Publications

Zhang, JY; Bai, JJ (2016). The Spatial-Temporal Dynamic Monitor of Spring Drought Based on TVDI Model in Guanzhong Area. 2016 FIFTH INTERNATIONAL CONFERENCE ON AGRO-GEOINFORMATICS (AGRO-GEOINFORMATICS), 507-512.

Abstract
The study of regional land surface soil water is a promising field in agricultural drought monitoring by remote sensing, and estimating soil moisture is one of the commonly used indicators in agricultural drought monitoring, based on this to establish Temperature Vegetation Dryness Index (TVDI) is an important method of reflecting agricultural drought condition, it refers to two parameters including surface temperature and vegetation index. Using the data set of the moderate-resolution imaging spectroradiometer (MODIS) MOD13A2 obtained every 16-day composite MODIS normalized difference vegetation index (NDVI) and MOD11A2 obtained every 8-day composite MODIS surface temperature (Ts) to construct Ts-NDVI feature space. Every 16-day soil moisture from February to May in Guanzhong area - s retrieved by using TVDI which - s calculated from the dry edge and the wet edge equations matched the feature space as an indicator in monitoring soil moisture. When verifying the inverse results with the homologous measured meteorology data coming from area meteorological site, the results shows that:(1) The deductive surface temperature could be used as the actual value, considering the average error is 0.258 degrees C by a comparison between measured temperature and temperature retrieval from MOD11A2 data. (2) TVDI is corrected to 10 similar to 20cm soil moisture significantly (alpha=0.05). The spatial pattern and temporal evolution in TVDI have been analyzed by using the crop phonological development, average atmosphere temperature and precipitation data over the years. The temporal evolution of drought is consistent with crop phonological development. The drought is the worst in March and April. From the point of the whole time, the drought is mainly in medium level in Guanzhong area, then is light drought, heavy drought, normality and moist, this result is also the same as the actual situation. And the spatial distribution of drought accords with the distribution of terrain, precipitation and manual irrigation. The drought in southwest of Baoji and Xi'an is the best, while the drought in Guanzhong middle part which traversing the east-west direction is the worst, it forms the so -called drought belt. The drought in Weihe Plain is worse than that of south Qinling region. The whole drought distribution presents that the northeast is dry, but wet in the southwest. There is a higher correlation between TVDI and 10 similar to 20cm soil moisture in linear fitting TVDI and 0 similar to 10cm 10 similar to 20cm soil moisture, which indicates that TVDI can reflect and instruct land surface 10 similar to 20cm soil moisture condition. These results suggest that TVDI can effectively reflect the spring actual drought in Guanzhong area. So, it can be used to monitor drought dynamically during spring in Guanzhong area.

DOI:

ISSN:
2334-3168