Drought Evolution in the Srepok River Basin (2000-2022) Based on the Vegetation Health Index (VHI) and Standardized Precipitation Index (SPI)
Main Article Content
Abstract
This study aims to evaluate drought dynamics using the Vegetation Health Index (VHI) in the Srepok River Basin during the period 2000–2022 and to analyze the relationship between meteorological drought and vegetation condition. The Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) data derived from MODIS satellite imagery were utilized to calculate the VHI, while rainfall data from meteorological stations were employed to compute the Standardized Precipitation Index (SPI). The analysis shows that VHI exhibits the strongest correlation with SPI at a 6-month scale (SPI6), particularly in April, marking the end of the dry season. During the 23-year study period, drought events demonstrated a recurrence pattern of approximately 3–5 years, with severe episodes occurring in 2005 and 2016, coinciding with strong El Niño events. Spatial analysis indicates that the northwestern middle and lower sub-basins were most severely affected, with drought durations exceeding six months and frequencies greater than 14%. Crop-specific assessment shows that annual crops and rice were the most drought-sensitive groups, while perennial crops exhibited higher drought tolerance but still sustained significant damage due to their extensive cultivation area. These findings underscore the effectiveness of integrating VHI and SPI6 as tools for agricultural drought monitoring and early warning in the region.
Keywords:
VHI, SPI, drought, El Niño, Srepok.
References
[1] S. Park, J. Im, E. Jang, J. Rhee, Drought Assessment and Monitoring Through Blending of Multi-sensor Indices Using Machine Learning Approaches for Different Climate Regions, Agricultural and Forest Meteorology, Vol. 216, 2016, pp. 157-169, https://doi.org/10.1016/j.agrformet.2015.10.011.
[2] C. Parmesan, M. D. Morecroft, Y. Trisurat, Climate Change 2022: Impacts, Adaptation and Vulnerability, GIEC, 2022, https://hal.science/hal-03774939v1.
[3] M. L. Parry, Climate Change 2007-Impacts, Adaptation and Vulnerability: Working Group II Contribution to the Fourth Assessment Report of the IPCC, Cambridge University Press, Vol. 4, 2007.
[4] U. Nations, The Impact of Disasters and Crises on Agriculture and Food Security, Food and Agriculture Organization, 2017.
[5] A. F. V. Loon, Hydrological Drought Explained, Wiley Interdisciplinary Reviews: Water, Vol. 2, No. 4, 2015, pp. 359-392, https://doi.org/10.1002/wat2.1085.
[6] D. A. Wilhite, M. H. Glantz, Understanding: The Drought Phenomenon: The Role of Definitions, Water International, Vol. 10, No. 3, 1985,
pp. 111-120, https://doi.org/10.1080/02508068508686328.
[7] A. K. Mishra, V. P. Singh, A Review of Drought Concepts, Journal of Hydrology, Vol. 391,
No. 1-2, 2010, pp. 202-216, https://doi.org/10.1016/j.jhydrol.2010.07.012.
[8] D. Manatsa, G. Mukwada, E. Siziba, T. Chinyanganya, Analysis of Multidimensional Aspects of Agricultural Droughts in Zimbabwe Using The Standardized Precipitation Index (SPI), Theoretical and Applied Climatology, Vol. 102, 2010, pp. 287-305, https://doi.org/10.1007/s00704-010-0262-2.
[9] S. M. V. Serrano, S. M. Quiring, M. P. Gallardo, S. Yuan, F. D. Castro, A Review of Environmental Droughts: Increased Risk under Global Warming?, Earth-Science Reviews, Vol. 201, 2020,
pp. 102953, https://doi.org/10.1016/j.earscirev.2019.102953.
[10] J. Sheffield, E. F. Wood, M. L. Roderick, Little Change in Global Drought Over the Past 60 Years, Nature, Vol. 491, No. 7424, 2012, pp. 435-438, https://doi.org/10.1038/nature11575.
[11] A. Dai, K. E. Trenberth, T. Qian, A Global Dataset of Palmer Drought Severity Index for 1870–2002: Relationship with Soil Moisture and Effects of Surface Warming, Journal of Hydrometeorology, Vol. 5, No. 6, 2004, pp. 1117-1130, https://doi.org/10.1175/JHM-386.1.
