Reservoir-induced seismicity in Karun III dam (Southwestern Iran)

Statistical analyses of the Karun III reservoir seismicity reveal a remarkable correlation between seismicity rate and water-level harmonic changes. It seems that seismicity in this dam depends on rapid water-level changes. The three biggest earthquakes of Karun III, measuring 4, 4.1, and 4.3 on the Richter scale (ML), occurred after two stages of rapid filling of the dam on March 22, 2005 and May 12, 2006. These earthquakes happened when the water reached the maximum operational level. Since the beginning of filling the reservoir on November 8, 2004 until March, 2006, most reservoir-induced seismicity has been localized in three main clusters. The majority of the earthquakes occurred in the frontal anticline of Keyf Malek; the second and third clusters happened near Karun Blind Fault (KBF) and Mountain Front Fault (MFF), respectively. Filling Karun III reservoir immediately led to an increase in the occurrence of earthquakes. Further, following abrupt water-level changes, a considerable increase in the number of earthquakes is observed. Finally, in terms of seismicity rate, vertical and horizontal migration, magnitude, and distance, the earthquakes of Karun III behave differently.     

马鞍石热电厂灰坝稳定性分析与地质灾害防治

为了对马鞍石热电厂灰坝工程做出安全性评价,对坝体在无渗水作用下可能发生的地质灾害进行了分析。选取坝体可能破坏的面进行理论计算,发现其安全系数值大于规范给定的数值,大坝是稳定的。经现场勘察及相应分析,该坝汇水面积较大,若不加整治,由强降雨引起的汇流雨水对坝体稳定造成一定的威胁,因此,提出了相应措施对大坝进行整治。     

Riverine input and air–sea CO2 exchanges near the Changjiang (Yangtze River) Estuary: Status quo and implication on possible future changes in metabolic status

Due to anthropogenic activities, the nutrient loadings of the Changjiang (Yangtze River) are strickly on the rise. The high nutrient concentrations notwithstanding, river water was pCO₂ supersaturated in the inner estuary during summer 2003 but decreased quickly in the mid-estuary due to mixing with low pCO₂ waters from offshore. In addition, settling of particles in the estuary resulted in better light conditions so that phytoplankton bloomed, driving down pCO₂ to ∼200 μatm. In the outer estuary and outside of the bloom area, pCO₂ increased again to near or just below saturation. Literature data also reveal that the mainstream of the Changjiang is always supersaturated with respect to CO₂ probably because the decomposition of terrestrial organic matter overwhelms the consumption of CO₂ due to biological production.     

Beach morphology and change along the mixed grain-size delta of the dammed Elwha River, Washington

Sediment supply provides a fundamental control on the morphology of river deltas, and humans have significantly modified these supplies for centuries. Here we examine the effects of almost a century of sediment supply reduction from the damming of the Elwha River in Washington on shoreline position and beach morphology of its wave-dominated delta. The mean rate of shoreline erosion during 1939–2006 is ~ 0.6 m/yr, which is equivalent to ~ 24,000 m³/yr of sediment divergence in the littoral cell, a rate approximately equal to 25–50% of the littoral-grade sediment trapped by the dams. Semi-annual surveys between 2004 and 2007 show that most erosion occurs during the winter with lower rates of change in the summer. Shoreline change and morphology also differ spatially. Negligible shoreline change has occurred updrift (west) of the river mouth, where the beach is mixed sand to cobble, cuspate, and reflective. The beach downdrift (east) of the river mouth has had significant and persistent erosion, but this beach differs in that it has a reflective foreshore with a dissipative low-tide terrace. Downdrift beach erosion results from foreshore retreat, which broadens the low-tide terrace with time, and the rate of this kind of erosion has increased significantly from ~ 0.8 m/yr during 1939–1990 to ~ 1.4 m/yr during 1990–2006. Erosion rates for the downdrift beach derived from the 2004–2007 topographic surveys vary between 0 and 13 m/yr, with an average of 3.8 m/yr. We note that the low-tide terrace is significantly coarser (mean grain size ~ 100 mm) than the foreshore (mean grain size ~ 30 mm), a pattern contrary to the typical observation of fining low-tide terraces in the region and worldwide. Because this cobble low-tide terrace is created by foreshore erosion, has been steady over intervals of at least years, is predicted to have negligible longshore transport compared to the foreshore portion of the beach, and is inconsistent with oral history of abundant shellfish collections from the low-tide beach, we suggest that it is an armored layer of cobble clasts that are not generally competent in the physical setting of the delta. Thus, the cobble low-tide terrace is very likely a geomorphological feature caused by coastal erosion of a coastal plain and delta, which in turn is related to the impacts of the dams on the Elwha River to sediment fluxes to the coast.     

