Hasil untuk "River, lake, and water-supply engineering (General)"

RAO Qingyang, YANG Qiongbo, CUI Dongwen

To improve over-fitting of data processing, weak time series modeling, and difficult selection of hyperparameters in the Kolmogorov-Arnold network (Kan), a groundwater level prediction model based on wavelet packet transform (WPT) secondary decomposition and Chinese Pangolin optimizer (CPO) algorithm was proposed to optimize KAN hyperparameters, and WPT-CPO-Transformer, WPT-CPO-LSTM, WPT-CPO-gated circulation unit (GRU), WPT-CPO-least squares support vector machine (LSSVM), WPT-CPO-extreme gradient ascent machine (XGBoost), WPT-CPO-MLP, and WPT-KAN were constructed. These seven kinds of comparative analysis models were verified by the daily average groundwater level time series prediction examples of Xicheng, Wenlan, Lin'an, and Caoba stations in Yunnan Province. Firstly, the WPT secondary decomposition technology was used to decompose the groundwater level time series data and divide the training set and the verification set. Then, the CPO was used to optimize the hyperparameters of KAN to overcome the tedious and inefficient manual debugging and avoid local optimization. Finally, the WPT-CPO-KAN model was established by using the optimal hyperparameters to train, predict, and reconstruct the decomposed components of the groundwater level time series. The results show that: (1) compared with that of the WPT-CPO-Transformer, WPT-CPO-LSTM, WPT-CPO-GRU, WPT-CPO-XGBoost, WPT-CPO-LSSVM, WPT-CPO-MLP, and WPT-KAN models, the prediction accuracy of the WPT-CPO-KAN model is improved by 15.6%, 37.4%, 26.5%, 36.4%, 18.6%, 7.2%, and 26.7%, respectively (MAPE index), which has a smaller prediction error and better universality. (2) Under the same WPT secondary decomposition and CPO, KAN can better capture the complex nonlinear space and time dependence in groundwater level time series data and is more suitable for the distribution of groundwater level time series data. Its performance is better than that of the transformer, LSTM, GRU, XGBoost models, traditional LSSVM, and MLP network. (3) The prediction error of the WPT-CPO-KAN model increases with the increase in the prediction step. Within three days, the prediction accuracy of the WPT-CPO-KAN model is higher. (4) The reasonable selection of hyperparameters is of great significance to improve the performance of the KAN model. By using CPO to optimize KAN hyperparameters, the performance of KAN and the level of prediction automation are significantly improved. The optimization method can provide a reference for improving the performance of KAN. (5) KAN can reveal the variation characteristics of groundwater level time series data with fewer parameters, thus enhancing the interpretability of the WPT-CPO-KAN model.

Chao Deng, Hong Zhang, D. P. Hamilton et al.

River flow regime is important for ecosystem integrity and biodiversity, and is impacted by artificial water exploitation and regulation, extreme events and climate change. Environmental flows are designed to mitigate these impacts. In this work, we used catchment hydrological output simulated by the Soil & Water Assessment Tool model, evaporation rates calculated with the General Lake Model and a water resource management tool to calculate a water balance for a sub-tropical reservoir located in southeast Queensland, Australia under extreme dry conditions impacted by climate change. Two environmental flows, the 90th percentile of the daily flow duration curve (Q90) and the 90th percentile monthly flow for each season (Q90M), were used to assess water availability for multiple purposes including environmental releases and water supply from a subtropical water supply reservoir. Risks for the downstream river system were assessed using a flow alteration screening method by comparing a 20-year baseline period of no-dam from 1990 to 2009 with future climate change and water regulation conditions with the dam in place. A significant decrease in maximum flood peak, persistence of high-flow duration and the annual discharge from the reservoir occurred with future climate change and water demand scenarios compared with the no-dam baseline. The future changes in flow regime indicate a medium-to-high ecological risk for high flow conditions and moderate ecological risk during low flow conditions compared with the no-dam condition. An increased water demand in combination with future climate change leads to high ecological risks occurring by the end of this century under the high emission scenario of representative concentration pathway 8.5, regardless of the water regulations and environment flow management. The findings of this work indicate moderate to high inability to meet water demand under future climate-induced hydrological change. Therefore, catchment managers will need to take further actions to mitigate impacts from future climate change and population growth on water resources in this subtropical system.

