Preliminary knowledge Overview of hydrogeological survey

Mainly master the purpose, tasks, and importance of hydrogeological survey, the main methods and means used in hydrogeological survey, stage divisions, and hydrogeological survey work procedures (work steps), etc. It is an introductory and comprehensive content on hydrogeological survey methods. During the learning process, attention should be paid to the understanding of hydrogeological survey methods, methods, and stage divisions, mastering the survey work procedures and steps, and applying what has been learned.

Learning Objectives

※ Knowledge Objectives

1) Master the purpose, tasks and importance of hydrogeological survey.

2) Master the working methods and working procedures of hydrogeological survey.

※ Ability objectives

1) Have the ability to conduct hydrogeological survey.

2) Learn the working procedures of hydrogeological survey.

Cognitive thinking

1) How to carry out hydrogeological survey?

2) What are the working steps of hydrogeological survey?

Learning content

(1) The purpose, task, importance and type of hydrogeological survey

The purpose of hydrogeological survey is to use various technical methods and means to reveal the hydrology of an area Geological conditions, and master the formation, occurrence, movement characteristics of groundwater and the changes in water quality and quantity. The task of hydrogeological survey is to provide hydrogeological data for national economic construction, development planning or engineering project design.

Hydrogeological survey is a complex and important task. Its complexity is due to the fluidity of groundwater, water quality and quantity changing over time and space, and there are many types of survey methods used. Its importance includes: ①Knowledge comes from practice. People's understanding of the hydrogeological conditions of a region and the answers to hydrogeological questions raised in various production and construction projects must be completed through various hydrogeological surveys, that is, hydrogeological data come from surveys. The quality of all hydrogeological production and scientific research results and the accuracy of the conclusions are mainly determined by the amount of data available and whether it is correct and reliable. ②Hydrogeological survey and exploration is a high-cost and long-term work. If the exploration project is improperly arranged or not carried out according to the technical requirements of the specification (program), the consequences will be a waste of survey expenses and the inability to provide engineering design information. Required hydrogeological data; if wrong conclusions are drawn based on it, it will cause huge losses to engineering construction, national property, production environment and many other aspects.

Hydrogeological survey work can be divided into three categories according to its purpose, tasks and characteristics of survey methods:

1) Regional hydrogeological survey. It refers to comprehensive hydrogeological survey of small and medium scale, also known as comprehensive hydrogeological survey. The purpose of its survey is mainly to provide hydrogeological basis for national economic construction and a certain national economic long-term plan. Sometimes, this kind of survey may also provide regional hydrogeological background data for a specialized hydrogeological survey task (such as urban water supply, mine drainage, environmental hydrogeological survey, etc.). For example, in some large-scale water supply projects, regional hydrogeological surveys are required to propose several possible comparison plans for water sources, or to identify the supply range, supply sources, supply boundary locations and properties of water sources. The main task of regional hydrogeological survey is to roughly identify regional macro-hydrological geological conditions, especially the basic types of groundwater in the region and the burial and distribution conditions of various types of groundwater, the formation conditions of groundwater quantity and quality, and groundwater resources. approximate quantity. The scope of regional hydrogeological survey is generally large, which can be hundreds or thousands of square kilometers. The specific scope depends on the needs of the task. It can be a certain natural unit, one or several larger hydrogeological units, or a certain administrative region. Most surveys are conducted based on international topographic maps. The scale of the survey maps is generally Less than 1:100,000.

2) Specialized hydrogeological survey. Specialized hydrogeological survey is survey work carried out for a special purpose or a certain production and construction.

