How can I model temperature advection due to percolating rain water in MATLAB?

Question

I have a vertical column of a rock layer with the following vertical temperature distribution in Kelvin:

Td =    [305.557543064521
283.841779658518
280.511694532208
279.032758050297
277.585218159758
276.266803864024
275.215826036983
274.441444325940
273.888287309701
273.482750462903
273.150000000000]   

I want to model how a raindrop advects heat if it enters on top of the layer and travels down via: cW * pW * P * deltaT with from left to right the specific heat capacity of water (4184 J kg-1 K-1), the density of water (1000 kg m-3), the rainfall rate (m s-1) and the temperature difference between the raindrop and the layer. I have been trying some stuff, but it seems to result in extremely low temperature increases at the bottom layer (only 0.0056 degrees). Can anybody help me on checking if this is correct or I am doing something wrong? Thanks!

rhow = 1000;                                         % Density of water (kg m^-3)
cW = 4184;                                           % Water specific heat capacity (J kg-1 K-1)
P = 0.0113;                                          % Precipitation rate (m 3h-1)
sechr = 10800;                                       % Seconds in 3 hour
vol_heat_cap_deb = 2784795.435;                      % Volumetric heat capacity (J m-3 K-1)
% Calculate energy fux
for j = 2:11
    Q_rain_deb(j,1) = ((max(0,rhow.*cW.*(P./(sechr)).*(Td(j-1,1)-Td(j,1)))));
end
% Calculate temperature differencee
for j = 1:11
    Q_rain_temp(j,1) = (sechr).*((Q_rain_deb(j,1)) ./ (vol_heat_cap_deb));
end