River Behaviour Research Articles

Constrained river, constrained choices: seasonal floods and colonial authority in the Red River Delta

AbstractThis article examines the problem of flooding in colonial Tonkin through two interrelated lenses: the history of disasters as social and political phenomena, and the history of technology and the constraints that shape its use. With a gradient ten times steeper than the Mekong, the Red River (Sông Cáiin Vietnamese) is notorious for its huge seasonal fluctuations and violent floods. For centuries, local rulers and cultivators constructed dikes to protect fields and settlements, though breaches and inundations were frequent. French administrators were convinced that they could improve the flooding situation with modern know-how. From the 1890s, colonial engineers carefully studied the river's behavior, examined a range of different schemes to control it, and debated the extent to which the straitjacketing of the river might gradually exacerbate flood risk. Despite their deep-seated misgivings about the problems caused by dikes, they were ultimately forced to work within the parameters of pre-colonial hydraulic works. The result was an intensification of existing dependencies and flood vulnerabilities, which finally came to a head under the combined pressures of extreme weather and war, and which ultimately played an important role in undermining colonial authority in the Red River delta.

Chaos arising from the hydrological behaviour of a floodplain river during the last century

AbstractThe hydrological regime is the main factor governing the functioning of floodplain rivers. A full comprehension of its dynamic leads to a better understanding of the system's behaviour. We analysed the daily water level of the Paraná River during the last century at three gauge stations using linear and non‐linear tools to characterise the hydrological dynamic and to analyse to what extent chaotic behaviour prevails. The three water level time series were characterised as non‐linear and non‐stationary by power spectrum, autocorrelation function, and surrogate test analyses. A strange attractor was developed when the phase space was reconstructed, having a low dimensional chaos supported by correlation dimension, positive maximum Lyapunov exponents, and recurrence quantification analysis. The sample entropy analysis shows that the system resulted unpredictable beyond a temporal threshold, and with an intermediate hydrological complexity, while Hurst exponent characterised it as persistent and with sensitive dependence on initial conditions. In a general overview, all the evidence obtained indicates that the Paraná River's behaviour is at the edge of chaos. A latitudinal gradient of decreasing chaoticity was observed as the floodplain extent increased, whereas complexity was highest at the intermediate river station due to the inflow of tributaries with different hydrology. This paper attempts to offer some additional insights for understanding the hydrological behaviour of floodplain rivers and the most appropriate methods to understand their complexity.

Analysis of a High Andean River's Behavior at Loads of Organic Matter Through the Use of Mathematical Models with Experimentally Determined Kinetic Rates

Using models of organic matter degradation and dissolved oxygen consumption, the concentrations of these compounds are analyzed in two stretches of a river after a discharge of raw sewage. The analyzed river has low drafts and widths, so the velocity is high and the aeration coefficient kr calculated with the Covar method is high, this indicates a rapid recovery of oxygen from the water consumed by the organic matter degradation processes, the river has been instrumented to measure flows and organic matter at various points to calibrate the model. The hydraulic parameters of the river section are analyzed in three control points, in each one sample are taken to analyze oxygen consumption by organic matter and nitrification through laboratory tests to determine and adjust the kinetics of the processes (kd; knit). This kinetics have been used in the development of a water quality model to verify its adjustment, obtaining higher RMSE results than with kinetics from secondary sources. It is observed that the river has an excellent capacity for self-purification due to the high income of dissolved oxygen, with a kr > 9 d-1.

Implication of classification of land types on the river banks on the layout of settlements planning (A case of the Ogan Ulu community, in South Sumatera, Indonesia)

ABSTRACT This article analyses the implications of the knowledge of the Ogan community in South Sumatra (Indonesia) about the types of land on the banks of the river on the layout of their settlements. Living on the river bank is an important identity for the Ogan Ulu community, but the condition of their rivers which tend to run watery and the inappropriate land use, of course, will have an impact on the destruction of settlements and their natural environment. Through anthropological studies, the results of the study show that the use of land on the river banks are not arbitrary, but it is based on how the community interprets the classification of soil types and the river’s behaviour in the river environment. This article confirms that the river's behaviour and classification of soil types have implications for the community's struggle to maintain settlements as their identity while preserving the river's environment.

