tailieunhanh - Estuarine Research, Monitoring, and Resource Protection - Chapter 7 (end)

Tijuana sông ở miền Nam California được chỉ định là trang web (NERR) cửa sông nghiên cứu dự trữ quốc gia vào năm 1982. 1025-ha trang web ở San Diego County, nằm ở biên giới Mỹ / Mexico, bao gồm một mảng rộng của các môi trường sống, bao gồm cả vùng cao, cây xô thơm ven biển, chuyển đổi đất ngập nước vùng cao, đầm lầy nước mặn, lạch thủy triều và các kênh, và mudßats và sandßats, như cũng như các đụn cát và bãi biển. Một phần signiÞcant của khu vực dự trữ bao gồm ngập mặn. | Case Study 6 Copyright 2004 CRC Press LLC 7 Tijuana River National Estuarine Research Reserve INTRODUCTION Tijuana River in Southern California was designated as a National Estuarine Research Reserve NERR site in 1982. The 1025-ha site located in San Diego County at the . Mexico border encompasses a wide array of habitats including uplands coastal sage upland-wetland transition salt marshes tidal creeks and channels and mudflats and sandflats as well as dunes and beaches. A significant fraction of the reserve area consists of salt marsh and riparian wetland habitats Table . The intertidal salt marsh habitat is particularly well developed. The Tijuana River watershed is extensive covering 1731 km2 and bisecting the estuary into northern and southern regions. More than 75 of the watershed area lies within Mexico Figure Nordby and Zedler 1991 Zedler et al. 1992 Zedler 2001 . The Tijuana Estuary is located at 32 34 N 117 7 W. It is a coastal plain estuary consisting of a network of stream channels with no well-defined embayment. Hydrographic conditions in this intermittent estuary are highly variable stream flow is greatly reduced during much of the year when drought conditions often exist but significant precipitation during the winter generally results in a river-dominated system. Because of the large seasonal flux in stream flow the estuary changes from a river-dominated system in winter to one that is partially mixed or vertically homogeneous during other seasons. Zedler and Beare 1986 reported a mean annual discharge of the Tijuana River amounting to 20 820 MLD million liters per day although they noted the flow was extremely variable. For example the coefficient of variability reported by these investigators was 325 . Flooding commonly occurs in years of very heavy precipitation such as during the period from 1978 to 1980. Tidal flushing peaks at the channel mouths and declines upstream. The Tijuana River NERR is an urbanized system surrounded by the .

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