Wiggs, Giles F.S. (2011). «Geomorphological hazards in drylands». In: Thomas, David S.G. Arid Zone Geomorphology: Process, Form and Change in Drylands. [S.l.]: John Wiley & Sons. p. 588. ISBN978-0-470-71076-0
The distribution of all the water on the earth's surface is not even. Some places have much fresh water (rivers, lakes, lagoons, ponds etc.) and are continuously replenished by rainfall, runoffs and water from underground. Others places too are known to have very little water.
Therefore, if a region that receives plentiful rainfall goes for a couple of weeks without rain, and people, animals and plants begin to experience a bit of dryness, it can be called drought. At the same time, that condition may be very normal for places with no water, and can go for months without rain with few problems.
Swain, S; et al. (2017). «Application of SPI, EDI and PNPI using MSWEP precipitation data over Marathwada, India». IEEE International Geoscience and Remote Sensing Symposium (IGARSS). 2017: 5505–5507. ISBN978-1-5090-4951-6. doi:10.1109/IGARSS.2017.8128250
The alleviating trend of drought in the Huang-Huai-Hai Plain of China based on the daily SPEI. International Journal of Climatology.2015. doi:10.1002/joc.4244 Wang, Qianfeng, Shi, Peijun, Lei, Tianjie, Geng, Guangpo, Liu, Jinghui, Mo, Xinyu, Li, Xiaohan, Zhou, Hongkui. and Wu, Jianjun
A.J. Dore; M. Mousavi-Baygi; R.I. Smith; J. Hall; D. Fowler; T.W. Choularton (junho de 2006). «A model of annual orographic precipitation and acid deposition and its application to Snowdonia». Atmospheric Environment. 40 (18): 3316–3326. Bibcode:2006AtmEn..40.3316D. doi:10.1016/j.atmosenv.2006.01.043
Cook, Benjamin I.; Mankin, Justin S.; Anchukaitis, Kevin J. (12 de maio de 2018). «Climate Change and Drought: From Past to Future». Current Climate Change Reports. 4 (2): 164–179. ISSN2198-6061. doi:10.1007/s40641-018-0093-2
Mukherjee, Sourav; Mishra, Ashok; Trenberth, Kevin E. (23 de abril de 2018). «Climate Change and Drought: a Perspective on Drought Indices». Current Climate Change Reports. 4 (2): 145–163. ISSN2198-6061. doi:10.1007/s40641-018-0098-x
A.J. Dore; M. Mousavi-Baygi; R.I. Smith; J. Hall; D. Fowler; T.W. Choularton (junho de 2006). «A model of annual orographic precipitation and acid deposition and its application to Snowdonia». Atmospheric Environment. 40 (18): 3316–3326. Bibcode:2006AtmEn..40.3316D. doi:10.1016/j.atmosenv.2006.01.043
Cook, Benjamin I.; Mankin, Justin S.; Anchukaitis, Kevin J. (12 de maio de 2018). «Climate Change and Drought: From Past to Future». Current Climate Change Reports. 4 (2): 164–179. ISSN2198-6061. doi:10.1007/s40641-018-0093-2
Mukherjee, Sourav; Mishra, Ashok; Trenberth, Kevin E. (23 de abril de 2018). «Climate Change and Drought: a Perspective on Drought Indices». Current Climate Change Reports. 4 (2): 145–163. ISSN2198-6061. doi:10.1007/s40641-018-0098-x