Monitoring of Irrigated Lands of the Hissar Valley of the Republic of Tajikistan

Abstract

Most of the territory of the Republic of Tajikistan (93%) is occupied by mountain ranges and only 7% of the territory is lands suitable for agriculture. In this regard, the population density is very high and amounts to 60 people per 1 square kilometer of the area. The population at the beginning of 2019 was 5.3 million people, and in 2021, it was 9,537,645 people, an increase of about 80%. The demographic situation, the lack of suitable land for agriculture leads to the violation of the ecological balance that has developed in the last 30 years in Tajikistan, including on irrigated lands, which led to a decrease in crop yields by 1.5–2.0 times. One of the reasons for the decrease in productivity is the irrational use of land resources and anthropogenic impacts on reclamation lands. The intensification of the use of agricultural lands leads to their degradation, the development of desertification; a special place is occupied by irrigated lands, the problems of their conservation and improvement of their condition. The solution of these problems is based on objective and up-to-date information about the state and use of irrigated lands, as well as timely and reliable information received. In this regard, there is a need to identify and assess the existing environmental and socio-economic problems in the use of reclamation lands, the timely reconstruction of reclamation systems, the development of ways to solve the identified problems, as well as the development of methodological recommendations to justify the effectiveness of the implementation of state agricultural land management programs, taking into account regional characteristics. The existing information on the state and use of agricultural lands is contained in various organizations, is fragmented, of different scales and of different information. To use such information, it is necessary to transform it, which can lead to a significant loss of information, a decrease in its accuracy, and, consequently, its reliability. Modern geoformation technologies using remote sensing methods of the Earth at the present time can significantly improve the quality of research conducted when monitoring irrigated lands. In this regard, monitoring, analysis, assessment and forecasting of the ameliorative state of irrigated lands of the Republic of Tajikistan, and their conservation based on the development of criteria for environmental and socio-economic assessment of the use of reclaimed lands and the development of recommendations for the reconstruction of melioration systems based on the use modern geoinformation technologies and the use of aerospace images is relevant.

1. Introduction

The main results of the work of the geoinformation system for managing irrigated lands of the Gissar region are reports on the use of reclaimed agricultural land, made according to standard forms, forecasts of changes in the reclamation and environmental and economic situation, and, most importantly, thematic maps (cartograms) in an easy-to-read graphical form that reflect information on the use and condition of irrigated lands. Farmers and dekhkan farms grow crops to meet the needs of the national economy in food. The main agricultural crops in the study area are: wheat, cotton, rice and vineyards.

The organization of monitoring of irrigated lands in the Gissar Valley using geographic information systems provides for the following steps:

Stage 1: Analysis of complex information on the state and use of natural environments on the territory of the Gissar Valley. The collection of information material on the object of study is carried out from various information sources, information is requested from the data bank of regional significance, multispectral space images are obtained from the Landsat 7 and Landsat 8 satellites, analysis of test data.

Stage 2: Mathematical analysis of multispectral satellite images on the territory of the Gissar valley. Analysis of multispectral satellite images from Landsat 7 and Landsat 8 satellites using ArcGis 12 software, determination of irrigated land areas in the Hissar Valley. Deciphering and vectorization of raster data for the study area.

Stage 3: Substantiation of the representativeness of indicators for assessing the state of irrigated lands. Establishment of negative processes arising in the Gissar Valley, grouping into the following groups: natural, technogenic, social. Analysis using software products “Statistica” v.10.0, JMP Statistic 15 and Minitab 19, on the basis of which an analysis of a set of indicators describing the state of natural environments in contact with irrigated lands is carried out: regression, correlation matrix. Determination of hidden factors affecting the state of irrigated lands and forecasting the development of changes in their state. Definition of areas for research.

Stage 4: Conducting field research. Inspection of the reclaimed area on the ground, search for interpretation parameters, visual analysis of the soil cover and crops of reclaimed lands, identification of areas with pronounced signs of salinization, control of intermediate interpretation, measurement of the depth of groundwater and sampling in a network of boreholes and wells, determination of the coordinates of reference observation points to correct data using modern technologies, GPS, UAVs, etc.

Stage 5: Organization of a single information space for monitoring irrigated lands in the Gissar Valley. It is envisaged to involve departmental services of the region, which carry out various types of monitoring, into a single information space.

Stage 6: Creation of digital thematic maps of the irrigated lands of the Gissar Valley, dekhkan farms in the form of: geographical (location, condition, connections of existing natural and social phenomena, cadastral information, etc.); environmental (pollution, infection, radioactivity, susceptibility to dangerous natural and natural-technogenic processes: mudflows, landslides, snow avalanches, landslides, earthquakes, etc.) and others; maps (including 3D terrain models); cartograms showing the required thematic characteristics of the factors of natural and anthropogenic impact.

Thematic maps are updated based on the collection of data obtained from various sources on various monitoring activities carried out on the territory of the Gissar Valley, formed on the basis of the proposed methodology for selecting the most representative monitoring indicators for irrigated lands in the Hissar Valley using software products “Statistica” v.10.0, JMP Statistic 15 and Minitab 19.

