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<br />19 <br /> <br />6. Data Requirements: <br />HEC-6 requires the following input data: <br /> <br />(1) Number of cross secti ons, i ndi vi dua 1 reach 1 engths, and tri butary <br />locations. <br />(2) Geometric data on movable-bed portion of each cross section, <br />thickness of movable bed, and bridges, and dredging information. <br />(3) Manning's roughness coefficient at each cross section. <br />(4) Data on sediment inflow, bed-material gradation, and sediment <br />properties. <br />(5) Upstream and 1 ateral i nfl ow hydrographs, downstream boundary <br />condition (stage-discharge curve or stage hydrograph), and water <br />te~eratures. <br /> <br />HEC-6 is a one-dimensional model with no provlslon for simulating the <br />development of meanders or specifying a lateral distribution of the sediment- <br />transport rate across the section. The entire movable-bed portions of the <br />cross sections are assumed to aggrade or degrade uniformly. The model is not <br />suitable for rapidly-changing flow conditions. The model can be applied to <br />predict reservoir sedimentation, degradation of the stream bed downstream from <br />a dam, and log-term trends of scour or deposition in a stream channel. The <br />influence of dredging activity can also be simulated. The model can be run in <br />the fixed-bed mode, similar to HEC-2, by removing all sediment-data cards. <br /> <br />E. FLUVIAL-ll: <br />1. Developer: Chang and Hill (San Diego State University), 1976 <br />2. Previous Applications: <br />(1) San Dieguito River (Chang & Hill, 1976) <br />(2) San El i jo Lagoon entrance channel (Chang & Hi 11, 1977) <br />(3) San Diego River (Chang, 1982) <br /> <br />3. Basic Concepts: <br />FLUVIAL-II was developed to simulate one-dimensional, unsteady, <br />