Aquifer recharge from flash floods in the arid environment: A mass balance approach at the catchment scale

Estimation of the infiltration/natural recharge to groundwater from rainfall is an important issue in hydrology, particularly in arid regions. This paper proposes the application of The Natural Resources Conservation Service (NRCS) mass balance model to develop infiltration (F)-rainfall (P) relationship from flash flood events. Moreover, the NRCS method is compared with the rational and the CYRILLIC CAPITAL LETTER EF-index methods to investigate the discrepancies between these methods. The methods have been applied to five gauged basins and their 19 sub-basins (representative basins with detailed measurements) in the southwestern part of Saudi Arabia with 161 storms recorded in 4 years. The F-P relationships developed in this study based on NRCS method are: F = 39% P with R-2 = 0.932 for the initial abstraction factor, lambda = 0.2. However, F = 77% P with R-2 = 0.986 for lambda = 0.01. The model at lambda = 0.01 is the best to fit the data, therefore, it is recommended to use the formula at lambda = 0.01. The results show that the NRCS model is appropriate for the estimation of the F-P relationships in arid regions when compared with the rational and the CYRILLIC CAPITAL LETTER EF index methods. The latter overestimates the infiltration because they do not take lambda into account. There is no significant difference between F-P relationships at different time scales. This helps the prediction of infiltration rates for aquifer recharge at ungauged basins from monthly and annual rainfall data with a single formula.

Automated summary

This study discusses the estimation of rainfall infiltration/natural recharge to groundwater in arid regions, compares different methods, and recommends the NRCS model with lambda = 0.01 as the most suitable formula.