Applications of Remote Sensing and GIS in Hydrological and Hydrogeological Studies

Integrated watershed management is a holistic approach aimed at linking upstream and downstream areas. It encompasses preventing the watershed from being polluted and maintaining the quality of water and prevention of soil erosion. Remote sensing and GIS techniques play a crucial role in assessing watershed conditions through modeling. These techniques are also very helpful in acquiring the spatial information of the land use, land cover, vegetation, water resources, etc. With the available data, characteristics of aquifers can easily be deciphered. Remote sensing aids in identifying and assessing the topographical features and alienates the unnecessary ones. Integration of GIS with remote sensing along with hydrological, hydrogeological, geomorphologic studies will make the practice of integrated watershed management more effective. The primary aim of this chapter is to encompass the remote sensing and GIS technologies currently in use for watershed monitoring and management.

Geophysical investigations in the Radovna River Spring area (Julian Alps, NW Slovenia)

The Radovna River Valley is located in the north-western part of Slovenia in the Julian Alps, where there is an extensive intergranular aquifer whose depth to pre-Quaternary bedrock is unknown. Therefore, to obtain information about the depth of the valley and the geometry of the aquifer two geophysical methods were used in our study; ground penetrating radar (GPR) and seismic reflection method. The low-frequency GPR method has shown to be useful for determining the depth of the groundwater and the predominant groundwater recharge. Also, the high-resolution seismic method provided an insight about the morphology of the pre-Quaternary basement with the deepest point at 141 meters below surface. Measurements of hydrogeological parameters such as groundwater level and river discharge measurements were carried out in the study area. Both data analyses showed that groundwater level and river discharge are highly fluctuating and rapidly changing, indicating a well-permeable aquifer, implying that such an aquifer is extremely sensitive and vulnerable to extreme climate events. Both the geophysical methods and the hydrogeological information have provided important information about the morphology of the valley and the alluvial aquifer, as well as increasing the knowledge about the Radovna springs system, which will contribute very important information for future hydrogeological studies.

Kherzet Youcef Mine Flooding of 2nd June 1990 Revisited (Northeastern of Algeria) Origine and Hydrogeological Consequences

This work is part of the hydrogeological study of the Kherzet Youcef deposit. The polymetallic deposit of Kherzet Youcef, known, since the beginning of the 20th century, by the exploitation of Lead and Zinc ore, is located 50 Km southeast of Setif (North-eastern Algeria) and 5.5 Km west of Ain Azel. Mineralization is represented by some ore bodies (about 25). The thickness variate from a few centimeters up to 3m. These bodies are located on the layers of dolomites and dolomitized marls and along the Kherzet Youcef fault. The geological reserves of Zinc and Lead ore are of the order of 1.6 million tons. This ore has a Pb content of 3.6% and Zn content of 18.4%. The projected annual exploitation was 100 thousand tons per year. Hydrogeological studies carried out successively (1973-1977) and (1981-1983) revealed the existence of an aquifer system located west of the Kherzet Youssef fault characterized by the presence of Karts and by strong cracking due to local brittle tectonics. These two characteristics define the filtration and storage capacity of very abundant groundwater. This groundwater represented a major handicap for mining in view of the large amounts of water that required the installation of major pumping and drainage devices. The Kherzet Youssef mine has experienced frequent flooding in the past at a time when technology could not pump efficiently. It caused the mine to close several times. In June 1990, the mine experienced a flood of great magnitude that has never been observed and despite the large installed means of pumping, this "water cost" led to the total drowning of the mine, the death of 19 workers and the stoppage of the exploitation of this deposit since. Pitting attempts were carried out with a pumping capacity of 1100 m3/h, then 1800 m3/h but without success. The interpretation of the drawdown data and field observations made it possible to conclude that this accident was only the result of the general destabilization of the massif. Our complementary work by geophysical prospecting made it possible to represent the configuration of the underground layers and demonstrate the hydrodynamic communication between the two East and West compartments of the deposit.

Determination and Analysis of Land Deformation in Nairobi City County Based ALOS/Palsar and Sentinel-1 InSAR Processing

Nairobi city is one of the fastest-growing cities in Africa. The rapid development has put pressure on the existing resources such as water resulting in overexploitation of groundwater. Nairobi had been reported to be susceptible to environmental hazards such as subsidence associated with the overexploitation of groundwater due to depletion of its aquifer. However, the subsidence has not been empirically quantified because Kenya lacks a functioning deformation monitoring framework. Through the use of InSAR, land subsidence in Nairobi was spatially quantified for the first time that confirms fears of subsidence as suggested by previous hydrogeological studies. We observed an increase in the spatial extends and the rates of subsidence, the highest rate of subsidence being approx. 62mm/yr located in the largest deforming area West of Nairobi. The deformation can majorly be linked to overexploitation of groundwater as it matches with regions with the highest rate of decline of groundwater levels. However, there exist also subsidence linked to rapid development. Given the significance of Nairobi to the Kenyan economy, the ripple effects of subsidence could be devastating and measures need to be taken to mitigate them. The deformation map provides an important tool for planning mitigation measures to prevent further deformation such as regulating the drilling of boreholes, planning of construction of buildings and transport networks, and locations for the observation wells for monitoring groundwater levels. It also reinforces the need for updating the geodetic network that has been rendered unreliable due to land subsidence.

