Peak Discharge Values Research Articles

The Technical Integration of Remote Sensing and Geographical Information System to Predict the Peak Discharge Which Uses the Characteristic of Physical Environment of Catchments Area In Elo Sub Catchments Area in Central java

This research is carried out in Elo sub catchments area that contains of the regency and the municipality of Magelang and Temanggung. The goals of this study are: (1) to predict the peak discharge by using the characteristic variable of catchments physical environment by means of the aerial photo interpretation, to examine the technical accuracy of remote sensing to detect coeficient run off which used to predict the peak discharge. The research uses the aerial photo of black and white panchromatic on the scale 1:50. 000 in I994. It issupported by secondary data and field survey.The research method is the integration between the technical remote sensing and the Geographical Information System (SIG). Field survey is used to check the result of aerial photo interpretation and to collect the data that cannot he obtained from the image. The sample uses the purposive stratified sampling.The results of the research show that: (1) the aerial photo of black and white panchromatic on the scale 1:50. 000 is obtained to interpret the slope area and it is not good to interpret the accuracy of the covered arm is about 87% and 77,4 %, (2) the current coeflicient which is accounted hased on the table of Cook method is about 40,36% - deviates 39,94% from the field data; (3) the peak discharge in Elo sub catchments area with rational formula is about 3022,03 m/second, while the peak discharge as the observation result is about 112,675 m/second. Its large of research area causs the time to peak takes a long time, which causes raining intensity increases. The increasing value of raining intensity and the flow coeficient makes the value of peak discharge increases that larger than measured peak discharge.

Chronology and Hazards of Large Debris Flows in the Cheekye River Basin, British Columbia, Canada

Stump Lake is strategically located to provide a sediment record of very large debris flows that travel down Cheekye River to lower Cheekye fan from the west flank of Mount Garibaldi, a Quaternary volcano in the southern Coast Mountains of British Columbia. Cores collected from Stump Lake span the last 11,500 years and consist largely of gyttja. However, a diamicton layer and an associated detrital organic layer, which is capped by a clay lamina, record a large debris flow derived from the headwaters of Cheekye basin. Radiocarbon ages indicate that this event occurred about 6,900 years ago. We estimated the peak discharge of the flow by measuring cross-sections of the Cheekye River channel adjacent to Stump Lake and by calculating flow velocity using a Newtonian flow model. Reasonable values of peak discharge, calculated in this way, were input into an empirical equation linking discharge and debris-flow volume, developed for non-granitic debris flows. The estimated minimum volume of the debris flow is 3 to 5 × 106 m3. Another large debris flow (ca. 3 × 106 m3), which occurred about 800 years ago, is not recorded in Stump Lake sediments and thus was too small to reach the lake. The Stump Lake sediment sequence indicates that no debris flows larger than several million cubic meters have reached lower Cheekye fan in post-glacial time.

Channel Infiltration in Solitario Canyon, Yucca Mountain, Nevada

It has been hypothesized that the Solitario Canyon watershed, just west of Yucca Mountain, Nev., could provide a zone of focused ground-water recharge through its ephemeral-stream channels that might be an important factor in the performance of the potential repository for high-level radioactive waste. To examine this possibility, the KINEROS2 rainfall-runoff model was used to estimate the infiltration from surface runoff in each of 79 channel elements using a 100-year simulated rainfall sequence and two sets of saturated hydraulic conductivity \IKS\N values. The annual average estimated infiltration ranged from 0.18 to 0.57 mm/year (expressed as depth over the entire 10.7 km² watershed). Evaporation and transpiration by vegetation near the channels were neglected, therefore these quantities of channel infiltration are not assumed to be ground-water recharge. The simulated rainfall intensities compared favorably with depth-duration-frequency curves for nearby stations. The simulated 100-year peak discharge rates for Solitario Canyon and for four subwatersheds exceeded the regionally estimated 100-year rates for the lowest values of \IKS\N and were slightly below those rates for the higher values of \IKS\N, suggesting the true value of peak discharge (and channel infiltration from surface runoff) is bounded by those obtained for the two 100-year simulations.

Instrumental lahar monitoring at Merapi Volcano, Central Java, Indonesia

More than 50 volcanic debris flows or lahars were generated around Mt Merapi during the first rainy season following the nuees ardentes of 22 November 1994. The rainfalls that triggered the lahars were analyzed, using such instruments as weather radar and telemetered rain gauges. Lahar dynamics were also monitored, using new non-contact detection instrumentation installed on the slopes of the volcano. These devices include real-time seismic amplitude measurement (RSAM), seismic spectral amplitude measurement (SSAM) and acoustic flow monitoring (AFM) systems. Calibration of the various systems was accomplished by field measurements of flow velocities and discharge, contemporaneously with instrumental monitoring. The 1994–1995 lahars were relatively short events, their duration in the Boyong river commonly ranging between 30 min and 1 h 30 min. The great majority (90%) of the lahars was recognized at Kaliurang village between 13:00 and 17:30 h, due to the predominance of afternoon rainfalls. The observed mean velocity of lahar fronts ranged between 1.1 and 3.4 m/s, whereas the peak velocity of the flows varied from 11 to 15 m/s, under the Gardu Pandang viewpoint location at Kaliurang, to 8–10 m/s at a section 500 m downstream from this site. River slopes vary from 28 to 22 m/km at the two sites. Peak discharges recorded in various events ranged from 33 to 360 m 3/s, with the maximum value of peak discharge 360 m 3/s, on 20 May 1995. To improve the lahar warning system along Boyong river, some instrumental thresholds were proposed: large and potentially hazardous lahars may be detected by RSAM units exceeding 400, SSAM units exceeding 80 on the highest frequency band, or AFM values greater than 1500 mV on the low-gain, broad-band setting.

