Within a single week, several major rivers in India’s northern Bihar state burst their banks under the onslaught of additional heavy rain. Rivers flowing out of the Himalaya Mountains in Nepal along the top of the image had expanded to such a degree by September 27, 2006, that it’s difficult to distinguish one from another in the top Moderate Resolution Imaging Spectroradiometer (MODIS) image. Already running high on September 20, when the lower image was taken, the Bagmati, Lakhandai, Sapt Kosi, and their tributaries are particularly flooded. The rivers flow south through Bihar and empty into the Ganges, the lower branches of which appeared flooded in an adjacent image. The southern tributaries of the Ganges shared a similar fate: The rivers form a large pool where they run parallel to the Ganges’ southern bank along the bottom of the image. A Reuters report issued on September 27 said that floods had killed 23 people in Bihar since September 20, and tens of thousands of additional people were homeless or stranded.
Both images shown here were created from both visible and infrared light. This combination makes water, which might otherwise blend in with the landscape, appear dark blue or black, while the surrounding plant-covered land is bright green. Because they increase the contrast between water and land, the infrared and visible images are useful for tracking floods. Clouds are light blue and white, while non-vegetated land is tan. The top image was made with data collected by the MODIS sensor on NASA’s Terra satellite on the morning of September 27, while the lower image was made with data collected by the MODIS sensor on NASA’s Aqua satellite on the afternoon of September 20, 2006. Both images are available in photo-like true color from the MODIS Rapid Response Team.
NASA images courtesy the MODIS Rapid Response Team at NASA GSFC.