[12] T. Chen, G. Xia, T. Liu, W. Chen, D. Chi, Assessment of Drought Impact on Main Cereal Crops Using A Standardized Precipitation Evapotranspiration Index in Liaoning Province, China, Sustainability, Vol. 8, No. 10, 2016,
pp. 1069, https://doi.org/10.3390/su8101069.
[13] M. A. Miyan, Droughts in Asian Least Developed Countries: Vulnerability and Sustainability, Weather and Climate Extremes, Vol. 7, 2015,
pp. 8-23, https://doi.org/10.1016/j.wace.2014.06.003.
[14] P. Le Nguyen, M. D. Nguyen, Drought Adaptation and Coping Strategies among Coffee Farmers in the Central Highlands of Vietnam, Journal of Agriculture and Environmental Sciences, Vol. 8, No. 1, 2019, pp. 52-66, https://doi.org/10.15640/jaes.v8n1a6.
[15] P. S. Baker, Coffee and Climate Change in the Central Highlands of Vietnam, Coffee&Climate, Hanns R. Neumann Stiftung, Germany, 2016.
[16] T. Tiemann et al., Crop Nutrition for Vietnamese Robusta Coffee, Better Crops with Plant Food,
Vol. 102, No. 3, 2018, pp. 20-23, https://www.cabidigitallibrary.org/doi/full/10.5555/20193173063 (accessed on: March 10th, 2025).
[17] UNDP, Vietnam Drought and Saltwater Intrusion: Transitioning from Emergency to Recovery, Vietnam: UNDP (United Nations Development Programme), 2016.
[18] T. V. Tran, D. X. Tran, D. B. Nguyen, Agricultural Drought in the Vietnamese Central Highlands at 1-km Resolution: Monthly and Annual Datasets, Data in Brief, Vol. 48, 2023, pp. 109194, https://doi.org/10.1016/j.dib.2023.109194.
[19] T. A. Räsänen, M. Kummu, Spatiotemporal Influences of ENSO on Precipitation and Flood Pulse in the Mekong River Basin, Journal of Hydrology, Vol. 476, 2013, pp. 154-168, https://doi.org/10.1016/j.jhydrol.2012.10.028.
[20] W. R. Sutton, J. P. Srivastava, M. Rosegrant, J. Thurlow, L. Sebastian, Striking a Balance: Managing El Niño and La Niña in Vietnam's Agriculture, World Bank, 2019, 103 pp, https://www.cabidigitallibrary.org/doi/full/10.5555/20203183816 (accessed on: March 10th, 2025).
[21] T. N. Thi et al., Climate Analogue and Future Appearance of Novel Climate in Southeast Asia, International Journal of Climatology, Vol. 41, 2021, pp. E392-E409, https://doi.org/10.1002/joc.6693.
[22] L. V. Viet, Development of A New Enso Index to Assess the Effects of Enso on Temperature over Southern Vietnam, Theoretical and Applied Climatology, Vol. 144, 2021, pp. 1119-1129, https://doi.org/10.1007/s00704-021-03591-3.
[23] W. C. Palmer, Meteorological Drought, US, Weather Bureau Res. Paper, Vol. 45, 1965,
pp. 1-58, https://cir.nii.ac.jp/crid/1570291225545846528.
[24] T. B. McKee, N. J. Doesken, J. Kleist, The Relationship of Drought Frequency and Duration to Time Scales, Proceedings of The 8th Conference on Applied Climatology, Vol. 17, No. 22, 1993,
pp. 179-183, https://climate.colostate.edu/pdfs/relationshipofdroughtfrequency.pdf (accessed on: March 10th, 2025).
[25] S. M. V. Serrano, S. Beguería, J. I. L. Moreno, A Multiscalar Drought Index Sensitive to Global Warming: the Standardized Precipitation Evapotranspiration Index, Journal of Climate,
Vol. 23, No. 7, 2010, pp. 1696-1718, https://doi.org/10.1175/2009JCLI2909.1.
