This gave rise to the construction of many private artificial irrigation ponds (approx. 9000 ponds; Casas et al., 2011b) to ensure the water supply for drip-irrigation. Groundwater is the main water source, but due to severe long-term groundwater imbalances, alternative water sources are increasingly used (recycled wastewater, rainwater collected from greenhouse covers and desalinized water) (Juan et al., 2012).