Effect of climate and structure on the progression of wooden check dam decay

Abstract

To gain better understanding of rates of decay of wooden check dams with different structures under different climate conditions, several dams of this type were examined under different environmental conditions over a 3 to 5-year period post-construction. Because a linear relationship was found between the mean (μ) and standard deviation (σ) of pilodyn penetration depth, mean penetration depth was taken as the indicator of deterioration, and relationships with check dam structural features and climate data recorded by AMEDAS were investigated. Multiple linear regression analysis revealed that temperature, climate index (CI) computed from rain days, warmth index computed from daily and annual mean air temperature, and altitude were the climate variables with the most effect on the rate of decay. With regard to dam structural features, factors such as specific discharge rate, water through width, dam length, and dam height had the most effect. Accordingly, in an effort to summarize the effects of climatic conditions and structural features, CI, altitude, and dam height were extracted as the most significant explanatory variables, and a formula for prediction of μ was obtained for each factor for up to 5 years post construction. The results showed that by taking into consideration regional conditions and calculating CI values from AMEDAS data, it is possible to predict the extent of decay of wooden check dams.

Keywords:

• Climate conditions
• Climate index
• Decay
• Structural features
• Wooden check dam

Acknowledgments

Instruction and advice on wooden check dam construction, including assistance with relevant records, were provided by several people, including Mr Michio Yamashima and Mr Takafumi Abe of the Aomori Prefecture Agriculture, Forestry, and Fishery department, and the Forrest Conservation Division of the Shizuoka Forestry Commission. Mr Yosuke Yamazaki and Mr Yasuhisa Shimizu of the Nagano Prefectural Government also provided invaluable assistance. Sincere gratitude is extended to all of the above.

Notes

Open AccessThis article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.