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Interdisciplinary baseline studies for the restoration of Cañada Joe Bill, east of Tecate, in Baja California, Mexico, are proposed. The Cañada Joe Bill is an important component of the Tijuana River Watershed, linking Campo Creek, in San Diego County, and Tecate Creek, in the municipality of Tecate. During the period 1989-2000, the Cañada Joe Bill was mined for sand and gravel, which was exported to the U.S. by rail. The sand-and-gravel mining operation was carried out in the absence of regulation, and left a scarred landscape, with 8-m deep borrow pits and little resemblance to natural conditions. The degraded condition of the canyon is worsened by an existing flood hazard, since the railroad crosses the creek through a 90-yr old earthen embankment, which is patently in a state of disrepair and may breach during an infrequent flood. The postulated breach failure is likely to significantly endanger life and property downstream, in Tecate proper. The following specific study components are identified: (1) a hydrologic study to determine flood flows, (2) a hydraulic study to determine flood conveyance, (3) a hydroecological study to determine appropriate stream restoration strategies, (4) an environmental study to determine the degree of alteration of the microclimate and riparian habitats, (5) a sociological study of local stakeholders to assist in the formulation of management strategies, (6) a geotechnical study for a deterministic evaluation of the safety of the railway embankment, (7) a risk-analysis study for a stochastic evaluation of the safety of the railway embankment, and (8) a dam-breach study to assess downstream damages under a postulated embankment failure. The hydrologic study will determine flood discharges for 2-, 5-, 10-, 20-, 50-, 100-, 200-, 500-, and 1000-yr return periods. Mathematical modeling with the U.S. Army Corps of Engineers HEC-HMS will be used to calculate the flood discharges. A geographic information system (GIS) will be used to support the hydrologic analysis. The hydraulic study will design a flood conveyance channel capable of safely carrying the 10-yr and 1000-yr floods. Mathematical modeling with the U.S. Army Corps of Engineers HEC-RAS will be used to determine flood stages, depths, and velocities. The hydroecological study will inventory and classify existing vegetation and examine ways to restore the degraded stream channel to productive stability. The environmental study will evaluate the degree of alteration of the microclimate and riparian habitats, and it will review the historic data on climatic conditions prior to and after the alteration. The sociological study will examine the rural and urban setting in the vicinity of Cañada Joe Bill, will perform a sociodemographic study of local communities and an identification of local individuals or entities having a stake in the social, economic, institutional and political development of Cañada Joe Bill. The geotechnical study will review the history and evolution of the existing railway embankment, the method of construction, and its usage for the past 90 years. The stability of the embankment will be analyzed under static and flood conditions. The competence of the existing outlet to pass the 1000-yr flood will be analyzed. The risk-analysis study will evaluate the current failure probability of the embankment. The analysis will be qualitative and quantitative, including a risk simulation provided by the Monte Carlo method, and by developing sensitivity analysis with risk variables. The dam-breach study will analyze the inundation downstream of the embankment following a postulated failure during an infrequent flood. The research team, consisting of two professors from SDSU, five professors from UABC, and three local consultants, will assemble relevant geographic, climatic, topographic, hydrologic, hydroecological, hydraulic, geotechnical, ecological, vegetation, demographic, historical, social, economic, institutional, and political data to underpin interdisciplinary synthesis aimed at the restoration of Cañada Joe Bill. The research team will coordinate and work closely with local stakeholders to ensure that the research results are relevant and meaningful to the proposed project. The requested amount is $88,500. |