Improving watershed management practices in humid regions

In many parts of the world, watershed management practices have been extremely effective. However, implementation of soil and water conservation technologies in the humid African highlands, while beneficial in the short term, were remarkably unsuccessful in the long term. Insights from community knowledge perspectives have revealed that alternative methods are needed. Although conservation practices are designed to conserve water in semi‐arid areas, safely draining excess water is needed in humid areas. The objective of this paper is to review current watershed management approaches used in humid regions as exemplified by those used in Ethiopian highlands and then based on these findings propose more effective practices. Although current government sponsored practices primarily protect the hillsides, direct run‐off is generated from areas that become saturated on valley bottoms near rivers and on specific parts of the hillsides with degraded soils (or with highly permeable surface soils) and with perched water tables on slowly permeable horizons at shallow depths. In these areas, direct run‐off is increasing with deforestation and the soil degradation, demanding additional drainage ways that evolve in the form of gullies. Therefore, watershed management interventions for erosion control should prioritize revegetation of degraded areas, increasing sustainable infiltration, and rehabilitating gullies situated at saturated bottomlands.     

‘This is my garden’: justice claims and struggles over forests in Vietnam’s REDD+

ABSTRACT

This paper explores dynamics of conflict over forests in Vietnam, as the country lays the groundwork for Reducing Emissions from Deforestation and Forest Degradation (REDD+). Drawing on a case study in Lam Dong province and applying an environmental justice lens, we examine how various social actors assert claims over forests and how these claims invoke different notions of justice, authority and identity. Our analysis highlights that the development and implementation of the project has generated renewed competing claims and conflicts over forests among social actors. Underlying these conflicts there are incompatible notions of justice and associated rights, which lead different actors to accord legitimacy variously to the global norms brought about by REDD+, the customary resource practices of indigenous people, or to the state’s laws. We show that the negotiations over forests in REDD+ reflect the influence of the specific historical and political-economic settings in which REDD+ activities take place, including pre-existing conflicts over forests and power relations underpinning forest management. From a policy perspective, our research suggests that any attempts to introduce simplified and uniform regulations for forest governance in REDD+ should be avoided, since local institutions and conceptions of justice will significantly influence what is regarded as legitimate policy and can thus be endorsed as inspiration for sustainable forest governance.

Key policy insights

• REDD+ in Vietnam has spurred contestations over who is legitimately entitled to govern and manage forests.

• Claims and conflicts over forests can be explained by incompatible and distinct notions of justice, authority and identity.

• Contestations over justice pose radical challenges to any global and national efforts that attempt to implement simplified rules and ideas for forest based-climate change mitigation.

• Attention to justice, especially to compatibility and differences in ideas about justice, is crucial for sustainable forest governance.

     

越南红河断裂活动性研究

通过中越两国对越南红河断裂带开展的联合野外考察,获取了地震、地质、地貌和年代学等反映该断裂最新活动的相关证据。综合研究表明,越南红河断裂带第四纪以来的右旋走滑活动延续和保持了在中国境内自北向南逐渐减弱的总体趋势。其第四纪主要活动时代为中更新世中晚期,且总体活动水平明显低于中国云南境内部分,特别是自晚更新世以来越南红河断裂带的活动已表现得十分微弱。结合断裂现今地震活动和区域GPS大地形变特征分析认为,自晚第四纪以来,来自青藏高原的"侧向挤出"动力作用对红河断裂右旋走滑活动在时间、空间和强度等方面的影响可能非常有限。文中还探讨了造成这一有限影响可能的大地构造和深部构造原因     

Multipurpose agroforestry as a climate change resiliency option for farmers: an example of local adaptation in Vietnam

