Morphological characteristics of Tirumalairajan river, East Coast of India—a GIS approach

Morphological mapping plays an essential role in understanding river processes. Evaluation of the morphological parameters requires preparation of basin, upstream and downstream, stream link, stream network, stream order, flow direction, flow accumulation, and digital elevation model, which help to understand the nature of the river. Assessments of morphological digital maps provide upstream and downstream flow rates, slope variation, sedimentation, and specific stream erosive power in river systems. The river patterns of the study area mainly controlled by geological nature. Therefore, this paper discusses conceptual foundations and illustrates how mapping approaches can be used to produce morphological information of Tirumalairajan river systems.     

Dynamics of greenhouse gases in the river–groundwater interface in a gaining river stretch (Triffoy catchment,Belgium)

This study investigates the occurrence of greenhouse gases (GHGs) and the role of groundwater as an indirect pathway of GHG emissions into surface waters in a gaining stretch of the Triffoy River agricultural catchment (Belgium). To this end, nitrous oxide (N₂O), methane (CH₄) and carbon dioxide (CO₂) concentrations, the stable isotopes of nitrate, and major ions were monitored in river and groundwater over 8 months. Results indicated that groundwater was strongly oversaturated in N₂O and CO₂ with respect to atmospheric equilibrium (50.1 vs. 0.55 μg L^?1 for N₂O and 14,569 vs. 400 ppm for CO₂), but only marginally for CH₄ (0.45 vs. 0.056 μg L^?1), suggesting that groundwater can be a source of these GHGs to the atmosphere. Nitrification seemed to be the main process for the accumulation of N₂O in groundwater. Oxic conditions prevailing in the aquifer were not prone for the accumulation of CH₄. In fact, the emissions of CH₄ from the river were one to two orders of magnitude higher than the inputs from groundwater, meaning that CH₄ emissions from the river were due to CH₄ in-situ production in riverbed or riparian zone sediments. For CO₂ and N₂O, average emissions from groundwater were 1.5?×?10⁵ kg CO₂ ha^?1 year^?1 and 207 kg N₂O ha^?1 year^?1, respectively. Groundwater is probably an important source of N₂O and CO₂ in gaining streams but when the measures are scaled at catchment scale, these fluxes are probably relatively modest. Nevertheless, their quantification would better constrain nitrogen and carbon budgets in natural systems.     

Geologic hazards of the Ocoña river valley,Peru and the influence of small-scale mining

Natural Hazards - The Ocoña River Valley, in the Arequipa Department in southern Peru, extends over 150 km from the Pacific coast to its headwaters in the Andes Mountains. While...     

Morphometric analysis of Colangüil river basin and flash flood hazard,San Juan,Argentina

This work analyzes various morphometric characteristics of the Colangüil river basin in order to evaluate flash flood hazards. Such high-water events pose a risk to the similarly named small village located at the basin’s foot area. For this purpose, the basin is divided into seven sub-basins and some basic measurements (surface, perimeter, basin length, river beds, elevations and slope of the main river bed, and of a number of minor river beds) are calculated. These measurements permit to predict approximately the behavior of the basin in the presence of a series of theoretical rainstorms that may generate unusual runoff volumes that make up such flash floods.     

Structures and morphotectonic evolution of the frontal fold–thrust belt,Kameng river section,Arunachal Himalaya,India

