception, soil water, lateral subsurface flow, and surface runoff. In addition, the isotopic composition of subsurface waters is analyzed. We have found that in the semiarid and rocky terrain of the Edwards Plateau, lateral subsurface flow is the dominant mechanism of runoff generation. We have also found that in areas where juniper cover is extensive, there is little surface runoff. Our investigations, although just getting under way, are beginning to shed light on how trees may potentially alter the water cycle and at what scale(s) these alterations may be important. Large-scale rainfall simulation is proving to be a useful technique for collecting detailed information on the role of woody plants in the water cycle, and we believe that simulations at scales even larger than that of the hillslope are feasible and will prove equally useful.
DE: 1615 Biogeochemical processes (4805)
DE: 1655 Water cycles (1836)
DE: 1884 Water supply
SC: Biogeosciences [B]
MN: 2003 Fall Meeting