清代承德旱河生态与园林文化

承德由于其特殊的地形,雨季容易引发山洪。避暑山庄建成后,康乾二帝修筑了大量的防洪设施,其中就包括贯穿城区的旱河。乾隆中后期,承德人口迅速增长,导致大量的林地被开垦为耕地,严重地破坏了承德地区的生态系统,加重了水土流失。大量泥沙淤积河道,严重地影响了旱河泄洪功能。乾隆末期,清政府不得不将旱河定为岁修工程。由此反映出旱河壅塞状况的出现主要是山林植被破坏、旱河周围环境恶化的结果。近几十年,承德市政府启动了旱河综合治理工程,使山体水土流失得到有效的控制,旱河周边的生态环境得到改善。如今承德市作为京津的生态屏障和重要水源地,在水源涵养功能区的建设中,其生态功能战略地位更是不可替代。

承德市二仙居旱河防洪与水景观治理措施探讨

承德市二仙居旱河通过河道防洪和两岸水景观的治理、污水处理和运行管理措施的实施,提高了河道的防洪标准,改善了居民生活环境,提高了城市品位,打造出以城市文化为背景的水景观长廊。

城市“旱河”综合整治措施研究

文章以某城区某条"旱河"的综合整治工程为例,针对其淤积干涸、生态环境严重破坏、丧失输水及行洪功能、水体黑臭的河道现状,结合当地城市规划,通过采取一系列综合整治技术,有效地解决该河道存在的问题,使河道"重生",将其打造成城市生态清洁小流域,为其他城市"旱河"的综合整治工程提供借鉴与参考。

浅析清乾嘉时期对承德旱河的治理

本文通过对清代乾嘉时期治理承德旱河的背景、过程、用度等方面进行分析,说明了乾嘉二帝对承德旱河的修浚治理给承德地区的发展带来了很大影响,极大地造福了承德地区人民。

北京市河道整治特色工程措施探究

文章以北京城市河道旱河整治为例,从改善防洪排涝条件、改善人居环境和满足城市发展等方面,对旱河综合整治特色工程措施进行了相关论证与分析。工程实施后,取得了较好的经济和社会效益,可供类似城市河道治理工程借鉴。

清代承德北部防洪设施建设及在现代城市发展中的意义

本文以《清宫热河档案》《清代海河滦河洪涝档案史料》为线索,着重论述避暑山庄以北地区狮子沟(包括裴家沟)旱河的修筑时间,以及对其岁修维护的执行,对外庙以及北部地区居民区的保护起到了重要作用。1840年后,因清政府财政困顿,旱河的维护时断时续,旱河抗洪能力大大减弱,城市发展逐渐衰落。以此揭示清代承德城市发展对当今京津冀水源涵养功能建设的历史借鉴作用。

Pollen Assemblage Features of Modern Water Samples from the Shiyang River Drainage, Arid Region of China

Pollen analysis of 30 modem water samples from the Shivang River, an internal river system located between the Tengger and Badain Jaran deserts, Northwest China was carried out to examine the river's capacity to carry pollen and spores, and to assess the contribution of the water-borne pollen to pollen assemblages in lake sediments at the end of the river system. Results indicate the pollen assemblages in water samples consist of both local and upland pollen. Percentages of upland pollen reach 30% - 60%, and pollen assemblages in water samples do not indicate the nature of local vegetation at the sampling sites. Fluvial currents have the capacity to transport large quantities of pollen long distances, and the contribution of this fluvial transported pollen is relatively high, For example, percentages of Picea Dietr. pollen in water samples at sampling sites 130 km and 145 km away from Picea forests reach 16.5% and 7.7%, respectively. Fluvial pollen transport occurs primarily during flood periods, and pollen concentrations from the flood samples are 17.1 - 12.5 times those from normal fluvial flow. Reservoirs affect pollen transportation since pollen is deposited at reservoir inlets and pollen concentrations are much reduced at reservoir outlets. Human activity can thus change natural features of pollen transportation and deposition. The main factors influencing pollen concentrations and assemblages are sampling time, sampling location, and rainfall intensity.

The Impact of Arid Climate Change on Agriculture of Dry Valley in Southwest China and Its Adaptive Countermeasures

The eco-environmental vulnerability and underdevelopment of the agriculture in Southwest China would strengthen its disadvantage conditions further on the condition of arid climate change.It is necessary to deal with the relations between resource utilization and eco-environment finely and ascertain the adaptive principles on the dry valley agriculture to the arid climate change in order to change the extensive utilization of the special agricultural resources.The paper gave some adaptive countermeasures that develop modern rangeland husbandry,strengthening the special agriculture and agricultural industrialization,emphasis on the ecological agriculture development,constructing the extension system of water-saving modern agriculture,encouraging the service industry related to ＂agriculture,peasants and the countryside＂,constructing water utilization facilities,and exploiting the renewable energies.

