High Water Levels Research Articles

Effect of Rural Sewage Irrigation Regime on Water-Nitrogen Utilization and Crop Growth of Paddy Rice in Southern China

Reclaimed water irrigation has become an effective mean to alleviate the contradiction between water availability and its consumption worldwide. In this study, three types of irrigation water sources (rural sewage’s primary treated water R1 and secondary treated water R2, and river water R3) meeting the requirements of water quality for farmland irrigation were selected, and three types of irrigation water levels (low water level W1 of 0–80 mm, medium water level W2 of 0–100 mm, and high water level W3 of 0–150 mm) were adopted to carry out research on the influence mechanismS of different irrigation water sources and water levels on water and nitrogen use and crop growth in paddy field. The water quantity indicators (irrigation times and irrigation volume), soil ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N), rice yield indicators (thousand-grain weight, the number of grains per spike, and the number of effective spikes), and quality indicators (the amount of protein, amylose, vitamin C, nitrate and nitrite content) of rice were measured. The results showed that, the average irrigation volume under W3 was 2.4 and 1.9 times of that under W1 and W2, respectively. Compared with R3, the peak consumption of rice was lagged behind under R1 and R2, and the nitrogen form in 0–40 cm soil layers under rural sewage irrigation was mainly NH4+-N. The changes of NO3−-N and NH4+-N in the 0–40 cm soil layer showed the trend of declining and then increasing. The water level control only had a significant effect on the change of NO3−-N in the 60–80 cm soil layer. Both irrigation water use efficiency and crop water use efficiency were gradually reduced with the increase of field water level control. The nitrogen utilization efficiency under rural sewage irrigation was significantly higher than that under R3. Compared with the R3, rural sewage irrigation could significantly increase the yield of rice, and as the field water level rose, the effect of yield promotion was more obvious. It was noteworthy that the grain of rice under R1 monitored the low nitrate and nitrite content, but no nitrate and nitrite was discovered under R2 and R3. Therefore, reasonable rural sewage irrigation (R2) and medium water level (W2) were beneficial to improve nitrogen utilization efficiency, crop yield and crop quality promotion.

Tsunami wave loading on a structural array behind a partial wall

This paper examines long wave loading on a building array behind a high-elevation, varying-length seawall through laboratory experiments conducted in Oregon State University's Directional Wave Basin. Long wave forcing in the form of solitary waves and error function waves was applied to both pre-inundated high water level conditions with currents, and to low water level runup loading without currents. Behind the wall, the cross-shore peak load declined as a function of the sheltering angle; on the other hand, the highest loads occurred with seawall lengths that exposed the instrumented structures. Flow concentration around the end of the wall caused higher velocities when a structure was just exposed, and led to large loads for nonbreaking waves at these wall lengths. For cases with breaking waves, particularly for inundation conditions, the wave breaking location was also a determining factor of the magnitude of loading, as larger loads were observed when a wave broke far enough in front of the first structure that a strong bore had developed. These results will serve to provide a better understanding of the wave impact to a coastal urban region in a tsunami event when the seawall is breached.

Low- versus High-water level effect on subtropical benthic freshwater meiofauna

Little is known about meiofaunal responses to Low- versus High-Water-Level (L- vs HWL) particularly in the subtropics. Meiofaunal reaction was evaluated in three locations (deeply-different) in two man-made freshwater channels in (Rowaina and Shalma) Northern Nile Egyptian delta: 50, 100, & 150, and 900, 950, & 1000 metres distances from the sluice, respectively. LWL and HWL were in January and July 2019 respectively. Eight vs ten and nine vs eleven major taxa were noted in Rowaina H- vs LWL and Shalma L- vs HWL, respectively. Taxa had different susceptibilities to L- vs HWL. Nematode, hydracarina, and oligochaetes dominated in L- and HWL, (Shalma), and in HWL (Rowaina). Whereas Nematoda, Copepod, and Oligochaeta prevailed in LWL (Rowaina). Oligochaeta biomass was generally high in LWL and HWL. Hydracarina in LWL, and Nematode & Copepod in HWL had low biomasses in Rowaina and Shalma respectively. Abundances and biomasses were significantly different within and among channels. Environmental variables were significantly different only between water levels. It could be concluded that L- vs HWL has both direct and indirect (variabilities in environmental factors) impacts on meiofauna. Channel width & morphology, may impose extra influences. This study may enhance invertebrate surveys with hydrologically different freshwater bodies.

