Region Selection and Map Preview with Ipyleaflet

# Import the necessary libraries to format, send, and parse our returned results
import os

import birdy
import geopandas as gpd
import ipyleaflet
import ipywidgets

If your notebook is version prior to 5.3, you might need to run this command jupyter nbextension enable --py --sys-prefix ipyleaflet. For more information see https://ipyleaflet.readthedocs.io/en/latest/installation.html.

# Create WPS instances
# Set environment variable WPS_URL to "http://localhost:9099" to run on the default local server
pavics_url = "https://pavics.ouranos.ca"
raven_url = os.environ.get("WPS_URL", f"{pavics_url}/twitcher/ows/proxy/raven/wps")

raven = birdy.WPSClient(raven_url)

# Build an interactive map with ipyleaflet

initial_lat_lon = (48.63, -74.71)

leaflet_map = ipyleaflet.Map(
    center=initial_lat_lon,
    basemap=ipyleaflet.basemaps.OpenTopoMap,
)

# Add a custom zoom slider
zoom_slider = ipywidgets.IntSlider(description="Zoom level:", min=1, max=10, value=6)
ipywidgets.jslink((zoom_slider, "value"), (leaflet_map, "zoom"))
widget_control1 = ipyleaflet.WidgetControl(widget=zoom_slider, position="topright")
leaflet_map.add_control(widget_control1)

# Add a marker to the map
marker = ipyleaflet.Marker(location=initial_lat_lon, draggable=True)
leaflet_map.add_layer(marker)

# Add an overlay widget

html = ipywidgets.HTML("""Hover over a feature!""")
html.layout.margin = "0px 10px 10px 10px"

control = ipyleaflet.WidgetControl(widget=html, position="bottomleft")
leaflet_map.add_control(control)


def update_html(feature, **kwargs):
    html.value = """
        <h2><b>USGS HydroBASINS</b></h2>
        <h4>ID: {}</h4>
        <h4>Upstream Area: {} sq. km.</h4>
        <h4>Sub-basin Area: {} sq. km.</h4>
    """.format(
        feature["properties"]["id"],
        feature["properties"]["UP_AREA"],
        feature["properties"]["SUB_AREA"],
    )

# Load the map in the notebook
leaflet_map

Before continuing!

Try dragging and placing the marker at the mouth of a river, over a large lake such as Lac Saint Jean (next to Alma, east of the initial marker position), or anywhere else within North America.

user_lonlat = list(reversed(marker.location))
user_lonlat

[-74.71, 48.63]

# Get the shape of the watershed contributing to flow at the selected location.
resp = raven.hydrobasins_select(location=str(user_lonlat), aggregate_upstream=True)

# Before continuing, wait for the process above to finish.

# Extract the URL of the resulting GeoJSON feature
feat = resp.get(asobj=False).feature
gdf = gpd.read_file(feat)
gdf

	id	HYBAS_ID	NEXT_DOWN	NEXT_SINK	DIST_SINK	DIST_MAIN	SUB_AREA	UP_AREA	PFAF_ID	SIDE	LAKE	ENDO	COAST	ORDER	SORT	geometry
0	USGS_HydroBASINS_lake_na_lev12.99410	7129001061	7120323452	7120034520	517.6	517.6	8470.5	8773.1	725209301000	L	56	0	0	2	99410	POLYGON ((-75.18990 47.99540, -75.18190 47.994...

# Add this GeoJSON to the map above!
# Scroll back up after executing this cell to see the watershed displayed on the map.
user_geojson = ipyleaflet.GeoData(
    geo_dataframe=gdf,
    style={
        "color": "blue",
        "opacity": 1,
        "weight": 1.9,
        "fillOpacity": 0.5,
    },
    hover_style={"fillColor": "#b08a3e", "fillOpacity": 0.9},
)

leaflet_map.add_layer(user_geojson)
user_geojson.on_hover(update_html)