A statistical methodology for assessing the long-term effects of antecedent drought conditions on stream runoff: applications to the Piedmont Province, southeastern United States

作者：Rose Seth^*

来源：Hydrological Processes, 2011, 25(6): 901-914.

DOI：10.1002/hyp.7875

• antecedent rainfall
• drought
• runoff coefficients
• Piedmont Province stream flow
• rainfall-runoff relationships

A method was developed to investigate the long-term (months-to-years) effects (both magnitude and duration) of antecedent rainfall upon subsequent runoff coefficients (RCs) or runoff/rainfall ratios. The method was applied to a four-state region (Georgia, South Carolina, North Carolina, and Virginia) within the southeastern Piedmont Province of the United States and incorporated a 59-year data set of 19 United States Geological Survey stream gages and 57 National Climatic Data Center rain gages. The method was designed to facilitate statistical comparisons [Mann-Whitney rank sum tests] between various groups of normalized runoff coefficients (NRCs) representing 6-36 month periods which differed in terms of antecedent rainfall conditions. The results of this study show that under all subsequent rainfall conditions, with the exception of excess rainfall, a 1-year period of antecedent drought lowered NRCs for at least 1 year following the drought. The principal finding of this study is that a year-long drought period within the southeastern Piedmont Province lowers NRCs by similar to 25% during the following year when rainfall returns to normal. In most cases, RCs are significantly lower during the second year following a drought than they would be when anteceded by normal rainfall; however, the effects of drought wane during this period. This is a statistical and regional method that can be modified to other study areas; however, it cannot be used to predict storm-event rainfall-runoff relationships for any specific basin.

• 出版日期2011-3-15