Investigating the Effects of Agricultural Water Management in a Mediterranean Coastal Aquifer under Current and Projected Climate Conditions

Vassilios Pisinaras,Andreas Panagopoulos,Charalampos Paraskevas

doi:10.3390/w13010108

Abstract

Coastal delta plains are areas with high agricultural potential for the Mediterranean region because of their high soil fertility, but they also constitute fragile systems in terms of water resources management because of the interaction of underlying aquifers with the sea. Such a case is the Pinios River delta plain located in central Greece, which also constitutes a significant ecosystem. Soil and Water Assessment Tool (SWAT) and SEAWAT models were combined in order to simulate the impact of current water resources management practices in main groundwater budget components and groundwater salinization of the shallow aquifer developed in the area. Moreover, potential climate change impact was investigated using climate data from Regional Climate Model for two projected periods (2021–2050 and 2071–2100) and two sea level rise scenarios (increase by 0.5 and 1 m). Modeling results are providing significant insight: although the contribution of the river to groundwater inflows is significant, direct groundwater recharge from precipitation was found to be higher, while capillary rise constitutes a major part of groundwater outflows from the aquifer. Moreover, during the simulation period, groundwater flow from the aquifer to the sea were found to be higher than the inflows of seawater to the aquifer. Regarding climate change impact assessment, the results indicate that the variability in groundwater recharge posed by the high variability of precipitation during the projected periods is increasing the aquifer’s deterioration potential of both its quantity and quality status, the latter expressed by the increased groundwater Cl− concentration. This evidence becomes more significant because of the limited groundwater storage capacity of the aquifer. Concerning sea level rise, it was found to be less significant in terms of groundwater salinization impact compared to the decrease in groundwater recharge and increase in crop water needs.

Highlights

The agricultural sector constitutes the dominant water consumer, as about80% of the total water consumption is accounted to agriculture [1], while according to Rost et al [2], irrigation water use, abstracted from rivers, lakes and aquifers has been estimated to be about 70% of total human blue water consumption
According to the results presented above, the dominant inflow to Pinios River Deltaic Plain (PRDP) phreatic aquifer is direct groundwater recharge from precipitation
Soil and Water Assessment Tool (SWAT) and SEAWAT models were implemented in the PRDP in order to simulate and quantify the effects of current agricultural water management practices to the groundwater budget and groundwater salinization status of the underlying shallow, unconfined aquifer under current and projected climate conditions

Summary

Introduction

The agricultural sector constitutes the dominant water consumer, as about80% of the total water consumption is accounted to agriculture [1], while according to Rost et al [2], irrigation water use, abstracted from rivers, lakes and aquifers has been estimated to be about 70% of total human blue water consumption. Irrigation demand is estimated to be higher in Mediterranean region and especially in the south and the east part, in which irrigation accounts for 74% and 81% of the total water withdrawals, respectively [3]. The relation between agricultural production and water resources is direct, especially in arid and semi-arid areas, such as located in the south and east Mediterranean, where agricultural production is largely dependent on irrigation. (b) the anticipated reduction in water resources availability in Mediterranean region due to 4.0/). According to Olesen et al [9] increasing irrigation amounts in Mediterranean region will possibly not be a viable option due to water resources availability reduction, as a consequence of total runoff and groundwater recharge reduction. Garrote et al [10] indicate that a reduction on future maximum potential water withdrawal for irrigation in the south

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