Composite Geoelectrical Investigation to Delineate Groundwater Feasibility in Hard Rock area of Raipur, Chhattisgarh, India.

In hard rock terrains, groundwater movement, migration, and storage occur through subsurface fractures. To assess the fractures and associated water, we carried integrated geophysical investigation with Wenner, (GRP), Schlumberger, and Pole-Dipole array in Indian State. The resistivity survey carried out using a CRM-500 resistivity meter. The analyzed results are also re-verified with the help of IPI2WIN software. Initially, lateral and surface variations of resistivity were plotted by using Wenner and Gradient Resistivity profiling array. Then the low resistivity points were investigated with Schlumberger and Pole-Dipole array. In interpretation, low resistive zones identified correspond to the possible fractured zones. The results allowed mapping of the weathering zone at depth 12 to 15 m, and deep fracture lies below depth 55.0 m depth. The present study validates that the integrated Geophysical survey is a powerful exploration technique to scrutinize and identify water-bearing fractures in the hard rock area.

Groundwater recharge pathway according to the environmental isotope: the case of Changwu area, Yangtze River Delta Region of China

Groundwater recharge is an important factor affecting water circulation. As groundwater has slow seepage, directly observing the seepage velocity and recharge path of groundwater in the aquifer is difficult. Environmental isotope technology has become an important means to clarify the mechanism of groundwater movement and the mechanism by which groundwater recharges from the micro and macro perspectives. The Changwu area of Jiangsu Province was taken as an example to identify the recharge sources of groundwater and the recharge paths of groundwater and surface water by using the measured data of isotopes D, 18O, 34S, and T. The results indicated that the shallow aquifer and the I confined aquifer in the Changwu area are mainly recharged by precipitation and surface lake water. The II confined aquifer along the Yangtze River is recharged by modern precipitation. Moreover, the II confined aquifer in the Henglin area was recharged by the ancient Yangtze River before 4,000 years ago, and no recharge relationship exists now. the recharge condition of the II confined aquifer around the northwest of Gehu Lake is in the climate environment of 8,000 years ago and was caused by the surface depression lake water at that time. Additionally, the concealed limestone aquifer is primarily supplied by the II confined aquifer, while the concealed sandstone aquifer supplies the II confined aquifer. Hence, to find out the recharge conditions of groundwater aquifers based on the environmental isotope is conducive to scientific and reasonable evaluation of groundwater resources and to ensure the sustainable development and utilization of groundwater resources.

Preliminary Conceptual Model of Hydrogeological System in The Raimanuk and its Surrounding Area on the Timor Island

There are several areas with groundwater potential in Timor island, one of which is the Raimanuk and its surrounding area. This study aims to determine the hydrogeological system in the Raimanuk and its surrounding area. The hydrogeological system is determined by the geological conditions, geomorphology, lithology, and groundwater flow patterns. Geological conditions and groundwater flow patterns are provided by conducting a field investigation. Twenty shallow wells and four springs were measured to provide the groundwater contour. The geoelectrical survey was conducted at eleven points to analyze subsurface lithology. The results show that the geology of the study area is dominated by alluvium (west area), carbonate siltstone, and crystalline limestone (middle to the east area). There are two types of aquifers in the study area: unconfined aquifers and confined aquifers with gravel sandstone lithology. The groundwater flow pattern shows that the groundwater movement is from the east to the southwest. Moreover, the groundwater also moved from the northern, southern, and western of the study area. It is implied that the aquifer’s shape at the Raimanuk area is formed as a bowl-like shape influenced by the geological, geomorphological conditions.

Identification of Preferential Runoff Belts in Jinan Spring Basin Based on Hydrological Time-Series Correlation

The Jinan karst system is one of the typical karst systems in North China. The karst springs in Jinan are important historical heritage in China. However, in recent years, due to urbanization and the excessive exploitation of groundwater resources in Jinan City, the rate of spring flow has decreased tremendously. Preferential runoff belts are channels of karst aquifers where fractures and conduits are well-developed and serve as the main pathways for groundwater movement and solute transport. In view of this, a study was conducted in the Jinan Spring Basin to identify preferential runoff belts based on hydrological time-series correlation. Firstly, through cross wavelet transform and Pearson correlation coefficient, the time-lag and correlation of spring water level and precipitation were analyzed, the result show that the precipitation in the areas of Xinglong, Donghongmiao, Qiujiazhuang, Xiying, Yanzishan and Liubu stations has a greater impact on spring water level. In addition, combined with the hydrogeological conditions of the Jinan Spring Basin, the above stations meet the characteristics of the preferential runoff belt. In conclusion, the above stations are most likely to be located on the preferential runoff belt. The results of this study can serve as great reference points for building a correct hydrogeological conceptual model, and for the future planning of spring protection measures.

