## 2 Materials and Methods
#### 2.1.4 The IH Technique to Evaluate Soil and Water Resources' Degradation  
Water resource management requires a comprehensive understanding of the interactions between the water cycle components, with the study of dynamic water systems requiring approaches capable of capturing processes across multiple spatial and temporal scales. The Global Precipitation Isotope Network is a global network for monitoring hydrogen and oxygen isotopes in precipitation, which operates with the cooperation of numerous partner institutions in IAEA Member States [105]. Water resources are the environmental element most vulnerable to the direct impacts of mining, as they are the most polluting anthropogenic sources [11, 15]. Industrial effluents seriously threaten aquatic biota and ecosystems, with textile waste being the most harmful pollutant. Municipal and industrial wastewater contains polluting chemicals that reduce water quality [10]. Water's most widespread contaminants are heavy metals, organically bound metals and metalloids, organic species, polychlorinated biphenyl, pesticides, detergents, and chemical carcinogens [14]. These pollutants make the environment so inhospitable that species can no longer thrive [1], thus destroying the environmental sustainability of water resources [106]. Hydrological information is essential for measuring water availability and exploring the nature of its problems and conflicts [107], supporting the sustainable development of water resources through their efficient management as a source of water supply to meet needs equitably while maintaining their quality. For this purpose, techniques such as water recycling are carried out, but there are other tools such as isotopic and nuclear techniques [8]. The results of their application support governmental decision-makers in policy formulation for strategic planning and management of water resources [108, 109]. Isotopic investigation of precipitation, surface water, and groundwater is necessary to sustain water resources and understand the present climate and its past and future variations [30]. Analyzing temporal and spatial variations in isotopes in precipitation, mainly oxygen-18 (18O) and deuterium (2H), provides essential data in the IH technique applied to the inventory, planning, and development of water resources. Using the IH technique in identifying groundwater sources is one of the latest scientific technologies, with isotopes of oxygen, hydrogen, carbon, and nitrogen being the most utilized [110]. Its many applications include analysis of groundwater recharge from both precipitation and irrigation water; determination of the frequency, rate, and origins of recharge; groundwater flow pathways, including deep-circulating mineral waters; groundwater mixing; paleosurface water origins; groundwater discharge through evaporation and surface water; modeling of dynamic tropical river inflows; submarine groundwater discharge; and groundwater salinity, among others [111]. Stable isotopes in water are widely applied in studies of river hydrological processes. Isotopic enrichment occurring along the flow direction is used as an indicator to estimate evaporation from the river surface [112]. These isotopic techniques provide essential information allowing us to develop strategies to improve water use efficiency in agriculture, providing solutions to growing water scarcity [113]. Agricultural production and food security depend on water availability [114]; thus, improving its management and quality is essential for productive and sustainable agriculture. Accurate measurement and evaluation of soil water content's spatial and temporal dynamics is a crucial first step in addressing water management problems. The isotopic variation of water (18O and 2H) in the water vapor surrounding plants allows the separation of the evapotranspiration process into the individual components of plant transpiration and soil evaporation, thus minimizing evaporation and improving water use efficiency in agriculture [115].