Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2016-562
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
14 Nov 2016
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
Spatial characterization of long-term hydrological change in the Arkavathy watershed adjacent to Bangalore, India
Gopal Penny1, Veena Srinivasan2, Iryna Dronova3, Sharachchandra Lele2, and Sally Thompson1 1Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, California, USA
2Ashoka Trust for Research in Ecology and the Environment, Royal Enclave Sriramapura, Jakkur Post, Bangalore, Karnataka
3Department of Landscape Architecture and Environmental Planning, University of California, Berkeley, Berkeley, California, USA
Abstract. The complexity and heterogeneity of human water use over large spatial areas and decadal timescales can impede the understanding of hydrologic change, particularly in regions with sparse monitoring of the water cycle. In the Arkavathy watershed in south India, surface water inflows to major reservoirs decreased over a 40 year period during which urbanization, groundwater depletion, modification of the river network, and changes in agricultural practices also occurred. These multiple, co-varying drivers along with limited hydrological monitoring make attribution of the causes of water scarcity in the basin challenging, and limit the effectiveness of policy responses. We develop a novel, spatially distributed dataset to understand hydrologic change by characterizing trends in surface water area in nearly 1700 rainwater harvesting and irrigation structures known as tanks. Using an automated classification approach with subpixel unmixing, we classified water surface area in tanks in Landsat images from 1973 to 2010. The classification results compared well with a reference dataset of water surface area of tanks (R2 = 0.95). We modeled water surface area of 42 clusters of tanks in a multiple regression on simple hydrological covariates and time, and found distinguishable trends in water surface area in different regions of the watershed. Agricultural areas with considerable groundwater irrigation exhibited the strongest drying. Urban land use was associated with intra-urban drying, likely due to tank encroachment, and downstream periurban wetting, likely due to increased urban effluents. Disaggregating the watershed-scale hydrological response via remote sensing of surface water bodies over multiple decades yielded a spatially resolved characterization of hydrological change in an otherwise poorly monitored watershed. This approach presents an opportunity for understanding hydrological change in heavily managed watersheds where surface water bodies integrate upstream runoff and can be delineated using satellite imagery.

Citation: Penny, G., Srinivasan, V., Dronova, I., Lele, S., and Thompson, S.: Spatial characterization of long-term hydrological change in the Arkavathy watershed adjacent to Bangalore, India, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2016-562, in review, 2016.
Gopal Penny et al.
Gopal Penny et al.
Gopal Penny et al.

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Short summary
Water resources in the Arkavathy watershed in southern India are changing due to human modification of the landscape, including changing agricultural practices and urbanization. We analyze surface water resources in man-made lakes in satellite imagery over a period of four decades and find drying in the northern part of the watershed (characterized by heavy agriculture) and wetting downstream of urban areas.
Water resources in the Arkavathy watershed in southern India are changing due to human...
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