Based on the relationship depicted inside Profile 4, the fresh new approximate extent of the destroying flooding might be projected

Based on the relationship depicted inside Profile 4, the fresh new approximate extent of the destroying flooding might be projected

The brand new examples in the above list show that this new estimate out of risks within the contact with glacier flooding can not be produced on such basis as you to definitely parameter by yourself (age.g. the outside section of good glacial lake (Post and Mayo 1971)). Instead, the mixture away from discharge amounts, rupture elements, peak-release values, lithology and you can choice inside the reach of the glacier weight keeps is reviewed. Outbursts from specialist-glacial lakes having moraine dams that has flat freeze are, nevertheless, unsafe and you will warrant preventive step, because they tend to allow it to be big rain situations. Hence the discharge may be layered on to ton caused by precipitation. Peak-release beliefs for outbursts as a result of progressive enlargement of ice streams should be calculated making use of the completely empirical Clague-Mathews formula:

For years and years, of several mountain communities was basically mainly based where they’re inspired by the such as events and therefore, on one-hand, are very uncommon, as well as on the other, might have major outcomes down the road

in which V is the outburst volume inside the cubic yards (Clague and you will Matthews 1973). Thinking computed this way is slightly higher than the highest noticed level launch beliefs (Dining table II).

The formula is, therefore, admirably suitable for estimates in such cases. However, much higher peak-discharge values are expected in the event of sudden ruptures of ice barriers (Table III). For such events, with the exclusion of the minimal outburst at Glacier Bas d’Arolla, the following formula has to be applied: Q maximum (sudden break (m 3 s ?1 )) = V/tw

where V is again the outburst volume in cubic metres and tw is an empirical time constant [about 1 000 to 2 000 s, cf. Table III). In Figure 4, the average slope between the place of rupture and the outermost limit of the recorded area of damage, as a measure of the potential area of damage in the valley, is plotted as a function of the expected value of the peak-discharge. Läs mer