Zhenjiang Ma, A. Enkhbold, Qier Mu et al.

Under the intensifying impacts of global climate change and the increasing frequency of droughts and harsh winters, the agricultural regions of the Selenge River Basin in Mongolia are facing persistent water scarcity. This study aims to identify and evaluate geomorphologically suitable sites for artificial lake construction in order to strengthen water supply, ensure environmental balance, and meet domestic water needs within the framework of Mongolia’s national initiative “333 Lakes, One District–One Lake.” A suitability assessment was conducted through spatial analysis based on a 30 m resolution Digital Elevation Model (DEM), employing the Analytical Hierarchy Process (AHP) method. From an engineering geomorphological perspective, the evaluation considered not only topography, hydrology, precipitation, and soil conditions but also additional land-use factors. The results reveal that 10.12% of the study area is classified as highly suitable, 69.45% as suitable, and 13.34% as moderately suitable, while the remaining 7.09% is either unsuitable or restricted by land-use constraints. Based on the comprehensive assessment, nine representative potential sites for artificial lakes were selected. For each site, potential irrigable areas, domestic water supply capacity, and livestock watering availability were estimated, and a general economic evaluation of potential water sources and dam construction costs was conducted. This study emphasizes that incorporating engineering geomorphological analysis and Geographic Information System (GIS)-based approaches provides essential scientific support for site selection of artificial lakes, thereby contributing to sustainable agricultural and pastoral development in the Selenge River Basin.

D. Mahmoodzadeh, Saeed Morid, H. Ketabchi

SUN Xuechao, ZHANG Youyuan, ZHU Jinxiang et al.

Broken wire electromagnetic detection technology for prestressed concrete cylinder pipes (PCCPs) is an important technical means to maintain the safety of PCCP engineering. Although electromagnetic detection technology has a high detection accuracy rate and wide application, it still faces the problems of complicated data processing and high labor time, which limits its large-scale application in actual engineering. In order to solve the problems of low identification efficiency and high labor cost of traditional broken wire detection equipment for PCCPs, a broken wire detection system based on raspberry pi and deep learning was proposed. The raspberry pi was used as the core of the main control system to collect data, and then the long short-term memory (LSTM) network model trained in advance on the PC platform was imported. The powerful feature extraction capability of the LSTM model was used to process the collected data, and the broken wire detection results were given in real time, successfully overcoming the limitations of traditional methods and realizing efficient and accurate identification of broken wires. The test results show that the detection accuracy of the system on the test set data reaches 80%, which provides a feasible solution for the engineering application of broken wire detection for PCCPs.

Dragana Milijašević Joksimović, Dejana Jakovljević, Dejan Doljak

High water quality in reservoirs used for drinking water supply and located within protected areas is of crucial importance for sustainable water-resource management. This study aims to evaluate the multi-depth water quality dynamics of the Ribnica Reservoir in western Serbia, combining two standardized assessment tools: the Serbian Water Quality Index (SWQI) and the Canadian Water Quality Index (CWQI). Data collected at various depths during 2021 and 2022 were analyzed to assess physico-chemical parameters and their impact on water quality, while the absence of microbiological data was noted as a limitation affecting the comprehensiveness of the assessment. The SWQI results indicated a general improvement in water quality over time, with values ranging from medium (82) to excellent (95) in 2021 and increasing from good (89) to excellent (98) in 2022. In contrast, the CWQI revealed specific risks, notably elevated concentrations of aluminum, mercury, and chromium, and reduced dissolved oxygen levels, with overall CWQI values ranging from poor (40) to good (88) depending on depth and parameter variability. The study highlights the necessity for continuous, comprehensive monitoring, including microbiological analyses and seasonal assessments, both within the reservoir and in the Crni Rzav River and its tributaries, to better understand pollutant sources and catchment influences. Strengthening microbiological and heavy metal monitoring, along with implementing proactive management strategies, is essential for preserving the Ribnica Reservoir’s ecological integrity and securing its long-term role in drinking water provision.

Tong Wang, Jiayi Kou, Fengjunxi Chen et al.