Habitat Range of two Alpine Medicinal Plants in a Trans-Himalayan Dry Valley,Central Nepal

Understanding of the habitat range of threatened Himalayan medicinal plants which are declining in their abundance due to high anthropogenic disturbances is essential for developing conservation strategies and agrotechnologies for cultivation. In this communication, we have discussed the habitat range of two alpine medicinal plants, Aconitum naviculare （Bruehl） Stapf and Neopicrorhiza scrophulariiflora （Pennel） Hong in a trans-Himalayan dry valley of central Nepal, Manang district. They are the most prioritized medicinal plants of the study area in terms of ethnomedicinal uses. A. naviculare occurs on warm and dry south facing slopes between 4090-4650 m asl along with sclerophyllous and thorny alpine scrubs, while N. scrophulariiflora is exclusively found on cool and moist north facing slope between 4000 and 4400 m asl where adequate water is available from snow melt to create a suitable habitat for this wetland dependent species. The soil in rooting zone of the two plants differs significantly in organic carbon （OC）, organic matter （OM）, total nitrogen （N） and carbon to nitrogen （C/N） ratio. Due to cool and moist condition of N. scrophulariiflora habitat, accumulation of soil OC is higher, but soil N content is lower probably due to slow release from litter, higher leaching loss and greater retention in perennial live biomass of the plant. The C/N ratio of soil is more suitable in A. navuculare habitat than that of N scrophulariiflora for N supply. Warm and sunny site with N rich soil can be suitable for cultivation ofA. naviculare, while moist and cool site with organic soil for N. scrophulariiflora. The populations of both the plants are fragmented and small. Due to collection by human and trampling damage by livestock, the population of A. naviculare was found absent in open areas in five of the six sampling sites and it was confined only within the bushes of alpine scrubs. For N. serophulariiflora, high probability of complete receding of small glaeiers may be a new threat in future to its habitat. The information about habitat conditions, together with the information from other areas, ean be useful to identify potential habitats and plan for cultivation or domestication of the two medieinal plants.

Impacts of Global Warming Perturbation on Water Resources in Arid Zone: Case Study of Kaidu River Basin in Northwest China

The main goal of this study was to assess the long-term impacts of global warming perturbation on water resources of the Kaidu River Basin in Northwest China. Temperature, precipitation and hydrology data during the past 29 years from 1979 to 2007 were collected and analyzed using parametric and non-parametric methods, the connection between temperature and precipitation by the combination of grey correlation analysis method and the hypothesis testing for trend of climate change. The results show a high increase in temperature in the study area as well as an extreme and highly variable hydrological regime in this region, where flash floods can exceed the total runoff from a sequence of years. These variations may be due to the geographical location of the Kaidu River Basin in arid zone. It also reveals that precipitation has a much greater impact on stream flow than that of temperature. The development of new approaches was proposed as responses to climate change in this arid region.

Agricultural Drought Resisting and Hydrological-Ecological Changes Taking Hebei Province in North China as an Example

Drought is usually supposed to be a rainfall deficiency problem. Most studies and practices to mitigate drought disaster are focusing on water development and irrigation, while neglecting that the agriculture system is a compounded human-natural system. Drought situation and tendency is also driven by human coping strategies. This paper takes Hebei Province in north China as an example, studing the spirally interact process of drought resisting and hydrological ecological feedback. The result shows that large scale water projects construction facilitated irrigation. With improved irrigation, farmers enhanced multiple crop index and land-use intensity greatly and increased the sowing area of water consuming crop, winter wheat. At the same time, both crop yield and gross output are raising steadily. Water demand and depletion in agricultural system increase year by year. This gradually leads to highly dependent on over exploitation of water resources, especially overdraw of groundwater. The process deteriorated the stability of hydrological-ecological system and made the ecological environment drying up. Drying up environment is breeding greater vulnerability and risk of drought in the long term. For sustainable development, integrated drought risk management should be based on the balance between sustainable water supply and water demand. The key is to improve agricultural system＇s adaptive and resilient capacity to drought.