Thus, the introduction of monitoring of irrigated lands in the Gissar Valley and based on the use of GIS technologies for monitoring irrigated lands makes it possible to create maps directly in digital form according to the coordinates obtained as a result of measurements on the ground or during the processing of Earth remote sensing (ERS) and UAV data obtained from various sources. Implementation of the analysis of multispectral satellite images from Landsat 7 and Landsat 8 satellites using ArcGis 12 software into the process of monitoring irrigated lands. When creating digital maps in a GIS environment, emphasis is placed on creating a structure of spatial relationships between objects.

Digital maps serve as the basis for the production of conventional paper and computer maps on a paper basis and contain data and rules describing the position and spatial and logical relationships of objects in the territory of the Gissar Valley.

The aggravation of the ecological situation makes more and more relevant work on the consciousness of information bases, applied geographic information systems and the use of GIS technologies to solve a set of problems that arise in the field of nature management and environmental protection. In the field of monitoring irrigated lands using GIS, it is possible to solve the following main tasks:

• reflection of the current state of the land and the adjacent water area of the shelf zone by individual parameters or their possible combinations in the form of maps of various scales for various territorial units and levels;

• assessment of the state and dynamics of irrigated lands according to various parameters (erosion, salinization, soil pollution, acidity, etc.);

• assessment of the area and productivity of agricultural land;

• forecast of possible changes in the quality of irrigated lands;

• assessment of economic damage from pollution of irrigated lands by air, water and other sources;

• modeling of ecological processes on irrigated lands and on the territory of the Gissar valley;

• assessment of the condition of ameliorative systems and design of their reconstruction;

• forecasting and designing the use of irrigated lands, their protection.

Using the developed methodology, data were collected from ground control points to obtain orthophotomaps from multispectral satellite images obtained from the Landsat 7 and Landsat 8 satellites in order to compare spatial data with the available data. To implement this approach, all locations of soil samples were recorded using a Garmin 90 hand-held GPS navigator, which recorded more than 150 points covering all parameters for linking remote sensing data to this territory.

Classification and generalization of input data was carried out on the basis of geographic databases compiled by the author, taking into account the table of attributes and primary materials.

For further research, the author selected the irrigated lands of the dekhkan farm “Istiklol” of the Gissar district, located in Central Tajikistan. The total area of key sites is 150 hectares or 0.2% of the total monitoring area.

Field observations were carried out in determining the on-farm boundaries of land use; conditions of windbreaks; when taking soil samples to analyze its content in order to determine the degree of soil fertility in irrigated ecosystems of the study area.

Further processing was carried out on the basis of the developed model for creating monitoring maps for irrigated lands of the Gissar Valley using GIS and statistical data processing presented by “Statistica” v.10.0, JMP Statistic 15 and Minitab 19.

Issues related to anthropogenic impacts on the destruction of the ecological balance of irrigated potential on the process of degradation and water erosion of lands, which was obtained by us on the basis of field observations. Field surveys of dekhkan farms also provided data on the number of major crops produced on each farm.

Mapping. On the basis of the proposed methodology, we have compiled a number of thematic maps related to the objectives of the study, as well as obtained actual maps of the study area using GIS technologies.

Rasterization was performed when processing a satellite image in order to obtain a raster image, as well as preparing digital data for entering into a database.

The method allowed us to prepare more than 20 types of spatial data and obtain raster data from the resulting vector files. Data digitization was carried out using ARC GIS & Microsoft Excel software.

Vectorization. The process of interpretation of space images was carried out by us in order to determine the varieties of agricultural crops in the study area and a number of photogrammetric approaches to determine the parameters of the studied physical objects reflected in the images. All physical objects located in the study area were vectorized.

Vectorization was carried out on the basis of Arc Catalog in Arc GIS program using the object editing method. As a result, vector files were obtained for all objects of study.

Mathematical and statistical methods. Mathematical calculation methods make it possible to determine the number of studied phenomena in a particular area. We needed to use this method when calculating the number of row crops and other physical objects, their location, area, which are reflected in satellite images.

When using statistical methods, we can write that all tabular data and demonstrative-schematic data were obtained on the basis of statistical calculations of data recalculations. The most informative indicators were determined using statistical methods and approaches.

Laboratory methods. The objectives of the study required the analysis of soil content in key areas in order to find out the proportion of soil fertility, as well as soil composition to increase the productivity of irrigated lands. Using laboratory analyses, soil samples were analyzed from three farms in the study area.

Thus, it can be considered a key indicator of the possibility of using this technique - this is the achievement of the goal, which is the implementation of state monitoring of the state and use of irrigated lands of the Gissar Valley using maps created using geoinformation technologies based on Arc Catalog in Arc GIS.

Based on this, we can single out the main criterion - the creation of thematic maps, for which the main indicators are: vector data, raster data, text data, their verification and processing.

Comparison of the two methods for these indicators. The indicators for data processing according to the second scheme depend on the specifics of the state and use of land in different areas of the valley. Comparing two methods of creating maps for the implementation of state monitoring of the state and use of land, it can be noted that when using any of them, you can get the desired result - a thematic map that displays the state and use of land of any territory of interest.

