Data time-step dependency of conceptual rainfall—streamflow model parameters: an empirical study with implications for regionalisation

Abstract

Employing 1-, 2-, 4-, 6-, 12- and 24-hourly data sets for two catchments (10.6 and 298 km²) in Wales, the calibrated parameters of a unit hydrograph-based model are shown to change substantially over that range of data time steps. For the smaller basin, each model parameter reaches, or approaches, a stable value as the data time step decreases, providing a straightforward method of estimating time-step independent model parameter values. For the larger basin, the model parameters also reach, or approach, stable values using hourly data, but, for reasons given in the paper, interpretation of the results is more difficult. Model parameter sensitivity analyses are presented that give insights into the relative precision on the parameters for both catchments. The paper discusses the importance of accounting for model parameter data time-step dependency in pursuit of a reduction in the uncertainty associated with estimates of flow in ungauged basins, and suggests that further work along these lines be undertaken using different catchments and models.     

On width function-based unit hydrographs deduced from separately random self-similar river networks and rainfall variability: Discussion of “Coding random self-similar river networks and calculating geometric distances: 1. General methodology” and “2. Application to runoff simulations”

Abstract

Hung & Wang (2005a,b) base their approach on successive steps related to a kind of geomorphometric modelling, the deduction of a rainfall—runoff transfer function, and the application to a Taiwanese basin subject to typhoons. Several conceptual points of each of these steps and their propagation through the whole approach are discussed; referring to the likelihood of the proposed separately random self-similar river networks, the deduction of width function-based unit hydrographs, and the accounting for variability of rainfall and of induced runoff.     

Infiltration in the Corgo River basin (northern Portugal): coupling water balances with rainfall—runoff regressions on a monthly basis

Abstract

A combination of water balances and rainfall—runoff regressions is used to calculate infiltration, overland flow, baseflow and change to the surface water reservoir, on a monthly basis; evapotranspiration from the underground reservoir, on an annual basis; and a lag phase of maximum infiltration and maximum baseflow within a hydrological year. The water balance equations are written for catchment areas formed on crystalline rocks and located in temperate climates. The regression lines are fitted to precipitations and river flows. In a first run, the model is tested with the Corgo River hydrographic basin, a small watershed in the Trás-os-Montes and Alto Douro province, northern Portugal. The results compare favourably with results of other groups, working under similar environmental conditions. The sensitivity of the model to changes in the basin characteristics and climate is tested by a second run using data from the Terva River basin, a nearby catchment that is much smaller than the Corgo basin and has a much lower effective precipitation, defined here as a difference between precipitation and potential evapotranspiration. As a consequence of having a lower effective precipitation, the river dry-out starts earlier in the Terva (May) than in the Corgo (June).     

Remarks upon numerical solutions of infiltration into a soil profile

Abstract

A methodology of time-step estimation for numerically solving the Richards equation is discussed. Its importance in simulating water movement in unsaturated—saturated soils is shown for infiltration into a soil profile by applying various time-step estimations and boundary conditions for different soils. In order to test the results of the computations, infiltration theory was applied. According to infiltration theory, the pressure head in the initially unsaturated part will not take positive values as long as the moisture front has not reached the phreatic level, or, in the case of a profile with a free-draining lower boundary, it is not saturated at the base. In other cases, the appearance of positive values of the pressure head produces incorrect values for the inflow rate q.     

Accuracy of contour lines using 3D bands

This article describes a new methodology for the planimetric control of contour lines. The method is based on the generation of buffers around the contour lines which define a 3D buffer around the maximum slope line. After that we analyze the quantity of points from a more accurate source which is inside this buffer. As a result, we obtain a distribution function of the control points included when we apply several widths to the buffers. We have also determined the angularity and height differences of these points. The method has been applied to several sets of contour line intervals derived from a digital elevation model (DEM) and to the contour lines of one published topographic map using the DEM as the control source. We have also analyzed the representative behaviour of the contour lines, taking into account the contour line interval and the detection of an uncertainty model based on the slope variation. This study demonstrates the viability of the proposed method for obtaining the uncertainty of the contour lines depending on a given level of confidence and the variability of this uncertainty in the map. Finally, we propose a range of contour line intervals based on the scale and slopes.     

