The role of rainfed agriculture in securing food production in the Nile Basin

A better use of land and water resources will be necessary to meet the increasing demand for food in the Nile basin. Using a hydro-economic model along the storyline of three future political cooperation scenarios, we show that the future of food production in the Basin lies not in the expansion of intensively irrigated areas and the disputed reallocation of water, but in utilizing the vast forgotten potential of rainfed agriculture in the upstream interior, with supplemental irrigation where needed. Our results indicate that rainfed agriculture can cover more than 75% of the needed increase in food production by the year 2025. Many of the most suitable regions for rainfed agriculture in the Nile basin, however, have been destabilized by recent war and civil unrest. Stabilizing those regions and strengthening intra-basin cooperation via food trade seem to be better strategies than unilateral expansion of upstream irrigation, as the latter will reduce hydropower generation and relocate, rather than increase, food production.     

Cars and fuels for tomorrow: a comparative assessment

Light duty vehicles, i.e. passenger cars and light trucks, account for approximately half of global transportation energy demand and, thus, a major share of carbon dioxide and other emissions from the transport sector. Energy consumption in the transport sector is expected to grow in the future, especially in developing countries. Cars with alternative powertrains to internal combustion engines (notably battery, hybrid and fuel-cell powertrains), in combination with potentially low carbon electricity or alternative fuels (notably hydrogen and methanol), can reduce energy demand by at least 50%, and carbon dioxide and regulated emissions much further. This article presents a comparative technical and economic assessment of promising future fuel/vehicle combinations. There are several promising technologies but no obvious winners. However, the electric drivetrain is a common denominator in the alternative powertrains and continued cost reductions are important for widespread deployment in future vehicles. Development paths from current fossil fuel based systems to future carbon-neutral supply systems appear to be flexible and a gradual phasing-in of new powertrains and carbon-neutral fluid fuels or electricity is technically possible. Technology development drivers and vehicle manufacturers are found mainly in industrialised countries, but developing countries represent a growing market and may have an increasingly important role in shaping the future.     

Emission Patterns under Alternative Congestion and Motor Vehicle Pollution Mitigation Policies in Shanghai

Abstract

Minqin Oasis is located in the lower reaches of the Shiyanghe River Basin, northeast of the Heixi Corridor, at the middle of the Silk Road. Because of the its existence, Badain Jaran Desert and Tengger Desert cannot converge and develop in the south. It has always been an important green barrier to guarantee the eco-security of Hexi Corridor and the Silk Road for thousands of years. But in recent decades, Minqin Oasis is becoming smaller and the desert is becoming larger. Many people, especially the governmental officials in the lower reaches think that the upper and middle reaches have robbed the lower reaches of water resources, and caused insufficient water usage and the deteriorated eco-environment, in the lower reaches, However, the governmental officials in the upper and middle reaches claim that the whole river basin should take the upper and middle reaches as the key regions to develop economy. To address the above argument, we analyze the reasons why Minqin Oasis is disappearing, and find that there are two main factors. One is the quick development of population and economy in the upper and middle reaches; the other is the rapid development of population and economy in the lower reaches. The two factors both have great effect on the water utilization for eco-environment in the lower reaches. So Minqin Oasis is disappearing not only because of the upper and middle reaches but also because of the growth of population and economy itself. The lower reaches should not completely blame the upper and middle reaches. The upper and middle reaches should also pay more attention to the eco-environment in the lower reaches. The whole river basin should develop a harmonious and sustainable relationship among the upper, middle and lower reaches.     

Interactive two-stage stochastic fuzzy programming for water resources management

In this study, an interactive two-stage stochastic fuzzy programming (ITSFP) approach has been developed through incorporating an interactive fuzzy resolution (IFR) method within an inexact two-stage stochastic programming (ITSP) framework. ITSFP can not only tackle dual uncertainties presented as fuzzy boundary intervals that exist in the objective function and the left- and right-hand sides of constraints, but also permit in-depth analyses of various policy scenarios that are associated with different levels of economic penalties when the promised policy targets are violated. A management problem in terms of water resources allocation has been studied to illustrate applicability of the proposed approach. The results indicate that a set of solutions under different feasibility degrees has been generated for planning the water resources allocation. They can help the decision makers (DMs) to conduct in-depth analyses of tradeoffs between economic efficiency and constraint-violation risk, as well as enable them to identify, in an interactive way, a desired compromise between satisfaction degree of the goal and feasibility of the constraints (i.e., risk of constraint violation).     