But at the same time, it should be noted that when using statistical data processing in the second method, it is possible to achieve a better and more correct display of the real situation on the ground due to a double check for the reliability of the data - statistical and expert.

Also, when using statistical processing, it is possible to find dependencies between indicators, determine trends in the development of indicators, predict the development of observed indicators, and make a management decision in advance to prevent the deterioration of the situation.

Conclusions. Thus, the authors in this article reviewed the analysis of the state of irrigated lands in the Gissar Valley based on the use of multispectral satellite images from the Landsat 7 and Landst 8 satellites using the ArcGis software. In the process of their analysis, maps were obtained for the NDVI index from 2010 to 2019, on the basis of which changes in the area of vegetation cover for the period 2010–2019 were obtained. And then, MNDWI maps were obtained from 2010 to 2019 of water coverage, and plots related to irrigated land were determined using the obtained vegetation and water coverage data.

On the basis of the received set, an analysis of the qualitative state of the lands in the Gissar Valley was carried out and it was found that in the territory of the valley, the development of processes of degradation of soil and vegetation covers is observed almost everywhere, which affects the efficiency of agriculture and causes the expansion of territories, the ecological state of which is problematic or even critical. Thus, one of the key directions in organizing the rational use of land in the region, as experience shows, should be land management of agricultural enterprises on an agrolandscape basis in combination with other works, which in turn requires up-to-date information about their condition and use, obtained as a result of monitoring of irrigated lands using modern information and telecommunication technologies and geographic information systems.

2. Development of theoretical provisions for monitoring irrigated lands in the Gissar Valley of the Republic of Tajikistan using GIS technologies

As noted earlier, land monitoring (Reimers, 1990) is based on a system of observations of various phenomena, conditions and processes, but a geographic information system is also very important for processing and predicting the state of the observed environment, given that in modern monitoring conditions, they receive a huge amount of various data that is almost impossible to process without the use of modern geoinformation technologies. Bearing in mind that information support for assessing the ecological state of irrigated lands should be based on obtaining up-to-date data on the state of the main components of the natural environment, the dynamics of changes and factors that affect the state of these lands.

Fomin et al. (1995), Derzhavin et al. (1999), Gostishchev et al. (2001); Biryulin and Manukyan (2002) note that the most important part of monitoring the state of irrigated lands is its information system.

Geographic Information System (GIS) - a software and hardware system capable of storing and using (showing, analyzing, managing) data describing objects in space, managed by special personnel, and the word “geographical” in this case means not so much “spatiality” or “territoriality”, but rather the complexity and consistency of the research approach. The use of geographic information systems allows you to quickly receive information on request and display it on a map basis, assess the state of the ecosystem and predict its development.

GIS uses a special type of information - spatial (geographic) and associated databases, this information can be social, political, environmental or demographic, that is, any information that can be displayed on a map.

GIS is the best way to store information about land or sea. GIS can help make management more efficient, promote scientific work and the protection of natural resources, which is carried out for all territories, regardless of their area.

In recent years, geoinformation systems and WEB technologies have been actively used for processing aerospace images, accumulating and transmitting data.

The introduction of GIS systems solves a number of problems: maintaining a centralized accounting of agricultural lands, their inventory, monitoring the state and use, supervision of their use, preparation of analytical information; entering information into the information system for agricultural land management; use of Earth remote sensing data for monitoring the state of crops; accounting of land plots from agricultural land and land of other categories; preparation of information with aggregation at various levels, including the level of the Republic; providing access to information provided on the basis of state information resources on agricultural lands based on the use of GIS technologies. In fact, this system demonstrates an integrated approach to monitoring agricultural land. An important advantage of this approach is the possibility of creating a single Internet resource and providing access to geospatial data to interested parties [1].

It is important to note that the collection of information on agricultural lands in all the described systems is carried out mainly in the context of the state, regional, district levels, except for individual agricultural enterprises, and even more so crop rotation fields.

Geoinformation technologies provide ample opportunities in the development of irrigated land management systems. GIS allows structuring information on the geographical (spatial) position of objects - data sources, which is of particular importance for managing the state of not only irrigated lands, but also the environment.

Nowadays, one of the urgent tasks of agricultural science is to improve the quality and scientific validity of irrigated agriculture management, including through the development and use of modern software and information tools to support decision-making. Their main task is to provide all persons making decisions on the management of the reclamation complex with detailed, complete, timely and high-quality information in a form convenient for human perception, to ensure its mathematical and heuristic processing. At the same time, it is very important to link information flows that are heterogeneous in origin, but spatially interconnected.

The scope of GIS technologies is land management, land cadasters; design, engineering surveys and planning in urban planning; thematic mapping; inventory and accounting of objects; terrain analysis; land transport navigation; air traffic control; geology; environmental monitoring; environmental management; natural resource management.

The use of GIS technologies for monitoring irrigated lands makes it possible to create maps directly in digital form according to the coordinates obtained as a result of measurements on the ground or during the processing of remote sensing materials. When creating digital maps in the GIS environment, the emphasis is on creating a structure of spatial relationships between objects, the concepts of exact and inaccurate coincidence of boundaries are clearly distinguished, it is easy to use previously digitized boundaries when creating adjacent objects, including when working in other industries, it is easy and relations of connectivity, neighborhood, adjacency, nesting, intersection, and other spatial objects necessary for solving a wide range of analytical and practical problems are fixed explicitly).