Two-dimensional finite volume method for dam-break flow simulation

A numerical model based upon a second-order upwind ceil-center f＇mite volume method on unstructured triangular grids is developed for solving shallow water equations. The assumption of a small depth downstream instead of a dry bed situation changes the wave structure and the propagation speed of the front which leads to incorrect results. The use of Harten-Lax-vau Leer （HLL） allows handling of wet/dry treatment. By usage of the HLL approximate Riemann solver, also it make possible to handle discontinuous solutions. As the assumption of a very small depth downstream oftbe dam can change the nature of the dam break flow problem which leads to incorrect results, the HLL approximate Riemann solver is used for the computation of inviscid flux functions, which makes it possible to handle discontinuous solutions. A multidimensional slope-limiting technique is applied to achieve second-order spatial accuracy and to prevent spurious oscillations. To alleviate the problems associated with numerical instabilities due to small water depths near a wet/dry boundary, the friction source terms are treated in a fully implicit way. A third-order Runge-Kutta method is used for the time integration of semi-discrete equations. The developed numerical model has been applied to several test cases as well as to real flows. The tests are tested in two cases： oblique hydraulic jump and experimental dam break in converging-diverging flume. Numerical tests proved the robustness and accuracy of the model. The model has been applied for simulation of dam break analysis of Torogh in Iran. And finally the results have been used in preparing EAP （Emergency Action Plan）.     

Lessons from and assessment of Boussinesq aquifer modeling of a large fluvial island in a dam-regulated river

The suitability of a numerical Boussinesq aquifer model for representing groundwater dynamics in a fluvial island surrounded by a regulated river is assessed and the model is used to compare exchange fluxes for varying configurations of island hydraulic conductivity (K) and diffusivity. The model results are qualitatively similar to field observations of the water table although there is obvious dissimilarity between modeled and observed heads suggesting that a Boussinesq aquifer model may not be the best option for representing the island. Nonetheless, the simulations show that pronounced ridges and valleys form in the water table and that their spatial configuration may change drastically with small variations in diffusivity. Stage fluctuations significantly increase exchange flux across the island relative to the case where stage is constant. The flux increases non-linearly when island K is low but then becomes quasi-linearly dependent on K with further increases in K. Regulated river stage fluctuations due to dams significantly affect surface water–groundwater interactions between a fluvial island and a river. This deserves further inquiry for both scientific and management reasons.     

Prediction of Density Flow Plunging Depth in Dam Reservoirs: An Artificial Neural Network Approach

Experimental findings and observations indicate that plunging flow is related to the formation of bed load deposition in dam reservoirs. The sediment delta begins to form in the plunging region where the inflow river water meets the ambient reservoir water. Correct estimation of dam reservoir flow, plunging point, and plunging depth is crucial for dam reservoir sedimentation and water quality issues. In this study, artificial neural network (ANN), multi‐linear regression (MLR), and two‐dimensional hydrodynamic model approaches are used for modeling the plunging point and depth. A multi layer perceptron (MLP) is used as the ANN structure. A two‐dimensional model is adapted to simulate density plunging flow through a reservoir with a sloping bottom. In the model, nonlinear and unsteady continuity, momentum, energy, and k–ε turbulence equations are formulated in the Cartesian coordinates. Density flow parameters such as velocity, plunging points, and plunging depths are determined from the simulation and model results, and these are compared with previous experimental and model works. The results show that the ANN model forecasts are much closer to the experimental data than the MLR and mathematical model forecasts.     