The purpose of its survey is to provide it with the required data. Sometimes, in order to conduct scientific research on certain aspects of groundwater (such as urban water supply, mine drainage, environmental hydrogeology, etc.), specialized hydrogeological surveys are also carried out. The task of specialized hydrogeological survey is to find out the hydrogeological conditions in the survey area in more detail, solve the production problems raised, and provide hydrogeological data and basis for engineering construction projects or other special purposes. The scope of specialized hydrogeological survey depends on the scale of the project or the needs of scientific research. For example, the scope of water supply hydrogeological survey should be determined based on the size of water demand, which should generally include the possible recharge range of the water source under mining conditions; the scope of mineral deposit hydrogeological survey should be based on the possible recharge range of the mine under the maximum dewatering depth. The scope of recharge mines (wells) should be determined; the scope of environmental hydrogeological survey should at least include groundwater pollution areas and pollution sources. The scale of specialized hydrogeological survey is generally required to be greater than 1:50,000.

3) Groundwater dynamics and equilibrium monitoring. Any type of hydrogeological survey and research work requires information on groundwater dynamics and equilibrium when qualitatively or quantitatively evaluating hydrogeological conditions. Therefore, groundwater dynamics and equilibrium should be monitored. Monitoring of groundwater dynamics and isostatic elements has been of varying duration. If the monitoring work is to provide groundwater dynamics and equilibrium data for regional or specialized hydrogeological surveys, it can only be carried out within a certain period of time, generally only requiring 1 to 2 years; if it is for long-term planning and comprehensive purposes of national economic construction (including groundwater The monitoring work carried out for resource management and protection is long-term.

With the large-scale development and utilization of groundwater resources, there are more and more environmental geological problems related to groundwater. Therefore, the monitoring of groundwater dynamics and equilibrium is increasingly important. Monitoring projects mainly include: groundwater level, water quantity, water quality, water temperature, and environmental geology projects.

(2) Main methods and means used in hydrogeological survey

There are mainly 10 basic methods, means or types of work used in hydrogeological survey: hydrogeological surveying and mapping, hydrogeological survey Drilling, hydrogeological geophysical prospecting, hydrogeological field experiments, long-term observation of groundwater dynamics, indoor analysis and experiments, application of isotope technology in hydrogeological survey, application of global positioning system (GPS), application of remote sensing (RS) technology, geography Information system (GIS) applications, etc. Any hydrogeological survey basically uses these methods and means, and the accuracy of these methods (or types of work) directly determines the quality of the survey results. In recent years, new technical methods such as geological and hydrogeological interpretation of aerial satellite films, GPS technology, geographic information systems (GIS), groundwater isotope testing technology, nuclear magnetic resonance technology, and direct measurement methods of hydrogeological parameters have been used in hydrology. In geological survey, the accuracy and work efficiency of hydrogeological survey have been greatly improved.

1. Hydrogeological surveying and mapping

Hydrogeological surveying and mapping is to conduct on-site observation, measurement, description and survey of the geological and hydrogeological boundaries and phenomena in the area according to certain accuracy requirements, and Draw them into maps to summarize the hydrogeological laws of a region. Hydrogeological surveying and mapping is the first step to understand the hydrogeological conditions of a region and is the basis for all hydrogeological work. At present, remote sensing technologies such as aerial satellite image interpretation are widely becoming modern and effective means in hydrogeological surveying and mapping.

2. Hydrogeological drilling

Hydrogeological drilling is a direct means of exploring groundwater, and it is also the main method of extracting groundwater. It is a major exploration work due to its high efficiency and large exploration depth. In order to obtain better results, hydrogeological drilling must be based on hydrogeological surveying and mapping. In addition, when it is only necessary to reveal groundwater outcrops near the surface or some stratigraphic and structural phenomena related to groundwater, pit exploration or trench exploration can be used directly.

3. Hydrogeological prospecting

Geophysical prospecting is one of the important means of hydrogeological exploration. It is combined with hydrogeological surveying and drilling to effectively identify many geological and hydrogeological problem, thereby saving the workload of other types of work.

It needs to be emphasized that various geophysical prospecting methods have limitations and their results have multiple interpretations. During use, analysis, comparison, and comprehensive research should be conducted based on specific geological conditions so that the interpretation results can truly reflect the objective situation. The main geophysical methods used in hydrogeological work include: electrical method, magnetic method, seismic method, radioactive method, etc. In recent years, new technologies and methods such as geological radar, geophysical tomography (CT), and nuclear magnetic resonance (NMR) have also been widely used.

