Simulation of streamflow with statistically downscaled daily rainfall using a hybrid of wavelet and GAMLSS models

ABSTRACT

A rainfall–streamflow model is proposed, in which a downscaled rainfall series and its wavelet-based decomposed sub-series at optimum lags were used as covariates in GAMLSS (Generalized Additive Model in Location, Scale and Shape). GAMLSS is applied in climate change impact assessment using CMIP5 general climate model to simulate daily streamflow in three sub-catchments of the Onkaparinga catchment, South Australia. The Spearman correlation and Nash-Sutcliffe efficiency between the observed and median simulated streamflow values were high and comparable for both the calibration and validation periods for each sub-catchment. We show that the GAMLSS has the capability to capture non-stationarity in the rainfall–streamflow process. It was also observed that the use of wavelet-based decomposed rainfall sub-series with optimum lags as covariates in the GAMLSS model captures the underlying physics of the rainfall–streamflow process. The development and application of an empirical rainfall–streamflow model that can be used to assess the impact of catchment-scale climate change on streamflow is demonstrated.     

长江中下游庐江-枞阳矿集区龙桥铁矿成矿时代研究

龙桥铁矿床是长江中下游地区隐伏的富铁矿床,位于庐江-枞阳火山岩矿集区的北缘,铁矿体主要赋存于下白垩统龙门院组火山岩之下和石英正长岩、二长岩之上的泥质粉砂岩和碳酸盐之中;本文分别采集了龙桥铁矿床井下370中段与黄铁矿矿体、方解石共生的黑云母样品(Lz370-1)和矿体围岩蚀变粗安岩中的黑云母样品(Lz370-2),进行A...     

Groundwater recharge in arid areas induced by tropical cyclones: lessons learned from Gonu 2007 in Sultanate of Oman

Younger groundwater found in some Omani aquifers is a result of recent recharge from cyclonic and storm events [Weyhenmeyer et al. (Science 287:842–845, 2000); Young et al. (J Appl Geophys 57:43–61, 2004)]. The analysis of the meteorological data in Oman indicates an anomalous rainfall on a decadal interval whereas cyclones frequency is expected to increase due to global climatic changes. The cyclone Gonu has severely struck the eastern Omani coasts in 2007 resulting in devastating floods. Huge volume of water (3,672 mm³) spread over the coastal plain calling for an assessment of potential groundwater recharge subsequent to this event. The present study evaluates groundwater recharge with respect to Gonu 2007 to assess the potential of recharge induced by such cyclones in the arid zones. The hydrographs of several piezometers sited along the coastal plain in Muscat Province have been studied and variation in water table rise has been analyzed. Significant water table rise is indicated for areas with geological and structural settings favoring rapid infiltration of water yielding considerable groundwater mound, whereas piezometers located in less favorable zones show minimum rise of water table. However, soon after the floods the aquifer hydrodynamics has readjusted to attain equilibrium and the groundwater mound dissipated. The cumulative rise of the water table on an areal extent does not exceed a few centimeters indicating lesser volume of recharge. Comparatively, recharge from frequent precipitation along favorable zones produces more significant recharge compared with cyclonic events where surface water residence time is shorter to allow for efficient infiltration.     

西藏波龙斑岩铜金矿床成矿斑岩年代学、岩石化学特征及其成矿意义

波龙斑岩铜金矿床是近年来在青藏高原中部发现的最大的斑岩型矿床,波龙矿床发育两期花岗闪长斑岩和一期花岗斑岩,两期花岗闪长斑岩是波龙矿床的成矿斑岩。本文开展了波龙矿床三期斑岩锆石U-Pb年龄、全岩岩石地球化学和Sr-Nd-Hf同位素组成分析。锆石U-Pb测年结果显示,三期斑岩在120Ma集中侵位。两期花岗闪长斑岩均富集轻稀土、大离子亲石元素,亏损重稀土、高场强元素,Eu异常不明显,显示出岛弧岩浆岩的特征;两期花岗闪长斑岩的(87Sr/86Sr)i值分别为0.70562－0.70711和0.70567－0.70850,εNd(t)分别为-4.0－-3.1和-8.0－-2.4,εHf(t)值分别变化于2.5－6.9和3.3－6.9,表明两期花岗闪长斑岩起源于新生的下地壳;花岗斑岩也具有岛弧岩浆岩的岩石化学特征,但其具有较高εNd(t)值(-0.7－-0.2)和εHf(t)值(1.3－12.2),可能表明花岗斑岩也起源于下地壳,但有更多幔源物质混入。波龙斑岩铜金矿床形成于班公湖－怒江洋壳向北俯冲末期,其成岩－成矿可能与洋壳俯冲关系密切,但波龙矿床的三期斑岩均起源于新生的下地壳,可能表明在120Ma南羌塘地块南缘开始逐步加厚。     