CONTENT AND DISTRIBUTION OF TRACE ELEMENTS IN SOILS OF THE DAM RIVER AND TUOTUO RIVER BASINS

ＣＯＮＴＥＮＴＡＮＤＤＩＳＴＲＩＢＵＴＩＯＮＯＦＴＲＡＣＥＥＬＥＭＥＮＴＳＩＮＳＯＩＬＳＯＦＴＨＥＤＡＭＲＩＶＥＲＡＮＤＴＵＯＴＵＯＲＩＶＥＲＢＡＳＩＮＳ￥ＳｈａｏＱｉｎｇｃｈｕｎ（邵庆春）ＤｅｎｇＷｅｉ（邓伟）ＳｕｎＧｕａｎｇｙｏｕ（孙广友）（Ｃｈ...     

Vertical Variation of Lead Content in Sediment Collected from Man‐made Tamagawa Dam Lake in Akita Prefecture,Japan

Alternation layered lake sediment that had accumulated over a period of 22 years, from 1990 to 2012, was collected from the Tamagawa Dam Lake, which is located in the northeastern part of Akita Prefecture. The lake water is acidified (pH = 4.1) by the inflow of high‐acidic thermal water (pH = 1.2) from the Obuki Hot Spring, the main hot spring in the Tamagawa Hot Spring area. The vertical variations in Si, Al, Fe, Ti, and Pb contents of the sediment were determined by XRF, EPMA, and LA‐ICP‐MS in order to clarify the sedimentation processes of the lake sediment. The layers consisting of the sediment could be mostly classified into three types: dark brown, yellowish brown, and reddish layers. The contents of Si, Al, Fe, and Ti corresponded to the variation in color of each layer in the sample. Based on the Si, Al, and Fe contents in the sediment of Tamagawa Dam Lake, the sources of these elements were classified as detrital origin in dark brown and yellowish brown layers (Si, Al, and Ti) and chemical precipitate origin in reddish layers (Fe). Detrital components were derived from volcanic rocks in the watershed of Tamagawa Dam Lake. The variation of Pb content did not accord with the color of layers. The content of Pb in the sediment of Tamagawa Dam Lake ranges from 45 to 522 ppm. The vertical variation of Pb content in sediment corresponded to the temporal variation of Pb content in thermal water from the Obuki Hot Spring from 1990 to 2012. A large influence of hydrothermal activity of the Tamagawa Hot Spring on the vertical distribution of Pb was found during the active period of the Obuki Hot Spring, resulting in high Pb content within layers at 5–8 cm from the bottom of the sample. T‐Fe₂O₃‐rich reddish layers were also found in this range. Therefore, it is assumed that T‐Fe₂O₃ and Pb originated from Obuki Hot Spring and precipitated in Tamagawa Dam Lake. However, no correlation was found between T‐Fe₂O₃ and Pb contents for any of the dark brown, yellowish brown, and reddish layers. Some layers with high Pb content were also found to have high SiO₂ and Al₂O₃ contents. These findings indicate that there are several possibilities for the sedimentation process of Pb. The sedimentation of Pb as well as that of T‐Fe₂O₃ in Tamagawa Dam Lake provides a good example of the accumulation of elements by chemical precipitation away from the source of elements.     

基于实验的黑木耳气象服务指标研究

【目的】黑木耳作为剑河县发展战略和特色农业,木耳的产量、质量与本县经济发展息息相关,本文旨在研究出剑河县黑木耳高产的气象条件指标及灾害性天气指标,以期为剑河县黑木耳的产业发展提供科学的气候依据。【方法】以黑木耳为试材,在剑河县气象局内建立黑木耳微型模拟观测站,本文分析数据主要源于实验过程中木耳生育期、产量、同期气象要素值等资料。【结论】当平均温度在13.2～17.1℃间,气温越高,耳芽生长周期越短,林下温差刺激、光照刺激较坝区小,出芽率低于坝区,但林下耳片质量更好。木耳最适宜生长温度条件为：气温22.0～22.5℃,草温24.4～31.1℃;适宜湿度条件：相对湿度＞70%。当日最高气温＞32.1℃、相对湿度≥69%,会产生高温灾害,易造成木耳流耳,气温日较差越小,流耳情况越严重;生长环境温度低于10℃时,抑制耳片生长。