Technogenic transformation of the underground hydrosphere of Kazan. Lower Kazanian aquifer complex

Relevance. By the beginning of the XXI century, the growth of cities, population concentration and the revival of industrial production led to an intense technogenic pressure on the underground hydrosphere. In ecological and hydrogeological studies, it becomes necessary to conduct monitoring observations of groundwater based on GIS technologies. Purpose of the work: study of the hydrogeochemical characteristics of underground waters of the aquiferous lower Kazanian carbonate-terrigenous complex to provide Kazan with high-quality drinking water from protected underground sources. Research methodology. Hydrochemical data from geological reports and archival materials for the period from 1960 years to 2019 years were used. Methods of mathematical statistics (basic, cluster and factor analyzes) made it possible to differentiate into natural and man-made components. Geographic information modeling using the “ArcGisMap” package showed the spatial variability of the main components in the waters of the Neogene complex at the turn of the 20th and 21st centuries. Conclusion. The hydrochemical parameters of the aquiferous lower Kazanian complex are assessed as favorable, since practically all the main components do not exceed the MPC values for drinking water.

Assessment of the Hydrogeological Conditions of the Territory Adjacent To the Tskneti-Samadlo Highway

The aim of researching the current hydrogeological state of the territory adjacent to the TsknetiSamadlo highway is to present such anti-landslide measures with the help of which normal operating conditions of the highway should be created. The study area is located on the northern side of the southeastern fork of the Trialeti Range, from the slopes of which many deep erosional ravines originate, filled in the spring-summer period with water that flows into the gorge of the r. Vere. The river is the main basis of erosion of the study area. To carry out hydrogeological studies, two water samples were taken - the water found on the landslide slope, which flowed along the surface of the bare slope, and a small amount of ground water from under the slope. The data of the chemical analysis of waters showed that these two samples are identical in chemical composition. The results of the total mineralization correspond to M = 1.9 g / l. Consequently, the water is not suitable for drinking, as it belongs to the category of slightly saline waters and is classified as sulphate-hydrocarbonate calcium-sodium. In addition to water samples along the road, one soil sample was taken to determine the degree of soil contamination. In the extract of a soil sample, the indicator of total mineralization is slightly increased (M = 0.3 g / l), according to its chemical composition, it is classified as hydrocarbonate-sulphate sodium-calcium. With regard to the anti-landslide measures proposed for the investigated area, the main one is the regulation of surface water flows using a system of spillways and drainages, which requires an accurate calculation of the height and steepness of slopes, in addition, maximum preservation of vegetation cover on deluvial slopes is required.

CURRENT STATE OF THE RESOURCE POTENTIAL OF FRESH GROUNDWATER OF THE KHANTY-MANSI AUTONOMOUS OKRUG

This article examines the resource potential and modern extraction of fresh groundwater for the needs of population and economic sectors in the Khanty-Mansi Autonomous Okrug – Yugra. The history of regional hydrogeological studies on the assessment of natural resources and exploitation reserves of groundwater reserves of the West Siberian mega-basin (WSMB) is revealed. The research results are shown and their comparative analysis is carried out. The article highlights the issue of formation and distribution of natural resources over the area of the considered territory. In conclusion, it is noted that the territory of the Khanty-Mansi Autonomous Okrug – Yugra is sufficiently supplied with natural resources of fresh groundwater (the predicted useful groundwater resources supply is 66.86 m3/day per person). However, more than 20 years have passed since the implementation of regional works on the assessment of predicted groundwater resources in the territory of the Khanty-Mansi Autonomous Okrug. During this period, the water-economic situation in the region has changed significantly, a large amount of factual material, which makes it possible to clarify and probably to revise the previously obtained results has been accumulated.

ANALYSIS OF LANDSLIDE PROCESSES ON THE ROADS OF KHAKASSIA BEFORE THE BRIDGES OVER THE YENISEI RIVER FROM THE PERSPECTIVE OF ALL STAGES OF THE LIFE CYCLE OF STRUCTURES

В статье проанализированы трудности в процессе строительства автомобильной дороги от Братского моста через Енисей в сторону Абакана, связанные с отсутствием учета на стадии проектирования осложнившихся гидрогеологических условий, влияющих на опускание моста и дороги. Оползневые процессы, созданные искусственно при сооружении выемки дна автомобильной дороги от Братского моста более 40 лет развиваются на участке дороги Абакан-Подсинее перед железным и автодорожным мостом через Енисей. Как и в первом случае на стадии проектирования не выполнены гидро-геологические исследования. The article analyzes the difficulties in the process of construction of the highway from the Bratsk bridge over the Yenisei river to Abakan, associated with not taking into account the complicated hydrogeological conditions at the design stage, associated with the lowering of the bridge and road. Landslide processes created artificially during the construction of the dredging of the road bottom from the Bratsk bridge have been developing for more than 40 years on the Abakan-Podsinee road section in front of the railway and road bridge over the Yenisei. As in the first case, hydrogeological studies were not performed at the design stage.