River fluvial discharge

Rias are estuaries which occupy former river valleys and occur on high relief coastlines the major difference in these systems is that in most rias the fluvial discharge is considerably weaker than that found in coastal plain systems. 

A dataset of measured concentrations of the radionuclides and the flow rate of river water was used to derive a relationship between the load of fluvial discharge of the radionuclides and the water flow rate. The load was obtained from the concentration of radionuclides in each form (dissolved or particulate) multiplied by the flow rate. Results showed that the load conforms empirically to the following relationship ... 

The preceding section describes methods for determining the current rate of fluvial discharge of Cs in the Kuji River watershed. In the present section, we describe a method for determining historical discharge rates for the Hi-i River watershed in Japan (Matsunaga et al., 1999). The watershed is located in the eastern part of the Shimane Prefecture (Fig. 5) it has an area of 2070 km and includes Lake Shinji (surface area, 79.7 km maximum depth, 5.5 m) at the lower part of the watershed, which is fed by a subwatershed of approximately 915.3 km . 

Yamagata et al. (1963) formulated a fluvial discharge of fallout Cs consisting of two components derived from the run-off of (a) fresh precipitation and (b) cumulative deposition, whereas those components are combined as a single component in the present analysis. As common values for Japanese rivers in the period of their study. 

The instances described here indicate the important role of fluvial discharge in the secondary transport of atmospherically derived, highly adsorptive radionuclides in a river watershed. A particulate form of radionuclides associated with suspended solids in river water is especially important. It was shown that the form can account for 90% of the annual discharge of Cs (mainly from the fallout from nuclear weapon testing), as was observed in the Kuji River watershed. The importance of this mechanism has also been stressed by other researchers (e.g. Walling et al., 1989). 

The Susquehanna River fluvial input of atrazine in the Upper Bay region is 1,700 kgtyr (8). The Chester and Choptank Rivers discharge proximately 100 kgtyr. Both contributions yield a total surface flux of 1,800 kg/yr into this region. To estimate the amount of atrazine introduced as groundwater inflow. 

In reservoirs with discharge of hypolimnetic water, the effects on the water temperature have been widely studied. If there is stratification, water temperature downstream from the dam is higher in winter, colder in summer, the daily and annual thermal amplitude is reduced and the maximum annual temperature is delayed [5-7]. Recently, it has been observed that hypolimnetic discharges can reduce the variability of the temperature of the water in reduced time scales, in the range of days to weeks [8]. The low temperatures in summer can modify the composition of the fluvial community, but they can also bring the river to a previous stage of the river continuum [9, 10]. 

The concentrations of LAS found in water and fluvial sediments show great variability (see Chapter 6.3). The values found in water (0— 600 p,gL 1) [7-10] and in sediments (0-600 p-gg-1) [7,9,11,12] show the pronounced affinity of the compound for the solid phase. The partition coefficients of LAS observed in fluvial sediments range from 100 to 2600 L kg-1 [9], The maximum concentrations have been detected close to urban centres in which untreated wastewater is discharged, and a rapid rate of decrease is observed as one moves downstream from these [9,13]. Some authors have found dilution to be the main factor responsible for decreasing concentrations along the course of a river towards the sea [9,13,14], but others consider biodegradation to be the most efficient process [9,15], while Rapaport and Eckhoff [16] hold adsorption onto solids in suspension to be a major factor for LAS removal from river water. 

The detection of short-chain sulfophenylcarboxylic acids (SPCs) [2,9, 13,17,18] is clear proof of the primary biodegradation of LAS in the natural medium. In general the concentrations detected are small, one order of magnitude less than those found for LAS [2,9,13], with the exception of the river Osellino [18] where the total concentration of SPC found exceeded that of LAS. The highest concentrations are also observed near zones into which wastewater effluents are discharged [9, 18]. Both SPC and dialkyltetralines (DATSs) have also been detected in some samples of fluvial sediments [9],... 

Milliman J.D. and Kao J.S. (2005). Hyperpycnal discharge of fluvial sediment to the ocean Impact of Super-Typhoon Herb (1996) on Taiwanese rivers. Journal of Geology, 113, 503-516. 

Differences in river basin morphology, soil characteristics, rainfall, and land use in a watershed Influence phosphorus transport in a fluvial system. However, the dominance of iron oxides as an inorganic phosphate sink and the discharge dependent behavior of calcium carbonate-phosphate minerals found in this study would be expected to exist in other calcareous agricultural regions of New York State as well. Mountainous terrain and areas of sand and muck soil would probably not exhibit the same behavior. It would seem that the results of this study could also apply to other agricultural watersheds adjacent to the North American Great Lakes. 

It can be seen by the temperature distribution (Fig. 5) that cold water from peripheral parts of the model are immersing with a simultaneous heating from the local thermal source. Hot water is discharged to a well-penetrable sub-fluvial alluvium of the Paratoonka river. 

Environments ofTerrigenous/Siliciclastic Sedimentation That Are Associated with Mouths of Large Rivers 2,5,1,1,2,1 Estuaries An estuary is a drowned mouth of a river valley forming a funnel-shaped coastal indentation in which seawater can circulate and mix with river freshwater. Estuaries form where the discharged fluvial sedimentary load is small (<16 mg/1), subsidence is greater than sediment accumulation, and in macrotidal zones. Most of the estuaries are located in humid temperate climatic zones where extensive vegetation effectively restricts erosion and riverine sediment transport (Friedman and Sanders, 1978). 

In addition to schwertmannite, some other minerals of Fe(in) are commonly recognized in the AMD systems, with a close relation between their occurrence and the water pH (Table 1). Jarosite is usually favored to precipitate from very acidic solutions, normally at pH < 2. Schwertmannite precipitates near the discharge points at pH 2.0-4.0, whereas ferrihydrite usually forms in fluvial environments (as in the confluences between AMD and unpolluted rivers) at... 

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