[26] Z. Hao, X. Yuan, Y. Xia, F. Hao, V. P. Singh, An Overview of Drought Monitoring and Prediction Systems at Regional and Global Scales, Bulletin of the American Meteorological Society, Vol. 98,
No. 9, 2017, pp. 1879-1896, https://doi.org/10.1175/BAMS-D-15-00149.1.
[27] A. A. Kouchak et al., Remote Sensing of Drought: Progress, Challenges and Opportunities, Reviews of Geophysics, Vol. 53, No. 2, 2015, pp. 452-480, https://doi.org/10.1002/2014RG000456.
[28] M. C. Anderson, C. A. Zolin, C. R. Hain, K. Semmens, M. T. Yilmaz, F. Gao, Comparison of Satellite-Derived LAI and Precipitation Anomalies over Brazil with A Thermal Infrared-Based Evaporative Stress Index for 2003–2013, Journal of Hydrology, Vol. 526, 2015, pp. 287-302, https://doi.org/10.1016/j.jhydrol.2015.01.005.
[29] F. N. Kogan, Droughts of the Late 1980s in the United States as Derived from NOAA Polar-Orbiting Satellite Data, Bulletin of the American Meteorological Society, Vol. 76, No. 5, 1995,
pp. 655-668, https://doi.org/10.1175/1520-0477(1995)076%3C0655:DOTLIT%3E2.0.CO;2.
[30] F. N. Kogan, Global Drought Watch from Space, Bulletin of the American Meteorological Society, Vol. 78, No. 4, 1997, pp. 621-636, https://doi.org/10.1175/1520-0477(1997)078%3C0621:GDWFS%3E2.0.CO;2.
[31] L. Zhang, W. Jiao, H. Zhang, C. Huang, Q. Tong, Studying Drought Phenomena in the Continental United States in 2011 and 2012 Using Various Drought Indices, Remote Sensing of Environment, Vol. 190, 2017, pp. 96-106, https://doi.org/10.1016/j.rse.2016.12.010.
[32] F. Zambrano, M. L. Saavedra, K. Verbist, O. Lagos, Sixteen Years of Agricultural Drought Assessment of the Biobío Region in Chile Using A 250m Resolution Vegetation Condition Index (VCI), Remote Sensing, Vol. 8, No. 6, 2016,
pp. 530, https://doi.org/10.3390/rs8060530.
[33] F. Kogan, W. Guo, W. Yang, Drought and Food Security Prediction from NOAA New Generation of Operational Satellites, Geomatics, Natural Hazards and Risk, Vol. 10, No. 1, 2019, pp. 651-666, https://doi.org/10.1080/19475705.2018.1541257.
[34] H. Imran et al., Impact of Land Cover Changes on Land Surface Temperature and Human Thermal Comfort in Dhaka City of Bangladesh, Earth Systems and Environment, Vol. 5, 2021, pp. 667-693, https://doi.org/10.1007/s41748-021-00243-4.
[35] O. Rojas, A. Vrieling, F. Rembold, Assessing Drought Probability for Agricultural Areas in Africa with Coarse Resolution Remote Sensing Imagery, Remote Sensing of Environment,
Vol. 115, No. 2, 2011, pp. 343-352, https://doi.org/10.1016/j.rse.2010.09.006.
[36] L. V. Viet, T. T. T. Thuy, Improving the Quality of Coffee Yield Forecasting in Dak Lak Province, Vietnam, through the Utilization of Remote Sensing Data, Environmental Research Communications, Vol. 5, No. 9, 2023, pp. 095011, https://doi.org/10.1088/2515-7620/acf6fd.
[37] N. V. Hiep, N. T. T. Thao, L. V. Viet, H. C. Luc, L. H. Ba, Affecting of Nature and Human Activities on the Trend of Vegetation Health Indices in Dak Nong Province, Vietnam, Sustainability, Vol. 15, No. 7, 2023, pp. 5695, https://doi.org/10.3390/su15075695.
[38] V. V. Luong, D. H. Bui, Evaluation of Models and Drought-Wetness Factors Contributing to Predicting the Vegetation Health Index in Dak Nong Province, Vietnam, Environmental Research Communications, Vol. 6, No. 4, 2024, pp. 045005, https://doi.org/10.1088/2515-7620/ad39a4.
