Assessment of groundwater recharge for a coarse-gravel porous aquifer in Slovenia

Zupanc, Vesna; Bračič Železnik, Branka; Pintar, Marina; Čenčur Curk, Barbara

Assessment of groundwater recharge for a coarse-gravel porous aquifer in Slovenia | Evaluation de la recharge des eaux souterraines pour un aquifère poreux constitué de graviers grossiers en Slovénie Evaluación de la recarga de aguas subterráneas para un acuífero poroso de grava gruesa en Eslovenia 斯洛文尼亚粗砾孔隙含水层的地下水补给评价 Análise da recarga da água subterrânea para um aquífero poroso de cascalho grosso na Eslovênia Ocena napajanja podzemne vode za debelozrnati medzrnski vodonosnik v Sloveniji

2020

Zupanc, Vesna | Bračič Železnik, Branka | Pintar, Marina | Čenčur Curk, Barbara

Research into the unsaturated zone and groundwater recharge can greatly improve understanding of hydrological processes and assist in sustainable groundwater management. Groundwater recharge of the Ljubljana Field aquifer, a coarse-gravel porous aquifer in Slovenia, was estimated with reference to soil characteristics, outflow data from a weighing lysimeter, and water-table fluctuation. The specific yield of the upper unsaturated zone determined from soil characteristics was 0.141 for the top soil layer (0–0.35 m), between 0.042 and 0.066 for the layer below the top soil (0.35–1.3 m), and between 0.239 and 0.219 for the underlying upper coarse layer. During long dry periods, especially in combination with times of high plant-water requirements, only substantial precipitation events directly contribute to considerable groundwater recharge, as ‘substantial precipitation’ is defined as those rainfall events that fill storage and exceed retention capacity of the upper soil layer. Lysimeter measurements show that 50% of the precipitation is lost by evapotranspiration and the other 50% contributes to groundwater recharge. Most infiltrated water was stored for a short time in the unsaturated zone and did not result in a significant discharge from the lysimeter. Average specific yield, calculated using the water-table fluctuation method, was 0.144. The nature of the gravely unsaturated zone is that once the retention buffer of the soil is exceeded, the water front travels through relatively quickly, which can be seen as an advantage for recharge or a disadvantage for prevention of groundwater pollution.

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