The Impact of Dam Reservoir on Flood Reduction (Case Study Logung Reservoir, Kudus, Central Java)

The Indonesian government targeted building 65 reservoirs and dams in 2015-2022. The purpose is to maintain food security facing the long-term climate crisis, besides reducing the impact of a flood. Logung Reservoir is located on the Logung River, Kudus, Central Java. This earth-fill dam was built to solve the flood and drought problems in Kudus. However, the existence of the Logung Reservoir gives a risk to the downsteam area. The purpose of this research is to study flood reduction and the risk of overtopping, which can cause a dam break, and to calculate the Logung Reservoir spillway's performance in handling floods. This study is based on four main steps: the rainfal-runoff modelling, the extreme rainfall estimation, the hydrograph inflow of the dam estimation, and the evaluation of food reduction. The results of the 1000-year rainfall analysis and PMP for the Logung dam basin were 409 mm and 704 mm, respectively. Rainfall distribution is made using ABM, and effective rainfall is calculated by the SCS method. Land use analysis in the Logung dam watershed obtained a CN-II of 71.4 and a CN-III of 85.2. The rainfall-runoff transformation method used a unit hydrograph. The Nakayasu and Gama-I unit hydrographs show significant differences from the peak discharge, although not for the time base. The flood hydrograph design affects the reservoir performance. The reservoir flood routing results a dumping efficiency of 35% for the 1000-year and 21% for PMF. The 1000-year flood routing shows that there was no risk of overtopping. The highest water level on the PMF flood routing at +94.1. Several solutions can prevent overtopping by reducing inflow discharge through small dams upstream, increasing the green area, or modifying spillway structure.

GEOMORPHOLOGY OF GARHWAL HIMALAYA, PARTS OF CHAMOLI TEHRI UTTAKASHI & PAURI UTTAR PRADESH (UTTRARKHAND) INDIA

The Geological and Geomorphological study in Upper Ganga basin has been attempted in parts of de Uttarkashi,Chamoli, Pauri and Tehri districts an area of 10000 Sq.kms in parts of QA sheet 53Jand 53 N on 1:50000 scale of Garhwal Himalaya U.P presently known as Uttrakhand State of Union of India. Out of total area of study, an area about 3500 sq.Kms has been selected for detailed Geological, Geomorphological and Sedimentological study. The area of Upper Ganga basin consisting of Alaknanda,Bhagirathi,Bhilangna, Nandakini, Mandakini, Pindar, Dhauli- Ganga Bal- Ganga , Madhmeshwar Ganga and Berhi Ganga The Alaknanda is chracterised by six terraces followed by Bhagirathi with five terraces , Bhilangna Nandakini four terraces Mandakini /Pindar/Dhauli-Ganga /Balganga three terraces , Madhmshwar Ganga two terraces and Bberhi Ganga one terrace,amidst these Alaknanda is trunk stream and others are tributaries. Geomorphologically the area is divided in to seven geomorphic units viz High relief formerly glaciated area, Structural hills, Denudational hills, Area of mass wasting, High level dissected fans, river Terraces and Present day flood plain of Alaknanda and its tributaries . These units area developed in response to lithology to erosional land depositional activities and tectonic in which they are embedded. Each unit is characterized by drainage, diagnostic geomorphic landform elements and features, photo charcters and morphogenetic expression. The other geomorphic features and elements identified in the area are point bar, channel bar, alluvial fans ,talus cone , rock cut terraces fan cut terraces , abandoned channel ,epigenetic gorges, strand lines landslides ,rock fall scree and scree slope, retreating scarp, abandoned cirque, arêtes, threshold, horn peak and glacial lake. The area genetically comprised of terraces of three domains, viz. Glacial, Fluvio-glacia and Fluvial which represent distinct environment of sedimentation of Pleistocene, late Pleistocene and Holocene time during Quaternary period. The Glacial terraces are identified at an average elevation of 1150 m above MSL, the fluvio-glacial terraces at an average elevation of 975m above MSL and Fluvial terraces at an average elevation between 650 to 900 m above MSL.