[39] T. V. Thuong, C. T. Xuan, N. T. Hieu, P. V. Tuan, D. Mon, Examininging Drought Intensity in Central Highlands during the 2001–2020 period using Daily MODIS Time–Series Imagery, Journal of Hydro-Meteorology, Vol. 733, 2022, pp. 1-14, https://doi.org/10.36335/VNJHM.2022(733).1-14 (in Vietnamese)..
[40] Statistical Data, Statistical Yearbook of Vietnam 2018, https://www.nso.gov.vn/en/data-and-statistics/2019/10/statistical-yearbook-of-vietnam-2018/, 2019 (accessed on: March 10th, 2025).
[41] B. N. Holben, Characteristics of Maximum-Value Composite Images from Temporal AVHRR Data, International Journal of Remote Sensing, Vol. 7, No. 11, 1986, pp. 1417-1434, https://doi.org/10.1080/01431168608948945.
[42] J. Li, K. Fan, L. Zhou, Satellite Observations of El Niño Impacts on Eurasian Spring Vegetation Greenness during The Period 1982–2015, Remote Sensing, Vol. 9, No. 7, 2017, pp. 628, https://doi.org/10.3390/rs9070628.
[43] H. Li, Y. Li, Y. Gao, C. Zou, S. Yan, J. Gao, Human Impact on Vegetation Dynamics around Lhasa, Southern Tibetan Plateau, China, Sustainability, Vol. 8, No. 11, 2016, pp. 1146, https://doi.org/10.3390/su8111146.
[44] H. Chu, S. Venevsky, C. Wu, M. Wang, NDVI-Based Vegetation Dynamics and Its Response to Climate Changes at Amur-Heilongjiang River Basin from 1982 to 2015, Science of the Total Environment, Vol. 650, 2019, pp. 2051-2062, https://doi.org/10.1016/j.scitotenv.2018.09.115.
[45] F. Kogan, L. Salazar, L. Roytman, Forecasting Crop Production Using Satellite-Based Vegetation Health Indices in Kansas, USA, International Journal of Remote Sensing, Vol. 33, No. 9, 2012, pp. 2798-2814, https://doi.org/10.1080/01431161.2011.621464.
[46] H. C. Luc, L. V. Viet, B. D. Hung, Determining Suitable Meteorological Drought and Vegetation Indices for Monitoring Drought and Crop Yield in Srepok River Basin, Vietnam, Agriculture and Natural Resources, Vol. 59, No. 1, 2025, https://doi.org/10.34044/j.anres.2025.59.2.09.
[47] N. V. Tuan et al., Spatio-Temporal Analysis of Drought in the North-Eastern Coastal Region of Vietnam Using the Standardized Precipitation Index (SPI), Atmospheric and Climate Science, Vol. 13, No. 2, 2023, pp. 175-200, https://doi.org/10.4236/acs.2023.132011.
[48] T. V. Ty et al., Assessment of Relationship Between Climate Change, Drought, and Land Use and Land Cover Changes in A Semi-Mountainous Area of the Vietnamese Mekong Delta, Land,
Vol. 11, No. 12, 2022, pp. 2175, https://doi.org/10.3390/land11122175.
[49] M. Vu, V. Raghavan, S. Y. Liong, Ensemble Climate Projection for Hydro-Meteorological Drought over A River Basin in Central Highland, Vietnam, KSCE Journal of Civil Engineering,
Vol. 19, No. 2, 2015, pp. 427-433, https://doi.org/10.1007/s12205-015-0506-x.
[50] N. Q. Thi, A. Govind, T. V. Ha, Spatial and Temporal Variability of Soil Moisture Active and Passive (SMAP) Droughts and Their Impacts on Vegetation in the Central Highlands of Vietnam, Environmental Monitoring and Assessment,
Vol. 197, No. 2, 2025, pp. 203, https://doi.org/10.1007/s10661-025-13622-5.
[51] N. L. Trang, L. L. Anh, L. A. Trung, and C. T. T. Huong, Research on Relationship between ENSO and The Intensity of the Aleutian Low, Journal of Hydro-Meteorology, Vol. 750, No. 1, 2023,
pp. 78-88, https://doi.org/10.36335/VNJHM.2023(750(1)).78-88 (in Vietnamese).
