A Improved Method for Drought Monitoring by Remote Sensing-Case of Mongolia

Abstract:

In recent years the annual drought caused great losses amounting to several tens of billions of dollars, such as USA Federal Emergency Management Agency (FEMA) estimates the drought caused 60-80 billion dollars in annual losses. Drought has not only affected the agricultural production, but also brings to the problems of drinking water, which poses a great threat to global food security and economic society for the sustainable development.

Remote sensing technology is effective and reliable for monitoring the drought status and change, which can provide drought information in near-real time, large areas, and long time series. With the satellite and spatial technology development, an effective drought monitoring methodology for supporting the disaster management and mitigation should be improved.

By now, we have many drought indices from remote sensing data, but these indices have the application scopes and appropriate conditions; for a certain region which has special geography and environmental features, how to apply for existed and available models? Is it enough to drought monitoring for coarse resolution data (MODIS, FY-3 and so on)? How to develop the combination drought model to express most of drought?

Aiming at serious drought of Mongolia, Making full use of the remote sensing technology, acquisition and analysis mechanism by the disaster information space, we try to find a drought monitoring method suitable for regions. Considering Mongolia’ geography, climate, land cover, we selected many indices to analyze the response to drought. Through correlation and spatial comparative analysis between RS indices, ground and drought statistics data from 2000 to 2014, the four indices (TCI, VCI, VHI and NDDI) has good reflection about the drought. Then based on three kinds land cover (forest, steppe and desert steppe) in different growing season, we determine sensitivity of different indices, and synthesizing them by combination method to monitor drought.

Also field campaign has been carried out for validation and calibration the drought results from remote sensing data. We found that the proposed method is good suitable for Mongolia drought monitoring. Similar to the Mongolia, California with a lot of steppe, less and unequal rainfall, combination methodology may be useful for California drought monitoring.