New Paper ” Dam Safety Effects Due To Human Alteration Of Extreme Precipitation” By Hossain Et Al 2010

Our paper

 Hossain, F., I. Jeyachandran, and R.A. Pielke Sr., 2010: Dam safety effects due to human alteration of extreme precipitation. Water Resources Research, 46, W03301, doi:10.1029/2009WR007704

has appeared.

The abstract reads

“Very little is known about the vulnerability of dams and reservoirs to man‐made alteration of extreme precipitation and floods as we step into the 21st century. This is because conventional dam and reservoir design over the last century has been “one‐way” with no acknowledgment of the possible feedback mechanisms affecting the regional water cycle. Although the notion that an impoundment could be built to increase rainfall was suggested more than 60 years ago, dam design protocol in civil engineering continues to assume as “static” the statistical parameters of a low exceedance probability precipitation event during the lifespan of the dam. It is time for us to change our perceptions and embrace a hydrometeorological approach to dam design and operations.”

Our conclusion reads

“Today, we know little about the impact of dams and reservoirs on the alteration in precipitation patterns as we step into the 21st century. Dam design protocol in civil engineering continues to assume as “static” the statistical parameters of a low exceedance probability precipitation event during the life span of the dam. Our study seems to indicate that the impact of large dams on extreme precipitation is clearly a function of surrounding mesoscale and land use conditions [e.g., see Pielke et al., 2007; Douglas et al., 2009], and that more research is necessary to gain insights on the physical mechanisms of extreme precipitation alteration by dams. The changes in land use, for example from added irrigation, add a significant amount of water vapor into the atmosphere in the growing season, thereby fueling showers and thunderstorms [e.g., see Pielke and Zeng, 1989; Pielke et al., 1997; Pielke, 2001]. Such landscape changes can even alter large‐scale precipitation patterns such as the Asian monsoon [e.g., see Takata et al., 2008].”

“Although the focus of our paper is primarily on how dams may alter extreme precipitation patterns and consequentially the flood frequency relationship, we should also recognize that there are other direct ways that the discharge into a reservoir may increase in frequency and magnitude (such as urbanization and other changes in land cover). Whatever the possible causes might be, it is timely for the civil engineering profession to change perceptions and embrace an interactive hydrology‐atmospheric science approach to safe dam design and operations for the 21st century.”

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