[52] E. Gidey, O. Dikinya, R. Sebego, E. Segosebe, A. Zenebe, Analysis of the Long-term Agricultural Drought Onset, Cessation, Duration, Frequency, Severity and Spatial Extent Using Vegetation Health Index (VHI) in Raya and Its Environs, Northern Ethiopia, Environmental Systems Research, Vol. 7, 2018, pp. 1-18, https://doi.org/10.1186/s40068-018-0115-z.
[53] Agriculture and Environment, The Central Highlands Faces a Severely Poor Coffee Harvest, Available at: https://nongnghiepmoitruong.vn/tay-nguyen-doi-dien-vu-ca-phe-that-bat-nang-d173609.html (accessed on: March 10th, 2025).
[2] C. Parmesan, M. D. Morecroft, Y. Trisurat, Climate Change 2022: Impacts, Adaptation and Vulnerability, GIEC, 2022, https://hal.science/hal-03774939v1.
[3] M. L. Parry, Climate Change 2007-Impacts, Adaptation and Vulnerability: Working Group II Contribution to the Fourth Assessment Report of the IPCC, Cambridge University Press, Vol. 4, 2007.
[4] U. Nations, The Impact of Disasters and Crises on Agriculture and Food Security, Food and Agriculture Organization, 2017.
[5] A. F. V. Loon, Hydrological Drought Explained, Wiley Interdisciplinary Reviews: Water, Vol. 2, No. 4, 2015, pp. 359-392, https://doi.org/10.1002/wat2.1085.
[6] D. A. Wilhite, M. H. Glantz, Understanding: The Drought Phenomenon: The Role of Definitions, Water International, Vol. 10, No. 3, 1985,
pp. 111-120, https://doi.org/10.1080/02508068508686328.
[7] A. K. Mishra, V. P. Singh, A Review of Drought Concepts, Journal of Hydrology, Vol. 391,
No. 1-2, 2010, pp. 202-216, https://doi.org/10.1016/j.jhydrol.2010.07.012.
[8] D. Manatsa, G. Mukwada, E. Siziba, T. Chinyanganya, Analysis of Multidimensional Aspects of Agricultural Droughts in Zimbabwe Using The Standardized Precipitation Index (SPI), Theoretical and Applied Climatology, Vol. 102, 2010, pp. 287-305, https://doi.org/10.1007/s00704-010-0262-2.
[9] S. M. V. Serrano, S. M. Quiring, M. P. Gallardo, S. Yuan, F. D. Castro, A Review of Environmental Droughts: Increased Risk under Global Warming?, Earth-Science Reviews, Vol. 201, 2020,
pp. 102953, https://doi.org/10.1016/j.earscirev.2019.102953.
[10] J. Sheffield, E. F. Wood, M. L. Roderick, Little Change in Global Drought Over the Past 60 Years, Nature, Vol. 491, No. 7424, 2012, pp. 435-438, https://doi.org/10.1038/nature11575.
[11] A. Dai, K. E. Trenberth, T. Qian, A Global Dataset of Palmer Drought Severity Index for 1870–2002: Relationship with Soil Moisture and Effects of Surface Warming, Journal of Hydrometeorology, Vol. 5, No. 6, 2004, pp. 1117-1130, https://doi.org/10.1175/JHM-386.1.
[12] T. Chen, G. Xia, T. Liu, W. Chen, D. Chi, Assessment of Drought Impact on Main Cereal Crops Using A Standardized Precipitation Evapotranspiration Index in Liaoning Province, China, Sustainability, Vol. 8, No. 10, 2016,
pp. 1069, https://doi.org/10.3390/su8101069.
[13] M. A. Miyan, Droughts in Asian Least Developed Countries: Vulnerability and Sustainability, Weather and Climate Extremes, Vol. 7, 2015,
pp. 8-23, https://doi.org/10.1016/j.wace.2014.06.003.
[14] P. Le Nguyen, M. D. Nguyen, Drought Adaptation and Coping Strategies among Coffee Farmers in the Central Highlands of Vietnam, Journal of Agriculture and Environmental Sciences, Vol. 8, No. 1, 2019, pp. 52-66, https://doi.org/10.15640/jaes.v8n1a6.