4. Hydrogeological field test

In field survey work, relevant hydrogeological test work is required to obtain various hydrogeological parameters or solve certain hydrogeological problems. Hydrogeological field tests mainly include: pumping tests, water injection tests, seepage tests, groundwater flow velocity and direction determination tests, connectivity tests, dispersion tests, etc. These tests should be arranged reasonably according to the needs of the survey work.

5. Long-term observation of groundwater dynamics

Since groundwater changes, in order to find its changing rules, it is necessary to observe the dynamics of groundwater (including water level, water volume, water quality, water temperature) to conduct long-term observation work. Based on the observation results, we can correctly evaluate and predict the formation and change patterns of groundwater, water quality, water quantity and water level in the area.

6. Indoor analysis, measurement and experiment

Indoor analysis, measurement and other work are mainly to obtain groundwater quality, hydraulic properties of rocks, rock damage and dissolution mechanisms, and aquifers particle composition, groundwater movement and groundwater age.

7. Application of isotope technology in hydrogeological survey

During the formation and migration of groundwater, the isotopic components of various chemical components will enter the water, and these isotope traces will It can provide important information for studying groundwater and its relationship with environmental media. Environmental isotopes can play a marking and timing role in groundwater. Therefore, it is widely used in hydrogeological survey work. At present, the application of isotope technology in hydrogeological survey mainly solves the following problems: ① Use radioactive environmental isotopes to determine the age of groundwater; ② Use stable environmental isotopes to study the origin and formation process of groundwater; ③ Use radioactive environmental isotopes to study the movement of vadose water; ④ Use environmental stable isotopes to study the sources of chemical components in water; ⑤ Use radioactive isotope tracers to study groundwater movement and hydrogeological processes.

8. Application of Global Positioning System (GPS)

Global positioning system (global positioning system, abbreviated as GPS), also known as global satellite positioning system. GPS has global, all-weather, continuous three-dimensional speed measurement, navigation, positioning and timing capabilities, and has good anti-interference and confidentiality. At present, GPS has become an all-weather, high-precision continuous positioning system, and has the characteristics of high positioning accuracy, automation, fast speed, easy instrument operation, high efficiency and practicality, and flexible and diverse methods. In the past decade or so, GPS has also been widely used in the fields of hydrogeology, engineering geology. GPS is mainly used in the following aspects in hydrogeological work: ① Determine the location and coordinates (or longitude, latitude) of various geological points (geological structures, landforms, Quaternary geology, lithology points, sampling points, etc.), And can determine its direction or tendency; ② determine the location and coordinates of various hydrogeological points such as wells, springs, underground rivers, etc.; ③ determine the elevation of various geological points and hydrogeological points such as wells, holes, springs, etc.; ④ determine The distance between various geological points and hydrogeological points; ⑤ map functions, navigation functions, etc.; ⑥ determine the direction of the exploration line or the orientation of the hydrogeological section line; ⑦ search for relevant information points and points of interest on the map; ⑧ data storage and memory Function, you can create a database, download and convert data, etc.

9. Application of remote sensing (RS) technology

Remote sensing (RS) is "distant perception". It is an application of detection instruments that does not have direct contact with the detection target. , a comprehensive detection technology that records the electromagnetic wave characteristics of the target from a distance, and through analysis, reveals the characteristic properties and changes of the object.

