Monitoring Of Drought In Qinghai Province Based On MODIS Products

Drought is a complex natural phenomenon that frequently occurs throughout the world. It would cause harm not only to the natural environment, but also to the human society. Qinghai Province is located in the Qinghai-Tibet Plateau, where the ecological environment is fragile. Because of the uneven distributions of precipitation, the Qinghai Province surrfers severe droughts in a large area frequently. The traditional method, due to the distributions of meteorological stations, there is some deficiency such as data randomness, not real-time processing and so on. On the other hand, the traditional method requires a lot of manpower, material and financial resources. A single point of data can not represent the wide range of difficult soil moisture and crop growing information. It can not meet the real-time drought monitoring of large area requirements.Compare with the traditional drought monitoring, remote sensing technology has a lot of advantange such fast, efficient, low cost and easy data acquisition. So it has important significance to using remote sensing technology in drought monitoring of Qinghai Province.In this paper, the currently most used remote sensing data sources for drought monitoring at home and abroad are collated and analyzed. Then analyzed and discussed the advantages and disadvantages of the different drought monitoring methods based on remote sensing and there scopes of application. Then useing MODIS land surface temperature data MOD11A2and normalized difference vegetation indecx data MOD13A2from NASA to compute Temperature Vegetation Drought Index (TVDI) in Qinghai Province. Spatial and temporal variation characteristics of drought in Qinghai Province were monitored and analyzed. Finally, the temperature data and precipitation data obtained in the12meteorological stations in study area and the the surface elevation data are used to discusse their relationship with TVDI. The main contents and conclusions were as follows:(1) TVDI index calculated from the MODIS land product data can basicly reflect the drought distribution in Qinghai Province.The drought in Qinghai Province has a distinct spatial distribution pattern, in line with the actual soil moisture conditions. Moist and humid areas are mainly distributed in Haibei Autonomous Prefecture, northeast of Haixi Autonomous Prefecture, and partial Southern Qinghai Plateau where Yushu Tibetan Autonomous Prefecture located in. Qaidam Basin is arid regions.(2) Qinghai Province severes spring drought, especially in the eastern part of Qinghai, where the ground water situation is mainly arid and partial drought. Although the rainy season as come as the summer, the precipitation increased as well, but the rise in temperature causes evaporation increasing. So the drought did not get eased. Into the fall, with lower temperatures and summer cumulative rainfall, the drought gets eased.(3) TVDI has a negative correlation with the monthly precipitation values, accumulative precipitation values and precipitation anomaly in Qinghai Province. It means that with the increases of regional precipitation, the surface gets moister, and so the drought gets eased, TVDI value decreased coincide. TVDI value of monthly average temperature in Qinghai Province was positively correlated with the monthly mean temperature. The higher of the monthly average temperature, the higher the TVDI value will be.(4) Drought distribution of Qinghai significantly affected by altitude. With the rise of altitude, moist and humid area ratio of partial regions showed an increasing trend. Drought and partial drought ares mainly distribute in low-lying areas which’s altitudes below3,200meters above sea level. In the area of land where there elevations between2600meters and2800meters, the arid and arid areas accounts for more than95%of the total area of this altitude band. Generally the high altitudes ares have good water condition. In the areas where elevations are above3800meters, arid areas of only take5%of the total area.