[15] P. S. Baker, Coffee and Climate Change in the Central Highlands of Vietnam, Coffee&Climate, Hanns R. Neumann Stiftung, Germany, 2016.
[16] T. Tiemann et al., Crop Nutrition for Vietnamese Robusta Coffee, Better Crops with Plant Food,
Vol. 102, No. 3, 2018, pp. 20-23, https://www.cabidigitallibrary.org/doi/full/10.5555/20193173063 (accessed on: March 10th, 2025).
[17] UNDP, Vietnam Drought and Saltwater Intrusion: Transitioning from Emergency to Recovery, Vietnam: UNDP (United Nations Development Programme), 2016.
[18] T. V. Tran, D. X. Tran, D. B. Nguyen, Agricultural Drought in the Vietnamese Central Highlands at 1-km Resolution: Monthly and Annual Datasets, Data in Brief, Vol. 48, 2023, pp. 109194, https://doi.org/10.1016/j.dib.2023.109194.
[19] T. A. Räsänen, M. Kummu, Spatiotemporal Influences of ENSO on Precipitation and Flood Pulse in the Mekong River Basin, Journal of Hydrology, Vol. 476, 2013, pp. 154-168, https://doi.org/10.1016/j.jhydrol.2012.10.028.
[20] W. R. Sutton, J. P. Srivastava, M. Rosegrant, J. Thurlow, L. Sebastian, Striking a Balance: Managing El Niño and La Niña in Vietnam's Agriculture, World Bank, 2019, 103 pp, https://www.cabidigitallibrary.org/doi/full/10.5555/20203183816 (accessed on: March 10th, 2025).
[21] T. N. Thi et al., Climate Analogue and Future Appearance of Novel Climate in Southeast Asia, International Journal of Climatology, Vol. 41, 2021, pp. E392-E409, https://doi.org/10.1002/joc.6693.
[22] L. V. Viet, Development of A New Enso Index to Assess the Effects of Enso on Temperature over Southern Vietnam, Theoretical and Applied Climatology, Vol. 144, 2021, pp. 1119-1129, https://doi.org/10.1007/s00704-021-03591-3.
[23] W. C. Palmer, Meteorological Drought, US, Weather Bureau Res. Paper, Vol. 45, 1965,
pp. 1-58, https://cir.nii.ac.jp/crid/1570291225545846528.
[24] T. B. McKee, N. J. Doesken, J. Kleist, The Relationship of Drought Frequency and Duration to Time Scales, Proceedings of The 8th Conference on Applied Climatology, Vol. 17, No. 22, 1993,
pp. 179-183, https://climate.colostate.edu/pdfs/relationshipofdroughtfrequency.pdf (accessed on: March 10th, 2025).
[25] S. M. V. Serrano, S. Beguería, J. I. L. Moreno, A Multiscalar Drought Index Sensitive to Global Warming: the Standardized Precipitation Evapotranspiration Index, Journal of Climate,
Vol. 23, No. 7, 2010, pp. 1696-1718, https://doi.org/10.1175/2009JCLI2909.1.
[26] Z. Hao, X. Yuan, Y. Xia, F. Hao, V. P. Singh, An Overview of Drought Monitoring and Prediction Systems at Regional and Global Scales, Bulletin of the American Meteorological Society, Vol. 98,
No. 9, 2017, pp. 1879-1896, https://doi.org/10.1175/BAMS-D-15-00149.1.
[27] A. A. Kouchak et al., Remote Sensing of Drought: Progress, Challenges and Opportunities, Reviews of Geophysics, Vol. 53, No. 2, 2015, pp. 452-480, https://doi.org/10.1002/2014RG000456.
[28] M. C. Anderson, C. A. Zolin, C. R. Hain, K. Semmens, M. T. Yilmaz, F. Gao, Comparison of Satellite-Derived LAI and Precipitation Anomalies over Brazil with A Thermal Infrared-Based Evaporative Stress Index for 2003–2013, Journal of Hydrology, Vol. 526, 2015, pp. 287-302, https://doi.org/10.1016/j.jhydrol.2015.01.005.
