Sand Gravel Mining as Flood Control Tool

XSM provide ore mining machine(Sand Gravel Mining as Flood Control Tool) for mining,aggregate,mineral processing industry

XSM can provide(Sand Gravel Mining as Flood Control Tool) magnetic separator,jaw crusher,impact crusher,new fine crusher,ball mill,ramond mill,sand maker,flotation machine,vibrating feeder,etc for mining,aggregate,mineral processing industry

XSM dedicated to the manufacture of low price magnetic separator.We provide magnetic roll separator,vertical wet magnetic separator,high intensity magnetic separatordry magnetic separator support to the mining, construction and quarry/aggregate industries.

Plat ring magnetic separator working
high intensity magnetic separator for sale
magnetic roll separator for sale

XSM dedicated to the manufacture of low price stone crusher machine.We provide Jaw Crusher,hammer crusher,impact crusher,cone crusher,mobile crushing plant support to the mining, construction and quarry/aggregate industries.

Mobile Crushing Plant prices
Impact Crusher for sale
Hammer Crusher for sale

XSM dedicated to the manufacture of low price grinding mill machine.We provide ball mill,Coarse Grinding Mill,Raymond Mill,High Pressure Grinding Mill support to the mining, construction and quarry/aggregate industries.

ball mill machine for sale
Coarse Grinding Mill for sale
Super-fine Powder Separator

Sand Gravel Mining as Flood Control Tool

chat online
Sand Gravel Mining as Flood Control Tool

Sand Gravel Mining as Flood Control Tool

Sand Gravel Mining as Flood Control Tool

Gravel extraction is widely perceived to yield flood control benefits, but there is little hard evidence tha t the perceived benefits are real or more than ephemeral. The change in sediment mass balance effected by instream gravel mining can be utilized as a tool for river control on reaches with high rates of aggradation, such as the Waimakariri River near Christchurch, New Zealand, which drains the rapidly eroding Southern Alps, with denudation rates of 20 mm/yr (0.8 in/yr). From 1929 to 1973, the Lower Waimakariri River aggraded an average of 2.9 m (9.5 ft), while aggregate extraction averaged 5.9 m (19 ft) and prevented greater aggradation and possible avulsion through the city (Griffiths 1979). However, most rivers do not have such high rates of bedload sediment supply, and the New Zealand literature also reports that mining-induced incision has undermined infrastructure, such as flood control embankments (e.g., Soil & Water 1985). Presumably, lower rates of gravel extraction could be used to control lower rates of aggradation, although no such successful approach has been documented.

When human settlement occurs on former active channel surfaces at virtually the same elevation as the current active channel, the potential for flooding and erosion damage to property is high (Figure 43). This situation often leads to calls for in-channel gravel extraction, levee construction, and channel straightening, with probable negative consequences for aquatic habitat.

Flood control benefits have commonly been cited as justification for instream mining projects (e.g., Bissell and Karn 1992). The fact that WDNR charges a royalty on gravel removed from rivers except when the removal is for purposes of flood control (WDNR 1989) may encourage articulation of perceived flood control benefits from instream mining, but the idea that removing gravel from the channel increases flood capacity appears to be a widely held view among members of the public.

In evaluating the potential flood control function of instream mining, it is important to place the reach in a larger basin context. Referring to Schumm’s (1977) idealized zonation of rivers (Figure 2), it stands to reason that mining- induced channel incision (and widening) in the transport zone would increase channel dimensions and therefore channel flood capacity (although a number of factors can render this effect insignificant as discussed below). However, reaches in the zone of deposition, including local depositional reaches within the transport zone, such as expansions, points of geologically controlled reductions in gradient, are likely to “re- fill” quickly with gravel, potentially during a single flood. In fact, it is such zones of abruptly reduced shear stress that Dunne et al. (1981) identified as more appropriate gravel mining sites because of their tendency toward deposition. Thus, any increased channel capacity from mining is likely to persist only a short time, until redeposition. As redeposition occurs, downstream reaches may be starved of sediment.

Moreover, flood elevations in a reach are controlled primarily by downstream hydraulic controls, such as constrictions or drops. In reaches with strong downstream controls (such as upstream of bridge constrictions), the roughness or elevation of the bed may be irrelevant, as the channel is filled with ponded water above the constriction during high flows. In such cases, gravel extraction would have no effect on flood elevations.

Gravel extraction and channel cleaning for flood control could be expected to have similar results to other channelization projects. By speeding velocities and lowering flood stage in the local project reach, peak flows are no longer attenuated in the project reach, and downstream flood peaks are thereby increased.

Although some such “trench” mines were excavated, we did not find a follow- up study published reporting the exact locations or amounts. However, the US Bureau of Reclamation (USBR) has conducted an analysis that indicates the aggradation (most pronounced in reaches confined by levees) is unlikely to continue in the absence of further mining, and that long-term gravel mining is probably not needed except if levees are set back, in which case the mining would be needed to locally restore predisturbance channel gradients and allow the river to continue flowing in its present course (otherwise avulsion would be likely) (T. Randle, US Bureau of Reclamation, Denver, personal communication. 2001). The USBR report was originally due in September 2001 but has been held up by funding issues. Once published, the Dungeness River case should provide a useful example of gravel mining used for flood control, especially if it reports specific locations and amounts.

Sand Mining and Beneficiation Plant Equipment in Australia

Shanghai XSM is a professional company which an supply perfect Sand Mining beneficiation plant. Sand Mining equipments contain jaw crusher, Cone Crusher, magnetic extractor, spiral classifier dryer and other machines. Shanghai XSM is a responsible company with the best service.

You can contact us if you would like to learn more about Sand Gravel Mining as Flood Control Tool, our engineers will provide you with quality service.

Previous:Phosphate Recycling in Phosphorus Industry

Next:Rock Phosphate Grinding Mill China

Tips:you may interested in high intensity magnetic separator,magnetic roll separator,dry magnetic separator,jaw crusher,mobile crusher plant,impact crusherHigh Pressure Grinding Mill,ball mill,Wheel Sand Washer,flotation machine,vibrating screen,etc.

Please complete the fields below and we will respond to your inquiry within 24 hours:
(* denotes a required field)
* Product You Need: *
* Your Name: *
* Your Email: *
* Country: *
Quote Request/Comments: