Application Of 137CS fingerprinting technique to interpreting sediment production records from reservoir deposits in a small catchment of the Hilly Loess Plateau, China

According to variations of Cs-137 and clay contents, 44 flood couplets were identified in a profile of reservoir deposit with a vertical length of 28.12 m in the Yuntaishan Gully. Couplet 27 at the middle of the profile had the highest average Cs-137 content of 12.65 Bq(.)kg(-1), which indicated the 1963s' deposits, then Cs-137 content decreased both downward and upward in the profile. The second top and bottom couplets had average Cs-137 contents of 2.15 Bq(.)kg(-1) and 0.92 Bq(.)kg(-1), respectively. By integrated analysis of reservoir construction and management history, variations of Cs-137 contents over the profile, sediment yields of flood couplets and rainfall data during the period of 1958-1970, individual storms related to the flood couplets were identified. 44 floods with a total sediment yield of 2.36 x 10(4) m(3) occurred and flood events in a year varied between 1 and 10 times during the period of 1960-1970. 7-10 flood events occurred during the wet period of 1961-1964 with very wet autumn, while only 1-2 events during the dry period of 1965-1969. Average annual specific sediment yield was 1.29 x 10(4) t(.)km(-2.)a(-1) for the Yuntaishan Gully during the period of 1960-1970, which was slightly higher than 1.11 X 10(4) t(.)km(-2-)a(-1) for the Upper Yanhe River Basin above the Ganguyi Hydrological Station and slightly lower than 1.40 X 10(4) t(.)km(-2.)a(-1) for the nearby Zhifang Gully during the same period. Annual specific sediment yields for the Yuntaishan Gully were correlated to the wet season's rainfalls well.