[29] F. N. Kogan, Droughts of the Late 1980s in the United States as Derived from NOAA Polar-Orbiting Satellite Data, Bulletin of the American Meteorological Society, Vol. 76, No. 5, 1995,
pp. 655-668, https://doi.org/10.1175/1520-0477(1995)076%3C0655:DOTLIT%3E2.0.CO;2.
[30] F. N. Kogan, Global Drought Watch from Space, Bulletin of the American Meteorological Society, Vol. 78, No. 4, 1997, pp. 621-636, https://doi.org/10.1175/1520-0477(1997)078%3C0621:GDWFS%3E2.0.CO;2.
[31] L. Zhang, W. Jiao, H. Zhang, C. Huang, Q. Tong, Studying Drought Phenomena in the Continental United States in 2011 and 2012 Using Various Drought Indices, Remote Sensing of Environment, Vol. 190, 2017, pp. 96-106, https://doi.org/10.1016/j.rse.2016.12.010.
[32] F. Zambrano, M. L. Saavedra, K. Verbist, O. Lagos, Sixteen Years of Agricultural Drought Assessment of the Biobío Region in Chile Using A 250m Resolution Vegetation Condition Index (VCI), Remote Sensing, Vol. 8, No. 6, 2016,
pp. 530, https://doi.org/10.3390/rs8060530.
[33] F. Kogan, W. Guo, W. Yang, Drought and Food Security Prediction from NOAA New Generation of Operational Satellites, Geomatics, Natural Hazards and Risk, Vol. 10, No. 1, 2019, pp. 651-666, https://doi.org/10.1080/19475705.2018.1541257.
[34] H. Imran et al., Impact of Land Cover Changes on Land Surface Temperature and Human Thermal Comfort in Dhaka City of Bangladesh, Earth Systems and Environment, Vol. 5, 2021, pp. 667-693, https://doi.org/10.1007/s41748-021-00243-4.
[35] O. Rojas, A. Vrieling, F. Rembold, Assessing Drought Probability for Agricultural Areas in Africa with Coarse Resolution Remote Sensing Imagery, Remote Sensing of Environment,
Vol. 115, No. 2, 2011, pp. 343-352, https://doi.org/10.1016/j.rse.2010.09.006.
[36] L. V. Viet, T. T. T. Thuy, Improving the Quality of Coffee Yield Forecasting in Dak Lak Province, Vietnam, through the Utilization of Remote Sensing Data, Environmental Research Communications, Vol. 5, No. 9, 2023, pp. 095011, https://doi.org/10.1088/2515-7620/acf6fd.
[37] N. V. Hiep, N. T. T. Thao, L. V. Viet, H. C. Luc, L. H. Ba, Affecting of Nature and Human Activities on the Trend of Vegetation Health Indices in Dak Nong Province, Vietnam, Sustainability, Vol. 15, No. 7, 2023, pp. 5695, https://doi.org/10.3390/su15075695.
[38] V. V. Luong, D. H. Bui, Evaluation of Models and Drought-Wetness Factors Contributing to Predicting the Vegetation Health Index in Dak Nong Province, Vietnam, Environmental Research Communications, Vol. 6, No. 4, 2024, pp. 045005, https://doi.org/10.1088/2515-7620/ad39a4.
[39] T. V. Thuong, C. T. Xuan, N. T. Hieu, P. V. Tuan, D. Mon, Examininging Drought Intensity in Central Highlands during the 2001–2020 period using Daily MODIS Time–Series Imagery, Journal of Hydro-Meteorology, Vol. 733, 2022, pp. 1-14, https://doi.org/10.36335/VNJHM.2022(733).1-14 (in Vietnamese)..
[40] Statistical Data, Statistical Yearbook of Vietnam 2018, https://www.nso.gov.vn/en/data-and-statistics/2019/10/statistical-yearbook-of-vietnam-2018/, 2019 (accessed on: March 10th, 2025).
[41] B. N. Holben, Characteristics of Maximum-Value Composite Images from Temporal AVHRR Data, International Journal of Remote Sensing, Vol. 7, No. 11, 1986, pp. 1417-1434, https://doi.org/10.1080/01431168608948945.