Operation State Evaluation of Miter Gate Based on On-Line Monitoring and Finite Element Analysis

As an essential part of the water conservancy hub, the miter gate undertakes the vital task of navigational operation and works in a complex basin with a high water level drop for a long time; therefore, it is necessary to ensure its safe operation. In this paper, taking the Gezhouba No. 2 ship lock miter gate as an example, the actual gate stress and crack signals are obtained using the online monitoring system. The stress distributions of the gate under different working conditions are studied using finite element simulation analysis. Combining simulation analysis with the collected signal analysis, the operation status of the actual gate under each working condition is evaluated. The results show that the stress analysis of the online monitoring is consistent with the finite element analysis results, which verifies the reasonableness of the sensor arrangement. The stress is more concentrated in the area of the gate shaft column, the middle door seam, and the rear flange plate during the operation of the miter gate, and the maximum stress appears on the central sector shaft column of the gate. The cracks of the miter gate mainly appeared in the lower layer of the gate body, and the cracks expand gradually during the long-term operation of the gate. The crack expansion speed corresponds to the miter gate’s stress magnitude.

Cliff-top boulder morphodynamics on the high–energy volcanic rocky coast of the Reykjanes Peninsula (SW Iceland)

Cliff-top boulder deposits (CBDs) are morphological indicators of high-energy conditions. Since 2014, a monitoring of CBDs dynamics has been undertaken on the south-western coast of Iceland (Reykjanes Peninsula) to monitor their long-term activation (quarrying, transport and deposition) as a proxy of the inter-annual winter storminess variations and basaltic cliff erosion processes in a context of rocky coast progradation. Annual topomorphological surveys of four study sites were conducted and Structure-from-Motion photogrammetry was performed to quantify CBDs displacements. Hydrodynamic conditions were analyzed based on offshore waves and water level. Results show that CBDs activation occurs every winter, regardless of the variability of hydrodynamic conditions. Depending on the site and the year, >2% and 17% of the CBDs accumulated above 8 m to 10 m asl at the top of the cliffs are regularly mobilized. While inland movements represent the main mode of transport of blocks (between 50% to 60%), seaward and longshore movements are also well represented (10% to 20%). Longshore displacement is favored by the wide tabular morpho-structural setting of the wave-scour cliff-top platforms, which is explained by the structure of pāhoehoe lava flows. The activation of CBDs –measured from the volumes of displaced boulders–, shows a good correspondence with the frequency and duration of storms. However, as was the case during the winter of 2018–2019, it was rather the intensity of two highly morphogenic episodes combining storm waves and especially very high spring tide water levels, that generated the largest boulders displacements. Substantial interannual activation of the CBDs confirms that they constitute an important and still understudied proxy of the morphogenic system of high-energy rocky coasts, whose the dynamic in terms of carrying, transport, and deposition, could significantly increase with rising sea level.