In other words, remote sensing technology is based on the theory of electromagnetic waves, using specialized instruments installed on various aircraft such as airplanes or artificial satellites to receive various spectrum information emitted or reflected by various geological bodies on the ground. Due to the different geological-hydrological geological bodies emitting , absorption, reflection, scattering and transmission of electromagnetic waves with different wavelengths and frequencies, thereby interpreting and determining the geomorphology, geology, and hydrogeological conditions of the measured area, and can be drawn into various maps. It is characterized by large survey area, fast cycle, and wide application. It has unique advantages in improving survey quality, accelerating survey progress, reducing surveying, mapping and exploration workload, and reducing physical labor. There are many types of remote sensing technology (RS). Currently, aerial photography, infrared detection and multi-band measurement are commonly used in hydrogeological survey. Aerial photos can be used to interpret aquifers and water-bearing structures, identify regional hydrogeological conditions, delineate water-rich areas, and divide water catchment areas. Infrared remote sensing technology has good results in searching for shallow groundwater (such as finding ancient river channels, finding the location, size, and quantity of groundwater outcrops, detecting underground hot water, studying hydrogeological conditions in karst areas, etc.). Earth satellite images can be used to survey earth resources and monitor the environment. They can interpret regional landforms, stratigraphic lithology and geological structures. They can also delineate alluvial aquifers and find springs and groundwater overflow zones, as well as shallow groundwater distribution areas. , as well as for surveying surface water resources and monitoring environmental pollution.

10. Application of Geographic Information System (GIS)

Geographical information system (GIS for short) is the acquisition and processing of various geographical information or spatial information. , analysis and application of computer technology systems. Geographic Information Systems (GIS) have begun to be used in groundwater research. The application of geographic information system (GIS) in hydrogeological survey mainly includes the following aspects: ①Establishing groundwater database and simulation system; ②Identifying aquifers and rationally developing and utilizing groundwater resources; ③Conducting groundwater quality research; ④Carrying out groundwater resource management ; ⑤ Preparation of hydrogeological maps; ⑥ Groundwater simulation and visualization.

Global Positioning System (GPS), Remote Sensing Technology (RS), and Geographic Information System (GIS), referred to as "3S" technologies. "3S" technology is a spatial information processing technology that has gradually developed since the 1960s and is now becoming increasingly mature. Due to the increasing maturity of "3S" technology, Australia, the United States, Canada and other countries began to use "3S" technology for digital geological mapping in the 1980s, thereby realizing the computerization and informatization of geological mapping, which greatly improved Improve work efficiency. my country's digital geological mapping work started in the 1990s. At present, digital geological mapping based on "3S" technology is gradually being promoted and applied in geological and hydrogeological survey work.

(3) Division of hydrogeological survey work stages

Specialized hydrogeological survey work is generally carried out in stages. The main reasons are: ①Specialized hydrogeological survey work Surveying serves special purposes or engineering construction projects, and the design work of the project is generally carried out in stages. The content and accuracy of hydrogeological data required at different design stages also have different requirements. In order to meet the needs of the design, hydrogeology The survey work should also be divided into corresponding stages; ② Dividing the survey work into different stages can make the entire survey work orderly and focused, gradually proceed in depth, and enable us to understand the hydrogeological conditions of the survey area from a shallow to a deeper level. , to prevent some negligence, omissions or one-sidedness, and to avoid making major and comprehensive mistakes in the survey work. The division of survey stages for specialized hydrogeological survey work with different tasks is generally different.

Usually, hydrogeological survey can be divided in principle into four stages: hydrogeological general survey, preliminary hydrogeological exploration (referred to as preliminary survey), detailed exploration (referred to as detailed survey) and mining. The preliminary exploration and detailed exploration are collectively referred to as the hydrogeological exploration stage. General hydrogeological survey belongs to comprehensive hydrogeological survey, while hydrogeological survey belongs to specialized hydrogeological survey.

1. Hydrogeological survey stage

It is a regional comprehensive hydrogeological survey carried out to provide hydrogeological data for economic construction planning. The scale used is generally 1:200,000. Or 1:100,000. The survey work mainly focuses on hydrogeological surveying and mapping, combined with a small amount of exploration and testing work. Its main task is to find out the preliminary rules of regional groundwater formation, provide regional hydrogeological condition data, and make a general evaluation of regional groundwater volume and development prospects. , providing a basis for national economic long-term planning and hydrogeological exploration design. The specific requirements are to initially identify the burial and distribution characteristics of the main aquifers, groundwater formation conditions, groundwater types, groundwater quality, groundwater recharge and discharge conditions, groundwater movement patterns, etc.

