Non-storage summer dry onion crop is among the top 10 agricultural commodities in New Mexico (NM), USA. In 2000, NM was ranked the second in the nation as the leading state in growing summer dry onion. According to USDA statistical records, onion production or sales in NM was valued at $91.4 million. Mesilla Valley is one of the major onion-producing regions of NM. Due to many years of drought in the region and the concern for climate change, irrigation managers and decision makers are interested in quantifying water use or evapotranspiration (ET) and the number of acreage of onion crop grown in the Valley. This information can then be used for managing the scarce water resources of the region. Plant phenology, Landsat-8 satellite data, and USDA crop data were used to identify onion crops in the Valley (area of about 47,000 ha) and to determine their consumptive water use or ET using remote sensing Regional ET Estimation Model (REEM) from 2014 through 2016. Time series of NDVI clearly identified Fall and Spring-season onion crops in the Valley. REEM estimated Springseason onion crop maximum ET of 973 mm in 2015 and 975 mm in 2016 during the growing season. These values compared reasonably well to ET estimates of 894 and 955 mm for the same periods (i.e. 2015 and 2016) using FAO-56 crop coefficient based method. The methodology presented could be used in other regions to identify onion crops and their consumptive water use.

The Global warming in the world cause to the climate change in this century. Agriculture is one of the sectors that can be most affected by climate change. Agricultural production is affected by precipitation and temperature variables. Due to the changes in these two parameters, the increase in the temperatures and the changes in the amount of precipitation in parallel with this disrupt the ecological balance and bring along the problems of desertification and drought. Agricultural production is highly dependent on meteorological factors in Thrace region. For this reason, it is expected that changes in climatic factors will affect the agriculture of the region positively or negatively. The aim of this study is to determine the frequency and severity of meteorological and agricultural drought with two indexes between 1963-2019 years in Kırklareli province. Standardized Precipitation Evapotranspiration Index (SPEI) was used to determine monthly, seasonal, six monthly and annual agricultural drought. According to annual agricultural drought results, it was calculated ten years mild arid (1969, 1985, 1986, 1990, 1991, 1992, 1993, 2011, 2016, and 2019), five years moderate arid (1983, 1989, 1996, 2008, and 2015), one year severe arid (1994), and two years extreme arid (2000 and 2001). Another drought index which is Standardized Precipitation Index (SPI) was used to determine meteorological drought. According to annual meteorological drought results, Eight years mild arid (1964, 1969, 1982, 1985, 1986, 1990, 1991, and 2011), seven years moderate arid (1983, 1989, 1992, 1993, 1994, 1996, and 2008), and two years extreme arid (2000, 2001) was figured out. According to linear correlation analysis, a good correlation was obtained for SPI and SPEI values, between annual, six monthly (Spring-Summer), and three monthly only winter and spring periods (R2=0.871, R2=0.901, R2=0.974, and R2=0.919), respectively. In the 57-year observation period; 18 years were determined as the arid year with SPEI index and 67% of these total arid years (12 arid years) occurred and 17 years were determined as the arid year with SPI index and 76% of these total arid years (13 arid years) occurred, between 1982 and 2002 years. The SPEI drought index which use precipitation, temperature and evapotranspiration data could give much good results to policy makers in drought mitigation policies in terms of giving results that are more accurate in agricultural production and drought assessments.