Surface water quality dynamics is a pivotal factor in sustainable water management. As a strategic waterway in Taihu Lake Basin (China), Taipu River plays a key role in integrating water management through flood control, water supply, and ecological preservation across Jiangsu, Zhejiang, and Shanghai. However, under evolving anthropogenic pressures, systematic studies characterizing its nutrient spatiotemporal variations and pollution drivers remain limited. In this study, the spatiotemporal (October 2020-July 2021 from upstream to downstream) distributions and source characteristics of key nutrients from Taipu River were evaluated through various water quality index methods, coupled with multi-approach source apportionment (principal component analysis and positive matrix factorization). Results indicated that the concentrations of total nitrogen (TN) and chemical oxygen demand (COD) in Taipu River gradually increased from upstream (TN: 0.9-1.2 mg L-1, COD: 11.5-15.2 mg L-1) to downstream (TN: 1.1-1.9 mg L-1, COD:11.0-21.7 mg L-1), and exceeded regulatory Class III limits in summer/winter (>1.0 mg L-1) and spring/autumn (>20 mg L-1), respectively. The increased TN likely resulted from nitrogen fertilizer loss due to rainfall, whereas the increase in COD is probably linked to the release of metabolic products from algae. Water contamination analyses identified a slightly-contaminated T7 site (i.e., TN = 1.51 ± 0.71 mg L-1, COD = 34 ± 9.0 mg L-1, exceeding Class IV), with primary contamination sources attributed to industrial activity (e.g., textile industry). For this T7 site with slight water contamination, the in-situ remediation strategies such as adding synthetic microbiomes, incorporating aquatic plants, and engineering intervention for nitrogen and COD pollution are recommended. These findings highlight the urgent requirement for targeted measures to mitigate nitrogen/COD loads, which is crucial to improve water quality and ecosystem health of the Taihu Lake Basin.

Peng-Fei Han, Yi Zhang

Shallow water waves phenomena in nature attract the attention of scholars and play an important role in fields such as tsunamis, tidal waves, solitary waves, and hydraulic engineering. Hereby, fortheshallowwaterwavesphenomenainvariousnaturalenvironments, westudytheKdV-Calogero-Bogoyavlenskii-Schiff (KdV-CBS) equation. Based on the binary Bell polynomial theory, a new general bilinear B\"acklund transformation, Lax pair and infinite conservation laws of the KdV-CBS equation are derived, and it is proved that it is completely integrable in Lax pair sense. Various types of mixed solutions are constructed by using a combination of Homoclinic test method and symbolic computations. These findings have important significance for the discipline, offering vital insights into the intricate dynamics of the KdV-CBS equation. We hope that our research results could help the researchers understand the nonlinear complex phenomena of the shallow water waves in oceans, rivers and coastal areas. Furthermore, the present work can be directly applied to other nonlinear equations.

P. A. Thilakarathna, Fazla Fareed, M. Makehelwala et al.

Exploration of the pollution status of river-based water sources is important to ensure quality and safe drinking water supply for the public. The present study investigated physicochemical parameters of surface water in the upper segment of River Mahaweli, which provides drinking water to the Nuwara Eliya and Kandy districts of Sri Lanka. River surface water from 15 intakes and treated water from 14 Water Treatment Plants (WTPs) were tested for pH, water temperature, turbidity, EC, COD, 6 anions, 21 cations, 3 pesticides, and 30 antibiotics once every 3 months from June 2022 to July 2023. Except for turbidity and iron concentrations, all other parameters were within the permissible range as per the Sri Lanka Standard Specification for Potable Water (SLS 614:2013). The uppermost Kotagala WTP raw water had a high concentration of iron due to runoff from areas with abundant iron-bearing minerals. Turbidity increased as the river flowed downstream, reaching its highest value of 13.43 NTU at the lowermost Haragama. Four intakes had raw surface water suitable for drinking as per the Water Quality Index (WQI). Pollution increased gradually towards downstream mainly due to agricultural runoff, industrial effluents, and urbanization. Poor water quality at the upstream Thalawakale-Nanuoya intake was due to highly contaminated effluent water coming from Lake Gregory in Nuwara Eliya. Cluster analysis categorized WTP locations in the river segment into 3 clusters as low, moderate, and high based on contaminations. Principal component analysis revealed that the significance of the 41.56% variance of the raw water was due to the pH and the presence of heavy metals V, Cr, Ni, Rb, Co, Sr, and As. All treated water from 15 WTPs had very good to excellent quality. In general, heavy metal contamination was low as indicated by the heavy metal pollution index (HPI) and heavy metal evaluation index (HEI). The treatment process could remove up to 94.7% of the turbidity. This is the first attempt to cluster the river catchment of the Mahaweli River based on physicochemical parameters of river water. We present here the land-use pattern-based pollution of the river and efficacy of the water treatment process using the Mahaweli River Basin as a case study. Regular monitoring and treatment adjustments at identified points are recommended to maintain the delivery of safe drinking water.