Increasing frequency, intensity and duration of severe weather events are posing major challenges to global food security and livelihoods of rural people. Agriculture has evolved through adaptation to local circumstances for thousands of years. Local experience in responding to severe weather conditions, accumulated over generations and centuries, is valuable for developing adaptation options to current climate change. This study aimed to: (i) identify tree species that reduce vulnerability of cropping systems under climate variability; and (ii) develop a method for rapidly assessing vulnerability and exploring strategies of smallholder farmers in rural areas exposed to climate variability. Participatory Rural Appraisal methods in combination with Geographical Information Systems tools and statistical analysis of meteorological data were used to evaluate local vulnerability to climate change and to investigate local adaptation measures in two selected villages in Vietnam, one of the countries most vulnerable to climate change. The low predictability of severe weather events makes food crops, especially grain production, insecure. This study shows that while rice and rain-fed crops suffered over 40 % yield losses in years of extreme drought or flood, tree-based systems and cattle were less affected. 13 tree species performed well under the harsh local climate conditions in home and forest gardens to provide income, food, feed and other environmental benefits. Thus, this research suggests that maintenance and enhancement of locally evolved agroforestry systems, with high resilience and multiple benefits, can contribute to climate change adaptation.     

Determination of groundwater solute transport parameters in finite element modelling using tracer injection and withdrawal testing data

The groundwater tracer injection and withdrawal tests are often carried out for the determination of aquifer solute transport parameters. However, the parameter analyses encounter a great difficulty due to the radial flow nature and the variability of the temporal boundary conditions. An adaptive methodology for the determination of groundwater solute transport parameters using tracer injection and withdrawal test data had been developed and illustrated through an actual case. The methodology includes the treatment of the tracer boundary condition at the tracer injection well, the normalization of tracer concentration, the groundwater solute transport finite element modelling and the method of least squares to optimize the parameters. An application of this methodology was carried out in a field test in the South of Hanoi city. The tested aquifer is Pleistocene aquifer, which is a main aquifer and has been providing domestic water supply to the city since the French time. Effective porosity of 0.31, longitudinal dispersivity of 2.2 m, and hydrodynamic dispersion coefficients from D = 220 m²/d right outside the pumping well screen to D =15.8 m²/d right outside the tracer injection well screen have been obtained for the aquifer at the test site. The minimal sum of squares of the differences between the observed and model normalized tracer concentration is 0.00119, which is corresponding to the average absolute difference between observed and model normalized concentrations of 0.035 5 (while 1 is the worst and 0 is the best fit).     

About the observed brightness distribution of solar radio bursts on decameter wavelengths and a possible effect from the ionosphere

Chen and Shawhan (1978) observed the brightness distribution of solar radio bursts at 26 MHz and fitted it to a double gaussian model. The small angle and large angle components were labelled core and halo. As an alternative to the scattering theory by coronal inhomogeneities, the authors introduced an interpretation of these components as the primary source and its reflected image on lower layers of the corona. We stress the difficulties with this interpretation because the corona is indeed very far from being spherically symmetric; the observed source structure may be due to a coronal scattering process involving both weak and strong inhomogeneities. But first of all we point out a relation between the halo dimensions and the local time which casts some doubt on the solar origin of the halo; we argue that it might result at least partially from instrumental or more probably from ionospheric effects.Laboratoire Associé du CNRS No. 264.     

Quasi-Thermal Noise Diagnostics in Space Plasmas

We present the method of plasma diagnostics by quasi-thermal noise spectroscopy and show examples of application in the solar wind and the Earth's plasmasphere. Using only an electric antenna and a radio receiver, diagnostics of various space environments (magnetized or not) can be obtained in situ. Because of its accuracy, this technique can be used to cross-check other plasma sensors. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evaluating the performance of an explicit dynamic relaxation technique in analyzing non-linear geotechnical engineering problems

Explicit dynamic relaxation is an efficient tool that has been used to solve problems involving highly non-linear differential equations. The key feature of this method is the ability to use explicit dynamic algorithms in solving static problems. Few attempts have been made to date to apply this technique in conventional geotechnical engineering. In this study, an algorithm that incorporates the application of a stiffness dependent time step scheme is proposed. The algorithm has been successfully used to solve 2D and 3D non-linear geotechnical engineering problems. To calibrate the developed algorithm, numerical simulations have been conducted for a strip and square footings supported by Mohr–Coulomb material. Performance of four different types of brick elements used in collapse load calculation is examined in terms of convergence speed and accuracy. In addition, the role of employing adaptive time steps in reducing the number of iterations needed for convergence is also evaluated.