Monitoring and Analysis of Meteorological and Groundwater Drought in Guenniche Basin (North Tunisia)

Nature is directly affected by drought, threatening human societies, ecosystems, and especially aquatic environments. This research is about: (i) monitoring the meteorological drought on the Guenniche Basin (Northern Tunisia) using the standardized precipitation index (SPI) and the standardized precipitation–evapotranspiration index (SPIE) based on available data covering a period between 1901 and 2018, (ii) comparing five (5) decades of groundwater level fluctuation with rainfall, and (iii) estimating the groundwater abstraction due to irrigation using the FAO-CROPWAT model. The SPIE 3-months and 12-months variability patterns are similar for each timeline, with major drought episodes classified as “Middle wet” to “Mild drought”. A total of 50% of the months had “Mild” to “Extreme” drought, while 11% had “Severe” to “Extreme” drought. The SPI-3 for the month of May in relation to the groundwater level fluctuation indicates the end of the rainy period and forecasts a potential drought. Guenniche shallow (since 1990) and deep (since 2010) aquifers have had significant water level declines, due to (i) increased water consumption and (ii) lengthy drought occurrences (95 months of severe drought in a 117-year span). The measured pumping water volumes and the injected artificial water recharge quantities are less than the crop annual irrigation needs, which are estimated to reach 36 Mm3. The results suggest that drought events due to climate are reflected in severe groundwater lowering. Therefore, finding solutions for groundwater rationing-use with considering SPI drought characterizing will help to reduce the depletion risk of Guenniche groundwater.