RIVER3 - SIMULATION OF RIVER DISCHARGE AND SEDIMENT TRANSPORT

RIVER3 is an ANSI standard FORTRAN-77 numerical model that simulates t he discharge and sediment load of rivers. From basic data on climate, hinterland geometry, and river characteristics, the model predicts fou r contributions to river how (nival melt, ice melt, rainfall, and grou ndwater). Input parameters include annual rainfall and snowfall, seaso nal evaporation, days per month with measurable rainfall, days per mon th with temperatures exceeding 5, 10, and 20 degrees C, topography, gl acier equilibrium line altitude, seasonal freezing line altitude, area l extent of lakes, sediment transport, and erosion coefficients. The m odel has both deterministic and stochastic elements for the simulation of daily flow and channel size, and the transport rates for five sedi ment size fractions (from clay to gravel). The model is deterministic in that given an input file, which includes a random seed number used to determine the magnitude and occurrence of a particular rainfall or snow or ice-melt event, the predicted stream hydrograph will be the sa me. The model is stochastic in that for each subsequent year being sim ulated, a different random number operator is used and a different hyd rograph is predicted, although the total discharge related to ice melt , snow melt, rainfall, and baseflow is conserved. Model output include s interannual variation of a river's discharge history and sediment tr ansport, and an input file for basin-fill models (DELTA and GRAIN) alr eady in use. RIVER3 is able to offer a variety of applications for the study of regional climatic change (past or future) on fluid discharge and sediment processes.