30 years of floods in India

Sun, 03 Sep 2017 19:01:00 +0530

Inspired by this post showing the major flooding events in the US, I created a similar graphic for India. You can find an interactive version here – hovering over each flooding, shows some more information about the event.

The graphic uses flooding related data from the Dartmouth Flood Observatory
The data for 2017 events is not up-to date.
It is very likely that there is some missing data, and some inaccuracies in the data. 1987, for instance, doesn’t show the Bihar flood.
The flood severity is indicated by the color of each shape
Each shape represents the geographic flood extents - based on information obtained from news sources.
The data for India map shape is obtained from this topojson collection

It is interesting to look at the severity definitions here – the extreme class floods, for instance, are defined to be those that have an estimated recurrence interval of over 100 years. In a span of 30 odd years, there are a whole bunch of regions which have been affected by extreme floods. Yet another case in point showing that the climate change shit has really hit the roof!

Code

I used ogr2ogr to convert the shape file obtained from the Dartmouth Flood Observatory

ogr2ogr -f geoJSON data/floods.json FloodArchive_region.shp

This file turned out to be about 6MB. I created a file with only Indian floods by parsing the json file.

import json

with open('floods.json', encoding='latin-1') as f:
    data = json.load(f)

india_features = [
    feature for feature in data['features']
    if feature['properties']['COUNTRY'] == 'India'
]
data['features'] = india_features

# FIX some names in the data
NAME_FIXES = [
    ('Tropical Storm K', 'Tropical Storm Komen'),
    ('Tropical Storm Hudhug', 'Tropical Storm Hudhud'),
]
for feature in india_features:
    for name, fix in NAME_FIXES:
        cause = feature['properties']['MAINCAUSE']
        if name in cause:
            feature['properties']['MAINCAUSE'] = cause.replace(name, fix)

with open('india-floods.json', 'w', encoding='latin-1') as f:
    json.dump(data, f)

The visualization code itself is about a hundred odd lines of d3 code.

Climate on Noetic Nought

30 years of floods in India

Code