Nitrogen removal efficiency in sustainable eco-ditches with floating ryegrass mats: The effect of loading (hydraulic and nitrogen) and water level on N removal

Drainage ditches are used for surface water management as well as for the interception of pollutants from farmlands. In this study, ditches with floating ryegrass mat (FRM), Vallisneria natans (VN) and the combination of the two (FRMVN) (including an unamended control ditch) were trialed to evaluate the N interception rates of simulated, low-concentrated run offs at low temperature. The nitrogen removal efficiency of FRMs under low and high-water level (25 cm and 50 cm, respectively) was also investigated during a warmer period. The results showed that the NH4+ removal efficiency was fairly stable for the ditches with FRMs and the interception rates were 30.5% ∼ 46.0% for the low and high influent N concentration (5 mg L−1 and 15 mg L−1) respectively. These NH4+ interception rates were higher than those from the control, especially in the phases of high influent N. The NO3− and TN removal efficiency was kept low for all treatments especially during the cold period likely due to lack of readily available carbon source. Water level had no significant influence to the FRM-based TN, NH4+, and NO3− removal - interception rates though were higher compared to those from the Control ditches during the low N period. In terms of nitrogen budget, the N reduction from FRMs treatments was 8.4% ∼ 16.9% higher than those of the controls due to plant uptake, adsorption, and other pathways. Further improvement in denitrification can be achieved by supplementing cellulosic carbon.

CORM QUALITY OF TARO UNDER IRRIGATION LEVELS AND DIFFERENT SOIL TYPES

Irrigation amount is an important factor in the development of taro (Colocasia esculenta L. Schott), however, there is little information focus on effects of water scheme on its corm quality under different soil textures. Thus, this study aimed to evaluate the taro corm quality in response to five irrigation levels (20%, 60%, 100%, 140% and 180% ETc - crop water requirement) under three soil textures (clay, sandy clay loam, and sandy soil) in a greenhouse. Results indicated that corm number total (CNt) and corm diameter (CD) of taro decreased with reduced irrigation levels, higher values were detected at 140%ETc and 180%ETc in all soil types. CD and CNt performed better in sandy soil than in other two soils, especially in water scheme lower than 100%ETc. In general, total sugar (TS), reducing sugar (RS), and starch content (SC) of taro corm performed better in higher water regime, except that for protein content (PC). Taro corm had higher TS and SC in sandy soil, while lower PC was observed in the same soil treatment. Overall, higher water level was more beneficial to improve corm quality, and SS could be more suitable for taro cultivation under water stress.

CORM QUALITY OF TARO UNDER IRRIGATION LEVELS AND DIFFERENT SOIL TYPES

Irrigation amount is an important factor in the development of taro (Colocasia esculenta L. Schott), however, there is little information focus on effects of water scheme on its corm quality under different soil textures. Thus, this study aimed to evaluate the taro corm quality in response to five irrigation levels (20%, 60%, 100%, 140% and 180% ETc - crop water requirement) under three soil textures (clay, sandy clay loam, and sandy soil) in a greenhouse. Results indicated that corm number total (CNt) and corm diameter (CD) of taro decreased with reduced irrigation levels, higher values were detected at 140%ETc and 180%ETc in all soil types. CD and CNt performed better in sandy soil than in other two soils, especially in water scheme lower than 100%ETc. In general, total sugar (TS), reducing sugar (RS), and starch content (SC) of taro corm performed better in higher water regime, except that for protein content (PC). Taro corm had higher TS and SC in sandy soil, while lower PC was observed in the same soil treatment. Overall, higher water level was more beneficial to improve corm quality, and SS could be more suitable for taro cultivation under water stress.

Climatic shifts, geomorphic change, ancient routes of migration and adaption in southwestern China: Site formation processes at Luojiaba, Sichuan Province