Heavy Metals Concentration and Speciation in Arid Zone Rivers （Amudarya and Syrdarya） of Central Asia

The arid zone rivers Amudarya and Syrdarya are located in Central Asia and are subjected to the influx of different kinds of natural and anthropogenic pollutants. The concentrations and speciation of heavy metals, namely, Hg, Cr, Cd, Co, U, Zn, Sc, Fe, Br, Au, and Sm. in the Amudarya and Syrdarya rivers water in the territory of Uzbekistan were investigated by applying the neutron-activation analysis and through experimental modeling using appropriate radionuclides. The heavy metals speciation in the rivers water was separated in cationic, anionic, and a combination of colloidal and neutral forms. The experimental results showed that heavy metals in the Amudarya and Syrdarya rivers water migrate as a complex set of suspended solids, cationic, anionic, and a combination of colloidal neutral forms. The ratio of neutral and colloidal forms averages approximately 40% for the majority of the investigated heavy metals, and the share of neutral and colloidal forms of heavy metals in the Syrdarya river water is slightly less than in the Amudarya river water （10-20%）, which might be due to discharge of water from agricultural and industry sectors into the river.

Drought analysis in middle Heihe River

Water shortage has become one of the severest problems in the middle Heihe River Basin because of high water demand but low available water supply. This paper is oriented to provide solutions to the problem through the analysis of drought. The main objectives to analyze the difference between water demand and supply in various water users in past, present (2000), and project (2010) situation, especially in agriculture, and the most important is to propose and assess a reasonable measure with the purpose of minimum drought and sustainable development. A simulation model, WAFLEX (Water Allocation Flow model in Excel) model is applied in this study to cope with water availability, distribution and requirement of various water users, and the result shows the model and the method is effective and feasible.

Impact of Meteorological Drought on Streamflow Drought in Jinghe River Basin of China

Under global climate change, drought has become one of the most serious natural hazards, affecting the ecological environment and human life. Drought can be categorized as meteorological, agricultural, hydrological or socio-economic drought. Among the different categories of drought, hydrological drought, especially streamflow drought, has been given more attention by local governments, researchers and the public in recent years. Identifying the occurrence of streamflow drought and issuing early warning can provide timely information for effective water resources management. In this study, streamflow drought is detected by using the Standardized Runoff Index, whereas meteorological drought is detected by the Standardized Precipitation Index. Comparative analyses of frequency, magnitude, onset and duration are conducted to identify the impact of meteorological drought on streamflow drought. This study focuses on the Jinghe River Basin in Northwest China, mainly providing the following findings. 1) Eleven meteorological droughts and six streamflow droughts were indicated during 1970 and 1990 after pooling using Inter-event time and volume Criterion method. 2) Streamflow drought in the Jinghe River Basin lagged meteorological drought for about 127 days. 3) The frequency of streamflow drought in Jinghe River Basin was less than meteorological drought. However, the average duration of streamflow drought is longer. 4) The magnitude of streamflow drought is greater than meteorological drought. These results not only play an important theoretical role in understanding relationships between different drought categories, but also have practical implications for streamflow drought mitigation and regional water resources management.

Determining Critical Support Discharge of a Riverhead and River Network Analysis： Case Studies of Lhasa River and Nyangqu River

A riverhead is the demarcation point of continuous water channel and seasonal channel, which is characterized by a criti- cal flow that can support a continuous water body. In this study, the critical support discharge （CSD） is defined as the critical steady flows required to form the origin of a stream. The CSD is used as the criterion to determine the beginning of the riverhead, which can be controlled by hydro-climate factors （e.g., annual precipitation, annual evaporation, or minimum stream flow in arid season）. The CSD has a close correlation with the critical support/source area （CSA） that largely affects the density of the river network and the division of sub-watersheds. In general, river density may vary with regional meteorological and hydrological conditions that have to be considered in the analysis. In this paper, a new model referring to the relationship of CSA and CSD is proposed, which is based on the physical mechanism for the origin of riverheads. The feasibility of the model was verified using two watersheds （Duilongqu Basin of the Lhasa River and Beishuiqu Basin of the Nyangqu River） in Tibet Autonomous Region to calculate the CSA and extract river networks. A series of CSAs based on different CSDs in derived equation were tested by comparing the extracted river networks with the reference network obtained from a digitized map of river network at large scales. Comparison results of river networks derived from digital elevation model with real ones indicate that the CSD （equal to criterion of flow quantity （Qc）） are 0.0028 m3/s in Duilongqu and 0.0085 m3/s in Beishuiqu. Results show that the Qc can vary with hydro-climate conditions. The Qc is high in humid region and low in arid region, and the optimal Qo of 0.0085 m3/s in Beishuiqu Basin （humid region） is higher than 0.0028 m3/s in Duilongqu Basin （semi-arid region）. The suggested method provides a new application approach that can be used to determine the Qo of a riverhead in complex geographical regions, which can also reflect the effect of hydro-climate change on rivers supply in different regions.

