Calculating sediment trapping efficiencies for reservoirs in tropical settings: A case study from the Burdekin Falls Dam, NE Australia

Abstract

[1] The Brune and Churchill curves have long been used to predict sediment trapping efficiencies for reservoirs in the USA which typically experience winter and springdominant runoff. Their suitability for reservoirs receiving highly variable summer-dominant inflows has not previously been evaluated. This study compares sediment trapping efficiency (TE) data with the predictions of the two established curves for the Burdekin Falls Dam, a large reservoir in northern tropical Australia which receives highly variable summer-dominant runoff. The measured TE of the reservoir ranged between 50% and 85% and was considerably less than estimates using the Brune and Churchill curves over the 5 year study period. We modified the original equations so that daily trapping can be calculated and weighted based on daily flow volumes. This modification better accounts for shorter residence times experienced by such systems characterized by relatively high intraannual flow variability. The modification to the Churchill equation reasonably predicted sediment TEs for the Burdekin Dam for four of the five monitored years and over the whole monitoring period. We identified four key sediment particle classes: (1) <0.5 mm which exclusively passes over the dam spillway ; (2) 0.5-5.0 mm which, on average, 50% is trapped in the reservoir ; (3) 5.0-30 mm most (75%) of which is trapped; and (4) >30 mm which is almost totally (95%) trapped in the dam reservoir. We show that the modification to the Churchill equation has broader application to predict reservoir TE provided that daily flow data are available.

Combining contemporary and long-term erosion rates to target erosion hot-spots in the Great Barrier Reef, Australia

“…Thirdly, the Burdekin Falls Dam (BFD) was constructed in 1987 and captures ~88% of the runoff in the Burdekin catchment. Lewis et al (2013) estimated that the Burdekin Dam has reduced the total sediment load from the Burdekin River by >50% for particle size fractions >0.5 µm. Although the dam represents a change in the sediment delivery rather than sediment erosion or generation, the dam has likely reduced the end of catchment (Lower Burdekin) contemporary erosion estimate used in this study.…”

Characteristics of Rainfall-Discharge and Water Quality at Limboto Lake, Gorontalo, Indonesia

“…Sediment trap measurements in the lake support watershed materials input prediction for evaluation of the dynamical sediment transport [14]. Sediment traps at the three sites of the lake were installed at 2/3 of the depth of the lake during field measurements in September 2012 for two days.…”

“…The explanation could be that L-3, located near the inlet rivers, received large quantities of waste and materials. The sediment total from sediment traps was also calculated and analyzed and compared with the data from 2004 and 2005 [14]. Table 2 shows the relationship between rainfall and sediment.…”

“…The explanation could be that the land use change, especially in the forest region, influences the erosion and sedimentation rates of the lake. In addition, Halida [14] reported that the total amount of sediment at the Limboto watershed increased from 8. …”

3D Numerical Modeling of Flow in Sedimentation Basin

“…These codes are mostly based on empirical approaches. A past study has shown that they may not provide accurate results, requiring a site specific modification [1]. However, a site specific design can be assessed using a laboratory experiment or a numerical model.…”