Digital maps serve as the basis for the production of conventional paper and computer maps on a solid substrate and contain data and rules that describe the position and spatial and logical relationships of terrain objects [2].

Since the adaptation of all components of irrigated farming systems requires complete and systematic information about the properties of soils, groundwater, irrigation network, etc. for specific fields of the economy, the information support should be based on local integrated GIS monitoring [3].

A natural and necessarily arising problem of monitoring agrolandscapes is the problem of transition from point-based data on the state of indicators of the ameliorative state of lands and their soil fertility to digital models of the spatial distribution of these indicators in the layers of digital maps. At present, many tools have been developed for constructing spatial distribution models using interpolation and approximation of point data. Our task was to select the best methods and develop algorithms for their application in the specific conditions of irrigated lands in Tajikistan on the territory of the Gissar Valley [4].

Thus, the monitoring of irrigated lands is created as a multi-level observation system, including complexes of ground and remote (including aerospace, from unmanned aerial vehicles) observation methods:

• Detailed - examination of the state of land on the objects included in the irrigation system, the system of water protection facilities.

• Local - ground and aerial photography, including from UAVs (local observations and forecasts).

• Regional - aerospace survey (regional observation forecasts).

The monitoring program for irrigated lands must necessarily include primary information on the state and use of lands, the main criteria for this level are the importance and completeness of the information collected, such information can be obtained at the local level [5]. Figure 1 shows the hierarchical structure of irrigated land monitoring using modern technologies.

Figure 1.

Hierarchical structure of monitoring of irrigated lands in the Gissar Valley in the Republican system (compiled by the author).

Monitoring of the state of irrigated lands is carried out during complex work in the natural and technogenic systems of these lands, the main task of which is to obtain reliable and sufficient information about the factors that have a negative impact, the nature of their flow on irrigated lands and adjacent natural environments located in different landscape conditions under the actual use of land for agricultural production.

The monitoring program for irrigated lands should take into account the specifics of both the natural, economic, and socio-economic conditions of the Gissar Valley region, which are not repeated in other regions. Irrigated land monitoring information should be highly informative, meet the requirements of objectivity, reliability, accuracy, comparability, efficiency and availability [6, 7].

The monitoring system of irrigated lands allows planning and predicting the use of lands and adjacent environments, taking into account their further safety, taking into account those degradation processes in irrigated agricultural landscapes that lead to a deterioration in their ameliorative state, are groundwater rise and secondary salinization.

The information base for monitoring irrigated lands is various thematic maps that serve to study the current state, identify disturbances and predict the state of lands and adjacent environments using regional features and informative indicators for monitoring irrigated lands in the natural-technogenic system of the Gissar Valley.

An important component for monitoring irrigated lands in the natural-technogenic system is the determination of the boundaries of irrigated lands, established as a result of work on the land cadaster, taking into account protected and sanitary protection zones (Figure 2).

Figure 2.

Geoinformation system in the structure of modeling the natural-technogenic system of the Gissar Valley (compiled by the author).

Spatial modeling of the use and condition of irrigated lands is carried out using a geographic information system, which includes the necessary set of basic objects of water management and melioration on irrigated lands and thematic layers, which include: a complex of engineering structures directly related to melioration and irrigation, for example, such as: ameliorative facilities; irrigation systems, mud storages; land reclamation sites; groundwater intakes; enterprises of motor transport and special vehicles; land resources, as well as other components of the environment (atmospheric air, soils, surface and ground waters, vegetation).

From this it follows that one of the most important components of a digital map are layers that reflect the level of groundwater and salinity of irrigated lands and adjacent areas. In this connection, requirements are imposed on the information system, which should provide the following indicators: (1) correspond to the organizational structures of the exploitation of irrigated lands; (2) reflect the structure, properties and relationships of the observed objects and processes occurring in them; (3) represent reclamation lands as an integral part of such an element of the natural environment as an agrolandscape; (4) ensure the security and confidentiality of information, as well as free access to information users; (5) have organizational, software, technical, mathematical, methodological, linguistic, metrological and legal support; and (6) provide promptly and in an accessible form information (digital or paper forms) for the entire observation period for various analysis and forecasting models.

In many cases, the land assessment procedure involves the use of not only soil, but also other indicators characterizing the relief (steepness, slope exposure), vegetation, hydrothermal regime, parent rocks, hydrographic network, as well as socio-economic conditions. Therefore, an objective assessment of land, taking into account all factors, is carried out on the basis of GIS technologies and its result can be presented in the form of thematic maps.

The software companies ESRI (Environmental Research Institute, USA) and ERDAS provide an excellent basis for the implementation of a full-featured land use management system of the subject (monitoring at the state level). This system involves deep analytical processing of large volumes of data of different scales, as well as interfacing with complex software applications.