2. The preliminary hydrogeological survey stage

It is a specialized hydrogeological survey carried out for a certain production task based on the hydrogeological survey. The main work is to carry out hydrogeological surveying and mapping at large and medium scales (1:100,000 or 1:50,000), a small amount of hydrogeological exploration, testing and long-term groundwater observation for a certain period. The tasks at this stage are to more accurately identify the geological conditions and groundwater formation conditions and occurrence characteristics, initially evaluate groundwater resources, compare water source plans, initially delineate water supply extraction areas (or key drainage areas), and predict water quantity, water quality, and water levels. Changes, propose reasonable development (or dewatering) measures, and provide a basis for preliminary design of water supply (drainage) or layout of detailed exploration work.

3. Detailed hydrogeological exploration stage

Usually further detailed exploration and research are carried out on the sections demarcated by the initial survey. The main work is mainly exploration and testing, and requires a Long-term observation data of more than 20 years, and comprehensive indoor experiments, analysis and research must be carried out. The work scale at this stage is generally 1:25,000, 1:10,000 or larger. The task at this stage is to accurately identify the hydrogeological conditions of the exploration area, make an accurate and comprehensive evaluation of water quality and quantity, propose a reasonable mining plan, and provide a basis for technical (construction) design.

4. Exploitation stage

The main work is to conduct research on the mining dynamics of water source areas, supplemented by supplementary exploration and specialized tests when necessary, to identify the possibility of expanding exploitation of water source areas. , or study the causes of water volume reduction, water quality deterioration and adverse engineering geological phenomena, verify the allowable mining volume of groundwater (exploitable volume), provide basis for rational mining and protection of groundwater resources, and provide basis for the design of water source improvement and expansion. When conditions are met, establish a groundwater resource management model and database. A specific engineering survey project should be divided into several survey stages, which should be determined based on the complexity of local hydrogeological conditions, the scale and importance of the engineering construction project, and the extent of existing hydrogeological research. For example: ① The hydrogeological conditions in the exploration area are extremely complex and the water demand (or drainage) is large. After detailed exploration, hydrogeological work in the mining stage should be carried out, which is also called thematic hydrogeological exploration. ② If there are already regional hydrogeological survey results at a scale of 1:200,000 or 1:100,000, or the water supply project is small in scale, the survey work in the general survey stage (or planning stage, or preliminary demonstration stage) may not be carried out, or only supplementary work may be carried out survey work. ③ If the water supply project does not have different water source comparison plans, the preliminary survey and detailed survey can be combined into one exploration stage. ④ For water supply engineering projects of individual factories, mines, enterprises and institutions with small water demand, when the hydrogeological conditions are not very complex and only 2 to 3 boreholes are needed to meet the water demand, exploration and mining can be used Combined methods, directly enter the exploration stage of mining. ⑤ For hydrogeological survey of farmland irrigation water supply, in view of the low degree of guarantee of farmland water supply, it is generally divided into three survey stages: general survey, detailed survey and mining. ⑥The division of hydrogeological exploration stages of mineral deposits should generally be consistent with the division of hydrogeological exploration stages of mineral deposits, and can be divided into three stages: general prospecting, preliminary prospecting and detailed prospecting.

(4) Procedures (work steps) for hydrogeological survey work

Hydrogeological survey work should be carried out in a planned and step-by-step manner according to certain work procedures. The general principle is: design first and then construction, first survey and then exploration.

The general work procedures are as follows:

1. Accept survey tasks

Survey tasks are divided into vertical tasks (assigned by superiors) and horizontal tasks (assigned by local governments). Vertical tasks can be either directive tasks issued by the superior authority, or tasks assigned by the production unit after the project is approved by the superior authority. If it is a horizontal task, the survey task must be formally determined only after a task entrustment contract is signed with the task entrusting unit (generally referred to as Party A).