The Neogene–Quaternary Siwalik foreland fold and thrust belt is studied for better understanding of tectonics along the Kameng river section of Arunachal Pradesh, India. The Kimi, Dafla, Subansiri, and the Kimin Formation correspond to Lower, Middle and Upper Siwaliks, respectively. The lithology in the foreland basin is dominantly sandstones, siltstones, claystones, carbonaceous shales, and boulder beds in the upper part. The structural style of the sedimentary sequence from the Main Boundary Thrust southward shows first order ramp-flat geometry. The brittle shear transfers slip across glide horizons to shallower depth. Repeated splay generations from a major regional-scale floor transfers slip from one glide horizon to another that shortens and thickens the crust. In the micro-scale, the lithological response in the structural development is well documented as pressure solution seams and other diagenetic deformation signatures. The basement asperity plays a significant role as the moving thrust front produced a major lateral ramp. The differential movement of the mountain front on both sides of the ramp is decipherable. This is especially true at the western part of the SE flowing Kameng river. The tectonic evolution of the area initiated with slip along the MBT \(\sim \)11 Ma ago along with the deposition of the Siwalik sediments. With southward propagation of the mountain front, the foreland basin shifted towards S, produced splay thrusts from the Himalayan Frontal Thrust-1 (HFT-1), which has been uplifting the Kimin and the older terraces.     

Contamination of shallow aquifers by arsenic in upper reaches of Tista river at Siliguri–Jalpaiguri area of West Bengal, India

Arsenic is present in groundwater at Siliguri–Jalpaiguri area, West Bengal, India. This is the place where Tista river descending from the Himalayas meets the alluvial plain. The area represents alluvial fan and floodplains of Tista, Mahananda-Balasan, Jaladhaka and its tributaries. In the river sediment samples, para- and ferro-magnetic minerals within 0.3–0.05 mm fraction contain 9–80 ppm of arsenic. The study indicates that iron bearing minerals viz. biotite, hornblende as well as iron coated grains of the sediment are major contributors towards arsenic budget. Though magnetite as a mineral shows maximum arsenic content (22 ppm), it is volumetrically not of much significance. Measurement of groundwater collected from tube wells shows up to 0.05 ppm of arsenic. These arsenic contaminated tube wells occur in a linear fashion along the course of the rivers. Moreover, localization of contaminated tube wells coincides with the change of channel gradient as observed in longitudinal section. The study enumerates a cause–effect relationship of arsenic occurrence with river gradient and fluvial sedimentation.     

Characteristics of isotope in precipitation,river water and lake water in the Manasarovar basin of Qinghai–Tibet Plateau

The stable hydrogen and oxygen of lake, river, rain and snow waters were investigated to understand the water cycle characteristics of the drainage basin of Manasarovar Lake in Tibet. Both δD and δ ¹⁸O of river water are larger than those of lake water and the effect of altitude on both δD and δ ¹⁸O is not very significant. This phenomenon was suggested to occur because Manasarovar basin is located in Qinghai–Tibet Plateau which has low latitude, high altitude, abundant glaciers, thin air and intensive solar radiation, resulting in higher evaporation in lake water.     

Mercury in river sediments, floodplains and plants growing thereon in the drainage area of the Idrija mine, Slovenia

Half a millennium mercury production at Idrija is reflected in increased mercury contents in all environmental segments. The bulk of roasting residues from the middle of the 19th century to 1977 was discharged directly into the Idrijca River, and the material was carried at high waters to the Soca River and farther into the Adriatic Sea. It has been estimated that 45500 tons of mercury were emitted into the environment during the operating period of the mine, which ceased production in 1994. In the lower reaches of the Idrijca the riverine deposits with high mercury contents have been, and will be in the future a source of mercury polluted sediment. Stream sediments were monitored at the same locations along the Idrijca and Soca rivers （70 kin） every 5 years since 1991 （1991-2005）. Grain size distribution was determined by dry sieving and fractions for geochemical analysis were prepared （〈0.04 and 〈0.125 mm）. Soils on river terraces were sampled at 5 localities in the lower course of Idrijca. At two locations of the terrace profiles the samples of averaged meadow forage and plantain （Plantago lanceolata） were collected within a 50-meters radius. We found that there was no decrease in mercury concentration in active river sediments during the last 20 years. Upstream from the Idrija Town the mercury concentrations in active river sediments vary from 1 to 10 mg/kg （average 3.3 mg/kg）. From Idrija to Spodnja Idrija the mercury concentrations increase extremely and vary greatly （32-4,121 mg/kg, the average is 734 mg/kg）. From Spodnja ldrija to the Idrijca-Soca confluence is the average 218 mg/kg, and 57 mg/kg downstream in the Soca River sediments.     