From the above examples, it can be seen that the efficiency, integration of environmental, socio-economic, biomedical, management information on a single geographical basis in conjunction with mathematical analysis tools distinguish geographic information systems from a number of existing applications. This versatility explains the attractiveness of their use for specialists in almost any industry, including the field of land reclamation.

If we talk in general about the use of information technologies in agroecological research, then it must be said that the creation of databases (Database) and GIS has been the basis of theoretical and applied research in the geosciences for many years. Their main purpose is to provide a spatial analysis of the placement, relationships, dynamics and other relationships of spatial objects. In combination with modern mathematical methods for processing thematic data, databases open up new ways to quantitatively study the patterns of functioning of bio-geosystems at different spatial levels. The introduction of new geoinformation technologies into the theory and practice of research is especially important when creating and monitoring irrigated agrolandscapes for the Republic of Tajikistan.

Based on the foregoing, let us consider the general theoretical provisions of monitoring irrigated lands. Since, as already discussed, the ameliorative state of lands and the development of new irrigated lands, together with natural objects, are a complex natural and technogenic system, the monitoring of these lands must be considered in conjunction with other types of monitoring: the state of water bodies and groundwater; atmosphere; soils; vegetation; surface waters; functioning of reservoirs of irrigation importance; relief, etc.

Information support is based on obtaining up-to-date data on the state of the main components of the natural environment, the dynamics of changes and factors that affect the state of irrigated lands.

The structure and content of the monitoring of irrigated lands at each specific facility will be largely determined by the complexity of the facility itself and the complexity of its involvement in its interaction with natural resources. In accordance with the tasks set, the Program for local monitoring of irrigated lands includes the following sections and areas of work [8]: (1) Determining the purpose and objectives of monitoring irrigated lands. (2) Compilation of the initial passport of the territories occupied by land reclamation facilities. (3) Determination of indicators and regulations for observations that take into account the cumulative impact of anthropogenic impact on land resources and adjacent environments. (4) Development of an observation network and means of observation. (5) Obtaining and processing monitoring information and (6) Assessment of the state of lands and adjacent environments.

In the course of research, the author developed a model for monitoring irrigated lands in the Gissar Valley (Figure 3).

Figure 3.

Scheme of the algorithm of the irrigated land monitoring model using geographic information systems (compiled by the author).

The presented model includes the following stages: study of the methodological base for land monitoring by classification criteria; identification of natural and geographical features of the Gissar valley; determination of factors of natural and technogenic processes that have a negative impact on the ecological state of irrigated lands based on the use of the software product “Statistica” v.10.0; determination of the most informative indicators for monitoring irrigated lands in the Gissar Valley; development of a methodology for the formation and updating of information on the state and use of irrigated lands in the Hissar Valley, obtained from open sources, within the established boundaries of irrigated lands, taking into account the land use zone, engineering reclamation and irrigation object, water management objecties, as well as the natural environment.

Based on the characteristics of the object under study, the scheme of the irrigated land monitoring model algorithm proposed by us includes the following levels: regional, local and detailed. For irrigated lands, a natural-technogenic system is determined, taking into account the established boundaries in accordance with the land cadastre and the zone of technogenic influence on adjacent natural complexes, observation parameters, methods and means of observation, as well as the frequency of observation, the observed network, the algorithm for processing and issuing the requested information.

The monitoring program for irrigated lands is developed in such a way that it is possible to ensure hierarchical subordination according to the main levels of monitoring: regional, subregional, local and detailed, taking into account natural regional, local features and technical features of reclamation systems (Figure 4).

Figure 4.

Scheme of hierarchical subordination of the main levels of monitoring of irrigated lands using GIS technologies (compiled by the author).

Thus, the main principles of building a monitoring system for irrigated lands should be the following:

• complexity, includes ground and remote means of monitoring the state of lands of reclamation systems and adjacent territories;

• openness of information necessary for monitoring both the state of irrigated lands and natural environments, and the state of engineering structures, making management decisions, monitoring the implementation of decisions;

• multi-level nature, taking into account the structure of objects and ensuring the sustainable development of agricultural production areas;

• information interaction with other environmental monitoring systems at all levels;

• strict observance of the requirements of international standards of environmental protection in the sustainable development of agriculture;

• obligatory formation of complex information (cadastral, ecological state of irrigated lands and the environment, technical state of reclamation, irrigation and other water management systems).

Information sources in this case are all available official statistical data and data from the authorities of municipal and regional entities. The most detailed is monitoring at the level of an irrigated land plot, the territory of which is established within the boundaries, taking into account the buffer zone and adjacent territories.

Based on the collected information material using various sources, it is processed using geographic information systems, which allow for an objective assessment of the ecological and reclamation state of irrigated lands at the local level, identify ongoing negative processes and give objective recommendations for their prevention or elimination of consequences [9].

The cumulative assessment of the ecological and reclamation state of irrigated lands consists of the following stages:

Stage 1 - preparatory includes:

• selection and acquisition of satellite images;

• collection of information on the problem under study;

• a selection of computer components and methods for performing identification;

• familiarization with the explicit identification attributes and indicators of the object;

• intermediate recognition and analysis of features;

• definition of areas for research.