AbstractArchaeologists frequently invoke climate change as a driving cause for ancient expansions of human populations, but geomorphic changes can also play an important role in opening or closing routes of migration. In China, archaeological evidence demonstrates that valleys in the Jialing River's watershed were important routes for the movement of Neolithic populations from the catchments of the Yellow River to the Yangtze River. Here, we examine how fluvial geomorphological regime shifts may have also influenced the migration pathways and adaptive strategies of Neolithic people into the Sichuan Basin by using a combination of sedimentological and palynological analysis at Luojiaba, an archaeological site located on one of the eastern tributaries of the Jialing River. The results show that people settled on seasonally stable landforms, including the Zhonghe River floodplain at Luojiaba (5300–4800 cal. B.P.). They carried out fishing and hunting activities on the front edge of the floodplain close to the river channel and built dwelling features on the higher ground at the back edge of the floodplain, which was not affected by seasonal floods. We hypothesize that during the Holocene Climatic Optimum before 5500 cal. B.P., high water levels as well as severe surface erosion caused by a strong East Asian Summer Monsoon (EASM) blocked pathways into the upper reaches of the Jialing River watershed. Only after a series of cold, dry climate events driven by a decrease in EASM intensity ca. 5500–5000 cal. B.P. did water levels recede significantly. This allowed alluvial aggradation to occur, which created floodplains and terraces along the valley that may have opened a new route for the migration into the Sichuan Basin. Our results reveal the human–environment dynamics surrounding Luojiaba in the uplands of southwestern China and highlight the impact of coupled climatic‐geomorphic regime shifts on human settlement and subsistence strategies, across both space and time.

Study the effect of different levels of aqueous extract of licorice on the carcass traits of Chinese ducks

This study was carried out at a private farm for duck breeding in Al-Muthanna Governorate, from 14/12/2021 to 14/2/2022. The field experiment was included to study the effect of adding aqueous extract of licorice to drinking water on the carcass trait from Chinese ducks. A total 60 unsexed, Chinese duck chicks one-day old were used, prepared from one of AlQadisiyah Governorate hatcheries, the chicks were distributed randomly to 4 treatments, included 3 replicates, (5 chicks each replicate), the treatments were as follows: T1: control treatment (without addition). T2, T3 and T4 treatments were 5, 10 and 15 ml aqueous extract of licorice /liter of drinking water, respectively. The results showed a significant improvement in all characteristics of the studied carcass (dressing percentage with and without geblet, the ratio of main and secondary cuts), when aqueous licorice extract is added to drinking water, in addition to the high level of water licorice extract (15 ml of licorice per liter of drinking water), which gave the best results and significantly.

Numerical simulation study on the mechanism of releasing ultra-deep water shallow gas by drilling pilot holes

This study proposed an operation mode that actively releases shallow gas from an ultra-deep water shallow gas reservoir by drilling pilot holes. This operation mode can help discharge underground shallow gas in advance and better guarantee the security of the subsequent drilling operation. The flow law of shallow gas in the release process was simulate according to the field data of the Shenhu area in the South China Sea to study the mechanism and feasibility of actively releasing shallow gas in ultra-deep water area. The findings of the study revealed that shallow gas and seawater driving each other behavior (DEO behavior) in the shallow gas reservoir and borehole zones (underground zone: refers to the zone comprising the borehole and shallow gas zones) existed in the early release process, and the DEO behavior exhibited an obvious cyclic phenomenon. Simultaneously, the morphological development of the shallow gas spewing into the static seawater and real seawater zones was studied to obtain a clearer understanding of the gas morphological development in seawater. Based on the above findings, further investigations revealed that the operation that released shallow gas with 8-3/8″, 9-5/8″, and 12-1/4″ pilot holes in the target field did not affect the buoyancy of the seawater or sink the platform; there was almost no fluctuation to the sea surface. This study examined and compared the shallow gas flow law and remaining shallow gas volume in the reservoir with time under the application of 8-3/8″, 9-5/8″ and 12-1/4″ pilot holes. Consequently, it found that under the condition of target field larger hole sizes exhibited lower collapsing and dispersing heights (the distance between the last shaped shallow gas bubble about to burst and the mud line) and faster shallow gas release velocity. Furthermore, a numerical simulation study on the operation mode of releasing shallow gas from an ultra-deep-water shallow gas reservoir by drilling pilot holes can provide theoretical support for subsequent shallow gas treatment decisions in ultra-deep-water drilling construction.

