Water quality assessment of urban catchment after the large-scale flood event: The worst natural tragedy at Pahang River, Malaysia

Floods are the most significant natural disasters, which have brought miseries to approximately 23 billion victims over the last 20 years. The 2014 flood tragedy is recognized as the “Tsunami-like disaster” in the history of Malaysia. In that disaster, more than 404,000 victims were evacuated and at least 24 of them were reported deaths. In this work, the physicochemical alterations of the Pahang River, encompassing the solution pH, water temperature, turbidity, dissolved oxygen (DO), biochemical oxygen demand (BOD 5 ), chemical oxygen demand (COD), ammonical-nitrogen (AN) and total suspended solids (TSS) were evaluated, after the largest flood tragedy. The significant relationship between the changing water quality parameters was assessed using the multivariate statistical analysis. Results revealed that the pollution loads showed a great amplification after the heavy flood event, with the mean values for BOD 5 , COD, DO, AN, solution pH, TSS, and overall water quality index of 17.28 mg/L, 64.5 mg/L, 3.97 mg/L, 1.52 mg/L, 5.23, 39.44 mg/L and 40.93, respectively, as compared with 4.65 mg/L, 15.3 mg/L, 6.62 mg/L, 0.26 mg/L, 7.22, 7.9 mg/L and 65.95, respectively before flooding. This complementary study highlights the pressing urgency to update the existing emergency water quality strategic plan, and establish better healthcare facilities for future emergency responses.