Methods for predicting peak discharge of floods caused by failure of natural and constructed earthen dams

Floods from failures of natural and constructed dams constitute a widespread hazard to people and property. Expeditious means of assessing flood hazards are necessary, particularly in the case of natural dams, which may form suddenly and unexpectedly. We revise statistical relations (derived from data for past constructed and natural dam failures) between peak discharge (Qp) and water volume released (V0) or drop in lake level (d) but assert that such relations, even when cast into a dimensionless form, are of limited utility because they fail to portray the effect of breach‐formation rate. We then analyze a simple, physically based model of dam‐breach formation to show that the hydrograph at the breach depends primarily on a dimensionless parameter η=kV0/gl/2d7/2, where k is the mean erosion rate of the breach and g is acceleration due to gravity. The functional relationship between Qp and η takes asymptotically distinct forms depending on whether η ≪ 1 (relatively slow breach formation or small lake volume) or η ≫ 1 (relatively fast breach formation or large lake volume). Theoretical predictions agree well with data from dam failures for which k, and thus η, can be estimated. The theory thus provides a rapid means of predicting the plausible range of values of peak discharge at the breach in an earthen dam as long as the impounded water volume and the water depth at the dam face can be estimated.

A catastrophic flood caused by drainage of a caldera lake at Aniakchak Volcano, Alaska, and implications for volcanic hazards assessment

Aniakchak caldera, located on the Alaska Peninsula of southwest Alaska, formerly contained a large lake (estimated volume 3.7 × 10 9 m 3 ) that rapidly drained as a result of failure of the caldera rim sometime after ca. 3400 yr B.P. The peak discharge of the resulting flood was estimated using three methods: (1) flow-competence equations, (2) step-backwater modeling, and (3) a dam-break model. The results of the dam-break model indicate that the peak discharge at the breach in the caldera rim was at least 7.7 × 10 4 m 3 s −1 , and the maximum possible discharge was ≈1.1 × 10 6 m 3 s −1 . Flow-competence estimates of discharge, based on the largest boulders transported by the flood, indicate that the peak discharge values, which were a few kilometers downstream of the breach, ranged from 6.4 × 10 5 to 4.8 × 10 6 m 3 s −1 . Similar but less variable results were obtained by step-backwater modeling. Finally, discharge estimates based on regression equations relating peak discharge to the volume and depth of the impounded water, although limited by constraining assumptions, provide results within the range of values determined by the other methods. The discovery and documentation of a flood, caused by the failure of the caldera rim at Aniakchak caldera, underscore the significance and associated hydrologic hazards of potential large floods at other lake-filled calderas.

The nature of the tile-drain outfall hydrograph in heavy clay soils

The outfall hydrographs of agricultural underdrainage installations in a heavy clay soil are examined over four drainage seasons. Seasonal differences in drainage response to rainfall are attributed to antecedent soil conditions and these are controlled in part by the influence of topography upon downslope seepage. Bowl-shaped landforms are kept moister by convergent interflow streamlines and drainage follows the onset of rainfall most quickly in winter. Well-drained convex slopes, on the other hand, are subject to greater summer desiccation and deep cracks convey autumn rainwater directly into the subsoil so that drainage response here is quicker at this time of year. Peak drain-flow occurs at ∼ 3.6 hr. after the rainfall centroid in winter for both topographical situations but median values of peak discharge can be up to four times those of the non-winter drainage period during which absorption of rainfall by the soil leads to a reduction in drainage outfall. The largest risk of flooding in river basins where under-drainage is widespread comes from complex storms. Secondary peaks in the drainage hydrograph not only arrive earlier by an average of 1.38 hr. but are also shown to reach discharges more than three times those associated with simple storms having equivalent rainfalls.

Frequency and Characteristics of Glacier Floods in the Swiss Alps

Damage due to glacier floods in the Swiss Alps occurs about once every two years at present, despite the pronounced retreat of glaciers during the twentieth century and the installation of many water reservoirs, which act as flood retention basins. Over half (60 to 70%) of the observed floods are caused by outbursts of marginal glacier lakes or sudden breaks of ice dams, and 30 to 40% by ruptures of water pockets. In a glacierized mountain region as densely populated as the Swiss Alps, even debris flows triggered by outbursts of very small water masses may be dangerous. Historical information about glacier floods in the Swiss Alps, although incomplete and heterogeneous, is used as an empirical basis for an attempt to recognize potential hazards at an early stage by considering outburst processes, volumes of water involved, potential peak-discharge values, lithology and inclination within the reach of glacier streams.

Frequency and Characteristics of Glacier Floods in the Swiss Alps

Damage due to glacier floods in the Swiss Alps occurs about once every two years at present, despite the pronounced retreat of glaciers during the twentieth century and the installation of many water reservoirs, which act as flood retention basins. Over half (60 to 70%) of the observed floods are caused by outbursts of marginal glacier lakes or sudden breaks of ice dams, and 30 to 40% by ruptures of water pockets. In a glacierized mountain region as densely populated as the Swiss Alps, even debris flows triggered by outbursts of very small water masses may be dangerous. Historical information about glacier floods in the Swiss Alps, although incomplete and heterogeneous, is used as an empirical basis for an attempt to recognize potential hazards at an early stage by considering outburst processes, volumes of water involved, potential peak-discharge values, lithology and inclination within the reach of glacier streams.