Daily scale modelling of aquifer–river connectivity in the urban alluvial aquifer in Langreo, Spain

Evaluating aquifer–river interactions is naturally complex, particularly within urban settings. This is largely due to the difficulties involved in quantifying most elements of the water balance. The ability of numerical models to deal with several dynamic variables simultaneously makes them valuable tools to address this kind of problem. An applied, modeling-based approach to investigate the spatial and temporal variations of aquifer–river connectivity within a shallow urban aquifer is presented. Model development is based on comprehensive field campaigns in Langreo, Spain. Two calibration runs (for summer and winter conditions) were carried out in order to evaluate the spatial distribution of recharge rates. The model suggests that baseflows are largely negligible in comparison with total streamflows. This is mostly attributed to the abrupt nature of the catchment, which prevents the existence of sufficiently large alluvial systems to a great extent. Modelling results also show that aquifer–river connectivity at the study site is constrained by urban pumping as well as by seasonal fluctuations.     

A study of the contaminated banks of the Mahoning River, Northeastern Ohio, USA: characterization of the contaminated bank sediments and river water–groundwater interactions

The Mahoning River is one of the five most contaminated rivers in the U.S. This study characterized the contaminated sediments in the river banks and investigated the hydraulic interconnection between shallow aquifer in the banks with the river water. The study was conducted along the most polluted section of the river, which is 50-km long, using over 50 monitoring wells. The characterization part of the study investigated the sedimentology, hydraulic conductivity, and spatial distribution of the contaminated sediments. Results of the characterization revealed that the contaminated sediments consist of fine-grained sand, silt, mud, and clay. The spatial distribution of the contaminated sediment is heterogeneous and positively correlates with the hydraulic conductivity values, i.e., the greatest contamination occurs in high conductivity areas. Hydraulic conductivity was determined by the Hazen formula using 82 sediment samples. Bioremediation, which is one of the remedial options considered for the banks, is found to be hydraulically feasible because of sufficient hydraulic conductivity values (≥10^?4 cm/s) that ensure reasonable rates of nutrient delivery. Monitoring of water levels in the river and groundwater for a 10-month period shows that flow occurs from the river to groundwater and vice versa. The exchange of flow is influenced by rainfall. Flow of groundwater to the river will continually transport the dissolved contaminants in groundwater to the river. Therefore, findings of this study show that one of the remedial options that proposes dredging of channel sediments and permits no action for bank sediments cannot be chosen due to river water–groundwater interactions.     

Energy gradient and geomorphological processes along a river influenced by neotectonics (the Saône river,France)

The purpose of this study is to link the sediment transit and the flood plain storage of the Saône to hydromorphological characteristics of the hydrosystem, which exemplifies a new approach to sediment dynamics. The study of suspended sediment concentration in terms of temporal evolution, together with sediment deposition in terms of spatial variability, is a way to record the longitudinal evolution of the sediment load, which expresses the available energy gradient from upstream to downstream in hydrosystem. The Saône river is a 480-km-long Rhone tributary, with an oceanic pluvial regime, and an average yearly discharge of 440 m s⁻¹ at Lyons. The watercourse is characterised by very gentle slopes controlled by the neotectonics of the Bresse trough and by Holocene fluvial dynamics. Sediments were sampled during the December 1993–January 1994 flood (2 375 m³ s⁻¹) and the 1995 January–February flood (1 826 m³ s⁻¹). A fine partition into homogeneous sectors, using stream power as well as shear stress, has been realized on a 400 km reach using longitudinal and cross-sections at one kilometre intervals. This partition, compared with the results of the field sampling, shows that the amount of energy is closely connected to the hydromorphological characteristics of the river.     

