Investigating the hydrogeology of the area and preparing thematic maps such as level and depth maps of underground water

Abstract

Babol-Babolsar study area with an area of ??1817 square kilometers is under the Babol-Amol area, which is located in Mazandaran province. About 898 square kilometers of the area is the plain and 919 square kilometers are the heights of the northern slopes of Alborz. Babulrud River is the main source of surface water in the area. The climate of Babol-Babolsar plain is very humid according to the Ambergate method. The Babol-Babolsar range is located in the Alborz zone in terms of geological divisions. The bedrock of Babol-Babolsar aquifer consists of marine sediments containing fossil saline water. Based on the geophysical and geoelectrical results, it can be concluded that the major part of the Babol-Babolsar study area aquifer is open type. The transferability of the aquifer ranges from (d/m2) 1500 in the southern areas to (d/m2) 100 in the northern areas. The main purpose of this research was a long-term investigation and study of the groundwater quality of the range (water years 80-81 to 90-91) and different quality zoning of the plain groundwater using the capabilities of the geographic information system (ArcGIS). In the average dry and wet periods, in terms of drinking, 71.9 and 75.9 percent of the range have acceptable quality, and 21.8 and 16.2 percent have poor quality, respectively. In terms of agriculture, 88.8 and 2.87 percent of the range are located in C3S1 class, respectively. The dominant type of groundwater in the area is calcic bicarbonate. Division of the range based on dry residue in average dry and wet periods, more than 80% of the total area has fresh water and the rest has brackish water. In terms of hardness, the groundwater in most of the sampling wells has a very hard quality. By examining the process of qualitative changes of groundwater in the region during the period of 11 years, the degradation of water quality can be observed in recent years. Keywords: Babol-Babolsar, groundwater, water quality, geographic information system. Chapter 1. Research overview. 1-1- Introduction. Water is the source of life and prosperity. is The importance of water in all aspects of human life is evident and not hidden from anyone. Most of the earth's water, i.e. 94.2% of it, is in the form of salt water in the oceans, which is unusable. Of the 5.8% of water available on land on the planet, underground water is the largest source of fresh water in the world and approximately 20% of the world's water consumption is provided from it (Velaiti, 1374). Iran is located in the semi-arid region of the world, where the average annual rainfall is about 253 mm. On the other hand, the distribution of rainfall in our country is not uniform in terms of space and time, therefore we are always facing the problem of water shortage in most parts of the country (Alizadeh 1385, 13), so knowing water in terms of quality and how to obtain it is a fundamental step to optimize consumption (Rex et al. 2007, 210) [1].

Groundwater is always subject to pollution due to its hydrogeological relationship with other water sources (agricultural and Akhund Ali 1385, 3:1620), therefore, in the discussion of groundwater system management where decisions are made based on the quantity and quality of water, it is necessary and necessary to identify groundwater polluting factors, investigate the spatial and temporal changes of pollutant concentrations, and maintain the quality of water resources within acceptable national and international standards. With underground water as one of the important sources of water supply, its quality assessment and protection. The use of various quality indicators helps to express the status and quality of water in a simple and easy way.

In order to continue or develop the exploitation of underground water for various uses and purposes, it is necessary to collect, store, analyze and draw conclusions from the set of quantitative and qualitative characteristics of the aquifer in question. To achieve this goal, it is necessary to carry out monitoring operations (quantitative and qualitative).

Water resources monitoring is divided into two categories: quantitative and qualitative monitoring. Carrying out quality monitoring while providing the information needed to understand the current situation, by simplifying and reducing the raw information, shows the process of quality changes over time and place and provides a suitable basis for timely control measures.According to the programs and activities of successful countries in the field of groundwater quality monitoring and the investigation of the unfavorable situation regarding the protection of the quality of groundwater resources that has led to its degradation, it can be seen the need to pay serious attention to the continuous monitoring of groundwater.

An example of very efficient and advanced facilities in this field is the use of geographic information system (GIS), which has received much attention in the last few years for its capabilities and efficiency in studying the groundwater table of a region. compared to the traditional and manual methods which are often time-consuming and expensive, it should be identified and introduced so that it is possible to apply better management on the condition of the groundwater table in the region at a high speed and at a lower cost, and by updating the information, and to be informed of the qualitative condition of the groundwater of the plain at any time (Ahmadi and Sadekmi 2008, 357) [2]. The qualitative trend of water resources can be used as a useful tool in the preparation of conservation and exploitation programs. In this research, the following objectives have been taken into consideration:- Investigating the hydrogeology of the region and preparing thematic maps such as maps of level and depth of groundwater, direction of groundwater flow, hydrograph of the groundwater unit of the plain with the help of geographic information system.

- Investigating the geochemical processes governing the studied aquifer and its effects. and cations) with the help of the geographic information system and drawing the graph of changes in quality parameters in the desired statistical period.

- Determining the type of groundwater in the region and preparing a spatial zoning map of the region in terms of drinking and agriculture.

1-4- Research hypotheses

- The groundwater quality of the Babol-Babolsar plain is acceptable in terms of drinking and agriculture.

- The trend of qualitative changes The groundwater of Babol-Babolsar plain is declining. Chapter 2: Overview of the research conducted 2-1- Geographical location of the study area: The catchment area of ??the rivers of Mazandaran, which is located in the north of the Middle Alborz mountain range and on the southern edge of the Mazandaran sea, has an area of ??about It is 25650 square kilometers. The coastal plain of Mazandaran is spread along the sea coast with an east-west trend with an area of ??5245 square kilometers. which starts from the catchment area of ??the Safaroud River in the west and ends at the catchment area of ??the Gorgan Bay rivers in the east (Tamab 1375, 4). The study area of ??Babol-Babolsar is located between 36 ?52 to 50 ?52 East and 36 ?42 to 36 ?45 North (Figure 1-2). To determine the boundaries of the area, the boundaries of the political divisions of Babol and Babolsar cities have been used. The length of the plain along the sea is about 21 km. The size of this study area is about 1817 square kilometers, of which about 898 square kilometers are the plain and 919 square kilometers are the heights of the northern slopes of Alborz. The four borders of this range lead from the north to the Mazandaran Sea, from the south to the Alborz Mountains, from the east to the Qaimshahr-Joibar study area and from the west to the Haraz River catchment. The maximum height of the study area is 3700 meters, corresponding to the heights of Alborz, and the minimum height is -22 meters on the shores of the Caspian Sea (Tamab 1375, 8). The heights of Alborz are cut by many large and small valleys, which are generally located in the north and south directions. The main valleys in which the important rivers of the region flow, including Babulrud, often consist of several sub-valleys whose directions are east-west. 

Important cities of the region

The main cities of the area are: Babol and Babolsar cities, which is given below a brief explanation about the cities located in the Babol-Babolsar study area.

Babol city: This city is limited from the north to the Babolsar city, from the south to the Alborz mountain range, from the west to the Amol city, and from the east to the cities of Qaimshahr and Sari. Its height from the north to ten kilometers south of Babylon is lower than the level of the open seas. The center of this city is the city of Babol. Babol city is located between ?5 36 and ?35 36 north latitude and 52' 30 and 52' 45 east longitude.