Climate change adaptation planning for Global South megacities: the case of Dhaka

Megacities in low- and middle-income countries face unique threats from climate change as vulnerable populations and infrastructure are concentrated in high-risk areas. This paper develops a theoretical framework to characterize adaptation readiness in Global South cities and applies the framework to Dhaka, Bangladesh, a city with acute exposure and projected impacts from flooding and extreme heat. To gather case evidence from Dhaka we draw upon interviews with national and municipal government officials and a review of planning documents and peer-reviewed literature. We find: (1) national-level plans propose a number of adaptation strategies, but urban concerns compete with priorities such as protection of coastal assets and agricultural production; (2) municipal plans focus on identifying vulnerability and impacts rather than adaptation strategies; (3) interviewees suggest that lack of coordination among local government (LG) organizations and lack of transparency act as barriers for municipal adaptation planning, with national plans driving policy where LGs have limited human and financial resources; and (4) we found limited evidence that national urban adaptation directives trickle down to municipal government. The framework developed offers a systematic and standardized means to assess and monitor the status of adaptation planning in Global South cities, and identify adaptation constraints and opportunities.     

Climate Change Adaptation: Putting Principles into Practice

Carrying out wildlife conservation in a changing climate requires planning on long timescales at both a site and network level, while also having the flexibility to adapt actions at sites over short timescales in response to changing conditions and new information. The Royal Society for the Protection of Birds (RSPB), a land-owning wildlife conservation charity in the UK, achieves this on its nature reserves through its system of management planning. This involves setting network-wide objectives which inform the 25-year vision and 5-year conservation objectives for each site. Progress toward achieving each site’s conservation objectives is reviewed annually, to identify any adjustments which might be needed to the site’s management. The conservation objectives and 25-year vision of each site are reviewed every 5 years. Significant long-term impacts of climate change most frequently identified at RSPB reserves are: loss of intertidal habitat through coastal squeeze, loss of low-lying islands due to higher sea levels and coastal erosion, loss of coastal freshwater and brackish wetlands due to increased coastal flooding, and changes in the hydrology of wetlands. The main types of adaptation measures in place on RSPB reserves to address climate change-related impacts are: re-creation of intertidal habitat, re-creation and restoration of freshwater wetlands away from vulnerable coastal areas, blocking artificial drainage on peatlands, and addressing pressures on freshwater supply for lowland wet grasslands in eastern and southeastern England. Developing partnerships between organizations has been crucial in delivering large-scale adaptation projects.     

热带飓风日益活跃及气候变化的相关指标:高盐度蓝藻藻垫

引言 当蒸发损失的水分大于补充的淡水时,盐浓度将超过正常海水浓度(大约35psu),就出现了高盐度的情况,处于高盐胁迫下的活组织遭受严重的水胁迫、渗透压压迫及干燥的威胁[1～5].长期的盐胁迫作用,形成了这些生物系统中的特定的生物区系[1～5].     

RISK ASSESSMENT METHODOLOGY FOR KARST AQUIFERS: (1) ESTIMATING KARST CONDUIT-FLOW PARAMETERS

Quantitative ground-water tracing of conduit-dominated karst aquifers allows for reliable and practical interpretation of karst ground-water flow. Insights into the hydraulic geometry of the karst aquifer may be acquired that otherwise could not be obtained by such conventional methods as potentiometric-surface mapping and aquifer testing. Contamination of karst aquifers requires that a comprehensive tracer budget be performed so that karst conduit hydraulic-flow and geometric parameters be obtained. Acquisition of these parameters is necessary for estimating contaminant fate-and-transport. A FORTRAN computer program for estimating total tracer recovery from tracer-breakthrough curves is proposed as a standard method. Estimated hydraulic-flow parameters include mean residence time, mean flow velocity, longitudinal dispersivity, Peclet number, Reynolds number, and Froude number. Estimated geometric parameters include karst conduit sinuous distance, conduit volume, cross-sectional area, diameter, and hydraulic depth. These parameters may be used to (1) develop structural models of the aquifer, (2) improve aquifer resource management, (3) improve ground-water monitoring systems design, (4) improve aquifer remediation, and (5) assess contaminant fate-and-transport. A companion paper demonstrates the use of these hydraulic-flow and geometric parameters in a surface-water model for estimating contaminant fate-and-transport in a karst conduit. Two ground-water tracing studies demonstrate the utility of this program for reliable estimation of necessary karst conduit hydraulic-flow and geometric parameters.     

A two-region nonequilibrium model for solute transport in solution conduits in karstic aquifers

A two-region nonequilibrium model was used to calibrate initial solute-transport parameter estimates generated from tracer-breakthrough curves (TBCs) developed from tracer tests conducted in uni-axial solution conduits in karstic aquifers. Two-region nonequilibrium models account for partitioning of solute into mobile- and immobile-fluid regions to produce a more representative model fit to the strong tails associated with TBCs than do equilibrium models. The nonequilibrium model resulted in an increase in average flow velocities and a decrease in longitudinal dispersion coefficients over comparable estimates using an equilibrium model. Increases in velocity and decreases in dispersion were obtained at the expense of including parameters that describe solute partitioning and mass transfer rate for the mobile- and immobile-fluid regions. In addition, nonidentifiable sorption and mass transfer parameters for the immobile-fluid regions could only be described in terms of upper and lower bounds using readily determined identifiable ratios representing solute partitioning and system constraints based on known physical properties. The identifiable ratios and system constraints serve to minimize model nonuniqueness and renders the nonidentification problem trivial.     

Cylinder cyclone (LARCODEMS) density media separation of plastic wastes

Cylindrical cyclone media separators using a suspended calcite separation media simulating industrial scale operations are demonstrated to effectively separate a wide variety of forms and a greater range of particle sizes of plastics by density than presently recycled. Purities of plastic products and recoveries obtained from mixed plastic wastes are comparable to those reported for established separations. Products of ≈100% purity with recoveries of >99% were obtained for high density fractions and >98% purities and recoveries for the low density fractions. Cyclonic centrifugal forces and/or the fine particle size of the separation media appear to minimize hydroscopic and particle shape effects.A mathematical model is proposed for defining plastic waste feed rates and treatable particle size ranges for the LARCODEMS media separator.Waste plastic separations yielded Ecart probable (Ep) values ?0.024 for a water only separation media. The Ep for 1.1 g cm^?3 separation medias was <0.032 with minimal to no variation in values for 1–8 mm particle sizes. Variation in the quality of separations is shown to be minimal with <72 μm, <45 μm and <2 μm media particle sizes. Media density offset created varied according to particle size.