2. Preparation work

After accepting the survey task, preparation work must be carried out, mainly in terms of personnel organization preparation, technical preparation, material logistics and other aspects. Among them, writing design documents in technical preparation is the main job of hydrogeologists. Before writing the design document, it is necessary to fully collect existing physical geographical data, geology, hydrogeological data and maps in the survey area, to have a preliminary understanding of the hydrogeological conditions and problems in the survey area, and to determine the degree of research in the survey area. When necessary, a field survey should be conducted. The survey route should strive to pass through sections with relatively complete stratigraphic development and representative hydrogeological conditions in the survey area. The natural and working conditions of the survey area should also be understood, so that the design document written can be more realistic.

The design document is the basic basis for arranging and conducting various survey work, and is the "battle plan" for hydrogeological survey. The types of design documents can generally be divided into overall design, annual design, individual design, etc. The main contents of the design document are as follows:

1) The physical geography, geology and hydrogeological conditions of the survey area, including: ① The purpose and tasks of the survey work, the location, area and traffic conditions of the survey area, the survey stage and the start and end time of the survey work; ② Overview of physical geography and economic geography; ③ Existing geological and hydrogeological research levels and existing problems; ④ Overview of geological and hydrogeological conditions in the survey area.

2) Survey work design, the main content includes: ① types of work to be invested in the survey work, work layout plan, main technical specifications based on the work, workload and main technical requirements of each work. When arranging survey work, it is necessary to not only meet the requirements of relevant specifications for workload quota and work accuracy, but also consider identifying important locations and completing key tasks to prevent the average use of survey workload; ② Material and equipment planning, personnel organization division of labor, and funds Budget and construction progress plan; ③ Expected survey work results.

3. Field work

Field work is to carry out various hydrogeological surveys in the field. The sequence of work types invested in hydrogeological survey is: hydrogeological surveying → geophysical prospecting → exploration → test → long-term observation. The former is the foundation of the latter, and the problems revealed are also gradually deepened. The amount of work invested in each type of work should be based on specific conditions, so as to be economically and technically reasonable and feasible, and to achieve high-quality results. During field work, it is necessary to conduct observations and measurements with quality and quantity, catalog original data, and correctly draw various drawings of field work. Comprehensive analysis should be strengthened during work, attention should be paid to the organic cooperation between various types of work, and attention should be paid to related indoor experiments, analysis, identification and other work. During the field work, the field work can also be divided into several periods, and the survey, inspection and summary can be organized according to the period. During the field work, the design document can be appropriately modified according to the actual situation. However, if there are major changes, supplementary designs should be proposed. The working methods and content of field surveys will be introduced later.

4. Indoor work

Indoor work is mainly to carefully check, organize and analyze the data obtained from field survey, and compile the results of hydrogeological survey. Survey results generally include hydrogeological maps and written reports.

Finally, organize the acceptance and appraisal of survey results according to prescribed procedures.

Knowledge summary

Through learning, you should master the following key contents: ① The 10 main methods used in hydrogeological survey, and master the application, advantages and disadvantages of each method; ② Hydrogeology The survey stages are divided into: general survey, detailed survey, exploration, and mining; ③ Hydrogeological survey work procedures (work steps): Accept survey tasks → Preparation work → Field work → Indoor work → Appraisal and acceptance.

Knowledge training

1. What is the purpose and task of hydrogeological survey?

2. What is the significance of hydrogeological survey?

3. How many types of hydrogeological survey work are there? What are the characteristics of each?

4. What are the methods and means of hydrogeological survey? What are the characteristics and functions of each?

5. Try to compare the advantages and disadvantages of the three methods of hydrogeological surveying and mapping, hydrogeological drilling, and hydrogeological geophysical prospecting.

6. Which is the most important test in hydrogeological testing?

7. What is "3S" technology? What are the functions of each?

8 .Why should hydrogeological survey stages be divided? How are hydrogeological survey stages divided in various industries (departments)?

9. How are hydrogeological surveys usually divided into survey stages? What are the tasks and requirements of each stage?

10. What are the working procedures (work steps) of hydrogeological survey work?