Taishi Yazawa, Kenn Joshua Geroy Rubite, Princess Eden Macabata-Rubite

This research conducted a citizen scientific field investigation and water quality assessment of nine major rivers using only on-site equipment and a smartphone in the Province of Antique, Philippines. Potential issues concerning water resources management in the province were discussed with local governors and citizens while conducting the water sampling and on-site measurement. The results of water quality assessments revealed that some of the rivers have experienced high turbidity, caused by anthropogenic activities such as embankment, sand mining, and dredging. In highly populated basins, such as the Sibalom and Malandog Rivers, a high biochemical oxygen demand level (>7 mg/L) was confirmed by the water quality analysis using an iPhone. Since high consumption of groundwater has already affected the lives of people in the province, surface water usage shifting from groundwater, involving the construction of a facility treating physical and chemical parameters, is needed. The citizen scientific approach employed in this research can provide more realistic insights into local environmental concerns, which would not be possible through quantitative measurements of water quality. HIGHLIGHTS The water quality of nine major rivers was assessed in the Province of Antique, Philippines.; Citizen scientific field investigation and water quality analysis used only an iPhone and an on-site water quality meter.; Some rivers have experienced siltation caused by anthropogenic activities.; A high biochemical oxygen demand level was confirmed in highly populated basins.; There is a need for a shift from groundwater to surface water usage.;

Milena Truba, Jacek Sosnowski, Krzysztof Pakuła

The aim of the study was to determine the effect of soil fertilising biopreparations, i.e. compost extract, vermicompost extract and humus extract, used against the background of NPK mineral fertilisation, on the content of manganese, iron, zinc and copper in the biomass of Lolium perenne, Festulolium braunii, and Dactylis glomerata. In the spring of 2019 and 2020, a single dose of the biological preparation was applied. During each vegetation period, the plants were mown three times. During mowing, fresh plant mass was taken from each plot, dried, ground and the content of Cu, Zc, Mn and Fe was determined using the ICP-AES method. The use of a biological preparation with the composition of an extract from compost significantly increased the content of Mn, Fe and Zn in the dry mass of the tested grass species. The grass species that accumulated the highest total content of microelements in its above-ground parts was Lolium perenne. The use of only biological preparations in the cultivation of the analysed grass species gave better production effects, for example in the form of a higher concentration of microelements in the dry mass of plants compared to objects fed only with minerals. This creates the possibility of using the tested biopreparations in organic farms. The Fe:Mn ionic ratio was too wide in relation to the standards on all experimental objects, which resulted from the excess of Fe in the plants. Only the combination of compost extract with mineral fertilisation narrowed the above relationship, but it was still too high.

F. Zăinescu, H. van der Vegt, J. Storms et al.

A complete annual cycle of the dynamics of fine-grained sediment supplied by the Omo and smaller rivers is simulated for Lake Turkana, one of the world’s large lakes, with the hydrodynamic, wave and sediment transport model Delft3D. The model is forced with river liquid and solid discharge and wind data in order to simulate cohesive sediment transport and resuspension. It simulates stratification due to salinity, wave generation and dissipation, and sediment advection and resuspension by waves and currents, with multiple cohesive sediment fractions. A comparison of the simulation results with remotely-sensed imagery and with available in-situ sediment deposition rates validates the model. By devising simulation scenarios in which certain processes were switched on or off, we investigated the contribution of waves, wind-induced surface and bottom currents, salinity-induced stratification and river jet, in resuspending and transporting fine sediments in the lake basin. With only the wind or river influence, most of the sediment deposition occurs in the first 10 km off the Omo River mouth and at a depth 30 m. This study sheds new light on sediment transport in Lake Turkana and in great lakes in general, favouring the view that wind-waves can be the main agent that transports sediment away from river mouths and to deeper areas, as opposed to river-plume or gravity-driven transport. (cid:1) 2023 The Authors. Published by Elsevier B.V. on behalf of International Association for Great Lakes Research. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/ 4.0/).