Impact assessment of Three Gorges Dam’s impoundment on river dynamics in the north branch of Yangtze River estuary,China

As one of the world’s largest hydropower projects, the Three Gorges Dam (TGD)’s 156–175 m height storing test in flood recession seasons during 2006–2011 has aroused international attention. The novel approaches of cross-wavelet transform and wavelet coherence were firstly introduced to reveal the significant coherence and time lag property in time–frequency space between river dynamics in hydrological stations along Yangtze River. Then, using the optimum lag time nodes, corresponding regression models between river dynamics in these stations were established and utilized to assess the river dynamics in stations downstream under the impact of TGD’s impoundment. Results showed that the average decrease ratio of 24.3 % in the Three-Gorge reservoir outflow was caused in TGD’s impounding periods during 2006–2011. The corresponding average decrease ratios of 25.1, 16.5 and 1.9 % in Yichang flow, Datong flow (with 6 days lag), and estuarine Santiao river stage (with 32 days lag), respectively, were caused by TGD’s impoundment during 2006–2011. In addition, the impact weights of multiple driving factors on estuarine river dynamics were discussed, and the main factor of the combined impacts of estuarine tidal fluctuation and sea level change while the secondary factor of the upper stream inflow were demonstrated. A further suggestion about the optimization design of TGD’s safety impounding scheme was proposed to prevent estuarine saline water intrusion by guaranteeing the average daily increase of Three Gorges reservoir water level lower than 1.11 m/day during TGD’s impounding period.     

Particle tracking analysis of river–aquifer interaction via bank infiltration techniques

Induced bank infiltration (BI) is commonly implemented in other countries, but remains new and unexplored in Malaysia. Increasing river pollution could affect drinking water resources. Given the threat of pollution to raw water sources, applying induced BI to sustain water management is essential. This paper presents a case study of the BI method, which evaluates the effects of groundwater pumping and BI operation on the installation of wells as well as determines the effect of pumping rate on flow paths, travel time, the size of the pumping and capture zone delineation, and groundwater mixing in a pumping well in Jenderam Hilir, Malaysia. The proposed method performs infiltration safely and achieves the ideal pumping rate. Numerical modeling packages, MODFLOW and MODPATH (particle tracking) were used. Results indicate that the migration of river water into the aquifer is generally slow and depends on the pumping rate and distance from well to the river. Most water arrives at the well by the end of a pumping period of 1–5 days at 3,072 m³/day for test wells DW1 and DW2, and during simultaneous pumping for DW2 and PW1 for a well located 36 and 18 m, respectively, from the river. During the 9.7-day pumping period, 33 % of the water pumped from the DW1 well was river water, and 38 % from DW2 throughout 4.6 days was river water. The models provide necessary information for water operators in the design and construction of pumping and sampling schedules of BI practices.     

Groundwater–river interaction and management in the context of inter-basin transfers

This study is focused on the management of coupled groundwater–river interaction (GRI) in the context of inter-basin transfers. The semi-coupled models, HEC-RAS and MODFLOW, were utilized in this study to replicate the River Tees experiment that had been conducted in 1976. Then the ‘surrogate’ models were applied to two “what if” scenarios in order to understand and manage GRI behavior and the nature of the reservoir control system. The results on the River Tees showed that the total temporary bankside storage volume was up to 17.5 % of the total reservoir release, given about 22 h of travel time. In addition, zones 4 and 5 of the river model with significant alluvium deposits were the best storage sites with values of 4.5 and 6.7 % of the total reservoir release, respectively, estimated as temporary losses. The final direct runoff received downstream at broken scar was about 95 % of the Cow Green total reservoir release. Furthermore, the closure rate proved to be vital to compute the effective return flow in respect of this study area. Finally, with careful reservoir and groundwater management, the River Tees proved to be an ideal natural aqueduct for inter-basin transfers when used as part of a major regional water resources scheme.     

