Local-scale
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Survey effort (m)
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Continuous
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Length of the segment surveyed
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Survey-segment specific
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100–400
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Hydrology
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River width (m)
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Continuous
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Distance between both the banks of the river was measured using Nikon Forestry Pro Range Finder (Nikon Inc., Minato, Tokyo, Japan) by standing on either sides of the river bank at every 50 m distance and then average was calculated for respective segment.
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Survey-segment specific
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22–537
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River depth (m)
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Continuous
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Depth of the river measured at every 50 m distance using a depth stick then averaged for the respective segment.
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Survey-segment specific
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0.3-5
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Topography
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Sand bank
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Binary
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Presence/absence of sand deposits on the river bank recorded every 50 m along the segment and then assigned to the site.
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Site
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1,0
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Islands
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Binary
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Presence/absence of prominent rock/sand mass in the river surrounded by water was visually recorded at every 50 m distance for the respective segment and then assigned to the site.
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Site
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1,0
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Stream substrate
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Categorical
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We recorded the dominant river bed substratum within 15 m x 15 m plot categorized as rocky, stony (fist-sized rocks), muddy (silt and clay), loose sand (coarse and loosely packed sand) and gravels (small-sized pebbles roughly under 5 mm in diameter) at every 50 m distance and assigned the dominant substratum to the respective segment.
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Survey-segment specific
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NA
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Vegetation
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Bank vegetation (ha)
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Continuous
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Area covered by bank vegetation in each sampling plot was recorded every 50 m distance in a 15 m x 15 m plot along each segment and then averaged for the site
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Site
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0.07-10
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Grass cover (%)
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Continuous
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Percent area covered by grasses was recorded every 50 m distance in a 15 m x 15 m plot and then averaged for the respective segment.
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Survey-segment specific
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5–90
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Proximity to natural vegetation (m)
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Continuous
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Distance to natural vegetation (woodland, grass and shrubs) from the river bank was measured at every 50 m and then averaged for the respective segment. The maximum distance was taken up to 300 m.
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Survey-segment specific
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10–300
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Riparian canopy Cover (%)
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Continuous
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The proportion of 15 m x 15 m plot covered by the vertical projection of the tree crowns measured at every 50 m along the banks of the segments and then averaged for the site
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Site
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5–60
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Disturbance
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Anthropogenic pressure (score)
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Continuous
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In total, six types of anthropogenic activities were observed in the study area (tourism, high weed cover, fishing, visual solid waste pollution, sand mining and poaching/snaring). The score was assigned based on the number of types of anthropogenic activities observed in the respective site i.e. higher the score indicates higher intensity of anthropogenic activities.
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Site
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1–6
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Water clarity
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Categorical
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We recorded the overall dominant type of water clarity based on water colour as turbid (dark, muddy and less clear) and non-turbid (clear) for the entire segment
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Site
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1,0
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Check dam/anicut
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Binary
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Presence/absence of check dams (anicuts) was recorded along the segments surveyed
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Site
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1,0
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Weed cover (%)
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Continuous
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Overall percentage of the total area in the sample plot (15 m x 15 m) covered by weed species (Ipomea carnea, Alternanthera philoxeroides, Polygonum chinensis and other species) were visually estimated every 50 m distance then averaged for the respective segment.
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Survey-segment specific
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2–80
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Landscape scale
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Topography
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Island size (ha)
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Continuous
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Using the Karnataka Geographic Information System Web Portal (https://kgis.ksrsac.in/kgis1/portal.aspx) we overlayed the State Wetland layer that had islands. We then used the area measurement tool to draw polygons around each island (ha). The total area covered by one or more islands in a site was calculated and assigned to each site.
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Site
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0.8–80
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Elevation (m.a.s.l; )
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Continuous
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Log-10 of average elevation of the reach
Downloaded 15 arc-seconds high resolution polyline feature of the Global river reach database RiverATLAS (Ouellet et al. 2018) and then used the intersect tool from the analysis toolbox in ArcMap 10.1 to measure the average elevation in each site.
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Site
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2.58–2.66
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Stream gradient (decimeters per km)
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Continuous
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Stream gradient is the ratio between the elevation drop within the river reach (i.e. the difference between min. and max. elevation along the reach) and the length of the reach (Linke et al. 2019).
Downloaded the 15 arc-seconds polyline features of hydro-environmental sub-basin and river reach characteristics (Linke et al. 2019). Wherever there was more than one polyline feature intersecting a site for stream gradient (originally derived from Robinson et al. 2014), we measured the average values of multiple polyline features for the particular layer and assigned it to the site.
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Site
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5–89
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River slope (°)
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Continuous
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Slope values calculated from 90 m elevation (CGIAR-CSI SRTM v4.1 and ASTER GDEM v2
data products) based on Horn’s method with latitudinal corrections (Linke et al. 2019).
Downloaded the 15 arc-seconds polyline features of hydro-environmental sub-basin and river reach characteristics (Linke et al. 2019). Wherever there was more than one polyline feature intersecting a site, we measured the average values of river slope (originally derived from Robinson et al., 2014) from multiple polyline features in each site.
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Site
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3–83
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Hydrology
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Total stream power (Kw/m2)
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Continuous
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Total stream power calculated as ‘water density [kg/m3] x gravitational acceleration [m/s2] x discharge [m3/s] x stream gradient [m/m]’; with stream gradient calculated as the maximum minus the average elevation of the reach, divided by the length of the reach (Ouellet et al. 2018).
Downloaded 15 arc-seconds high resolution polyline feature of the Global river reach database RiverATLAS (Ouellet et al. 2018) and then used the intersect tool from the analysis toolbox in ArcMap 10.1 to measure the total stream power in each site.
