Poster Title:Tracking rainfall enhancement signal in the UAE using rainfall reanalysis (ERA-5) and satellite gravimetry data
Full Name:Fatima Alhammadi
Affiliation / Institution:1. Department of Environmental Sciences and Sustainability, College of Natural and Health Sciences, Zayed University, Abu Dhabi, UAE
Co-Author
Full Name:Shahad Alabdouli
Affiliation / Institution:1. Department of Environmental Sciences and Sustainability, College of Natural and Health Sciences, Zayed University, Abu Dhabi, UAE
Co-Author 2
Full Name:Muhammad Naseem
Affiliation / Institution:1. Department of Environmental Sciences and Sustainability, College of Natural and Health Sciences, Zayed University, Abu Dhabi, UAE
Co-Author 3
Full Name:Muhammad Usman
Affiliation / Institution:1. Department of Environmental Sciences and Sustainability, College of Natural and Health Sciences, Zayed University, Abu Dhabi, UAE
Abstract:The freshwater resources are quite scarce in the UAE. Due to arid conditions, the natural rainfall is mostly less than the annual groundwater withdrawal rates, which results in the continuous decline of groundwater. To address the issue, since the 1990s, the country mainly relies on cloud seeding, which helps to enhance the rainfall. The primary goal of this research is to assess the influence of cloud seeding on rainfall in four Emirates: Dubai, Sharjah, Ras Al Khaimah, and Fujairah, through the use of rainfall reanalysis data. Furthermore, we want to assess its influence on long-term groundwater variability by analyzing the Gravity Recovery and Climate Experiment (GRACE/GRACE-FO) satellite data. The reanalysis products are generated by utilizing different types of observations as input for various climate models and mostly contain data at the nodal points with a grid size of 0.25x0.25 degrees. During the processing time, small variability in climatic parameters usually gets masked. The temporal baseline of rainfall data is from 1940 to 2024, and we divide it into two spans, i.e., 1940-1990 and 1991-present. On the other hand, GRACE/GRACE-FO data has a temporal range from 2002 to the present. For the rainfall data, we calculate the logarithmic regression model using the Weibull formula. The results indicate that for the timespans mentioned above, slope values increase from ~13 mm/month (1940–1990) to ~17 mm/month (1991–Present) for all the observed settlements. It indicates that rainfall enhancement in recent times can be tracked using reanalysis data. We further test the enhanced rainfall by creating the average monthly distributions for the two timespans and apply the t-test. The results prove that one can reject the null hypothesis with a 96% confidence interval, indicating that rainfall enhancement in the recent data (from 1991 to the present) can be observed in the reanalysis data. However, in the satellite gravimetry data, the groundwater trend component analysis indicates a continuous falling rate at the observed locations with the highest decline in Fujairah. It suggests that either the enhanced rainfall has a limited effect on recharging the groundwater or its influence is so localized that it is beyond the resolving power of satellite gravimetry.