Minimizing Errors in the Prediction of Water Levels Using Kriging Technique in Residuals of the Groundwater Model (MODFLOW)

Groundwater monitoring and water level predictions have been a challenging issue due to the complexity of groundwater movement. Simplified numerical simulation models have been used to represent the groundwater system; these models however only provide the conservative approximation of the system and may not always capture the local variations. Several other efforts such as coupling groundwater models with hydrological models and using geostatistical methods are being practiced to accurately predict the groundwater levels. In this study, we present a novel application of geostatistical tool on residuals of groundwater model. Kriging method was applied on the residuals of the numerical model (MODFLOW) generated by the TWDB (Texas Water Development Board) for the Edwards-Trinity (Plateau) aquifer. The study was done for the years 1995 through 2000 where 90% of the observation data was used for model simulation followed by cross-validation with the remaining 10% of the observations. The kriging method reduced the average absolute error of approximately 31 m (for MODFLOW simulation) to less than 5 m. Also, the residuals’ average standard error reduced from 9.7 to 4.7. This implies that the mean value of residuals over entire period can be a good estimation for each year separately. The use of kriging technique thus can provide with improved monitoring of groundwater levels resulting in more accurate potentiometric surface maps.

Evaluation and Delineation of Sulfur Groundwater Leakages Using Electrical Resistivity Techniques in Hit Area, Western Iraq

Electrical resistivity methods are one of the powerful methods for the detection and evaluation of shallower geophysical properties. This method was carried out at Hit area, western Iraq, in two stages; the first stage involved the use of 1Dimensional Vertical Electrical Sounding (VES) technique in three stations using Schlumberger array with maximum current electrodes of 50m. The second stage included the employment of two dimension (2D) resistivity imaging technique using dipole-dipole array with a-spacing of 4m and n-factor of 6 in two stations. The 1D survey showed good results in delineating contaminated and clear zones that have high resistivity contrast. Near the main contaminated spring, the 2D resistivity imaging technique was applied in four sections length (100 m) using a dipole-dipole array position coincided with the three points VES. We compared the results of the interpretation of imaging the techniques 2D and VES. We found that the 2D imaging resistivity technique was better than VES survey in determining the distribution of pollution under the surface in the area surveyed. It was also found that the polluted water is located about 5 m below the surface. The largest amount of leakage was found towards the northeast and coincided with the direction of the groundwater movement. Spring water has leaked from outside the region through the Kubaisah area. Most of this water is contained in quaternary deposits and karst gypsum fractures.

Effect of Tigris River's Stage on the Groundwater Level

The research studies the effect of change of the Tigris River's surface stage on groundwater movement by building a three-dimension model using GMS model for a catchment area in Baghdad city. The model is built and calibrated by using the information of 16 wells for the year 2015 . Three scenarios of river elevation stage are used when the stage elevation is maximum, average and minimum. The movement of groundwater according to the results was from the north-west to the Tigris River location. Also, the results show the velocity of groundwater in case of the minimum water surface level stage is greater than the other cases because of the high hydraulic gradient. The velocity of groundwater in layer one for all cases is very slow because of the low permeability.

Hydrotechnical construction, water engineering and water technologies: some modern issues and training of professionals

The article considers modern problems and problems that currently exist in hydraulic engineering and hydropower, problems of land and water resources. And also problems of training of experts. able to solve these problems Recently, the problems caused by existing large hydraulic structures are increasingly mentioned. The main problem is that the nodes of hydraulic structures often form artificial reservoirs of a large plane. It often happens that the depths of reservoirs are insignificant. This situation is very unsatisfactory because the land is used irrationally. which is a valuable resource and has a high cost and can be used effectively for agriculture. Creation of hydraulic structures, complexes of hydraulic structures significantly change the hydrological, biological. salt and thermal regimes of the river on which they are built, the regime of groundwater movement, cause climate change in the surrounding areas. Cascades of hydraulic structures have a special influence. As an example, we can cite the Dnieper cascade of hydroelectric power plants and compare the area of its reservoirs and the amount of electricity generated by its power plants with the world's largest hydroelectric power plants. In addition, shallow water bodies cause a significant deterioration in water quality. And since reservoirs are often a source of water supply for settlements and industrial enterprises, this situation is controversial. Intensive construction of hydraulic structures and their complexes took place during the twentieth century, many of them exhausted their resources and needed either reconstruction or decommissioning. The reasons for this state of affairs are the development of technology, the emergence and development of other alternative energy sources for thermal and nuclear power plants, other than hydraulic. Also, since the construction of many buildings, approaches to determining their profitability and efficiency have changed. Aspects of training specialists in hydraulic engineering and water engineering, able to solve these problems of the industry today, and those that will face them in the near future are considered. The ability of a competent professional to anticipate the consequences of any action must be an integral part of it. Attention is drawn to the need to apply conceptually new approaches to solving problems of construction of new hydraulic and hydropower facilities, operation and reconstruction of existing facilities.

A Novel Physically Based Distributed Model for Irrigation Districts’ Water Movement

The water movement research in irrigation districts is important for food production. Many hydrological models have been proposed to simulate the water movement on the regional scale, yet few of them have comprehensively considered processes in the irrigation districts. A novel physically based distributed model, the Irrigation Districts Model (IDM), was constructed in this study to address this problem. The model combined the 1D canal and ditch flow, the 1D soil water movement, the 2D groundwater movement, and the water interactions among these processes. It was calibrated and verified with two-year experimental data from Shahaoqu Sub-Irrigation Area in Hetao Irrigation District. The overall water balance error is 2.9% and 1.6% for the two years, respectively. The Nash–Sutcliffe efficiency coefficient (NSE) of water table depth and soil water content is 0.72 and 0.64 in the calibration year and 0.68 and 0.64 in the verification year. The results show good correspondence between the simulation and observation. It is practicable to apply the model in water movement research of irrigation districts.