Water Resources Engineering (WRE) connects engineering hydrology and hydraulics with global, economic, environmental , and societal issues. Our student Cambria Ziemer makes this connection here. . .
The journal article entitled, “Response of Rainfall and Vegetation to ENSO Events during 2001-2011 in Upper Wardha Watershed, Maharashtra, India” was reported by the American Society of Civil Engineers Journal of Hydrologic Engineering in March 2014. This article relates to the WRE domain of hydrology and the specific issue of the distribution of rainfall during the El Nino Southern Oscillation. This study looked at daily precipitation data and the Normalized Difference Vegetation Index (NDVI) and correlated anomalies with El Nino or La Nina years. It was concluded that El Nino years produce dry conditions while La Nina years produce wet conditions with prolonged rainfall, as seen in Figure 1. In addition, NDVI anomalies revealed similar patterns with low values during El Nino years and high values during La Nina years. Based on my engineering education my opinion is that the WRE facts in the news are accurate, as supported by the following research citations. Researched in Kenya and Tanzania have also analyzed the effect of ENSO events on rainfall and NDVI and concluded that the occurrence of droughts and floods coincided with the occurrence of ENSO events (Ogutu et al., 2008). Many researchers have conducted studies in India relating ENSO events to other parameters, such as the occurrence of monsoons (Krishna Kumar et al., 2006). Krishna Kumar found that severe droughts in India coincide with El Nino events. Based on critical thinking on this journal article, I think the article is missing information regarding the change in growing season length. The article mentions this as an application of the study, but it does not state how the length of the growing season changes between normal, El Nino, and La Nina years.
The results of this study relate to the broader context of economics, which relates the behavior of individuals as well as organizations as they manage and use limited resources to provide needs and meet goals. Rainfall patterns affect economics because it affects how much water is available for irrigation and for crop use, which in turn affects crop yields over a season. Predicting precipitation patterns, as revealed in this study, allows farmers to change management practices to accommodate for climatic factors year to year. Researchers found that there was a decrease in the agricultural economy during El Nino years as a result of the dry conditions (Gadgil et al., 1999). The cause effect relationship between ENSO and the economy is that ENSO induces dry conditions that are not suitable for agriculture and many crops fail during these years, which reduces the supply of food in a demanding market.

Figure 1. Rainfall anomaly maps: top row represents El Nino years and bottom row represents La Nina.

Figure 1. Rainfall anomaly maps: top row represents El Nino years and bottom row represents La Nina.

References

Gadgil, S., Abrol, Y. P., and Seshagiri Rao, P. R., “On growth and fluctuation of Indian food grain production.” Curr. Sci., 1999, 76, 557-569.

Krishna Kumar, K., Rajagopalan, B., Hoerling, M., Bates, G., and Cane, M. Unraveling the mystery of Indian monsoon failture during El Nino. Science, 2006, 314(5796), 115-119.

Ogutu, J. O., Piepho, H. -., Dublin, H. T., Bhola, N., & Reid, R. S. El niño-southern oscillation, rainfall, temperature and normalized difference vegetation index fluctuations in the mara-serengeti ecosystem. African Journal of Ecology, 46(2), 2008, 132-143.

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