Monitoring of drought during pasture cover growth in Ardebil Province

The aim of this study was to monitor the drought condition of the rangelands of Ardabil province along with the preparation of the rangeland dispersal map and the study of basins and bogs in the province, as well as the selection of the most suitable indices for assessing the drought condition in the rangelands of Ardabil province and estimating the effect of rainfall during the growing season. On the amount of vegetation production in rangelands. Research method: In this research, in the first stage, based on the rainfall and temperature of 4 synoptic stations in Ardebil province during the period 2016- 1996 (1995-1376), the standard rainfall index (SPI) and the SEPI fuzzy index in time intervals 1, 3, 6 and 9 Monthly Estimated. Using GPS and Google Earth, more than 30,000 training points were required for the land use classification of the study area. Then, based on the images produced in July 2000 and 2015, land use change and distribution of rangelands in Ardebil province were estimated. To this end, an appropriate file shape should be prepared for distribution of pastures in the province of Ardabil. Then based on Landsat satellite imagery with fitting of various vegetation indices including NDVI, SAVI, TDVI and DVI indices, LST index, Ardabil province's rangeland condition was estimated for vegetation and temperature. Finally, based on Pearson correlation and multivariate regression, the relationship between each of the indices was calculated to identify the most suitable indicators for studying drought in the rangeland of Ardabil province. Based on the most suitable indices, drought monitoring was carried out in two Shirvan valley basins and Ghorbakhsh Basin. Findings: According to the extracted results of the SPI and SEPI indices at all stations studied in four different time periods, the SEPI index, considering the effect of temperature and evapotranspiration, compared with the SPI index, has a more normal situation than drought conditions for The province was estimated. Also, in 1396, based on both indicators, a total of 4 study stations and 4 time intervals were identified as the driest years during the studied period, and Khalkhal and Ardabil stations have the highest drought occurrences, respectively Severity and frequency occur. Based on the comparison of the results of the classification in the two study dates (1379 and 1394), it is shown that in some parameters, some parameters have been positive changes since 2000, including the area of dry land, dryland farms, gardens and Residential areas and in some other parameters, such as the coverage of snow cover, pastures and forests, are decreasing. According to the results of vegetation indices, the peak of rangeland cover density in Ardebil province in two different periods due to the growth of vegetation in hill and bay areas is observed between November and November, and May to late May, respectively. According to the results of vegetation indices, May-May have the highest vegetation cover and the highest vegetation density in August is Ardabil province. The LST index also showed that the month of July has the highest frequency of maximum temperature and D-moon also has the highest frequency of minimum temperature, and the march of the month also has the most range of temperature variations. The results of the evaluation of the studied indices based on Pearson correlation test and multivariate regression showed that there was a significant correlation between SPI and SEPI index in different intervals, as well as 3-month SEPI indices and LST had minimum correlation with other indices. And no significant correlation was found at any of the levels of 0.05 and 0.01, and the 6-month SEPI index shows the highest correlations with vegetation indices, as a result of 6-month SEPI indices and NDVI vegetation index as The most suitable indices for drought study were introduced in the rangelands of Ardabil province. Based on the results of the 6-month SEPI index and NDVI, the drought condition of the rangelands in the two basins of Shirvan valley and Quri Tea was estimated. The results of the assessment in these two basins indicate a significant relationship between the monthly precipitation, the 6-month SEPI index and the NDVI index Be Also, the study of vegetation status in Shirvan Dareh basin in dry and wet periods during rangeland growth in the basin showed that drought and rainfall reduction during the growth period will have a very high effect on the amount of vegetation cover in rangelands. Conclusion: Based on the conclusions of the monitoring of drought in pastures Ardabil index of SEPI taking into consideration temperature and cold and mountainous region as well as the results of assessments, the best indices for the drought in the province of Ardabil And pastures are also directly related to monthly precipitation as natural resources. Therefore, the 6-month SEPI index is the most suitable drought index for drought monitoring in rangelands in the province. The vegetation index NDVI having the highest correlation with other vegetation indices and the amount of monthly precipitation as well as high impact as the independent variable for the amount of monthly precipitation as the most appropriate vegetation index for estimating drought and density of vegetation in the province Ardebil is.