Factors controlling variations in suspended sediment concentration for single-valued sediment rating curves, Fraser River, British Columbia, Canada

Abstract

Functional (regression) and cause-and-eect analytical methods were employed in the investigation of factors controlling single-value sediment±discharge relationships for individual hydrological events in the Fraser River Basin. Of 1025 hydrological events identi®ed in the 97 years of the 9-stations discharge record monitored by the Water Survey of Canada (1960±1988), 49 were associated with linear, non-linear (concave and convex) sediment rating curves. Analysis revealed that time of events oered a partial explanation for the occurrence of single-valued curves because events occurring in isolation or in quick succession did not always produce singlevalued curves owing to variations in hydrograph characteristics and temporal and spatial peak attenuation factors. Hydrologically, linear and non-linear sediment rating curves were distinguished by the in¯uence of preceding discharge or antecedent moisture, which tends to generate quick or delayed runo, thereby causing rapid or slow increases in sediment concentration in concert with discharge changes. Hydraulically, linear curves were shown to be controlled by rates of stream bed scour (rising stage) similar to those for channel ®lling (falling stage); concave curves by rates of scouring (rising stage) similar to those of ®lling but dierent from those of rescouring (falling stage); and convex curves by rates of ®lling and scouring (rising stage) dierent from those of ®lling and rescouring (falling stages), all in relation to the timing of the exceedance of the threshold discharge for stream bed scour. Meteorologically, bed scour and ®ll approximately coincided with the timing of precipitation, if any, on the rising and/or falling stages under subzero (T 4 0 8C), low (1 4 T 4 9 8C) and moderate (10 4 T 4 19 8C) temperature conditions. It is concluded that a combination of temporal, spatial, hydrological, hydraulic and meteorological factors control variations in sediment concentration during single hydrological events on the Fraser River in a complex fashion. Multivariate analysis of these factors should greatly improve prediction of sediment transport in the Fraser River Basin. #

Impact of Sedimentation and Bathymetry of Selected Small Reservoirs on the Priority Water-Linked Sectors in the Zambezi River Basin

“…The regional regression model in Figure 12 could potentially help predict siltation in reservoirs when maximum sediment depth is known. Crop farming was one of the main causes of siltation, and previous research (Muchanga & Sichingabula, 2021;Simweene and Muchanga, 2021) (Sichingabula, 2018) (Alemaw et al, 2013) (Sichingabula, 1997) (Walling, & Webb, 1996) (Rooseboom & Lotriet, 1992) also suggest that it is responsible for siltation of most reservoirs and riverine habitats. Moreover, (Kamtukule & Kaseke, 2012) and (Mavima et al, 2015) have previously observed that human activities like crop growing posed a serious risk to the reservoirs in Malawi and Zimbabwe's usable economic life spans.…”

“…Governments throughout the Zambezi Basin have also been confronted with significant financial costs related to the management and control of reservoir siltation (Sichingabula, 2018). Findings from earlier studies (Mwiinde, 2017) (Saruchera & Lautze, 2019) revealed that governments will have to spend a lot of funds (>ZMW 500,000) to address dwindling water scarcity through desilting and rehabilitation of reservoirs and other water sources.…”

“…The local communities used both constructive and harmful strategies to deal with the problems of water shortage and siltation, which should be carefully evaluated in future planning for sustainable water resource management and silt control. Data from the research (Sichingabula, 2018) (Mavima et al, 2015) (Global Water Forum, 2007) (Rooseboom, & Lotriet, 1992) sampled reveals intra-basin variability in how communities respond to various issues of water shortage and siltation. Furthermore, (Saruchera, & Lautze, 2019) noted that 25% of African communities experience high levels of chronic water stress and 40% experience drought stress every 30 years, arguing that a well-engineered increase in use may be helpful in reducing water-related development and pollution constraints, which also give rise to a variety of social science and engineering issues (Vörösmarty et al, 2005).…”

Respuesta de una cuenca de cabecera durante eventos de crecida (Aixola, País Vasco)

“…Además de estudiar la relación entre los parámetros hidrológicos y de transporte de sedimentos del evento, también se ha analizado la relación entre la concentración de sedimentos en suspensión y el caudal a lo largo del evento. La mayoría de las veces esta relación no es homogénea durante los eventos produciendo bucles de histéresis (WILLIAMS, 1989;LLORENS et al, 1997;SICHINGABULA, 1998;LENZI y MARCHI, 2000;PICOUET et al, 2001;ALEXANDROV et al, 2003;SEEGER et al, 2004). Así, de los 76 eventos analizados, 22 presentan una relación lineal entre la concentración y el caudal, 18 un bucle en sentido horario, 26 un bucle anti-horario, 1 en forma de ocho y 9 no han sido definidos.…”

Intra-Annual Dynamics Dissolved Solids and Suspended Sediment in the Extreme Hidrological Events – Case Study Nišava River

“…On the other hand, during the wet season (January-May period) the exponent b has extremely high values, so that the curve has a more pronounced convex shape. Generally, previous studies have shown that the exponent b is significantly higher in spring than in winter [42,43,44]. The spring is the time when the annual peak of the flow occurs.…”