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Accueil du site → Doctorat → Allemagne → 2018 → Analysis and Projection of spatio-temporal Drought and Climate Change Impacts on Groundwater Resources and Surface-Groundwater Interactions for three Iranian Case Studies

University of Kassel (2018)

Analysis and Projection of spatio-temporal Drought and Climate Change Impacts on Groundwater Resources and Surface-Groundwater Interactions for three Iranian Case Studies

Taie Semiromi, Majid

Titre : Analysis and Projection of spatio-temporal Drought and Climate Change Impacts on Groundwater Resources and Surface-Groundwater Interactions for three Iranian Case Studies

Auteur : Taie Semiromi, Majid

Université de soutenance : University of Kassel

Grade : Doktor der Ingenieurwissenschaften (Dr.-Ing.) 2018

Résumé partiel
Climate change and variability, manifesting itself either in its extremes in terms of droughts or floods, impacts on different components of the hydrological cycle, i.e. the water resources, including groundwater resources, which is an invaluable source of water in Iran, affording more than 80% of the water demand for all sectors in that country, including agriculture, domestic, and industry. Thus, it is of paramount importance for ascertaining adaptation and alleviation strategies to cope with these anticipated climate stressors, in order to secure a sustainable water resources management. In this respect, physically based coupled surface-subsurface hydrological models and data-driven/machine learning algorithms can be an asset to address such types of complex and dynamic hydrological and hydrogeological systems, particularly, in response to the ongoing climate change, recurrent droughts/floods, and increasing population growth. The methodologies used here are applied to three Iranian case studies and the results obtained are being prepared for 6 promising research publications at the time of this writing. (1) To identify and project how a wide range of meteorological drought severities/scenarios propagate through the groundwater system and impact upon the groundwater storage in the Garbaygan plain located in the southeastern area of Iran, standard Z-scores, as a meteorological drought index, were integrated into the Modular Three-Dimensional Finite-Difference Groundwater Flow (MODFLOW) model. The results indicate that even under very wet and normal scenarios (≥ annual average of long-term precipitation), the groundwater budget will not be recovered to a positive quantity, because groundwater over-utilization is found to be the determining factor, which means that groundwater scarcity is the major reason for the sharp drawdown and a negative groundwater budget. (2) Climate change impacts on groundwater storage are projected using a rainfall-runoff model called Identification of unit Hydrographs And Component flows from Rainfall, Evaporation and Streamflow data (IHACRAS) in the light of analyzing the recession curves of streamflow hydrographs in the Bar watershed located in northeastern Iran. The results show that, compared to the reference period (1970- 2010), the streamflow will be decreased by 9, 44 and 66%, for the projected periods 2010-2039, 2040- 2069 and 2070- 2099, respectively. Also, the findings reveal that compared with the reference period the groundwater storage will be decreased by 36.9, 52 and 61%, for the three projected periods, respectively. (3) To impute substantial missing values of groundwater level (GWL) data (as one of the calibration targets) for the calibration and validation of the subsequently developed coupled surface-groundwater hydrological model, reconstruction of the GWL is carried out using Singular/Multichannel Spectrum Analysis (SSA/MSSA) in the Gharehsoo River Basin (GRB), with the enclosed Ardabil aquifer, located in northwest Iran. The results indicate that MSSA, taking advantages of both temporal and spatial correlations, outperforms SSA in the reconstruction and imputation of missing GWL data. Even more, the suitable eigentriples used in this study are found to be sinusoidal which correspond closely to the seasonal fluctuations of the GWL ensuing from the recharge and discharge periods. (4) A fully coupled surface-subsurface hydrological model by means of the latest versions of the Soil and Water Assessment Tool (SWAT) and MODFLOW-NWT (Newton-Raphson Technique to improve the solutions of unconfined groundwater-flow problems) model is set up to represent the intricate and sporadic surfacegroundwater interactions in the GRB. The results show that the groundwater discharge from the aquifer towards the river network (effluent conditions) is the dominant flux exchange, relative to the groundwater recharge from the river network to the aquifer (influent conditions). Also, the findings demonstrate that most of the tributaries across the GRB have been converted from a perennial regime to an ephemeral/intermittent system over the last decades.

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