Problem

Why am I getting a warning message that says, " Relaxed Convergence" when I run a basin routing analysis?

Solution

In general, convergence warning messages are displayed when a solution does not converge/barely converges within the minimum tolerance even after reaching the specified maximum iterations.Check the specified tolerances and look into if these need to be relaxed to converge the model. Max./Min. HW Tol: If PondPack is checking computed headwater (HW) elevations during the iterative HW convergence computations, Max. HW Tol and Min. HW Tol values specify the minimum target convergence and the maximum allowable difference between the computed value and the known headwater value. Iterative computations on headwater are ended when either the solution converges within the minimum HW tolerance, or when more than the specified maximum iterations are performed. In general, smaller minimum HW tolerances should yield more precise convergence.Min./Max Q Tol: If the program is checking computed flow during the iterative TW convergence computations, these tolerance values specify the minimum target convergence and the maximum allowable differencebetween the computed flow value, and the known flow value. Iterative computations on flow are ended when either the solution converges within the minimum flow tolerance, or when more than the specified maximum iterations are performed. In general, smaller flow tolerances yield more precise convergence.You may want to increase the maximum number of iterations or increase the tolerances.