10 May 2020

Revealing the extent of the Hawke's Bay drought

12:52 pm on 10 May 2020

New images released by Nasa show the impact of the drought on the Hawke's Bay region.

A Nasa image of the wider Hawke's Bay region taken on 29 April, 2020.

Photo: Nasa

Niwa recently said Napier had experienced its driest January to April period on record, while Hastings has been in drought for over a month.

Some farmers have said it's the worst their family has seen in 113 years on the land.

Nasa's images, from its "Aqua" satellite, show the drought's impact on plants and trees.

The green image was taken on 2 May 2019 and the brown image on 29 April 2020.

A Nasa image of the wider Hawke's Bay region from 2 May 2019.

Photo: Nasa

"Much of the light green areas, which saw the most change, are pastoral and agricultural land; darker green areas are forested," Nasa said.

Another way to detect stressed vegetation was via a "Normalised Difference Vegetation Index" - (NDVI).

This Normalised Difference Vegetation Index (NDVI) image has brown areas, which show where plants are more stressed than normal, and greens indicate vegetation that is healthier than normal.

Photo: Nasa

Also obtained using a satellite, the NDVI is a measure of the health or "greenness" of vegetation based on how much red and near-infrared light it reflects, according to Nasa.

"Healthy vegetation with lots of chlorophyll reflects more near-infrared light and less visible light."

The NDVI image compares vegetation health from 5 March to 3 May 2020, against the longer-term average (2000-2010) for those months.

"Brown areas show where plants were more stressed than normal, and greens indicate vegetation that was healthier than normal."

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