Simulation on the spatio-temporal distribution and emission flux of dust aerosol over East Asia in 2000–2009

A regional climate model (RegCM3), coupled with an online dust module, is used to simulate the spatio-temporal distribution and emission flux of dust aerosol (smaller than 20 μm in diameter) over East Asia in the period from 2000 to 2009. The model performance is firstly evaluated against available observations. Simulation results show that the model can capture the characteristics of spatio-temporal distribution of dust aerosol very well over East Asia. There always exist two extremes of dust aerosol optical depth (AOD) and column burden (CB), one is in the Taklimakan Desert of Xinjiang Uygur Autonomous Region, China, and the other is in the Badain Jaran Desert of Inner Mongolian Autonomous Region, China. The maximum value of CB appears in spring, secondary maximum in winter and minimum in autumn. To the east of 110°E, dust is transported eastward from a maximum center at a height of 700 hPa over the East Asian continent. Dust emission sources are mainly located in the Taklimakan Desert, Badain Jaran Desert, North Qinghai-Tibetan Plateau and Southwest Mongolia. There is also an obvious seasonal variation of dust emission flux (EF). Annual mean dust EF is 1,015.34 mg/(m 2 ·d), of which 62.4% and 2.3% are re-deposited onto the East Asian continent through a dry and wet deposition process, respectively, and the remaining 35.3% is injected into the atmosphere or subject to long-range transport.     

西部地区的经济发展模式与碳排放量增长关系的实证研究

随着“西部大开发”战略的深入实施,西部地区已经成为我国经济发展最快的区域,然而西部经济的快速增长已经造成了碳排放量的犬幅增加,严重影响了我国节能减排目标的实现。为了有效地控制西部地区碳排放量的急速增加,我们必须全面分析引致西部碳排放量增加的主要因素。本文在已有研究的基础上,从西部地区产业转型和消费升级的视角出发,利用1991—2009年的省际面板数据对西部地区的经济发展模式与碳排放量增长之间的相关关系及其传导机制进行了实证检验。检验结果表明：自进入上世纪90年代以来,西部地区的经济发展与碳排放量增长之间存在显著的正相关关系,而且在西部大开发战略实施以后,这种关系更加显著。同时,检验还发现西部地区的消费升级和产业转型对碳排放量增加产生重要影响,其中三次产业间结构变动的影响系数达到16．4,二次产业内部采掘业和重工业比重上升的影响系数达到14．3,人均居住支出和人均交通支出的影响系数也分别达到5．6和6．5,而传统的人口规模、收入规模则对西部地区碳排放量的影响微弱。影响系数仅为0．73和0．86。因此在制定西部地区“十二五”节能减排战略时,需要更多的从消费升级和产业转型的视角出发。     

Variations of solar coronal hole area and terrestrial lower tropospheric air temperature from 1979 to mid-1998: astronomical forcings of change in earth''s climate?

The temperature anomaly of the terrestrial lower troposphere, inferred from the Microwave Sounding Unit (MSU) radiometers, is found to be inversely correlated with the area of the Sun covered by coronal holes. The correlation between the monthly time series of global tropospheric temperature anomaly and total coronal hole area from January 1979 to April 1998 has a Pearson coefficient of −0.46, which is different from zero at a 95% confidence level. Physical reasonings for the explained and unexplained parts of the correlation are discussed. The coronal hole area is a physical proxy for both the global-scale, 22-yr geometrical and shorter-term, dynamical components of the cosmic ray modulation, as well as the corpuscular emission of the Sun. Other solar parameters that may indicate a solar radiative effect on climate are also evaluated. It is concluded that variable fluxes either of solar charged particles or cosmic rays modulated by the solar wind, or both, may influence the terrestrial tropospheric temperature on timescale of months to years.     

镇泾油田红河105—1057井区微生物异常与含油气性关系

油气微生物勘探（MPOG）是地表油气藏评价的一个分支,主要研究近地表土壤层中微生物异常与地下深部油气藏的相关关系,它以成本低廉,简便快速,多解性小的特点,在镇泾油田得到充分的验证。在镇泾油田内,以微生物异常为基础,结合已有的区域油气地质、钻井和测井等资料,对微生物异常区域进行分析研究,重点解释说明了镇泾油田红河105—1057井区长821小层与油气异常的关系,并圈定出2个异常区,其异常连片分布,异常区的异常平均值较高,反映本工区内油藏控制面积较大。本工区天然气微生物异常整体水平较低,且基本上与油藏微生物异常区吻合,异常区零星分布,表明本工区的天然气多系原油溶解气。最后对工区油藏分级评价,并根据微生物勘探结果和地质特征等综合因素,在工区部署3口建议井。     

甘孜—理塘结合带通宵—理塘沿线蛇绿岩研究

蛇绿岩以岩块形式镶嵌于甘孜—理塘结合带内,经拼合可见一个较为完整的蛇绿岩套。形成于洋中脊环境,火山岩显示张裂速率大于3cm.a-1,形成时代为晚三叠世。