宁夏引黄灌区水文监测排水变化影响解析与高质量精准监测对策建议

为深入推动先行区建设和新阶段水利高质量发展,研究水文现代化高质量发展在未来灌区水文监测发挥的作用,探究宁夏引黄灌区水文监测排水变化影响与高质量精准监测现实意义,解析影响排水量变化原因,提升灌区排水高质量精准监测能力,准确分析灌区排水量、耗水量,落实最严格水资源管理,进一步探讨推动灌区水文监测高质量发展的对策和建议。

隧道施工扰动下排水水质及环境影响初探

从环境科学的角度对中国安能集团第三工程局有限公司成都分公司在进行类似西气东输工程的隧道施工排水过程中水质变化及其环境影响进行了初步探讨。研究指出,隧道施工排水活动显著改变了排水区域的水质参数,包括但不限于pH值的变化、悬浮物的增加以及重金属的潜在释放。此外,排水对地下水流动模式造成的改变可能对周边生态系统和地下水资源产生长远影响。针对上述问题,提出了一系列施工排水管理措施,包括水质处理、水量控制、生态保护和监测预警系统的建立,以及预防和应急响应机制的制定,旨在减少环境影响并促进施工活动与环境保护的协调发展。通过综合性的管理措施,可有效缓解施工排水对环境的不良影响,保护水资源和生态环境,同时确保工程建设的顺利进行。

基于SWMM的管网变化对城市水文特征的影响分析

城市排水管网的变化对其控制区域内的产流量、下渗量以及洪峰流量有着较大影响.利用ArcGIS水文分析模块将研究区域划分为若干自然汇水区域,考虑道路和大型建筑物对水流约束作用,再对研究区域细分为更多的子汇水区域,率定SWMM(雨洪管理模型)模型参数,在研究区域上建立起了基于两套不同管网条件的SWMM工程,以南京市P为30%的24 h降雨过程为降雨输入,进行模拟分析.结果表明受管网增加影响的子汇水区域下渗量有所减少,径流量有所增加,洪峰流量增大,且洪峰出现时间提前.

The Role of Hydropower in Climate Change Mitigation and Adaptation： A Review

Hydropower is a clean,renewable,and environmentally friendly source of energy.It produces 3930(TW·h)·a–1,and yields 16% of the world's generated electricity and about 78% of renewable electricity generation(in 2015).Hydropower and climate change show a double relationship.On the one hand,as an important renewable energy resource,hydropower contributes significantly to the avoidance of greenhouse gas(GHG) emissions and to the mitigation of global warming.On the other hand,climate change is likely to alter river discharge,impacting water availability and hydropower generation.Hydropower contributes significantly to the reduction of GHG emissions and to energy supply security.Compared with conventional coal power plants,hydropower prevents the emission of about 3 GT CO2 per year,which represents about 9% of global annual CO2 emissions.Hydropower projects may also have an enabling role beyond the electricity sector,as a financing instrument for multipurpose reservoirs and as an adaptive measure regarding the impacts of climate change on water resources,because regulated basins with large reservoir capacities are more resilient to water resource changes,less vulnerable to climate change,and act as a storage buffer against climate change.At the global level,the overall impact of climate change on existing hydropower generation may be expected to be small,or even slightly positive.However,there is the possibility of substantial variations across regions and even within countries.In conclusion,the general verdict on hydropower is that it is a cheap and mature technology that contributes significantly to climate change mitigation,and could play an important role in the climate change adaptation of water resource availability.However,careful attention is necessary to mitigate the substantial environmental and social costs.Roughly more than a terawatt of capacity could be added in upcoming decades.

Softening response under undrained compression following anisotropic consolidation

Experimental evidence has indicated that clay exhibits strain-softening response under undrained compression following anisotropic consolidation.The purpose of this work was to propose a modeling method under critical state theory of soil mechanics.Based on experimental data on different types of clay,a simple double-surface model was developed considering explicitly the location of critical state by incorporating the density state into constitutive equations.The model was then used to simulate undrained triaxial compression tests performed on isotropically and anisotropically consolidated samples with different stress ratios.The predictions were compared with experimental results.All simulations demonstrate that the proposed approach is capable of describing the drained and undrained compression behaviors following isotropic and anisotropic consolidations.

