Lin Pingyi, July 1, 1897 - January 24, 1979
Lin Pingyi, a native of Ningbo City, Zhejiang Province in China, graduated from the Department of Civil Engineering of Tianjin Beiyang University (Tianjin University) in the summer of 1923. Then he went to study in the Department of Civil Engineering of Cornell University in September of 1923 and transferred to the Water Conservancy Engineering College of the University of Iowa in February of 1924. He got a master's degree in engineering in the spring of 1925. From 1925 to July 1927, he worked as an intern in an American Bridge Company and the New Allen Mississippi River Engineering Committee. From 1928 to 1930, he served as a professor at National Central University. From 1930 to 1937, he worked at the design group of the Guiding Huai River Committee. After the Anti-Japanese War broke out in 1937, Lin Pingyi moved to Chongqing with the Guiding Huai River Committee, and returned to Nanjing in July 1946. During this period, he served as the director of Qijiang Waterway Engineering Bureau, from 1938 to 1942 and chief engineer of the Guiding Huai River Committee in 1943. From October 1944 to April 1945, he went to the United States to investigate water conservancy. In July 1947, the Guiding Huai River Committee was reorganized into the Huai River Water Conservancy Engineering Bureau. Lin Pingyi served as the director until his departure in January 1949. After the founding of People’s Republic of China (PRC), he worked successively at the Ministry of Water Resources, technical committee of the Ministry of Water Resources and Electric Power, and a first-level engineer of the Water Resources and Hydropower Research Institute. He was elected as a member of the third and fourth National Committee of the Chinese People's Political Consultative Conference.
Lin Pingyi is one of the pioneers in Huai River governance. From 1928 to 1949, he presided over the design and construction of ship locks and dams, governed the excavation of the Yellow River into the sea, started the nation's construction of new water conservancy projects. He proposed the concept and method of unit hydrograph in the Masters’ thesis “Analysis on flood wave propagation speed”, which was earlier than Sherman unit hydrograph. He proposed the flood calculation method of small watershed, which was known as the “Lin Pingyi method” and widely used in hydrologic design. It is difficult to determine the parameters of the frequency curve with the shortage of hydrological series. In order to solve this problem, he proposed the “Short-series frequency line-fitting point method ( “Three point method” for short)”. It met the needs of constructing small and medium-sized conservancy projects. From 1962 to1966, he analyzed the peak-volume relationship of rainstorm floods in more than 300 small watersheds in eastern China and revealed the nonlinear characteristics of the peak-volume relationship. Based on these analysis, he proposed the nonlinear concentration calculation method for small and medium watersheds.