Meteorological Drought in Nujiang and Lancang River Basins during Recent 50 Years

Drought is one of the main natural disasters that cause economic loss in the basins of international rivers such as Nujiang and Lancang rivers. Based on the monthly precipitation and temperature data of 31 meteorological stations in Nujiang and Lancang river basins in Yunnan Province during 1965-2013, the standardized precipitation evapotranspiration index(SPEI) in each of the two bio-climate zones was calculated. In addition, the drought process in annual, seasonal and monthly scale was analyzed respectively to reveal the spatial and temporal characteristics and the intensity variation of meteorological drought in Nujiang and Lancang river basins in Yunnan Province. The results showed that there was a significant increasing trend in seasonal(especially winter's) and monthly drought since the late 1970 s; the drought occurred in the two bio-climate zones showed no obvious spatial distinction, and it was synchronized with that occurred throughout Yunnan Province; and in the recent 50 years, the significant increase of drought in the study area may be attributed to the significant rise in temperature, rather than the slight decline of the precipitation.

Agricultural water-saving potential and feasibility of developing semi-dryland farming in Henan Province

Based on the collected data in the current status of developing and utilizing water resources and imple- menting water-saving agriculture in Henan Province, and taking into account the influence of engineering, agro- nomic and management measures, the water-saving potential in past years and the feasibility of implementing semi-dryland farming were analyzed in Henan Province. Finally, specific technical measures of developing semi- drvland farming in different areas of Henan Province were orooosed.

徐寡妇的羊

赶着羊在河沿上转了几圈儿,徐寡妇觉着身上暖了,只是风刮在脸上还有些疼。徐寡妇就把羊赶到河沟里,找个避风的地方。河是旱河,这几年没有水,河床上长满了矮矮的草,早已经干枯了,在风中摇摇摆摆,顶着薄薄的一层霜。一共三只羊,老母羊和它的一双儿女。有时候望着两只小羊羔,徐寡妇就说老母羊的命好,有儿有女。

《董存瑞舍身炸暗堡》教学构想

一、初读,编拟小标题 初读的任务是:①简介董存天瑞;②学习生字,联系课文理解“震撼、旱河、迸射、暗堡”等词语;③给课文分段,概括段意,编拟小标题。重点放在第③点。可先让学生默读,然后思考;课文是按照什么顺序写的?可分为几段?如果学生分段有困难,也可分两步进行:先让学生按“事情的起因、经过、结果”

Stoichiometry of leaf carbon, nitrogen, and phosphorus along a geographic, climatic, and soil gradients in temperate desert of Hexi Corridor, northwest China

Aims Understanding the regional pattern of leaf stoichiometry and its contributing variables are of importance for predicting plant responses to global change and modelling the productivity and nutrient fluxes of ecosystems.In this study,we investigated leaf stoichiometry of plants that sampled from Hexi Corridor,a typical arid region in China,and tried to explore the contribution variables on leaf stoichiometry along the geographic,climatic,and soil gradients.Methods In August 2012,70 sites in Hexi Corridor were investigated.Plant leaves and soils from five equivalent plots within each site were sampled.C,N,and P contents of leaf and soil were measured.Important findings Compared with leaf N and P contents in regional and global scales,leaf N content in Hexi Corridor was close to them with the value of 20.19 mg g^(-1),while leaf P content was lower than them with the value of 1.34 mg g^(-1).Overall,leaf N:P value in Hexi Corridor was 15.70.Individually,leaf N:P values of shrubs and herbs were 16.81 and 14.80,respectively.Scaling exponents for leaf N vs.P of overall and shrubs in Hexi Corridor were 1.29,higher than the scaling exponent of herbs(1.08).Leaf stoichiometry of shrubs and herbs did not show significant latitudinal and longitudinal patterns,meanwhile,it has no significant correlation with mean annual precipitation(MAP),mean annual temperature(MAT),and soil elements.However,only leaf stoichiometry of herbs has significant correlation with altitude and aridity degree.These results indicate that plants in Hexi Corridor are possibly co-limited by N and P,while shrubs are mainly limited by soil P and herbs are limited by soil N.Scaling relationship reveals that leaf N vs.P of herbs is isometric.With increasing altitude,the quadratic regression for leaf C and N contents and the linear regression for leaf P content of herbs reflect the difference responses of the three elements on the variation of MAT along the altitude and it could be explained by plant physiology hypothesis and biogeochemical hypotheses.With decreasing aridity,leaf N and N:P of herbs increased significantly,inferring that herbs growth would be limited by P increasingly and strengthening the increasing nitrogen availability with increasing precipitation.In conclusion,different altitude and aridity patterns for leaf stoichiometry of herbs and shrubs reveal the plastic survive strategies of different xerophytes in Hexi Corridor.Moreover,leaf stoichiometry of herbs in Hexi Corridor could be as indicator of the changing environment that caused by aridity.