CHANNEL SILTATION AND NATIONAL ECONOMIC DEVELOPMENT BENEFITS OF MAINTAINING AUTHORIZED DEPTHS IN TEXAS

摘要

This analysis of the economic effects of a lack of maintenance dredging focuses primarily on the cost of transporting commodities between two end points on the Marine Transportation System. In analyzing the cost of transporting commodities, the researchers used the inverse of the concept of "National Economic Development (NED) Benefit", as defined by the US Army Corps of Engineers (USACE). This concept is typically applied to the potential benefits of deepening or widening a channel (USACE 2000). However, in this study, the focus is on the increased costs that will be incurred if a channel becomes shallower. For purposes of this analysis, it is assumed that the volume of cargo moved will be held constant-industry will attempt to maintain the same level of economic activity. The channels analyzed in this study consist of (1) selected deep draft channels connecting port facilities with the Gulf of Mexico, and (2) the Gulf Intracoastal Waterway, along with certain "tributary" channels. The channels analyzed in depth are: 1. Gulf Intracoastal Waterway (for all of Texas and in three separate reaches) 2. Chocolate Bayou 3. Arroyo Colorado (Port of Harlingen) 4. Channel to Victoria 5. Port of Brownsville 6. Port of Corpus Christi 7. Port of Port Lavaca 8. Port of Galveston 9. Port of Texas City (also analyzed by Martin & Associates) The approach used in the shallow draft analysis is to examine the effect of allowing the channel to silt in to the point where barges are limited to a maximum draft of 2.4 meter (8 feet). The analysis for deep draft channels uses the maximum sailing draft reported by the port (or pilots) as the baseline draft and then subtracts five feet from the baseline draft to measure the economic effect of siltation. The shipping cost penalty that would be incurred due to siltation of the four selected deep draft channels (excluding Texas City) is estimated at $13 million annually (in US dollars); for the GIWW the figure is $103 million annually (in US dollars).