Stage 2 - field studies of selected areas using Landsat multispectral images, the selection of images is carried out depending on the task being solved, which corresponds to the maximum determination of the state of the study area for the annual period.

Stage 3rd - office processing using GIS.

Information collected during field research and interpretation of images is modified in GIS using the ArcGIS online program. Thus, the GIS “Gissar irrigation system” will contain the following data:

• about the object: areas, boundaries, terrain, hydraulic structures, etc.;

• according to available soils and growing vegetation: type, soil properties, level and mineralization of groundwater, names of species of plant organisms, etc.;

• obtained as a result of work on the ground: areas in the fields with pronounced processes of soil salinization; places where soil samples were taken, etc.;

• obtained after the processing of satellite information: areas of swamping and salinization of lands.

Thanks to the use of geographic information systems, a combination of heterogeneous information can be achieved to conduct a qualitative analysis of the ecological and reclamation state of irrigated lands.

3. Development of a model for creating maps of the state of irrigated lands in the Gissar Valley based on the developed methodology for using GIS technologies and software products

Using the developed methodology, data were collected from ground control points to obtain orthophotomaps from multispectral satellite images obtained from the Landsat 7 and Landsat 8 satellites in order to compare spatial data with the available data. To implement this approach, all locations of soil samples were recorded using a Garmin 90 hand-held GPS navigator, which recorded more than 150 points covering all parameters for linking remote sensing data to this territory.

Classification and generalization of input data was carried out on the basis of geographic databases compiled by the author, taking into account the table of attributes and primary materials.

For further research, the author selected the irrigated lands of the dekhkan farm “Istiklol” of the Gissar district, located in Central Tajikistan. The total area of key sites is 150 hectares or 0.2% of the total monitoring area (Figure 5).

Figure 5.

Map of general land use in the study area (Tursunzade, Shakhrinau, Gissar districts) (compiled by the author).

Field observations were carried out in determining the on-farm boundaries of land use; conditions of windbreaks; when taking soil samples to analyze its content in order to determine the degree of soil fertility in irrigated ecosystems of the study area.

Further processing was carried out on the basis of the developed model for creating monitoring maps for irrigated lands of the Gissar Valley using GIS and statistical data processing presented (“Statistica” v.10.0, JMP Statistic 15 and Minitab 19) (Figure 6).

Figure 6.

Scheme for creating monitoring maps of irrigated lands in the Gissar Valley using Minitab 18.

On the basis of the studies performed, we proposed the following organization of work to study the state of irrigated lands on the territory of the Gissar Valley using geoinformation technologies, consisting of the following stages:

1. Field work was carried out to determine the on-farm boundaries of land use, the state of windbreaks, to take soil samples and analyze its content in order to determine the degree of soil fertility in the irrigated ecosystems of the study area.

   Issues related to anthropogenic impacts on the destruction of the ecological balance of irrigated potential on the process of degradation and water erosion of lands, which was obtained by us on the basis of field observations. Field surveys of dekhkan farms also provided data on the number of major crops produced on each farm.

2. Mapping. On the basis of the proposed methodology, we have compiled a number of thematic maps related to the objectives of the study, as well as obtained actual maps of the study area using GIS technologies.

3. Rasterization was performed when processing a satellite image in order to obtain a raster image, as well as preparing digital data for entering into a database. The method allowed us to prepare more than 20 types of spatial data and obtain raster data from the resulting vector files. Data digitization was carried out using ARC GIS & Microsoft Excel software.

4. Vectorization. The process of interpretation of space images was carried out by us in order to determine the varieties of agricultural crops in the study area and a number of photogrammetric approaches to determine the parameters of the studied physical objects reflected in the images. All physical objects located in the study area were vectorized.

   Vectorization was carried out on the basis of Arc Catalog in Arc GIS program using the object editing method. As a result, vector files were obtained for all objects of study.

5. Application of mathematical and statistical methods. Mathematical calculation methods make it possible to determine the number of studied phenomena in a particular area. We needed to use this method when calculating the number of row crops and other physical objects, their location, area, which are reflected in satellite images.

   When using statistical methods, we can write that all tabular data and demonstrative-schematic data were obtained on the basis of statistical calculations of data recalculations. The most informative indicators were determined using statistical methods and approaches.

6. Laboratory methods. The objectives of the study required the analysis of soil content in key areas in order to find out the proportion of soil fertility, as well as soil composition to increase the productivity of irrigated lands. Using laboratory analyses, soil samples were analyzed from three farms in the study area.

Thus, it can be considered a key indicator of the possibility of using this technique - this is the achievement of the goal, which is the implementation of state monitoring of the state and use of irrigated lands of the Gissar Valley using maps created using geoinformation technologies based on Arc Catalog in Arc GIS.

Based on this, we can single out the main criterion - the creation of thematic maps, for which the main indicators are: vector data, raster data, text data, their verification and processing.

Table 1 clearly shows the comparison of the two methods for these indicators.

