The hydraulic loading rate (HLR) of the free water surface flow CW was calculated for the dry and rainy seasons by q=Q/A (Kadlec and Wallace 2009) where q is the HLR, in meters per hour (m h−1), Q is the inlet water rate, in cubic meters per hour (m3 h−1), and A is the wetland land area (m2). Detention times for the two periods were measured as Tr=V/Q hours (h); V is the maximum volume of the canal (m3), and Q is the inlet water rate (m3 h−1).