A preliminary study of the bacteriological evaluation of raw milk from Kogi State University dairy farm

Milk is a food that inherently favours microbial growth and due to its characteristics, several precautions must be taken to prevent contamination in its production, processing and consumption, which are routinely subject to changes. Raw milk is a complex mixture which is highly nutritious, contain high level of water (85%) and a pH close to neutral which makes it highly perishable and a suitable medium for the growth and multiplication of microorganisms. This study was carried out to evaluate the bacteria associated with raw milk from a dairy farm. A total of seven (7) raw milk samples were -gotten from different lactating cows. The samples were examined for pH, organoleptic property, and turbidity. Isolation of bacteria was done using the pour plate method, gram staining and various biochemical test were conducted to identify the organisms. The pH value of the samples ranged from 6.5 to 6.9. The total bacterial count ranged from 4.3x106 to 9.0x104 CFU/ml, and total coliform count ranges from 5.1x106 to 4.0x104 the bacteria isolated were Bacillus spp Escherichia coli, Staphylococcus aureus, Klebsiella spp and Streptococcus spp. The high bacteria count obtained in this study is an indication of poor sanitary condition and this calls for strict hygienic measure during handling of raw milk and its products.

Impact of Seepage on the Underground Water Level in a Complex Soil-Water-Structure System

The antifloating design of underground structures is very important in areas with high underground water levels, and reasonable evaluation of the buoyancy is based on accurately describing the distribution of the groundwater level. However, the natural groundwater flow would be disturbed by the structure, which is not considered in the antifloating design. In the present paper, the influence of the width of an underground structure on the groundwater level in homogeneous soil is investigated through an indoor physical model test in the first place, which serves as a benchmark for the numerical simulation. Then, the parametrical study is carried out with numerical simulation. The results show that the width of the structure has the greatest influence on the water level around the structure, followed by the influence of the insertion depth, whereas the length has little influence. The hydraulic gradient has a significant effect on that as well. Moreover, the hydraulic conductivity ratio between different soil layers also affects the water level magnitude. Based on the results, a prediction method for the groundwater level around the structure for both homogeneous soil and multilayer soil has been developed and evaluated.

Variability of the coastal currents, waves and wind surge along the shore of the South-Eastern Baltic (Kaliningrad Oblast, Russian Federation)

The coastline of the Kaliningrad Oblast is an area of the South-East Baltic, which continues from the Vistula Spit to the Curonian Spit via Sambia Peninsula. The coastline has been subject to severe erosion over the past years. The goal of the paper is to analyse whether the alongshore variations of the storm surge water level, field of waves and currents are the reason for the erosion alongshore variability. The numerical simulations were carried out using the quasi-stationary approach for the model wind. The offshore wave breaking distance and the non-linear dependence between wind surge and wind speed were estimated for four typical coastline sites. The alongshore velocity on most of the coastline was enough powerful to transport the fine, medium and coarse sands. West, northern-west and north winds were defined as the most dangerous for coastal erosion. The convergence and divergence of alongshore currents as well as the vortex zones were identified for each wind direction. The results were used to analyse the alongshore current velocity, wind surge, and significant wave height variability against the shore erosion characteristics. The hypothesis that the places of convergence and divergence of alongshore currents correspond to the accumulative and erosion zones was not confirmed with one exception on the western shore of the Sambia Peninsula. Three options were supposed to explain the absence of correlation between the monitoring results on coastal erosion and modelled hydrodynamic conditions: the studied shore has not had enough free sand to demonstrate the typical behaviour of dissipative shores; the erosion characteristics depend on the very local conditions which were not resolved by numerical model; the main erosion has happened at the short term event basis when waves reach the shore at the background of a general Baltic Sea high-water level and is not a result of the general alongshore distribution of waves, wave surge and current characteristics.

Going Public: Performing Dying in the Second Decade of the 21st Century

It is now more than a decade since the death of celebrity television personality Jade Goody – a high water mark in public dying comparable to the watershed moment in public mourning marked by the death of Diana, Princess of Wales, a decade or so earlier. As Walter has noted in this journal, Goody’s very public and highly mediated dying will not be the last. With that in mind, this article analyses the sociological significance of public dying in the decade following Goody’s death – the ‘tens’ of the 21st century. It does so chiefly by focusing on a number of high-profile instances which gained significant media traction, using these to examine the ways in which dying is both performed and made meaningful in contemporary 21st century culture. The argument presented operates on the assumption, following Goffman, of life – and by extension, dying – as performance.

