Title page for ETD etd-03312005-162802


Type of Document Dissertation
Author Wu, Kangsheng
Author's Email Address kwu1@lsu.edu
URN etd-03312005-162802
Title Long-Term Freshwater Input and Sediment Load from Three Tributaries to Lake Pontchartrain, Louisiana
Degree Doctor of Philosophy (Ph.D.)
Department Renewable Natural Resources
Advisory Committee
Advisor Name Title
Yi-Jun Xu Committee Chair
Jim L. Chambers Committee Member
Vijay P. Singh Committee Member
William E. Kelso Committee Member
Paul LaRock Dean's Representative
Keywords
  • Lake Pontchartrain
  • Tangipahoa River
  • climate change
  • hydrologic response
  • Amite River
  • Tickfaw River
  • SWAT
  • hydrologic modeling
  • inflow
  • sediment
  • freshwater
Date of Defense 2004-11-10
Availability unrestricted
Abstract
Lake Pontchartrain and the drainage basin have experienced environmental degradation because of human settlement, land use and climate changes. A thorough understanding of hydrologic trends and variability associated with the changes is critical for sustainable water resources management and ecosystem restoration in the region. This study examined freshwater inflow (1940-2002) and suspended solids loadings (1978-2001) from three upper Lake Pontchartrain watersheds that contribute to the lake estuary: the Amite, Tickfaw, and Tangipahoa river watersheds. The relationships of freshwater inflow and suspended solids loadings with climate variables and population growth were investigated. Using observed daily discharge, a spatially-distributed hydrologic model (SWAT) was evaluated, and the model then was employed to assess hydrologic responses of the coastal watersheds to potential climate change. The study showed an annual freshwater inflow of 5 km3 yr-1 and average suspended solids inputs of 210,360 tons yr-1 entering Lake Pontchartrain. More than 69% of annual water yield and 66% of suspended solids occurred from December to May and from January to April, respectively. Over 80% of the variation in annual freshwater inflow could be explained by annual precipitation. A significant increase in freshwater inflow was found in the Amite River watershed over the past sixty years, coinciding with both climatic variation and population growth. The hydrologic modeling showed a good agreement between the simulated and observed daily discharge, with a relatively high Nash-Sutcliffe model efficiency (> 0.811) and low mean error (< 5.6%). The simulation further indicated that, unlike upland watersheds, calibration of the surface and channel routing parameters in the SWAT model became most critical for lowland coastal watersheds with gentle relief. The climate change assessment showed a significant influence of precipitation on annual freshwater yield with an increase of 19.3%-40.1% in response to a 10%-20% increase in annual precipitation. Potential air temperature increase would have only a marginal effect on freshwater yield as shown by a 1.4%-2.9% decrease in the annual freshwater yield for a 1.6 oC-3.3 oC increase in temperature. Warming, however, may pose risks of drought during spring and summer in this humid subtropical region.
Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  Wu_dis.pdf 1.57 Mb 00:07:16 00:03:44 00:03:16 00:01:38 00:00:08

Browse All Available ETDs by ( Author | Department )

If you have more questions or technical problems, please Contact LSU-ETD Support.