Short term drought monitoring using remote sensing technique: A case study of Potohar region, Pakistan

Drought has frequently been witnessed in the country due to various environmental changes such as rise in atmospheric pollution and climatic changes. Pakistan is predominantly arid and semi-arid with a diversified climate, where agriculture contributes 20.9 percent to national GDP. The Barani (rainfed) land covering Salt Range and Potohar Plateau (about 22,256 km
²
centered at 33.2° N and 72.75° E, at an elevation of 1,200 to 1,900 feet ASL). This area is more vulnerable to short term droughts with mean monthly rainfall in this area ranges from 30 to 200 mm with max. temperature up to 47 °C. Solar radiation (over 3,000 hours of sunshine/year) results in higher rate of evapo-transpiration. Such conditions and prolonged absence of regular rainfall lead to drought conditions affecting crop yield and economy of the country. NDVI product of MODIS Satellite was used for Rabi season (October to February) in order to investigate vegetation state and effects of drought on these crop. Soil Moisture data was incorporated to analyze water deficit pattern using NCEP global weather data from 2000–2012. The results showed that, there was a drastic decrease in mean NDVI during 2009–2010 winters' months due to low rainfall. This decrease in NDVI value seen from 2.2 in 2009–2010 as compared to average mean value of 2.9 for 2000–2012 of winter Monsoon months. Such relationship would help devise an early warning system to detect the onset of drought conditions and developing a continuous drought monitoring system. Based on such studies, future strategies for water management, mitigations could be worked out, such as preservation of water during summer monsoons to overcome the water stress in the coming winter season.