Abstract
This study presents an integrated modeling system for the evaluation of the quantity and quality of water resources of coastal agricultural watersheds. The modeling system consists of coupled and interrelated models, including (i) a surface hydrology model (UTHBAL), (ii) a groundwater hydrology model (MODFLOW), (iii) a crop growth/nitrate leaching model (REPIC, an R-ArcGIS-based EPIC model), (iv) a groundwater contaminant transport model (MT3DMS), and (v) a groundwater seawater intrusion model (SEAWAT). The efficacy of the modeling system to simulate the quantity and quality of water resources has been applied to the Almyros basin in Thessaly, Greece. It is a coastal agricultural basin with irrigated and intensified agriculture facing serious groundwater problems, such as groundwater depletion, nitrate pollution, and seawater intrusion. Irrigation demands were estimated for the main crops cultivated in the area, based on precipitation and temperature from regional weather stations. The models have been calibrated and validated against time-series of observed crop yields, groundwater table observations, and observed concentrations of nitrates and chlorides. The results indicate that the modeling system simulates the water resources quantity and quality with increased accuracy. The proposed modeling system could be used as a tool for the simulation of water resources management and climate change scenarios.
Highlights
This study aims to address this question with the development of an integrated modeling system, which includes coupled and interrelated models of surface and groundwater hydrology, a crop growth/nitrate leaching model, and groundwater models for the simulation of groundwater, nitrate contamination, and seawater intrusion, set up for use in agricultural coastal watersheds
The seawater intrusion, encountered in themodeling semi‐arid system consisting of coupled interrelated models surface and groundwater hyMediterranean coastal region and Theofdeveloped integrated modeling drology, crop growth/nitrate leaching, and groundwater contaminant transport and its system consisting of coupled and interrelated models of surface and groundwater hydrol‐
System validate effectiveintrusion implementater flow, nitrate pollution by fertilizer practices, andthe seawater tion of the developed crop growth/nitrate leaching model (REPIC) for the simulation of crop yields and nitrate leaching in grid and basin/watershed scale
Summary
The complexity of the problems of such water systems arises mainly from: (i) the limited use of surface water, (ii) the excessive groundwater abstractions for irrigation, and (iii) the over-fertilization practices for crop yield magnification [1]. These actions cause the lowering of the water table of aquifers, increase nitrate groundwater pollution, and invoke seawater intrusion to groundwater systems [2]. Some known examples of coastal water systems where intensive agricultural practices, for irrigation and fertilization purposes, have caused serious degradation of the groundwater resources and documented in the international literature, including Italy (Nurra region of Sardinia [3] and central-southern Italy [4]), south-eastern France (Lower Var Valley) [5], Spain
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