Shrinkage of Nepal’s Second Largest Lake (Phewa Tal) Due to Watershed Degradation and Increased Sediment Influx
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Univ Arizona, Dept Hydrol & Atmospher SciIssue Date
2019-02-02
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Watson CS, Kargel JS, Regmi D, Rupper S, Maurer JM, Karki A. Shrinkage of Nepal’s Second Largest Lake (Phewa Tal) Due to Watershed Degradation and Increased Sediment Influx. Remote Sensing. 2019; 11(4):444.Journal
REMOTE SENSINGRights
© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Phewa Lake is an environmental and socio-economic asset to Nepal and the city of Pokhara. However, the lake area has decreased in recent decades due to sediment influx. The rate of this decline and the areal evolution of Phewa Lake due to artificial damming and sedimentation is disputed in the literature due to the lack of a historical time series. In this paper, we present an analysis of the lake's evolution from 1926 to 2018 and model the 50-year trajectory of shrinkage. The area of Phewa Lake expanded from 2.44 +/- 1.02 km(2) in 1926 to a maximum of 4.61 +/- 0.07 km(2) in 1961. However, the lake area change was poorly constrained prior to a 1957-1958 map. The contemporary lake area was 4.02 +/- 0.07 km(2) in April 2018, and expands seasonally by 0.18 km(2) due to the summer monsoon. We found no evidence to support a lake area of 10 km(2) in 1956-1957, despite frequent reporting of this value in the literature. Based on the rate of areal decline and sediment influx, we estimate the lake will lose 80% of its storage capacity in the next 110-347 years, which will affect recreational use, agricultural irrigation, fishing, and a one-megawatt hydroelectric power facility. Mitigation of lake shrinkage will require addressing landslide activity and sediment transport in the watershed, as well as urban expansion along the shores.Note
Open access journalISSN
2072-4292Version
Final published versionSponsors
NASA IDS grant [80NSSC18K0432]; NASA HMA grant [NNX16AQ61G]Additional Links
http://www.mdpi.com/2072-4292/11/4/444ae974a485f413a2113503eed53cd6c53
10.3390/rs11040444
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Except where otherwise noted, this item's license is described as © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.