[42] J. Li, K. Fan, L. Zhou, Satellite Observations of El Niño Impacts on Eurasian Spring Vegetation Greenness during The Period 1982–2015, Remote Sensing, Vol. 9, No. 7, 2017, pp. 628, https://doi.org/10.3390/rs9070628.
[43] H. Li, Y. Li, Y. Gao, C. Zou, S. Yan, J. Gao, Human Impact on Vegetation Dynamics around Lhasa, Southern Tibetan Plateau, China, Sustainability, Vol. 8, No. 11, 2016, pp. 1146, https://doi.org/10.3390/su8111146.
[44] H. Chu, S. Venevsky, C. Wu, M. Wang, NDVI-Based Vegetation Dynamics and Its Response to Climate Changes at Amur-Heilongjiang River Basin from 1982 to 2015, Science of the Total Environment, Vol. 650, 2019, pp. 2051-2062, https://doi.org/10.1016/j.scitotenv.2018.09.115.
[45] F. Kogan, L. Salazar, L. Roytman, Forecasting Crop Production Using Satellite-Based Vegetation Health Indices in Kansas, USA, International Journal of Remote Sensing, Vol. 33, No. 9, 2012, pp. 2798-2814, https://doi.org/10.1080/01431161.2011.621464.
[46] H. C. Luc, L. V. Viet, B. D. Hung, Determining Suitable Meteorological Drought and Vegetation Indices for Monitoring Drought and Crop Yield in Srepok River Basin, Vietnam, Agriculture and Natural Resources, Vol. 59, No. 1, 2025, https://doi.org/10.34044/j.anres.2025.59.2.09.
[47] N. V. Tuan et al., Spatio-Temporal Analysis of Drought in the North-Eastern Coastal Region of Vietnam Using the Standardized Precipitation Index (SPI), Atmospheric and Climate Science, Vol. 13, No. 2, 2023, pp. 175-200, https://doi.org/10.4236/acs.2023.132011.
[48] T. V. Ty et al., Assessment of Relationship Between Climate Change, Drought, and Land Use and Land Cover Changes in A Semi-Mountainous Area of the Vietnamese Mekong Delta, Land,
Vol. 11, No. 12, 2022, pp. 2175, https://doi.org/10.3390/land11122175.
[49] M. Vu, V. Raghavan, S. Y. Liong, Ensemble Climate Projection for Hydro-Meteorological Drought over A River Basin in Central Highland, Vietnam, KSCE Journal of Civil Engineering,
Vol. 19, No. 2, 2015, pp. 427-433, https://doi.org/10.1007/s12205-015-0506-x.
[50] N. Q. Thi, A. Govind, T. V. Ha, Spatial and Temporal Variability of Soil Moisture Active and Passive (SMAP) Droughts and Their Impacts on Vegetation in the Central Highlands of Vietnam, Environmental Monitoring and Assessment,
Vol. 197, No. 2, 2025, pp. 203, https://doi.org/10.1007/s10661-025-13622-5.
[51] N. L. Trang, L. L. Anh, L. A. Trung, and C. T. T. Huong, Research on Relationship between ENSO and The Intensity of the Aleutian Low, Journal of Hydro-Meteorology, Vol. 750, No. 1, 2023,
pp. 78-88, https://doi.org/10.36335/VNJHM.2023(750(1)).78-88 (in Vietnamese).
[52] E. Gidey, O. Dikinya, R. Sebego, E. Segosebe, A. Zenebe, Analysis of the Long-term Agricultural Drought Onset, Cessation, Duration, Frequency, Severity and Spatial Extent Using Vegetation Health Index (VHI) in Raya and Its Environs, Northern Ethiopia, Environmental Systems Research, Vol. 7, 2018, pp. 1-18, https://doi.org/10.1186/s40068-018-0115-z.
[53] Agriculture and Environment, The Central Highlands Faces a Severely Poor Coffee Harvest, Available at: https://nongnghiepmoitruong.vn/tay-nguyen-doi-dien-vu-ca-phe-that-bat-nang-d173609.html (accessed on: March 10th, 2025).