Stream power

About: Stream power is a research topic. Over the lifetime, 1135 publications have been published within this topic receiving 51324 citations.

Sediment concentration and hydraulic characteristics of rain-induced overland flows in arid land soils

Abstract: Rain-induced overland flow involves the detachment of soil particles by raindrop impact and the transportation by the resultant overland flow. The purpose of this study was to investigate the relationship between sediment concentration and different hydraulic parameters including flow depth, flow velocity, shear stress, stream power, and unit stream power. The effects of soil particle size distribution, rain intensity, and slope steepness on measured sediment concentration in rain-induced sheet flow were also examined. Two arid land soils with different particles size distributions (D2mm and D4.75mm) were subjected to simulated rains using a detachment tray under infiltration conditions. Two rain intensities of 57 and 80 mm h−1 were simulated on slope gradients ranging from 0.5 to 20 %, resulting in rain-induced overland flows. After pre-wetting each soil, the sediment-laden overland flow was sampled at several time intervals (2, 5, 15, 20, 30, and 40 min) and the sediment concentration was determined. Different hydraulic parameters including flow depth, flow velocity, shear stress, stream power, and unit stream power were measured. The hydraulic parameters were used to model the sediment concentration, and the model performance was evaluated. The result showed that the measured sediment concentration was greater in the higher rainfall intensity and at steeper slopes. With increasing slope steepness, sediment concentration increased from 4.3 to 15.5 kg m−3 and from 3.8 to 12.5 kg m−3 for soils D2mm and D4.75mm, respectively. There was a direct relationship between sediment concentration and the rain-induced flow velocity, shear stress, stream power, and unit stream power. Nevertheless, the values of sediment concentration increased as flow depth decreased on steeper slopes. Also, sediment concentration was lower in the soil containing larger aggregates than in the finer soil. The hydraulic parameters tended to overestimate low amounts of sediment concentration and underestimate high values. In general, the accuracy of the hydraulic parameters in predicting sediment concentration was: flow velocity > stream power > shear stress > unit stream power > flow depth. Flow velocity was the best predictor of sediment concentration with a linear relationship, whereas the other parameters showed nonlinear relationships. This study revealed that rain-induced sediment concentration at small scales can be modeled precisely on the basis of the flow velocity parameter.

Three-Dimensional Seismic Architecture of Fluvial Sequences on the Low-Gradient Sunda Shelf, Offshore Indonesia

Abstract: The sequence stratigraphy of fluvial–deltaic strata deposited near the center of the wide, gradually subsiding Sunda Shelf differs from standard highstand examples because low accommodation and low depositional gradients restricted the thickness of fluvial–deltaic sequences and the depth of lowstand fluvial incision. In this setting sea-level fluctuations may have had less influence on fluvial depositional patterns, and fluvial stratigraphy is more likely to be defined by changes in river discharge during gradual aggradation. The upper Muda Formation in West Natuna Basin, offshore Indonesia, is a 225-m-thick, dominantly fluvial succession that prograded onto the middle part of the Sunda shelf from Pliocene to Holocene. The succession changes upward from offshore shelf deposits, through a thin interval of deltaic deposits, a succession of fluvial deposits, and finally a thin transgressive succession directly beneath the modern sea floor. A high-resolution seismic survey (17 km by 40 km in area) of Belida Field near the middle of the Sunda shelf provides exceptional images of changing fluvial architecture within five erosionally based, fluvial sequences. Sequences, each several tens of meters thick, are characterized by low-relief basal incisions that extend laterally onto interfluves cut by a network of gullies. Although a regressive stacking pattern of successive sequences is defined to some extent by an increase in the relief of basal erosion and a decrease in average sequence thickness, it is best defined by progressive increase in the extent of gully formation onto interfluve areas (indicating longer periods of interfluve exposure). Channel size tends to decrease upward within individual sequences, recording both a decrease in the size of the largest channels and greater preservation of smaller tributary and floodplain drainage channels. The largest channels preserved directly above the better developed sequence boundaries tend to be more sinuous and to have more extensive inner-bend accretion deposits than those that cut down from horizons higher within sequences. This suggests that incised channels had more stream power to erode their banks relative to the sediment loads they carried. Although mechanisms controlling the episodic shallow incision and then aggradation of these fluvial systems are difficult to constrain from variations observed in this small study area, the consistent thickness of the Muda Formation observed in regional 2D seismic sections is evidence against significant syndepositional tectonic deformation or differential subsidence. Low regional gradients and great distance of the study area from the paleo-shelf edge (~ 1000 km) are evidence against direct sea-level influence. Larger channel sizes directly above sequence boundaries supports temporal changes in channel discharge, perhaps related to climatic changes within the drainage basin. Recognition of episodic channel incision and bypass alternating with periods of floodplain aggradation influences predictions of channel-deposit connectivity based on channel proportion.

Snow cover variation and streamflow simulation in a snow-fed river basin of the Northwest Himalaya

Abstract: Snowmelt is an important component of any snow-fed river system. The Jhelum River is one such transnational mountain river flowing through India and Pakistan. The basin is minimally glacierized and its discharge is largely governed by seasonal snow cover and snowmelt. Therefore, accurate estimation of seasonal snow cover dynamics and snowmelt-induced runoff is important for sustainable water resource management in the region. The present study looks into spatio-temporal variations of snow cover for past decade and stream flow simulation in the Jhelum River basin. Snow cover extent (SCE) was estimated using MODIS (Moderate Resolution Imaging Spectrometer) sensor imageries. Normalized Difference Snow Index (NDSI) algorithm was used to generate multi-temporal time series snow cover maps. The results indicate large variation in snow cover distribution pattern and decreasing trend in different sub-basins of the Jhelum River. The relationship between SCE-temperature, SCE-discharge and discharge-precipitation was analyzed for different seasons and shows strong correlation. For streamflow simulation of the entire Jhelum basin Snow melt Runoff Model (SRM) used. A good correlation was observed between simulated stream flow and in-situ discharge. The monthly discharge contribution from different sub-basins to the total discharge of the Jhelum River was estimated using a modified version of runoff model based on temperature-index approach developed for small watersheds. Stream power — an indicator of the erosive capability of streams was also calculated for different sub-basins.