Variation Of Sediment Discharge Of The Drainage Areas Of Gan River, Fu River And Liao River From 1957 To 2007 And Its Environmental Significance

Based on long series data (1957-2007) of the sediment discharge at the three hydrological stations of the Waizhou Station of Gan River, the LijiaDu Station of Fu River and the Wanjiabu Station of Liao River, this paper aimed to reveal the variation pattern of the sediment discharge and the causes of water loss and soil erosion in the three drainage areas. Based on the study, some conclusions can be drawn:1,The annual average runoff of the three rivers tended to fluctuate without any periodicity from year to year in the 51 years. Sum of the monthly average runoff of the high flow period (from March to June) amounts to 49.01%,54.40% and 46.94% of the annual runoff in Gan River, Fu River and Liao River, respectively.2,There is a significant positively linear correlation between sediment concentration and runoff of each river. It indicates that the sediment concentration is controlled by the amount of precipitation in the three drainage areas. The sediment concentration represents the erosive power of rainfall on the earth's surface. The relation between decennial runoffs and sediment concentrations was studied, and the slope and intercept of the regression equations indicates:the erosive power of rainfall on the earth's surface has a tendency of decreasing after 1980s in the Gan River Basin, whereas it increased from 1950s to mid-1980s and decreased subsequently in Fu River Basin, and it increased from 1950s to the late 1970s and decreased subsequently in Liao River Basin.3,The annual average sediment discharge from 1957 to 2007 was 898.47±457.75 Mton for Gan River Basin,140.23±75.33 Mton for Fu River Basin and 36.87±23.80 Mton for Liao River Basin, respectively. The monthly average sediment discharge in the high flow period (from March to June) amounts to 49.01%,54.40% and 46.94% of the annual sediment discharge in Gan River Basin, Fu River Basin and Liao River Basin, respectively.4,The annual average sediment transport modulus from 1957 to 2007 was 111 t/km2·a for Gan River Basin,88.7 t/km2·a for Fu River Basin and 104.1 t/km2·a for Liao River Basin, respectively. Based on the distribution of the sediment transport modulus, it can be concluded that the loss of water and soil was most serious in Gan River Basin before 1970s, however the intensity of water and soil loss increased from Gan River Basin (47.05t/km2·a), through Fu River Basin (73.81 t/km2·a), to Liao River Bain (76.88 t/km2·a).