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

Abstract

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 Ф-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, λ = 0.2. However, F = 77% P with R 2 = 0.986 for λ = 0.01. The model at λ = 0.01 is the best to fit the data, therefore, it is recommended to use the formula at λ = 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 Ф index methods.The latter overestimates the infiltration because they do not take λ 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.

Modeling Aquifer Responses from Flash Flood Events through Ephemeral Stream Beds: Case Studies from Saudi Arabia

“…This means that 85% of the runoff water is recharged and joins the aquifer system to raise the water table. In a similar event-scale approach, [38] reports 77% of total spatial average precipitation is transferred to infiltration at a catchment scale based on a water balance model in the area using Soil Conservation Service (the SCS method).…”

“…Figure 2 shows sample plots modified from [38] for two rainfall stations (SA003 and SA004) in Figure 2a,b, that belong to the Ministry of Environment, Water and Agriculture (MEWA) and are located in the vicinity of the study basins. It summarizes the time series of the monthly rainfall depth over the period of 1967 to 2005.…”

“…Previous groundwater studies, like [21][22][23]25,26,28,38], in the region have identified that the aquifer is generally composed of wadi infill, wadi alluvium, and coastal plain sediments containing the only significant groundwater systems. According to the Dams and Moor report, project investigation drilling, previous studies, and data from the wells inventory, all showed that groundwater could also be obtained or lost, often readily, from fractured bedrock beneath the alluvium.…”

“…Figure 2. Yiba basin rainfall data: time series of monthly rainfall depth (a,b) from stations in the vicinity of the basin; depth-duration-frequency (DDF) (c); (d) the symbols are the event rainfall depth that has happened on the basin in 1984-1987 and the lines are the depth-duration-frequency (DDF) curves for different return periods (2, 5, 10, 25, 50, 100, and 200 years) calculated from the stations SA003 and SA004 in the vicinity of the basins (modified from[38]). …”

Integrated Surface Water and Groundwater Modeling in Arid Environment, Al-Lusub Watershed, Saudi Arabia

“…Farran et al [28] explained that for arid environments, such as Saudi Arabia, there is a correlation between infiltration (F) and rainfall (P), as shown in Equation (6).…”