Update doc/source/math_num_documentation/forward_structure.rst

Co-authored-by: Francois Colleoni <[email protected]>

doc/source/math_num_documentation/forward_structure.rst

@@ -382,7 +382,7 @@ Hydrological processes can be described at pixel scale in `smash` with one of th
     with :math:`q_{t}` the elemental discharge, :math:`P` the precipitation, :math:`E` the potential evapotranspiration,
     :math:`m_{lt}` the melt flux from the snow module, :math:`c_i` the maximum capacity of the interception reservoir,
     :math:`c_p` the maximum capacity of the production reservoir, :math:`c_t` the maximum capacity of the transfer reservoir,
-    :math:`t_e` controls the slope of the recession, 
+    :math:`b_e` controls the slope of the recession, 
     :math:`k_{exc}` the exchange coefficient, :math:`a_{exc}` the exchange threshold, :math:`h_i` the state of the interception reservoir, 
     :math:`h_p` the state of the production reservoir and :math:`h_t` the state of the transfer reservoir,
     :math:`h_e` the state of the exponential reservoir.