Index exceeds the number of array elements - water balance for euler loop

Question

NOtway 2022-10-16

0
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https://ww2.mathworks.cn/matlabcentral/answers/1827728-index-exceeds-the-number-of-array-elements-water-balance-for-euler-loop

回答： Torsten 2022-10-16

I am constructing a water balance within a euler loop

for i=1:nt
    time(i+1) = time(i) + dt;
     
            % Determine lake overflow for each timestep
        if V(i) + RAINFALL(i+1) - EVAP(i+1)  >= V_max
            Overflow(i+1) = V(i) + RAINFALL(i+1) - EVAP(i+1) - V_max;
        else
            Overflow(i+1) = 0;
        end

Where V(i) is:

dV(i) = (RAINFALL(i) * A_catch * C / 1000) - Overflow(i) - (EVAP(i) * A / 1000);    % units = m3
V(i+1) = V(i) + dt * dV(i);    % volume lake in m3

The Overflow, RAINFALL and EVAP must all be applied to the same timestep (ie water overflows at the same time the lake capacity is exceeded, not in the next timestep)

However, I am getting the error "Index exceeds the number of array elements. Index must not exceed 3650"

The RAINFALL and EVAP data are both stored in 1x3650 interpolated vectors that have been extracted from an excel sheet

[date, t, Rainfall, Evap, I_t] = readvars("BOM_Data.xlsx"); %load daily data
%define desired timestep (10 points per day)
dt = 0.1;                       % step size (days)
time = 1:dt:(size(t,1)+0.9);    % the range of time (days) (1.0 t0 365.9)
%interpolated vectors
RAINFALL = interp1(t,Rainfall,time);
EVAP = interp1(t,Evap,time);

Any suggested workarounds for getting this water balance to run? I assume the error is due to using i+1 in the water balance eq's, but I'm not sure how else to make sure that the overflow is applied in the correct timesteps.