Influence of grain size on species-habitat models

High resolution remote sensing data facilitate the use of small-scale habitat features such as trees or hedges in the analysis of species-habitat relationships. Such data potentially enable more accurate species-habitat mapping than lower resolution data. Here, for the first time, we systematically investigated this hypothesis by altering the spatial resolution from 1 m up to 1000 m grain size in species-habitat models of 13 bird species. The study area covered the Nidda river catchment in central Germany, a large heterogeneous landscape of 1620 km². A high resolution habitat map of the area was converted to coarser spatial and thematic resolutions in seven steps. We investigated how model performance responded to grain size, and we compared the differential effects of spatial resolution and thematic resolution on model performance. Explained deviance (D²) of the bird models generally decreased with coarser spatial resolution of the data, although it did not decrease monotonically in all species. On average across all species, model D² decreased from 41.5 at 1 m grain size to 15.9 at 1000 m grain size. Ten species were best modelled at 1 m, two species at 3 m and one species at 32 m grain size. Model performance degraded continuously with increasing grain size, both in habitat generalist and habitat specialist bird species, and was systematically lower in habitat generalists. The higher model performance observed at finer grain sizes was most likely caused by the combination of three factors: (1) high spatial accuracy of bird records and (2) a more precise location and delineation of habitat features and, (3) to a lesser degree, by more habitat types differentiated in maps of finer resolution. We conclude that higher spatial and thematic resolution data can be essential for deriving accurate predictions on bird distribution patterns from species-habitat models. Especially for bird species that are sensitive to specific land-use types or to small-scaled habitat features, a grain size of 1-3 m seems most promising.     

The consequences of being colonial: Allee effects in metapopulations of seabirds

Most seabirds live in large colonies. This fact signifies that there is an advantage in living and breeding together. Four explanations are put fore ward for this colonial behaviour, more birds have: (1) a reduced per capita predation of chicks in colonies, (2) a better anti-predator defence, (3) a more efficient foraging in temporally patchy environments and (4) sex ratios that are more likely to be close to one. These factors induce a strong Allee-type density-dependent relation, a positive relation between density and population growth rate at low density. Nevertheless, these Allee effects are generally ignored in seabird population studies. Therefore we study the consequences of introducing Allee-type density-dependent relations in a spatially explicit metapopulation model for the Common Tern (Sterna hirundo). Simulations show that Allee effects might be responsible for a 20-fold decline in the recolonization distances, causing patches and parts of metapopulations to effectively become more isolated. This leads to long recolonization times of empty breeding patches which consequently cause slower metapopulation expansion and recovery. Additionally, we show that the typical early warning signals, that show that a population is near its critical threshold induce by Allee effects, is less pronounced in colonies that are part of a metapopulation. Hence, we offer some simple equations to estimate critical densities and thresholds in a colony.     

高分辨电感耦合等离子体质谱法测定地下水中稀土元素

采用高分辨电感耦合等离子体质谱法测定地下水中14种稀土元素,并选择Rh作内标,可消除测定中的质谱干扰和非质谱干扰,使方法在0μg/L~100μg/L范围内线性良好。方法检出限为0.002μg/L~0.005μg/L,实际水样的加标回收率为80.0%~117%,RSD为2.1%~3.8%。     

Building consensus on divisive issues: a case study of the Yukon wolf management team

This article presents a case study of a successful effort to reach agreement on one of the most intractable environmental issues of our time: wolf management. This case is unusual in several ways. In this case, the members of the negotiating team were ordinary citizens rather than leaders of organized groups. This team was given an unusually high level of authority to write the plan as they saw fit; the agency pledged to implement “whatever they came up with.” The agency convened the process, but agency personnel were not members of the team and attended only when they were invited. The team members were able to reach agreement on this tough issue even though polar opposites were at the table—one who felt that wolves are a “spiritual essence” and another who felt that, as he put it, “wolves, coyotes, and cockroaches have a lot in common”. They produced a detailed plan that addressed all the issues in just 5 months. Another unusual aspect of this effort is that the final agreement does not list the team members. They explained that they wanted their plan to “stand alone” and be judged based on what it said, not on who was involved.However, just after their agreement was completed, a new, pro-wolf control government was elected that refused to endorse the plan. While the government gave various reasons for not ratifying the plan, more and more diverse interest groups came out in support for both the plan and the process that created it. Eventually, overwhelming public support forced the government to sign and implement the plan as written. This demonstrates that, while it is important for a team to seek the sanction of decision-makers, it is perhaps even more important for the general public to see the effort and the final agreement as fair. Strong support from a broad spectrum of the public can help win the necessary political support.In addition to discussing the unorthodox aspects of this consensus-building effort, this article also attempts to give the reader a front row seat to this process by using the informants' own words—words rich in detail, brimming with color and spoken straight from the heart. Certainly their experience dispels any notion that such efforts are simply a matter of following a recipe. During the process, members of the negotiating team experienced the entire gamut of emotions—anger, defeat, humor and, finally, a genuine sense of pride. As team member Patty Denison put it, “We showed that a random group of people could work together and do something truly monumental.”     

基于TOPAZ的无人机冲突解脱安全评估技术

针对当前无人机空域运行安全评估体系缺乏的现状,利用TOPAZ构建了一种用于无人机飞行冲突解脱技术的安全评估体系。构造了无人机的空域运行环境,加入单机45°交叉相遇、90°交叉相遇和双机同时交叉相遇的冲突场景。选取一种典型的无人机冲突解脱算法作为安全评估对象,依据TOPAZ的评估流程展开了系统的评估,得出冲突解脱算法的安全水平。对冲突解脱算法提出了改进方案,加入了动态的启发式因子,有效提高了冲突解脱技术的安全性能。通过基于TOPAZ的迭代评估过程进一步找出了无人机冲突解脱算法的安全瓶颈所在,证实了当前各类冲突解脱技术还无法满足有人机与无人机共域飞行的安全需要。