# Hydrochemical Characteristics and Suitability Assessment of Groundwater Quality for Irrigation
## 1 Introduction  
Irrigation takes a special place in the water resource management system, given that globally, agricultural water use accounts for 70% of the total amount of freshwater used [1]. Approximately 20% of arable land worldwide is irrigated, and in the European Union, it averages around 6% [2]. The use of unsuitable water quality has led to soil salinity, alkalinization, and overwetting, impacting 20% of global irrigated land [3]. Specific challenges in irrigation, such as soil salinization, soil pollution, water and air pollution, high energy costs, and social and sanitary impacts indicate the need to monitor the quality of irrigation water and its impact on soil resources [4]. In the face of climate change predictions, elevating temperatures and decreasing precipitation in northern Serbia highlight the necessity of irrigation. According to the projected climate scenarios obtained using different climate models, by the year 2080, the average annual air temperature will increase approximately 2.3 to 2.6 \({}^{\circ}\)C and the trend of decreasing total annual precipitation will occur in the entire area of northern Serbia [5]. Such predictions elevate irrigation to the status of a necessary measure, without which intensive and profitable agricultural production will most likelynot be possible. The quality of irrigation water profoundly affects crop yields, soil properties, and poses challenges like salinization and pollution. Problems that can occur in the soil such as salinity,odicity, limited infiltration, contamination, etc. are caused by the use of low-quality water for irrigation [6]. Groundwater resources are under numerous natural (geological-pedological, climatic, and topographic characteristics) and anthropogenic (settlements, industry, and agriculture) influences [7; 8]. A crucial resource, such as groundwater, faces influences from both natural and anthropogenic factors in the northern part of Serbia, where it serves both drinking and irrigation purposes. Research on water quality for irrigation in this area has a long tradition, therefore some classifications and guidelines of local character have been developed, for example, [PERSON]'s classification.  
Previous research in this region, like [PERSON]'s classification, indicates significant variability in groundwater quality for irrigation [9; 10; 11]. The picture of water quality consists of an analysis of various physical, chemical, and biological parameters. Based on the results of the hydrochemical parameters, it is possible to obtain relevant data on water classification. From the aspect of irrigation and its negative influences on soil, water quality is viewed through the content of major cations and anions, salinity indicators (electrical conductivity, EC and total dissolved salts, TDS) and specific indices. These indices, such as Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), total hardness (TH), etc. represent relative relationships between ions, and are important due to the fact that ion exchange is a geochemical process that plays an important role in the formation of groundwater chemistry. Guided by this approach, researchers in different parts of the world assess the quality of groundwater for irrigation purposes [12; 13; 14; 15].  
This study aims to contribute broader insights into the suitability of groundwater for irrigation, in a typical agricultural region, in the Republic of Serbia, considering its potential impact on regional agriculture and development plans.