Using SWAT and Fuzzy TOPSIS to Assess the Impact of Climate Change in the Headwaters of the Segura River Basin (SE Spain)

Abstract

Abstract:The Segura River Basin is one of the most water-stressed basins in Mediterranean Europe. If we add to the actual situation that most climate change projections forecast important decreases in water resource availability in the Mediterranean region, the situation will become totally unsustainable. This study assessed the impact of climate change in the headwaters of the Segura River Basin using the Soil and Water Assessment Tool (SWAT) with bias-corrected precipitation and temperature data from two Regional Climate Models (RCMs) for the medium term (2041-2070) and the long term (2071-2100) under two emission scenarios (RCP4.5 and RCP8.5). Bias correction was performed using the distribution mapping approach. The fuzzy TOPSIS technique was applied to rank a set of nine GCM-RCM combinations, choosing the climate models with a higher relative closeness. The study results show that the SWAT performed satisfactorily for both calibration (NSE = 0.80) and validation (NSE = 0.77) periods. Comparing the long-term and baseline periods, precipitation showed a negative trend between 6% and 32%, whereas projected annual mean temperatures demonstrated an estimated increase of 1.5-3.3 • C. Water resources were estimated to experience a decrease of 2%-54%. These findings provide local water management authorities with very useful information in the face of climate change.

A Comparison of SWAT and ANN Models for Daily Runoff Simulation in Different Climatic Zones of Peninsular Spain

“…The effect of the parameters on the simulated streamflow was evaluated with p-value which determines the significance of the sensitivity and t-stat which provide a measure of sensitivity. The ranking of most sensitive parameters observed in this study (Table 5) was also supported by the findings of Raposo et al, (2013) [55] in the LRB and Senent-Aparicio et al, (2017) [26] in the HSRB. Some of the most sensitive parameters are common for both basins with a similar order of sensitivity, as for example ALPHA_BF, CH_N1, CH_N2, SOL_K, CN2 and GWQMN.…”

“…The mean annual precipitation ranged from 412 to 1234 mm. The main soil type is Rendzic Leptosol (88% of the total area) with good drainage [26]. The catchment is characterized by conditions which allow the infiltration of a large amount of water and which smooth the hydrological response, and groundwater is crucial in surface hydrology [27].…”

“…After performing a global sensitivity analysis, the most sensitive parameters were selected for each studied basin, which are shown and defined in Table 6. All the selected parameters were also selected as the most relevant in other research [23,26,41,55]. The fitted values of these parameters reflect the contrasting climatic characteristics of the two basins.…”

“…Another big difference between the two basins is the soil evaporation compensation factor (ESCO). The ESCO was higher in the LRB, with an Atlantic climate, than in the HSRB, with a Mediterranean climate where evapotranspiration has a higher relevance [26]. When the ESCO value decreases, the ability of the model to extract the evaporative demand from lower soil layers increases [58].…”

Cost-Benefit Analysis of the Managed Aquifer Recharge System for Irrigation under Climate Change Conditions in Southern Spain

“…In order to simulate future scenarios, the combination of the Global Climate Model (GCM) EC-EARTH and the Regional Climate Model (RCM) HIRHAM5 was downloaded from the EURO-CORDEX initiative [25] and was used to evaluate climate change in the study area for the period 2021-2050 under two different representative concentration pathway (RCP) emission scenarios (RCP4.5 and RCP8.5). This GCM-RCM combination has been recently and satisfactorily applied near the study area [26]. A bias correction technique based on distribution mapping of precipitation and temperature was applied to the downscaled data in order to increase the accuracy of the results.…”