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Site
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0.002–64.32
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Distance from the most downstream pixel of the reach (km)
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Continuous
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Distance from the reach outlet (Lehner and Grill 2013)
Downloaded 15 arc-second resolution polyline feature of the global river network delineation derived from HydroSHEDS data (Lehner and Grill 2013) to extract the distance from the most downstream pixel of the reach for each site using the intersect tool in ArcMap 10.1.
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Site
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746.8-783.2
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Area of the catchment (km2)
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Continuous
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Area of the catchment that contributes directly to the individual reach (Lehner and Grill 2013)
Downloaded 15 arc-second resolution polyline feature of the global river network delineation derived from HydroSHEDS data (Lehner and Grill 2013) to extract the area of the catchment for each site using the intersect tool in ArcMap 10.1.
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Site
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2.48-128.08
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Order strata
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Categorical
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River order following the Strahler’s ordering system: order 1 represents headwater streams; when two 1st order streams meet, they form a 2nd order river; when two 2nd order rivers meet, they form a 3rd order river
Downloaded 15 arc second resolution polyline feature of the global river network delineation derived from HydroSHEDS data (Lehner and Grill 2013) to extract the Strahler’s stream ordering system (Strahler 1957) in each site using the intersect tool in ArcMap 10.1.
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Site
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1–4
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Flow direction
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Categorical
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Flow direction determines the direction where the water flows in a given cell
Downloaded the 3-arc sec high-resolution global hydrogeography raster data based on the latest topography dataset, MERIT Hydro by Yamazaki et al. (2019) and applied Zonal statistics from the Spatial Analyst toolbox in ArcMap 10.1 to measure majority of the flow direction category in each site.
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Site
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NA
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Surface water transition
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Categorical
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The transition layer captures changes between seasonal and permanent water (Pekel et al. 2016).
Downloaded the 30 m high resolution Global Surface Water (1984–2019; Pekel et al. 2016) raster data that measures the long-term history of water detections. We applied Zonal statistics from the Spatial Analyst toolbox in ArcMap 10.1 to extract majority of the transition phase in each site.
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Site
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NA
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Occurrence change intensity of surface water (%)
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Continuous
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The occurrence change intensity captures the direction of change and its intensity (increased, decreased or remained the same; Pekel et al. 2016).
Downloaded the 30 m high resolution Global Surface Water (1984–2019; Pekel et al. 2016) raster data and applied Zonal statistics from the Spatial Analyst toolbox in ArcMap 10.1 to measure the mean values of occurrence change intensity in each site.
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Site
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-100-100
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Recurrence of surface water (%)
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Continuous
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The recurrence layer captures the frequency with which water returns from year to year (Pekel et al. 2016).
Downloaded the 30 m high resolution Global Surface Water (1984–2019; Pekel et al. 2016) raster data and applied Zonal statistics from the Spatial Analyst toolbox in ArcMap 10.1 to measure the mean recurrence of water in each site.
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Site
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1-100
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River network geometry ( χ' )
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Continuous
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An index of the river structure that integrates channel length and drainage area by the scaling relationship between slope and area, resulting in a characteristic length parameter, under the influence of precipitation distribution on the river discharge.
Downloaded the 15 arc-seconds global river network geometry polyline feature (Giachetta and Willett 2018) and then used the intersect tool from the analysis toolbox in ArcMap 10.1 to extract the river network geometry ( χ' ) for each site.
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Site
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7.42–9.18
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Stream confluence
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Binary
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Junctions/nodes in each site which had multiple sub-stream features
Downloaded the 15 arc-seconds global river network geometry polyline feature (Giachetta and Willett, 2018). Then using ArcMap 10.1 we identified the nodes in each site which had multiple sub-stream polyline features.
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Site
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1,0
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River area (ha)
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Continuous
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The surface area of the river reach by multiplying channel width and length.
Downloaded the 15 arc-seconds polyline features of hydro-environmental sub-basin and river reach characteristics (Lehner and Grill 2013). Wherever there was more than one polyline feature intersecting a site, we measured the average values of river area from multiple polyline features in each site.
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Site
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0.23-78
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Land uses
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Sugarcane fields, rice fields, banana plantations, coconut plantations, barren land, fallow land (ha)
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Continuous
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We identified the major land cover types using Google Earth Pro 2018 imagery and digitized the shapefiles of land cover types for further processing in ArcMap 10.1. Then, using the intersect tool from the analysis toolbox in ArcMap 10.1, the shapefiles of each land use type within the 100 m buffer surrounding the boundary of TOCR was intersected with the polygon grid layer to measure the proportion of each land use (ha) in each site.
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Site
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0.1–22
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Disturbance
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Soil erosion (kg/ha)
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Continuous
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Based on the Global Potential Soil Erosion model (Borrelli et al. 2017)
Downloaded the 15 arc-seconds polyline features of hydro-environmental sub-basin and river reach characteristics (Lehner and Grill 2013). Wherever there was more than one polyline feature intersecting a site, we measured the average values of soil erosion from multiple polyline features in each site.
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Site
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2454–35954
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Area of road (ha)
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We identified roads and settlements using Google Earth Pro 2018 imagery and digitized the shapefiles for further processing in ArcMap 10.1. Then, using the intersect tool from the analysis toolbox in ArcMap 10.1, the shapefiles of road and settlement layer within the 100 m buffer surrounding the boundary of TOCR was intersected with the polygon grid layer to measure the proportion of area covered by roads and settlements (ha) in each site.
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0.04-2
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Area of settlement (ha)
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0.05-3
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