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Exploring Linkages between Ecological Stream Health, and Land-use in the Kathmandu Valley, Nepal
Jeff Davids, Nischal Devkota, Petra Izbound, Anusha Pandey, Ram Devi Tachamo Shah, Deep Narayan Shah, Martine Rutten

Last modified: 2017-08-28

Abstract


It is undeniable that comprehensive scrutiny of linkages between water quality, water flow, and land-use is essential for proper urban planning and land management. However, in developing cities like Kathmandu, unintegrated land planning and water resource management have put undesired pressure on freshwater resources, thus disrupting the stability between land-use, stream quality and flow. To investigate this scenario further, we conducted a study in nine perennial tributaries of Bagmati river in monsoon and pre-monsoon seasons. We used the RSA (Rapid Stream Assessment protocol) to characterize stream ecological health, hand-held probes to measure dissolved oxygen, electrical conductivity and water temperature, and a SonTek Flowtracker to measure flow. A land-use coverage classification into six different land-use types at a 30m spatial resolution was produced from a Landsat 8 image scene captured in the fall of 2015, which was further validated from ground-based observations. Catchment areas of measurement locations and relative areas of different land-use types were determined using a SRTM (Shuttle Radar Topography Mission) 30-meter Digital Elevation Model. Overall, we found strong correlations between stream ecological health, land-use and flow. RSA showed the headwaters of all streams except Balkhu to be in good conditions in both seasons.  The downstream sections where developed land within the catchment exceeded 20% were polluted. Stream health in some downstream reaches were better in monsoon compared to pre-monsoon, which could be attributed to the difference in discharge. We are currently working towards involving citizen scientists to collect land-use data and assess ecological health and flow of streams.



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