Zongliang Zhang, Xueming Wu, Enshang Xiao et al.

Abstract Based on the emergency rescue, the subsequent disposal, and the development and utilization projects of the Hongshiyan Landside Dam in Ludian, Yunnan, China, research has been conducted on key technical issues facing the development and utilization of landside dams, including the possibilty evaluation of development and utilization, structure analysis of wide gradation material, performance evaluation, investigation and design, dam seepage control, construction technology and equipment, and safe operation assessment. And innovative results has made in all seven aspects mentioned above, writing the history in this field. The achievements were directly applied to the development planning, investigation and design, construction, and operation and maintenance of the Hongshiyan Landside Dam, a comprehensive water conservancy project that integrates flood control, water supply, irrigation, and power generation, with significant comprehensive benefits.

Marta J. Kiraga, Anna Markiewicz

Changes in river channel morphological parameters are influenced by anthropogenic factors, such as climatic changes, river catchment management changes, and hydrotechnical development of rivers. To assess the intensity of individual pressures and the resulting changes in abiotic and biotic factors in the riverbed, water quality monitoring is conducted, including the assessment of the hydromorphological status. The assessment can be based on the River Habitat Survey (RHS) which is a synthetic method that includes the evaluation of habitat character and river quality based on their morphological structure. The input data, which characterise any river include physical features of hydrotechnical structures, bed granulation, occurrence of bedforms, visible morphodynamic phenomena, and a sediment transport pattern. The RHS method allows to determine two quantitative indices used to evaluate the hydromorphological status: Habitat Modification Score ( HMS), which determines the extent of transformation in the morphology of a watercourse, and Habitat Quality Assessment ( HQA), which is based on the presence and diversity of natural elements in a watercourse and river valley. The proposed method can be divided into three stages. The first assesses the river section hydromorphological indices, describing the degree of technical modification ( HMS) and the ecological quality of the reach ( HQA), using the RHS method. The second stage describes morphological changes resulting from the technical regulation and estimates indices for the regulated reach. Finally, we compare HQA and HMS indices before and after the regulation. This comparison is described by numerical indicators and related to reference values.

Paul Dominique Barrette, Karl-Erich Lindenschmidt

This article addresses the question: What is expected from frazil ice activity in rivers, taking into account the changing climate? It begins with an overview of what frazil ice is and what is required for the occurrence of frazil ice events, namely a supercooled water column. Methodologies to anticipate frazil ice events in the short term are based on air temperature and water discharge, underlining the significance of these two parameters for any predictive methods. Longer-term approaches, calibrated against past events (hindcasting), are used to anticipate frazil ice activity into the future, with indicators such as frazil ice risk, water temperature and frazil volume. Any of these approaches could conceivably be applied to frazil-prone river stretches. To assess climate impact, each location should be treated separately. River ice dynamics can lead to the formation of a hanging dam, a frequent outcome of frazil ice generation in the early winter, causing flow restriction. Flood modeling and forecasting capabilities have been developed and implemented for operational use. More frequent mid-winter breakups are expected to extend the occurrence of frazil ice events into the winter months – the prediction of these will require climate model output to adequately capture month-to-month variability. HIGHLIGHTS Previous modeling endeavors aimed at foreseeing frazil ice generation in rivers are summarized.; Frazil ice risk, water temperature and frazil ice volume are model outputs.; Each frazil-prone location should be the subject of its own climate impact study.; Mid-winter breakups (MWBs) will likely be more frequent in the future, which implies that clogging risks at water intakes will extend well into the winter months.;

MA Jinghang, XIAN Yongcai, HE Xueping et al.

