Parametric uncertainty and sensitivity analysis of hydrodynamic processes for a large shallow freshwater lake

Figures & data

Fig. 1 Location of the study area, surrounding rivers and monitoring stations in and around Lake Taihu, China. Water level monitoring stations (1)–(4) represent Dapukou, Jiapu, Xiaomeikou and Xishan, respectively.

Fig. 2 Methodology flowchart.

Table 1 Statistical features of the hydrodynamic parameters used for the Latin hypercube sampling method.

Parameter group	Parameters	Min	Max
Air–water interface factor	Wind drag coefficient (Cs)	5 × 10^-4	5 × 10^-3
Surrounding terrain factor	Wind shelter coefficient (ws)	0.5	1
Water–sediment interface factor	Roughness height (z0)	5 × 10^-3	5 × 10^-2
Turbulent diffusion parameters	Horizontal eddy viscosity (Hv)	1	100
	Horizontal turbulent diffusivity (Hb)	1	100
	Wall roughness (Wr)	1 × 10^-4	1 × 10^-2
	Vertical eddy viscosity (Av)	0	10
	Vertical turbulent diffusivity (Ab)	0	10
Turbulent intensity parameters	Turbulent intensity (q)	1 × 10^-5	1 × 10^-3
	Turbulent length scale (l)	1 × 10^-5	1 × 10^-3

Note The unit for roughness height (z₀) is m; while other parameters are dimensionless.

Fig. 3 (a) Mean, (b) 5th percentile, (c) 95th percentile and (d) variance of simulated water level with uniform distributions.

Fig. 4 (a) Mean, (b) 5th percentile, (c) 95th percentile and (d) variance of simulated flow velocity at the surface layer with uniform distributions.

Fig. 5 Mean and variance of simulated flow velocity: (a) and (b) at the middle layer, and (c) and (d) at the bottom layer.

Table 2 Sensitivity assessment for parameters with different distributions.

Output target	Parameter distribution	Sensitivity analysis	Gonghu Bay	Meiliang Bay	Zhushan Bay	Northwest Zone	Southwest Zone	Dongtaihu Bay	East Epigeal Zone	Central Zone
Water level	Uniform	cs SRRC^2	0.649	0.688	0.691	0.684	0.656	0.691	0.631	0.650
		ws SRRC^2	0.265	0.266	0.271	0.262	0.265	0.266	0.228	0.233
	Normal	cs SRRC^2	0.602	0.682	0.694	0.675	0.629	0.686	0.589	0.584
		ws SRRC^2	0.268	0.274	0.267	0.272	0.255	0.278	0.215	0.235
	Lognormal	cs SRRC^2	0.694	0.751	0.762	0.751	0.733	0.776	0.657	0.644
		ws SRRC^2	0.200	0.202	0.212	0.214	0.216	0.173	0.134	0.133
	Triangular	cs SRRC^2	0.688	0.752	0.752	0.745	0.688	0.760	0.663	0.667
		ws SRRC^2	0.143	0.164	0.177	0.171	0.164	0.175	0.153	0.138
Flow velocity at surface layer	Uniform	cs SRRC^2	0.701	0.679	0.725	0.670	0.643	0.646	0.706	0.671
		z0 SRRC^2	0.055	0.081	0.030	0.087	0.112	0.099	0.038	0.083
		ws SRRC^2	0.205	0.230	0.230	0.219	0.211	0.237	0.245	0.212
	Normal	cs SRRC^2	0.676	0.603	0.680	0.621	0.624	0.614	0.663	0.658
		z0 SRRC^2	0.062	0.131	0.050	0.115	0.102	0.093	0.057	0.080
		ws SRRC^2	0.228	0.227	0.242	0.224	0.223	0.246	0.254	0.229
	Lognormal	cs ^SRRC2	0.770	0.773	0.731	0.780	0.717	0.740	0.750	0.754
		z0 SRRC^2	0.054	0.056	0.046	0.066	0.120	0.048	0.067	0.065
		ws SRRC^2	0.161	0.143	0.196	0.148	0.111	0.190	0.178	0.152
	Triangular	cs SRRC^2	0.772	0.707	0.774	0.722	0.708	0.685	0.750	0.746
		z0 SRRC^2	0.051	0.100	0.041	0.096	0.100	0.098	0.046	0.073
		ws SRRC^2	0.160	0.163	0.167	0.165	0.152	0.162	0.172	0.165

Fig. 6 Mean and standard deviation (SD) of standardized regression coefficient (SRRC²) of the five parameters for flow velocity uncertainty at different vertical layers with a uniform distribution.