Abstract: The influences of input parameter errors on the calculation result of 2-D river water quality model were analyzed using local sensitivity analysis and Morris global sensitivity analysis respectively. The sensitivity of analytical solution to input parameters were calculated and compared; the influence of system disturbance on calculated results of pollutant concentration under the action of single parameter or multiple parameters was analyzed. Furthermore, curves of sensitivity obtained from local sensitivity analysis method were given. The results reveal that the sensitivities to parameters were different: the average flow velocity of river is the most influential, whereas the location of pollutant discharge has the weakest influence on pollutant concentration. The sensitivity of calculation result to parameters follows the order of |S_u|>|S_Dy|>|S_y0|>|S_x0|. Besides, the sensitivity calculated by local analysis under the changes of single parameter is different from that by Morris global analysis. Morris global analysis considers the interaction among multiple parameters, therefore is more reliable than local analysis and better reflects the real situation.

Key words: local sensitivity analysis, global sensitivity analysis, 2-D model of river water quality, analytical solution, relative error, sensitivity