Author(s): Guoxian Huang; Jianjun Zhou; Binliang Lin; Qiuwen Chen; Roger A. Falconer
Keywords: Distributed hydrological model; Hydraulic modelling; Yangtze River basin; Large cascaded reservoirs and lakes
Abstract: With the continuous developing of technology and economy, the degree of mankind’s impact on the large river basin in hydrology, sediment transport, eco-environment is becoming more and more intense. How to develop or apply reasonable numerical models and evaluate quantitatively these impacts is one of urgent tasks at present. In the paper, a distributed hydrological model for large river basin is developed based on the grid-distributed Xinanjiang model in which a 1D unsteady hydrodynamic model for hybrid river networks based on Pressiman and Three-Grade solution is coupled to calculate the complex hydrological and hydrodynamic processes especially in the main channels, lakes and upper, middle and lower reaches of important branch and hybrid river networks from source region to river estuary, and the model is applied to calculate the hydrological and hydrodynamic processes of total Yangtze River (YR) catchment. After some draft validation and verification, some special physical processes are discovered and these processes are important to the hydrological processes including (1) the hydrological circling related to slope, the soil, plant, depression, flood diversion region, land use and etc. ; (2) the exchange processes between the deep and shallow ground water; (3) The snow and glacier condensation and melting govern by the energy equilibrium equation; (4) natural and man controlled storing and releasing processes in ponds, lakes and reservoirs especially the large cascade reservoirs and lakes, In the paper, the basic hydrological and hydrodynamic models are focus with some the necessary modification above. Validation and verification using measured hydrological data in 1997-1999 at more than 160 stations shows the calculated flow discharge and water level is fit general well with the measured data especially on the middle and lower catchment. After some refinement, the model can be applied to evaluate quantitatively the influences of mankind’s activities and climate variation for large catchment in the future.