| Applicability analysis of NDWI for drought monitoring in Henan Province |
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| DOI：10.7606/j.issn.1000-7601.2020.06.28 |
| Key Words: normalized difference water index (NDWI) soil moisture drought monitoring information entropy |
| Author Name | Affiliation | | GU Jiahe | School of Surveying and Land Information, Henan Polytechnic University, Jiaozuo, Henan 454003, China； Heihe Water Resources and Ecological Protection Research Center, Lanzhou, Gansu 730030, China | | XUE Huazhu | School of Surveying and Land Information, Henan Polytechnic University, Jiaozuo, Henan 454003, China | | Dong guotao | Heihe Water Resources and Ecological Protection Research Center, Lanzhou, Gansu 730030, China | | CHENG Jiehai | School of Surveying and Land Information, Henan Polytechnic University, Jiaozuo, Henan 454003, China |
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| Abstract: |
| This paper analyzed the heterogeneity of places near weather stations by means of the entropy of 30 m NDVI images in Henan Province. Homogenous land cover sites were selected to calculate the correlation index between NDWI and measured soil moisture data, thus to demonstrate the applicability of NDWI in drought monitor\|ing.The results show that information entropy method can effectively screen soil moisture observation data; In time series, the measured soil moisture has a negative correlation with NDWI, and the correlation is higher when EVI>0.4. This demonstrates that high vegetation cover zones are more sensitive to the retrieval of soil moisture; According to the topography, Henan Province is divided into four regions of northern, central, southern and western regions. Day 121, day 201 and day 313 are selected to analyze the correlation between soil moisture and NDWI. The negative correlation between NDWI and soil moisture was the most stable and the correlation coefficient was high in the north\|central region where the terrain was relatively flat; According to the spatial distribution of NDWI, most areas of Henan Province suffered from drought in 2014 and most of the arid areas were located in the plain, especially in the north. In general, NDWI can be used to monitor crop drought in plain area and estimate drought trends and level. |
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