Processing of aerial photographs in geoinformation systems for constructing models of possible flooding zones in a flood-prone period

The natural and geological conditions of the Khabarovsk Territory determine the specificity of any region, characterized by the annual occurrence of spring mash phenomena, their gradual transition to the summer-autumn flood-hazardous period and the departure into winter with a high water level. Forecasting the scale of possible flooding of territories is the basis for early response of the forces and means of the Unified State System for the Prevention and Response of Emergency Situations (RSChS) The paper discusses the professional experience of specialists from the Crisis Management Center of the Main Directorate of the EMERCOM of Russia for the Khabarovsk Territory in preparing models of possible flooding of settlements applying the QGIS geographic information system during the flood-prone period of 2021 in the Khabarovsk Territory. The authors identify peculiarities of the unmanned aerial vehicles used to predict areas of possible flooding such as the need for early aerial photography of human settlements; dependence of the quality of orthophotomaps on the experience of specialists performing aerial photography; variability of coastline relief; dependence on weather conditions; short period, favorable for aerial photography; inaccessibility of settlements; location of settlements in the border area. The matching of models obtained with the help of QGIS with the actual situation developed during the 2021 flood crest was identified. Also, some peculiarities and disadvantages were defined despite the positive experience of forecasting by modeling flood zones (flooding).

Geoinformation support for studies of the boundaries of flood zones in urban areas

The article presents the results of the use of geoinformation modelling of the processes of urbanised territories’ flooding by river waters. Physical, geographical, and climatic parameters of the key river basin (Vezelka River within the boundaries of the city of Belgorod) have been determined. A list of input data and methods that were used to create geoinformation models is presented. The peculiarities of the technique of aerial photography and the creation of a digital terrain model on its basis are disclosed. The formulas for the calculation of the level of water rise and calculation of the flooding model corrected by the terrain are disclosed. The results of determining high levels of river water by calculated sites are shown, longitudinal and transverse profiles with estimated water levels during flooding with different levels of the expected probability of occurrence have been created. The final map of the boundaries of flood zones in the urban area, which are calculated using geoinformation modelling, is demonstrated. We propose that the results of geoinformation modelling of flooding scenarios for large rivers be included in the regional GIS portal.

Effects of Future Increases in Tidal Flooding on Salinity and Groundwater Dynamics in Coastal Aquifers

AbstractFuture increases in the frequency of tidal flooding due to sea level rise (SLR) are likely to affect pore water salinities in coastal aquifers. In this study, we investigate the impact of increased tidal flooding frequency on salinity and flow dynamics in coastal aquifers using numerical variable‐density variably‐saturated groundwater flow and salt transport models. Short (sub‐daily) and long (decadal) period tides are combined with SLR projections to drive continuous 80‐year models of flow and salt transport. Results show that encroaching intertidal zones lead to both periodic and long‐term vertical salinization of the upper aquifer. Salinization of the upper aquifer due to tidal flooding forces the lower interface seaward, even under SLR. System dynamics are controlled by the interplay between SLR and long period tidal forcing associated with perigean spring tides and the 18.6‐year lunar nodal cycle. Periodic tidal flooding substantially enhances intertidal saltwater‐freshwater mixing, resulting in a 6‐ to 10‐fold expansion of the intertidal saltwater‐freshwater mixing area across SLR scenarios. The onset of the expansion coincides with extreme high water levels resulting from lunar nodal cycling of tidal constituent amplitudes. The findings are the first to demonstrate the combined effects of gradual SLR and short and long period tides on aquifer salinity distributions, and reveal competing influences of SLR on saltwater intrusion. The results are likely to have important implications for coastal ocean chemical fluxes and groundwater resources as tidal flooding intensifies worldwide.