Morphology and dynamics of the Malekhu Khola, Dhading district, central Nepal

Rivers have always been an indispensable part of the human civilization. They play a vital role in daily life purposes to big engineering constructions such as dams, reservoirs or hydropower projects. It is mandatory to understand the morphology and dynamics of the river before initiating any projects for easier planning and to prevent possible damage to structures. The Malekhu Khola area is one of the potential areas for urbanization and has already been undergoing development of settlement and other infrastructures. This paper describes the morphology and dynamics of the Malekhu Khola to classify and characterize the river's behavior and competency. The Malekhu Khola is a sixth-order river having its total length of 24.83 km, watershed area of 101.28 km2 and the average gradient of 0.041 m/m. Various morphological parameters were measured with the aid of topographic maps, aerial photographs and Geographic Information System (GIS). The hydraulic parameters, channel sediment and slopes were measured at 10 different transects sites through field surveys. The river was classified using the Rosgen's Level II criteria. The river reaches have been classified as A4-, B4- and C4-type streams. A4- and B4-type streams are moderate-gradient gravelly and low sinuosity rivers whereas C4-type streams are low-gradient gravelly meandering river. The Malekhu Khola gradually changes from A4- to B4-type streams up to 12 km downstream, and then to C4-type stream further downstream, but B4-type streams reappear within the distance of 15 km to 19 km from the origin. This study presents temporal changes in river channel, and flow competence and aggrading/degrading potential evaluation of the Malekhu Khola.

Spatiotemporal evolution of a unique preserved meandering system in Central Europe — The Morava River near Litovel

Rivers are naturally dynamic over time and space and respond to the variability of water and sediment inputs and to anthropogenic pressures that cause changes to the river's behaviour and form. This study describes the evolution of part of the Morava River and the Kenický meander in the Litovelské Pomoraví protected area near the city of Olomouc. The research describes the historical development of the study area using aerial photos, UAV images and geodetic measurements. Long-term measurements and imaging using UAV technologies have allowed a large amount of information to be collected. This information was used to study the Kenický meander and the Morava River. Significant lateral channel changes in the banks have occurred in the past and generated the Kenický meander. A significant event occurred in the spring of 2012, when high water levels were caused a rupture of a meander-natural cutoff. The water level was monitored in the Kenický wood accumulation, which formed in the Kenický meander, before and after the rupture. Monitoring the movement of wood in the river basin is particularly important because the movement of ice in the winter can cause blockage of the channel and subsequent flooding of water over the banks and into the surrounding communities.

Two steps back, one step forward: reconstructing the dynamic Danube riverscape under human influence in Vienna.

As part of an interdisciplinary project on the environmental history of the Viennese Danube, the past river landscape was reconstructed. This article describes the different types of historical sources used for the GIS-based reconstruction, the underlying methodological approach and its limitations regarding reliability and information value. The reconstruction was based on three cornerstones: (1) the available historical sources; (2) knowledge about morphological processes typical for the Austrian Danube prior to regulation; and (3) the interpretation of past hydraulic measures with respect to their effectiveness and their impact on the river’s behaviour. We compiled ten historical states of the riverscape step-by-step going backwards in time to the early 16th century. After one historical situation had been completed, we evaluated its relevance for the temporally younger situations and whether corrections would have to be made. Such a regressive-iterative approach allows for permanent critical revision of the reconstructed time segments already processed. The resulting maps of the Danube floodplain from 1529 to 2010 provide a solid basis for interpreting the environmental conditions for Vienna’s urban development. They also help to localise certain riverine and urban landmarks (such as river arms or bridges) relevant for the history of Vienna. We conclude that the diversity of approaches and findings of the historical and natural sciences (river morphology, hydrology) provide key synergies.