Geochemical distribution of arsenic,cadmium, lead and zinc in river sediments affected by tailings in Zimapán,a historical polymetalic mining zone of México

High arsenic (As) groundwater is widely distributed in northwestern Hetao Plain, an arid region with sluggish groundwater flow. Observed As concentration in groundwater from wells ranges from 76 to 1,093 μg/l. Most water samples have high total dissolved solids, with Cl and HCO₃ as the dominant anions and Na as the dominant cation. The major hydrochemical types of most saline groundwaters are Na–Mg–Cl–HCO₃ and Na–Mg–Cl. By contrast, fresh groundwaters generally belong to the Na–Mg–HCO₃ type. High concentrations of arsenic in shallow aquifers are associated with strongly reducing conditions, as evidenced by high concentrations of dissolved organic carbon, ammonium, as well as dissolved sulfide and Fe, dominance of arsenite, relatively low concentrations of nitrate and sulfate, and occasionally high content of dissolved methane (CH₄). High As groundwaters from different places at Hetao Plain experienced different redox processes. Fluoride is also present in high As groundwater, ranging between 0.40 and 3.36 mg/l. Although fluorosis poses an additional health problem in the region, it does not correlate well with As in spatial distribution. Geochemical analysis indicates that evapotranspiration is an important process controlling the enrichment of Na and Cl, as well as trace elements such as As, B, and Br in groundwater. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Bridge construction and river channel morphology—A comprehensive study of flow behavior and sediment size alteration of the River Chel,India

Human has always modified its surroundings for better adaptation which include the building of urban landscapes, dams, and engineering constructions like bridges and other infrastructures. It has been unveiled from the study of River Chel that when the rail bridge was constructed before 1913, the natural width of the river was nevertheless maintained but the problem was initiated and after the road bridge construction in 1970s when the river width was minimized,the morphological changes started in a large scale. Such modifications have affected nature as well as human communities both positively and negatively. This paper will try to portray the evolution of channel shifting and changes of sediment size regime that the River Chel is experiencing due to the construction of bridges across the middle part of its course. So, this study is concerned about the changes in channel pathway since last 100 years and field-based hydrological parameters and sediment size analysis reveals some distinct changes in the channel planform with alteration of sediment size regime. Simulation of the hydraulic modeling in HEC-RAS specifies the probable affected area with bridges and without bridges in both upstream and downstream of the river course. Hence, the study unveils the alteration of the river hydrology and sediment size caused due to anthropogenic effects and impact of such flow analysis has been evaluated through the bridge scour calculation by CUS method. The discussion concludes that the Odlabari road bridge construction (after 1970) has modified the normal hydrological behavior of the river with a higher probability of bank erosion in downstream and floods in upstream resulting river bottleneck condition.     

Geological controls and effects of floodplain asymmetry on river–groundwater interactions in the southeastern Coastal Plain, USA

Channel sediment and alluvial aquifer hydraulic properties exert a major control on river–groundwater interactions. Channels and floodplains are often asymmetrical, resulting in differences in sediment hydraulic properties across the river. Floodplain asymmetry is common along Coastal Plain rivers in South Carolina and North Carolina, USA. The Tar River, North Carolina, has an asymmetrical valley. The study objective was to characterize the effects of floodplain asymmetry and geological controls on river–groundwater interactions. Floodplain and river channel sediments adjacent to the river were characterized with split spoon cores and hand auger samples along a 22-km reach. Hydrogeology was characterized with 38 piezometers and water level recorders in and adjacent to the river. Ground penetrating radar was used to define the shallow stratigraphy. Channel sediments were significantly different between the north and south sides of the river. Hydraulic conductivity and groundwater inputs were greater on the side of the river (north) that contained more permeable fluvial deposits. Groundwater chemistry (δ¹⁸O, specific conductance) data also suggested greater exchange between surface water and groundwater on the north side of the river channel. A conceptual hydrogeological model illustrates that groundwater movement and contaminant transport to the river differs across the channel due to asymmetrical geology.