Data processing indicators Figure 1	(without statistical processing)	Scheme 2 (with statistical processing)
Collection of vector data
Support for various formats	+	+
Support for various sources	+	+
Collecting raster data
Support for various formats	+	+
Support for various sources	+	+
Collection of text data
Support for various formats	+	+
Support for various sources	+	+
Vector data processing
Correction of existing vector data	+	+
Drawing new vector data	+	+
Snap to project coordinate system	+	+
Raster data processing
Image correction	+	+
Digitizing raster data	+	+
Snap to project coordinate system	+	+
Text data processing
Data validation	−	+
Correlation analysis	−	+
Forecast for the development of indicators	−	+
Entering text data into the project database	+	+
Create a thematic map
Output of the finished product	+	+

Table 1.

Comparison of methods for creating maps for monitoring the condition and use of irrigated lands in the Gissar Valley.

The indicators for processing data according to the second scheme (Table 1) depend on the specifics of the state and use of land in different areas of the valley. Comparing two methods of creating maps for the implementation of state monitoring of the state and use of land, it can be noted that when using any of them, you can get the desired result - a thematic map that displays the state and use of land of any territory of interest.

But at the same time, it should be noted that when using statistical data processing in the second method, it is possible to achieve a better and more correct display of the real situation on the ground due to a double check for the reliability of the data - statistical and expert. Also, when using statistical processing, it is possible to find dependencies between indicators, determine trends in the development of indicators, predict the development of observed indicators, and make a management decision in advance to prevent the deterioration of the situation.

TIN is a form of vector digital geographic data that is built by triangulating a set of vertices (points). The vertices are connected by a series of edges and form a network 03 of triangles. Therefore, in order to model the TIN surface for the study area - alluvial marches, we first of all use the Global Mapper GIS to download data on the surface of the study area from the Advanced Spaceborne Thermal Emission and Reflection Radiometer to find the height points of the study area (Figure 7). Territory (Figure 8). Next, surface points with height data were displayed (Figure 9).

Figure 7.

Map of rehabilitation measures for the irrigation system of the Gissar Valley on the Landsat 8 satellite image.

Figure 8.

Map of rehabilitation measures for the irrigation system of the Gissar Valley.

Figure 9.

Map of rehabilitation measures for the irrigation system of the Gissar Valley.

The next step is to create an irregular triangulation network based on the surface height data, a way of modeling a continuous surface with points and values at these points selected with variable density (Figure 10). Further, based on the TIN-model of the surface, knowing the heights, slopes and exposure of any point on the surface, a model of the drainage areas of the territory is created (Figure 11).

Figure 10.

Map of rehabilitation measures for the irrigation system of the Gissar Valley.

Figure 11.

Map of watershed areas of the surface of the Gissar Valley.

4. Summary

Obtaining relevant and timely information obtained as a result of monitoring irrigated lands is one of the main problems in solving issues of studying the state and use of irrigated lands. Formation of up-to-date and reliable information, obtained in a timely manner with the help of modern information and telecommunication technologies, and processing of the obtained large-scale big data in geoinformation systems and other software products, will allow timely assessment, design and development of a management decision for carrying out measures to improve soil fertility, protection of irrigated lands and irrigation systems.

The problem of land degradation and environmental pollution when using irrigated lands requires the improvement of theoretical and methodological approaches to monitoring irrigated lands using modern technologies for remote sensing of the Earth, obtaining big data and processing based on the use of software products for processing big data, geographic information systems also for processing and assessing the ecological state and use, which will make it possible to obtain reliable graphic information that allows it to be used for designing, predicting the state of lands and developing measures to prevent the negative impact of the impact on these lands or eliminate the consequences of these impacts.

The studies conducted by the author made it possible to obtain up-to-date and reliable information on the state and use of irrigated lands for planning the rational and efficient use of these lands. The region of the Gissar Valley of the Republic of Tajikistan was chosen for research, the analysis of the results of which allowed the author to draw the following conclusions and suggestions:

1. The study of the theoretical provisions of the monitoring of irrigated lands showed the need to collect a large amount of data that combine the characteristics of various indicators that make up the environmental objects of the study area. It has been established that the prompt and most complete obtaining of such indicators for irrigated lands is possible based on the use of modern technologies and geoinformation systems for processing the obtained data. As a result of the research, the author proposed the basic principles for building a monitoring system for irrigated lands, one of which is the principle of the mandatory formation of complex information (cadastral, ecological state of irrigated lands and the environment, technical state of reclamation, irrigation and other systems water management). Based on the developed principles of monitoring irrigated lands, the author has developed a model for monitoring irrigated lands in the Gissar Valley of the Republic of Tajikistan, the main goal of the algorithm is to create a methodology for monitoring irrigated lands for the conditions of increased natural and anthropogenic pressure. The proposed algorithm for the monitoring model of irrigated lands in the Gissar Valley includes such stages as: study of the methodological base for monitoring lands by classification criteria; identification of natural and geographical features of the Gissar valley; determination of factors of natural and technogenic processes that have a negative impact on the ecological state of irrigated lands based on the application of various statistical programs; formation of a system of indicators for monitoring irrigated lands in the Gissar Valley; development of a methodology for monitoring irrigated lands based on the developed system of monitoring and updating indicators for study sites on the territory of irrigated lands, engineering reclamation and irrigation facilities, water management facilities, as well as the natural environment.