Riverbank migration and island dynamics of the braided Jamuna River of the Ganges–Brahmaputra basin using multi-temporal Landsat images

As one of the largest braided rivers in the world, the Jamuna River (JM) of the lower Brahmaputra regularly undergoes significant erosion, causing major bankline migration, making thousands of families homeless and sizeable land loss every year, e.g., the dynamic nature of Jamuna causes great suffering to the people living along its course and on its islands. Therefore, gaining a better understanding of the river's behavior should contribute to mitigate these sufferings and also to reduce the possible damage of the river to public infrastructure. In this study, using thirteen selected images of Landsat MSS and TM acquired from 1973 to 2003, the riverbank migration patterns and island dynamics of JM resulted from accretion/erosion processes for 30 years were investigated. For short-term analysis, the migration rate from one Landsat image to the next is estimated. For long-term analysis, the migration rates are based on the difference between the 1973 image as the reference, and subsequent images. For the short-term (long-term) analysis, the average erosion and accretion rates are 227 and 271 m/y (90 and 104 m/y) on the left bank, and 187 and 148 m/y (75 and 50 m/y) on the right bank of Jamuna, respectively. Because of human interventions and the averaging effect of erosion and accretion, the long-term migration rate is lower than that of the short-term migration rate on both banks. The short-term rate of accretion (erosion) on the left (right) bank follows the general pattern of river bank migration, while the accretion (erosion) of the right (left) bank does not follow such a pattern. On the other hand, the long-term erosion and accretion processes for both banks partly follow the general pattern of river bank migrations. From one flood to another, large islands tend to be more stable with little changes, but smaller islands underwent more changes. From results obtained from analyzing multi-temporal Landsat images, this study provides new and accurate information about the riverbank migration of JM.

A temporal change study of the Muda River system over 22 years

The Muda River has been dramatically affected by unsustainable human activities that sacrificed environmental values for national development. The removal of the forest canopy causes a decrease in the interception and transpiration in a basin. The decrease in transpiration leads to an increase in the amount of water stored in the soil. These changes can increase the soil's moisture content, allowing more water to be available to drain into channels. Tree clearing can also cause increased erosion at logged sites and a subsequent increase in sediment yield. In this study, an investigation of the spatial and temporal changes in the environment imposed by new land usages on a long timescale (over 22 years) was carried out in the Muda River area. Detecting the changes in land usage will help predict both the consequent changes in the Muda River's behaviour and flood risks. In addition, computer modelling (InfoWorks RS) was used to help determine the long-term behaviour of the Muda River and its flooding behaviour.

Characterisation of streamflow regimes in central Spain, based on relevant hydrobiological parameters

The biotic composition, structure, and function of aquatic, wetland, and riparian ecosystem depend largely on the hydrological regime ( Poff, N.L., Ward, J.V., 1990. Implications of streamflow variability and predictability for lotic community structure: a regional analysis of streamflow patterns. Can. J. Fisheries Aquat. Sci. 46, 1805–1818; Richter, B.D., Baumgartner, J.V., Wiginton, R., Braun, D.P., 1997 How much water does a river need? Freshwater Biol. 37, 231–249). Available flow data for many rivers in the world can be used to validate these ecological theories. There is a demand for studies that use hydrological indices to establish criteria, which serve to group together regime types at a local level. Once this has been done, these hydrologically similar groups can be used to identify communities of living organisms that are linked to specific aspects of the river's behaviour. An approach to characterise flow regimes in the river network of the Tagus basin in Spain is presented. The river Tagus (río Tajo) is one of the seven major rivers of the Iberian peninsula. All hydrological data were acquired from the measurements made in the Tagus basin, at 25 gauging stations. Twelve variables were derived for each gauged site to describe variability and predictability of average streamflow conditions, and to describe the frequency, timing and intensity of high flow and low flow extremes. A hierarchical clustering routine was used to identify similar groups of rivers as defined in terms of similar characteristics of their streamflow regime. The variables were also examined with simple correlations to determine if multicollinearity occurred, in order to reject redundant parameters or to identify similar behaviour trends between pairs of parameters. Some parameters have shown a tendency to increase or decrease along the east–west axis, suggesting that some of the studied characteristics may have a geographical cause. Cluster analysis, with the values of the 12 parameters, reveals two main groups, each of which splits into two main subdivisions. One of these subgroups contains six rivers with similar characteristics, can be considered to be ‘classic regular rivers’, the stations in this first subgroup are mostly situated geographically close to each other. At the other end, we have found a subgroup, with a high variation of flows over the year and high flood flows; these rivers are highly irregular rivers with great changes. This regular–irregular gradient found between the groups is similar to that observed by others authors (Poff, N.L., Allan J.D., 1995. Functional organization of stream fish assemblages in relation to hydrological variability. Ecology 76, 606–627), and strong associations have been documented with compositions of populations and probably reflect differences in other similar important environmental factors.