Groundwater flow modelling of Hindon-Yamuna interfluve region, Western Uttar Pradesh

The study area Hindon -Yamuna interfluve region is underlain by a thick pile of unconsolidated Quaternary alluvial deposits and host multiple aquifer system. Excessive pumping in the last few decades, mainly for irrigation, has resulted in a significant depletion of the aquifer. Therefore, proper groundwater management of Hindon-Yamuna interfluve region is necessary. For effective groundwater management of a basin it is essential that careful zone budget study should be carried out. Keeping this in view, groundwater flow modelling was attempted to simulate the behavior of flow system and evaluate zone budget. Visual MODFLOW, pro 4.1 is used in this study to simulate groundwater flow. The model simulates groundwater flow over an area of about 1345 km² with a uniform grid size of 1000 m by 1000 m and contains three layers, 58 rows and 37 columns. The horizontal flows, seepage losses from unlined canals, recharge from rainfall and irrigation return flows were applied using different boundary packages available in Visual MODFLOW, pro 4.1. The river — aquifer interaction was simulated using the river boundary package. Simulated pumping rates of 500 m³/day, 1000 m³/day and 1500 m³/day were used in the pumping well package.The zone budget for the steady state condition of study area indicated that the total annual direct recharge is 416.10 MCM and the total annual groundwater draft through pumping is of the order of 416.63 MCM. Two scenarios were considered to predict aquifer system response under different conditions. Sensitivity analysis on model parameters was conducted to quantitatively evaluate the impact of varying model inputs. Based on the results obtained from the sensitivity analysis, it was found that the model is more sensitive to hydraulic conductivity and recharge parameter. Present study deals with importance of groundwater modelling for planning, design, implementation and management of groundwater resources.     

云南景谷半坡含钛磁铁矿成矿地质条件

半坡磁铁矿位于澜沧江深断裂成矿带,于辉长岩冷凝晚期因重力分异作用而结晶析出,且硅酸盐矿物比磁铁矿晶出更早。     

Seismic design and response evaluation of unbonded post‐tensioned hybrid coupled wall structures

This paper presents an analytical investigation on the seismic design and response of coupled wall structures that use unbonded post‐tensioned steel coupling beams. Both monolithic cast‐in‐place reinforced concrete wall piers and precast concrete wall piers are considered. Steel top and seat angles are used at the coupling beam ends for energy dissipation. The seismic design of prototype structures to achieve target displacement‐based performance objectives is evaluated based on nonlinear static and dynamic time history analyses. Additional recommendations are provided on shear design. Comparisons with ‘conventional’ structures that use embedded steel coupling beams as well as isolated walls with no coupling are provided. The results indicate that while the peak lateral displacements of unbonded post‐tensioned coupled wall structures are larger than the peak displacements of structures with embedded beams, the residual displacements are significantly reduced as a result of the restoring effect of the post‐tensioning steel. Copyright © 2008 John Wiley & Sons, Ltd.     

大岗山水电站地下厂房稳定性的流固耦合计算分析

地下水对岩体的强度和变形有显著的影响,由于地下裂隙水的渗流作用,岩体强度降低,围岩稳定性减弱。为了有效反映地下裂隙水对大岗山地下洞室群围岩稳定性的影响,根据岩体流固耦合作用机理,采用FLAC3D计算程序对该工程体稳定进行了计算分析。计算结果表明,渗流的作用虽然致使围岩稳定性更加不利,但由于加固措施得当,运行期的洞室群整体已趋于稳定。     

山西堡子湾金矿床元素地球化学成矿预测研究

堡子湾金矿是华北地台北缘受印支－燕山期线性隐爆角砾岩带控制的金矿床,产于角砾岩体内,产状与角砾岩体基本一致,对该金矿进行了平面,剖面,纵投影面的元素地球化学研究,通过相关分析确定了最佳指示元素,建立了元素地球化学异常模式,进行了回归预测、用与金相关性最好的Ａｓ／Ｎｉ值进行了预测及综合预测,确定了有利的找矿部位。     

吐哈盆地及邻区早二叠世沉积特征与构造发育的耦合关系

通过对不同露头剖面和探井资料的分析,在吐哈盆地及邻区区分出三种不同类型沉积相：（1）裂谷型海相火山喷发沉积相;（2）裂谷型陆相火山喷发沉积相;（3）造山带磨拉石相;不同沉积相特征并结合构造分析认为,早二叠世在吐哈及邻区存在二种不同类型的盆地,即前陆盆地和裂谷盆地,同时,还探讨了大陆一大陆碰撞带上两种不同类型盆地的形成机理。