Flood forecasting is one of the important non-engineering flood control measures and is the main basis for flood control command and decision-making.In order to avoid the uncertainty of the prediction results of a single model,the Majiagou Reservoir in Chenggu County was taken as the object to simulate the daily runoff and flood process from 2019 to 2021 by using the Xin'anjiang model and tank model respectively,and the simulation results and accuracy of the two models were compared by using the model parameters calibrated and optimized by the genetic algorithm.In the daily runoff simulation,the simulation effect of the tank model is better than that of the Xin'anjiang model,with a relative error of flood volume of less than 16%,a relative error of flood peak of less than 4%,a difference of peak time of less than 1 h,and a Nash-Sutcliffe efficiency coefficient of greater than 0.58,all of which meet the evaluation accuracy requirements of the Standard for Hydrological Information and Hydrological Forecasting,and the simulation effect of deluge in the reservoir is ideal.In the flood process simulation,the difference of peak time between the two models is similar;the simulation effect of the Xin'anjiang model is smoother,and the flood volume and flood peak simulated by the tank model are closer to the measured flow process.On the whole,the tank model is more suitable for flood forecasting in Majiagou Reservoir than the Xin'anjiang model.

Juanjuan Fang, Yitian Li, Dong Wang et al.

Lake systems are of fundamental significance for the ecological environment and social development. Driven by climatic changes and human activities, the hydrological situation of rivers and lakes has been altered considerably, and it has directly affected the reliability of irrigation and water supply in lake areas. In the case of the Yangtze River–Dongting Lake area, the quasi-equilibrium of their hydrological states and water balance have been affected by the operation of the Three Gorges Project that has led to irrigation and water supply problems across the lake area. Ever since, the available water supply in the Dongting Lake area has decreased by 31.5% and 47.7% during the months of September and October, and the overall water level in the lake area has dropped by 0.8–2.0 m. The proportion of domestic and agricultural irrigation water demands to available water supply in the Dongting Lake area is very small, and the decline of water level is the main reason for the lack of water supply in Dongting Lake area, Although the total amount of water in the lake area is still above the water supply threshold, an obvious decreasing trend has been observed in the fulfillment of the demand for both irrigation and water supply in urban and rural regions. Additionally, the fulfillment of secured water supply and irrigation requirements has respectively dropped from 95% to 78% before the operation of the Three Gorges Project to 82% and 46% after it. Meanwhile, the total water shortage increased from 57.683 to 143.607 million cubic meters. By advancing or postponing impoundment schedules, the impact of the Three Gorges Reservoir on irrigation and water supply in the lake area during September and October can be alleviated, and the water supply capacity can be respectively increased by approximately 1.3% and 1.4%. The highlights of this study include the quantification of the impacts of the operation of large-scale water conservancy projects at the level at which the requirements on irrigation and water supply in the lake area are satisfied, and the prediction of the trends for future evolvement. In addition, corresponding strategies that provide a technical reference for the comprehensive regulation and control over water resources and the security of water supply in the river basin are discussed.

Mojtaba Pakparvar, Gholamali Nekooeian, Gholamreza Ghahari et al.