Sensitivity of Climate Changes to CO_2 Emissions in China

In this study, the authors demonstrate that the Coupled Model Intercomparison Project Phase 5 （CMIP5） models project a robust response in changes of mean and climate extremes to warming in China. Under a scenario of a 1% CO2 increase per year, surface temperature in China is projected to increase more rapidly than the global average, and the model ensemble projects more precipitation （2.2%/℃）. Responses in changes of climate extremes are generally much stronger than that of climate means. The majority of models project a consistent re- sponse, with more warm events but fewer cold events in China due to CO2 warming. For example, the ensemble mean indicates a high positive sensitivity for increasing summer days （12.4%/℃） and tropical nights （26.0%/℃）, but a negative sensitivity for decreasing frost days （-4.7%/℃） and ice days （-7.0%/℃）. Further analyses indicate that precipitation in China is likely to become more extreme, featuring a high positive sensitivity. The sensitivity is high （2.4%/℃） for heavy precipitation days （〉 10 mm d l） and increases dramatically （5.3%/℃） for very heavy precipitation days （〉 20 mm d-1）, as well as for precipitation amounts on very wet days （10.8%/℃） and extremely wet days （22.0%/℃）. Thus, it is concluded that the more extreme precipitation events generally show higher sensitivity to CO2 warming. Additionally, southern China is projected to experience an increased risk of drought and flood occurrence, while an increased risk of flood but a decreased risk of drought is likely in other regions of China.

Water discharge variability of Changjiang(Yangtze) and Huanghe(Yellow) Rivers and its response to climatic changes

Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation （ENSO） and the Pacific Decadal Oscillation （PDO）, on the temporal variations of the annual water discharge at the Lijin station in the Huanghe （Yellow） River and at the Datong station in the Changjiang （Yangtze） River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis （EMD- MESA） method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the inter- annual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.

Annual Discharge and Sediment Load Variation in Jialing River During the Past 50 Years

Annual discharge and annual suspended sediment loads of Beipei Hydrological Station of the Jialing River catchment were analyzed to describe the trend of Jialing River over the last five decades (1956-2006). These loads were also analyzed to ascertain the influential factors associated with its variation with the help of Kendall's Tau-b correlation analysis and regression analysis. The results indicated that the Jialing River annual discharge showed no significant trend at >95% confidence level while the annual sediment load appeared to have a significant decrease trend over the last 50 years. A decrease in the annual sediment load was particularly apparent after the year 1985, at which a substantial shift in the sediment level occurred. This shift is attributed to the construction of numerous dams in 1980s. However, after the year of 1985, two periodical stages (1986-1991 and 1992-2006) with distinct sediment load and sediment-runoff ratio were identified. The period 1992-2006 is characterised by low sediment load, which is most probably due to the impact of large scale of soil and water conservation, which took place at the end of the 1980s. Last, models describing the relationship between the discharge and the sediment load, discharge and sediment-runoff ratio as well as between the sediment load and sediment-runoff ratio were constructed.

Revitalizing and Preparing Drainage Operation and Maintenance to Anticipate Climate Change in Semarang Heritage City

Semarang urban coastal areas are experiencing tidal flood. In addition, land subsidence of 5 to 10 centimetres per year is taking place. The climate change phenomenon provokes land areas that are lower than sea water level from time to time. This makes the situation with respect to flooding increasingly risky. Semarang Old City （heritage） as part of principal Semarang area is suffering also from regular flooding and pollution that hamper the revitalisation of the old city. These areas used to be productive lands, but flooding make the existing public infrastructure does no longer function, and residential areas have changed into unhealthy slams. To overcome these problems, the Government of Semarang chooses a polder drainage system to address the flooding in Semarang. In the framework of the cooperation between Indonesia and the Netherlands, these activities consist of research and workshops on Urban Heritage. The scope consists basically of five components： experiences with urban drainage and flood protection in Semarang with a focus on Semarang Old City, field visit to relevant places with respect to urban drainage and flood protection of Semarang Old City, lectures on the relevant aspects of urban drainage and flood protection, exercises to get an insight in the processes that can take place under normal and extreme conditions, formulation of a preliminary plan to improve the situation with respect to urban drainage and flood protection of Semarang Old City. In this paper, the various relevant points are described, such as scenarios analysis as well as the findings and recommendations for improvement of the urban drainage system and flood protection of Semarang Heritage City.