Simulation and Evaluation of Water Resources Management Scenarios Under Climate Change for Adaptive Management of Coastal Agricultural Watersheds

Abstract

The main objective of this paper is to analyze the impact of climate change on water resources management and groundwater quantity and quality in the coastal agricultural Almyros Basin, in Greece. Intensive groundwater abstractions for irrigation and nitrogen fertilization for crop production maximization, have caused a large water deficit, nitrate pollution, as well as seawater intrusion in the Almyros aquifer system. Multi-model climate projections for Representative Concentration Pathways (RCPs 4.5 and 8.5) from the Med-CORDEX database for precipitation and temperature have been used to evaluate the impacts of climate change on the study area. The multi-model climate projections have been bias-corrected with Delta, Delta change of Mean and Variance, Quantile Delta Change, Quantile Empirical Mapping, and Quantile Gamma Mapping methods, and statistically tested to find the best GCM/RCM multi-model ensemble. Simulation of coastal water resources has been performed using an Integrated Modelling System (IMS) that contains connected models of surface hydrology (UTHBAL), groundwater hydrology (MODFLOW), nitrate leaching/crop growth (REPIC), nitrate pollution (MT3DMS), and seawater intrusion (SEAWAT). The results indicate that the best climate multi-model ensemble consists of three (3) climate models for both RCP4.5 and RCP8.5 using the Quantile Empirical Mapping bias-correction method. The IMS was applied for historical and future periods with observed and simulated meteorological inputs (e.g. precipitation and temperature) and various irrigation and agronomic scenarios and water storage works development (i.e. reservoirs). The results indicate that at least deficit irrigation and deficit irrigation along with rain-fed cultivation schemes, combined with or without the development and operation of reservoirs, should be applied to overcome the degradation of groundwater quality and quantity in the study basin. Based on the findings of this work, the water resources management should be adaptive to tackle the water resources problems of the Almyros Basin.

An integrated reservoir operation framework for enhanced water resources planning

“…In support of the findings by 37 , 44 , the present study depicted that under adequate precipitation and reservoir inflow scenario, the proposed reservoir operation rule can meet both irrigation demand and environmental flow adequately, highlighting the explicit climatic control on the supply–demand dynamics. An overview on the climate change impact on the reservoir operation revealed the difference between the supply–demand was the highest during the dry periods of many global studies, which is also evident in the current study region during the month of April and May 45 – 47 . To ascertain more practical water management scenario, 30% cut-off in the actual irrigation demand is recommended in this study, which is in line with the study conducted by 48 depicting 30% reduction in agricultural demand under RCP 4.5 scenario resulted higher sustainability index.…”

Climatic Modeling of Seawater Intrusion in Coastal Aquifers: Understanding the Climate Change Impacts

“…Groundwater flows from high elevated areas towards the lowlands and the sea in the central region of the aquifer, and the flow directions change on the northern coast and in the southern region, according mostly to hydrogeological permeability and to the difference in elevation between the water table and sea level. Nowadays, the Almyros basin is a basin which faces severe seawater intrusion that has evolved through the years, mostly at the northern coastline, as observed and estimated in previous studies [35,37,38] in the region and as described in the next section.…”

“…between the water table and sea level. Nowadays, the Almyros basin is a basin which faces severe seawater intrusion that has evolved through the years, mostly at the northern coastline, as observed and estimated in previous studies [35,37,38] in the region and as described in the next section. Coastal water resources were studied using an integrated modeling system, developed in a previous study [35].…”

“…The studies by Lyra and associates (2021) [35] and Lyra and Loukas (2022) [37] gave rise to the development of the integrated modeling system, utilized to model and project the potential effects of climatic changes on the Almyros basin and its aquifer system, in Thessaly, Greece, covering both the worst-case (RCP8.5) and moderate (RCP4.5) climate scenarios. The findings of the simulation process implemented for the evaluation of seawater intrusion and climate change scenarios and climatic models are provided and analyzed in the following paragraphs.…”

“…After obtaining climate models from Med-CORDEX for the RCP8.5 and RCP4.5 scenarios, a crucial step was taken in guaranteeing the precision and dependability of the data. The bias correction technique of Quantile Empirical Mapping, a highly regarded method, was utilized to refine and harmonize the model outputs, which was undertaken in earlier studies [36,37], the results of which were used in the present simulations. Critical efficacy scores are summarized in Appendix A.…”