For grain size distribution of floodplain sediments, sediment samples were first sieved through a 2 mm diameter sieve. Samples less than 2 mm in diameter (10 g) were left overnight in 50 ml of 35 % hydrogen peroxide (H2O2) and heated the next day to remove organic matter. Subsequently, the samples were dispersed using 10 ml of 0.4 N sodium pyrophosphate solution (Na4P2O7) and got ultrasonic treatment for 45 minutes. Grain size analysis was performed for the sand fraction using the dry sieving technique (2000-630 µm: coarse sand, 630-200 µm: medium sand, 200-125 µm: fine sand, 125-63 µm: very fine sand). The finer fractions (63-20 µm: coarse silt, 20-6.3 µm: medium silt, 6.3-2.0 µm: fine silt, 2.0-0.6 µm: coarse clay, 0.6-0.2 µm: medium clay and <0.2 µm: fine clay) were measured by X-ray granulometry (XRG) using a SediGraph III 5120 (Micromeritics). Freely available program GRADISTAT v9.1 was used to calculate D50 (median of grain size), D75/D25 and D75-D25.