Introduction Water scarcity due to climate change and growing water demand in different consumption sectors is a major environmental crisis that drives arable lands to a state of degradation, especially in dry regions. Artificial recharge of groundwater (ARG) through floodwater spreading (FWS) which is a potential measure for reversing this emerging trend is investigated in this research. Floodwater harvesting has become an increasingly important technique to improve water security and caused a renewed interest in research and implementation. According to the diverse objectives and methods of implementing artificial recharge of groundwater (ARG) systems, various factors must be considered when choosing a method for quantifying recharge. Therefore, the rate of aquifer recharge is one of the most difficult items to measure in groundwater (GW) resources evaluation. In the soil water balance method (and in the Zero Flux Plane method), soil water movement is inferred by measuring the changes in water content of the soil profile by gravimetric sampling or automatic devices. These methods have not been proven satisfactory in low flow conditions, as there is often insufficient resolution to detect the movement of small quantities of water. Therefore, other methods, based on hydraulic conductivity, potential gradients, and directly calculated water fluxes for unsaturated flow were developed. The Buckingham-Darcy law can be used under the steady flow condition where water contents and fluxes change with depth but do not vary as a function of time. It has been employed in arid and semiarid conditions for recharge estimation. or for assessing the exchange flow between the surface water reservoir and GW. The method requires measurements or estimates of the vertical total head gradient and the unsaturated hydraulic conductivity at the ambient soil water content following the Buckingham-Darcy equation. The overall objective is to evaluate a floodwater spreading system that was installed in 1981 at the Gareh Bygone Plain, southern Iran for recharging the groundwater table.   Materials and Methods To assess the artificial recharge of groundwater through turbid floodwater spreading, three wells, ~30 m deep, were dug in a 37-year-old recharge basin in planted Acacia forest, bare soil, and pasture land uses, respectively. Soil hydraulic parameters of the vadose zone layers (30 m thickness) were measured in the field and laboratory. One well was equipped with pre-calibrated TDR sensors throughout the well profile for measuring the changes in soil water content along the vadose zone. The volumetric soil-water content was measured continuously from Sep. 2010 to Sep. 2020 with closer temporal increments after floodwater spreading events. Rainfall, ponding water depth, and duration were also measured. Recharge through the vadose zone was assessed by the soil-water balance (SWB) method, as measured in the field as well as by calibrating the Hydrus-1D (H1D) model through the inverse solution.   Results and discussion Results showed that the wetting front was interrupted at a layer with fine soil accumulation over a coarse-textured gravely layer at a depth of ~4 m. The large differences in hydraulic conductivity of the two successive layers seemed to cause the transformation of the wetting front water movement into fingering flow. The changes in downward water flux complicated TDR measurement after the depth of 4 m. However, noticeable but temporary changes in the soil water content were detected in some of the layers below the 4 m was evidence for fingering flow after the flood events. Validation of the simulated flow by the H1D model vs. the one observed by SWB (with RMSE 3.45; R2 0.994) showed that the model performed well in flux estimation. The recharge ratio was calculated for the 2010 to 2020 events as 26 to 84 average of 55 % for all events and 63 to 84 average of 75 % for large impounded floodwater in the basin, respectively.   Conclusion Although a reliable set of data is obtained for calculating recharge at the very location of this study, up-scaling of the results for the entire floodwater systems and for the other flooding events with extreme volume and flow rate needs an extended investigation period and thorough identification of the underlying layers. The determined hydraulic properties of the RLs obtained in this study will be utilized in future research works in the FWS systems in our study site. The contributions of this thesis can be summarized as a) development of approaches for application, calibration, and validation of existing models with limited available data, b) the incorporation of new concepts into the models used, c) generating a unique and robust field data set to support the modeling approaches and d) provision of new information in the context of floodwater harvesting and its impact on groundwater recharge. Floodwater harvesting, especially in the form of FWS, is an emerging issue in water management in dry regions, which needs a better understanding and evaluation of its impact on the surrounding environment. Small-scale but nature-friendly water management plans, such as FWS systems, are seriously criticized since there are numerous methods, which are more attractive in terms of investments and money return to investors. However, they are rarely investigated. This study provided quantitative evidence that proves the effectiveness of FWS systems.

Xiaohe Lai, H. Chen, Yuebao Hou et al.

T. L. Kondratyeva, I. Ushakova, I. Trotsenko et al.

The article describes the sources of water supply inKormilovka district of Omsk region. The main sources of water are surface waters of the Om and Taburga rivers, lakes and artificial reservoirs, groundwater. In general, the territory of Kormilovka district lacks fresh groundwater. Currently, water is supplied by hydraulic structures on the Omriver as part of water intake and treatment facilities, water pipelines and a pressure distribution network. Water supply from underground sources is carried out from tubular wells with a depth of 5.0 - 9.0 m, from wells with a depth of 200 m and deep-water wells of about 1100 m. Water intakes from underground sources are available in almost all rural settlements, but they are used for technical and (or) economic purposes. An ecological assessment of the state of surface and underground sources isprovided. The results of an analysis of the geological and hydrogeological situation are presented. Of greatest interest are Neogene-Quaternary, Upper Oligocene-Lower Miocene and Lower Upper Cretaceous (Pokursky) complexes. According to the generalized characteristics of quality of groundwater from three underground aquifers in Kormilovka district, the most acceptable is the Pokursky aquifer, since itsgroundwaters are less mineralized, softer, more protected, and, consequently, their microbiological and parasitic indicators comply with the sanitary standards. When using both surface and groundwater for household and drinking purposes, it is environmentally safe for the population only after adjusting such indicators as turbidity, color, chlorine, iron, and dry residue content and bringing the microbiological indicators to SanPiN 2.1.4.1074-01 and SanPiN 2.1.4.544-96.