Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 19, 1905-1917, 2015
https://doi.org/10.5194/hess-19-1905-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
22 Apr 2015
Why is the Arkavathy River drying? A multiple-hypothesis approach in a data-scarce region
V. Srinivasan1, S. Thompson2, K. Madhyastha1, G. Penny2, K. Jeremiah1, and S. Lele1 1Ashoka Trust for Research in Ecology and the Environment, Royal Enclave Sriramapura, Jakkur Post, Bangalore, Karnataka, India
2Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, California, USA
Abstract. Water planning decisions are only as good as our ability to explain historical trends and make reasonable predictions of future water availability. But predicting water availability can be a challenge in rapidly growing regions, where human modifications of land and waterscapes are changing the hydrologic system. Yet, many regions of the world lack the long-term hydrologic monitoring records needed to understand past changes and predict future trends.

We investigated this "predictions under change" problem in the data-scarce Thippagondanahalli (TG Halli) catchment of the Arkavathy sub-basin in southern India. Inflows into TG Halli reservoir have declined sharply since the 1970s. The causes of the drying are poorly understood, resulting in misdirected or counter-productive management responses.

Five plausible hypotheses that could explain the decline were tested using data from field surveys and secondary sources: (1) changes in rainfall amount, seasonality and intensity; (2) increases in temperature; (3) groundwater extraction; (4) expansion of eucalyptus plantations; and (5) fragmentation of the river channel. Our results suggest that groundwater pumping, expansion of eucalyptus plantations and, to a lesser extent, channel fragmentation are much more likely to have caused the decline in surface flows in the TG Halli catchment than changing climate.

The multiple-hypothesis approach presents a systematic way to quantify the relative contributions of proximate anthropogenic and climate drivers to hydrological change. The approach not only makes a meaningful contribution to the policy debate but also helps prioritize and design future research. The approach is a first step to conducting use-inspired socio-hydrologic research in a watershed.


Citation: Srinivasan, V., Thompson, S., Madhyastha, K., Penny, G., Jeremiah, K., and Lele, S.: Why is the Arkavathy River drying? A multiple-hypothesis approach in a data-scarce region, Hydrol. Earth Syst. Sci., 19, 1905-1917, https://doi.org/10.5194/hess-19-1905-2015, 2015.
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Short summary
The paper asks why the Arkavathy River in southern India is drying. The study results indicate that anthropogenic drivers like groundwater pumping, eucalyptus plantations and channel fragmentation are much more likely to have caused the decline than changing climate. The multiple-hypothesis approach presents a systematic way of quantifying the relative contributions of different drivers, contributing to the policy debate and prioritizing new scientific research.
The paper asks why the Arkavathy River in southern India is drying. The study results indicate...
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