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   "source": [
    "# Prepare lake bounds shapefile\n",
    "---\n",
    "### This notebook writes a shapefile to use to create a mask around Lake Mead\n",
    "\n",
    "We will use this shapefile to create a mask with the time slider and other visualizations in this repository."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# notebook dependencies\n",
    "import geopandas as gpd\n",
    "import rasterio as rio\n",
    "import xarray as xr\n",
    "import pyproj\n",
    "from rasterio.mask import mask"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We use a [2003 USGS shapefile of the shores of Lake Mead](https://pubs.usgs.gov/of/2009/1150/gis/basemap/lakebndsmeta.htm). This is located in `aux_files/lakebnds`. We will write a new shapefile `aux_files/bufferlakebnds.shp`. We also load in one DSWx GeoTIFF as a reference image."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "shapepath = 'aux_files/lakebnds/lakebnds.shp'\n",
    "bufferpath = 'aux_files/bufferlakebnds/bufferlakebnds.shp'\n",
    "filepath = 's3://opera-pst-rs-pop1/products/OPERA_L3_DSWx-HLS_T11SQA_20201002T180918Z_20230118T203131Z_L8_30_v0.0/OPERA_L3_DSWx-HLS_T11SQA_20201002T180918Z_20230118T203131Z_L8_30_v0.0_B01_WTR.tif'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We reproject the shapefile to the same coordinate system as DSWx, create a 500 pixel buffer, and write to a new shapefile."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "df = gpd.read_file(shapepath)\n",
    "df_new = gpd.GeoDataFrame(columns=['BNDTYPE', 'geometry'], geometry='geometry')\n",
    "f = xr.open_rasterio(filepath)\n",
    "df_new['BNDTYPE'] = df['BNDTYPE']\n",
    "df_new['geometry'] = df.geometry.to_crs(pyproj.CRS.to_epsg(pyproj.CRS.from_proj4(f.crs))).buffer(4000,join_style=2)\n",
    "df_new.to_file(bufferpath)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The new shapefile `aux_files/bufferlakebnds.shp` is already provided as part of this repository."
   ]
  }
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