2. The unique location of the Republic of Tajikistan (elongation up to 700 km from west to east, with large elevation changes from 300 to 7495 m) determines the climatic and natural features, the distribution of the population on the territory of the republic, its population, and the development of economic activity. It has been established that the annual population growth averages 2.24%, the population density of Tajikistan is 65.7 people. For 1 sq. km, and in the Gissar region the density is 277 people. For 1 sq. km, which indicates the special conditions of the territory, its attractiveness for living in terms of natural and climatic conditions, as well as the possibility of developing agriculture, and this also indicates an ever-increasing anthropogenic pressure on the environment and, above all, land resources based on irrigated lands. In addition, the mountainous territories of the Republic are a habitat for unique animals, birds, mammals and rare plants listed in the Red Book.

3. The author has made an analysis of natural and technogenic factors that have a negative impact on the state of irrigated lands. The area of degraded lands in Tajikistan is about 97.9% of the territory. Every year, about 50 thousand hectares of cultivated land are subject to varying degrees of desertification. Factors that have a negative impact on irrigated lands in the studied areas of the Gissar Valley have been established, the main of which are: the impact of geomorphological, geological, climatic, soil-vegetative and economic conditions that cause soil degradation (water and wind (deflation) erosion, gully formation, waterlogging and waterlogging, salinization and schistosity, compaction and stylization). In addition to natural factors (as mentioned above), anthropogenic factors that affect irrigated lands lead to degradation, which include, for example, the state of the collector-drainage system (CDS), the length of which is 13096.2 km, the total length irrigation system is 29793.9 km.

4. It has been established that one of the main environmental pollutants in the Gissar Valley is the Aluminum plant, located in the Tursunzade district, which produces man-made pollution with emissions of heavy metals and metalloids into the atmosphere. It is shown that in the Gissar Valley, desertification is severely affected, more than 14 thousand hectares of land, and almost 22 thousand hectares to a medium-low degree, including land in the old irrigated territory of the valley, arable land by almost two thirds are subject to water erosion (63.4%) and more than half of them are moderately and severely eroded. More than 93% of pasture lands are subject to erosion.

5. Collection and analysis of multispectral satellite images from the Landsat 7 and Landst 8 satellites using the ArcGis software was performed. In the process of their analysis, maps were obtained for the NDVI index from 2010 to 2019 and traced changes in the area of vegetation cover during 2010–2019. And then we got MNDWI maps from 2010 to 2019, water coverage, and identified areas that belong to irrigated land using the received vegetation and water coverage data.

6. Grouping of negative processes occurring in the Gissar valley into the following groups was carried out: natural, technogenic, social; and factor analysis make it possible to identify the most significant pressures on agricultural landscapes. The developed methodology for substantiating the establishment of relevant, reliable indicators, processing with the help of modern big data software products, the results of processing monitoring measurements were used to assess the state of irrigated lands in the Gissar Valley and draw up maps for the areas of the Gissar Valley, which includes: Shakhrinavsky; Tursunzadevskiy. The analysis carried out shows that the system of controlled indicators for monitoring irrigated lands fully fits into the model determined by such indicators as: state, impact, productivity.

7. Hidden factors affecting the state of irrigated lands and forecasting the development of changes in their state have been identified. The indicators for water resources and vegetation of irrigated lands, which are influenced by climatic factors, are considered: average monthly temperature; average annual precipitation; average humidity; average annual wind speed; average number of sunny days per year. The obtained indicators are processed using statistical software products JMP Statistical Discovery, Minitab 19, Statistica. First of all, the indicators are checked for the normality of the distribution of data in order to select a criterion for the purpose of further analysis. Based on the data obtained by the Holt-Winters method, using the ANOVA method, we calculate the impact of groups of indicators on irrigated land and water coverage in the next 3 years. It has been established that the following groups of factors will most strongly influence the irrigated lands: temperature and precipitation; temperature and humidity; temperature and wind speed; temperature and sun; humidity and wind speed; humidity and sun. And the water will be affected by: temperature and precipitation; temperature and humidity; temperature and wind speed; temperature and sun; precipitation and humidity; precipitation and wind speed; precipitation and sun; humidity and wind speed; humidity and sun.

8. Analysis of the qualitative state of the irrigated lands of the Gissar Valley by the author made it possible to establish that almost the entire territory of the valley is characterized by the development of processes of degradation of soil and vegetation cover, a critical ecological state. Carrying out land management work on these lands on an agrolandscape basis in combination with other works will ensure their rational use and achieve their sustainable state. For these purposes, up-to-date information on their condition and use is required, obtained as a result of monitoring of irrigated lands based on remote sensing materials, field research and processing of a set of data obtained using various statistical software products and geographic information systems.

9. The author, based on the developed methodology for selecting the most informative indicators and using Landsat satellite images obtained for the period from 2010 to 2020, using geoinformation systems to process the received monitoring data of irrigated lands, developed maps that reflect the current state of the art. - the state of the irrigated lands of the Gissar Valley based on and developed proposals for the rehabilitation of the irrigation system of the Hissar Valley, which will ensure the sustainable development of the use of these lands.