Climatic and Human Influences on Groundwater in Low Atolls

Population centers in low, small islands have water supply problems that are among the most critical in the world. Limited land areas and extremely large soil hydraulic conductivities severely reduce surface runoff and surface storage, so that thin lenses of fresh groundwater floating over seawater comprise the major source of fresh water for people in many atolls. Atoll groundwater is extremely vulnerable to frequent El Niño Southern Oscillation (ENSO)-related droughts, salinization due to storm surges and sea-level rise, and to human activities with vadose zone transit times from surface to shallow groundwater being less than 1 h. We examine the relationship between groundwater, rainfall, and ENSO events in a low atoll, Tarawa, in the central and western Pacific Republic of Kiribati. Droughts can last as long as 43 months and occur with a current frequency of 6 to 7 years. The impact of droughts on the quality and quantity of a fresh groundwater lens is explored. The local drawdown of the water table due to pumping from long horizontal infiltration galleries is found to be less than diurnal tidal variations. The saturated hydraulic conductivity, K0, of the Holocene unconsolidated coral sands was estimated from infiltration gallery drawdown in two islands. The geometric mean K0 was 14.6 m d?1 with a range from 0.9 to 111 m d?1. These large K0 values cause the rapid transmission of rainfall and surface pollutants through the unsaturated zone to groundwater. An example is given of Escherichia coli pollution due to traditional activities. Strategies for improving the adaptation of island communities and increasing resilience to climate change are discussed

Urban and rural sanitation in the Solomon Islands:How resilient are these to extreme weather events?

The Solomon Islands, like other small island developing states in the Pacific, face significant challenges from a changing climate, and from increasing extreme weather events, while also lagging behind the rest of the world in terms of drinking water, sanitation and hygiene (WaSH) services. In order to support planning for the implementation of national WaSH strategies and policies, this study contextualizes representative urban and rural baselines for Sustainable Development Goal (SDG) 6 (“by 2030, achieve access to adequate and equitable sanitation and hygiene for all and end open defecation”). We highlight specific threats to the current sanitation services under extreme weather events such as flooding and drought, both of which are commonly observed in the country, and provide suggestions for structural improvements to sanitation facilities to increase resiliency. As the first detailed nationally representative cross-sectional sanitation study in urban and rural areas in the Solomon Islands, the results of this paper inform national WaSH policy, strategic planning and programming by the Solomon Islands Government and stakeholders

Shortest path queries in rectilinear worlds

Abstract In this paper, a data structure is given for two and higher dimensional shortest path queries. For a set of n axis-parallel rectangles in the plane, or boxes in d-space, and a fixed target, it is possible with this structure to find a shortest rectilinear path avoiding all rectangles or boxes from any point to this target. Alternatively, it is possible to find the length of the path. The metric considered is a generalization of the Ll-metric and the link metric, where the length of a path is its L1-Iength plus some (fixed) constant times the number of turns on the path. The data structure has size 0« n log n )d-l), and a query takes O(logd-l n) time (plus the output size if the path must be reported). As a byproduct, a relatively simple solution to the single shot problem is obtained; the shortest path between two given points can be computed in time O(ndlogn) for d ~ 3, and in time 0(n 2 ) in the plane

Urban and rural sanitation in the Solomon Islands: How resilient are these to extreme weather events?

The Solomon Islands, like other small island developing states in the Pacific, face significant challenges from a changing climate, and from increasing extreme weather events, while also lagging behind the rest of the world in terms of drinking water, sanitation and hygiene (WaSH) services. In order to support planning for the implementation of national WaSH strategies and policies, this study contextualizes representative urban and rural baselines for Sustainable Development Goal (SDG) 6 (“by 2030, achieve access to adequate and equitable sanitation and hygiene for all and end open defecation”). We highlight specific threats to the current sanitation services under extreme weather events such as flooding and drought, both of which are commonly observed in the country, and provide suggestions for structural improvements to sanitation facilities to increase resiliency. As the first detailed nationally representative cross-sectional sanitation study in urban and rural areas in the Solomon Islands, the results of this paper inform national WaSH policy, strategic planning and programming by the Solomon Islands Government and stakeholders

Geographical inequalities in drinking water in the Solomon Islands

Sustainable Development Goal 6.1 seeks to “by 2030, achieve universal and equitable access to safe and affordable drinking water”, which is challenging particularly in Small Island Developing States (SIDS) and Pacific Island Countries (PIC). We report drinking water sources and services in the Solomon Islands and examine geographical inequalities. Based on two quantitative baseline datasets of n = 1,598 rural and n = 1,068 urban households, we analyzed different drinking water variables (source type, collection time, amount, use, perceived quality, storage, treatment) and a composite index, drinking water service level. We stratified data by urban and rural areas and by province, mapped, and contextualized them. There are substantive rural–urban drinking water inequalities in the Solomon Islands. Overall, urban households are more likely to: use improved drinking water sources, need less time to collect water, collect more water, store their water more safely, treat water prior to consumption, perceive their water quality as better and have an at least basic drinking water service than rural households. There are also provincial and center-periphery inequalities in drinking water access, with more centrally located provinces using piped water supplies and more distant and remote provinces using rainwater and surface water as their primary source. There are also inter-national inequalities. Out of all PICs, the Solomon Islands have among the lowest access to basic drinking water services: 92% of urban and 55% of rural households. Of all SIDS, PICs are least serviced. This study shows that drinking water inequality is a critical issue, and highlights that all identified dimensions of inequality - rural–urban, provincial, center-periphery and inter-national - need to be explicitly recognized and addressed and included in pro-equity monitoring, policy and programming efforts by the Solomon Islands Government and stakeholders to reduce inequalities as per the Agenda 2030

The genome of the yellow potato cyst nematode, Globodera rostochiensis, reveals insights into the basis of parasitism and virulence

BACKGROUND: The yellow potato cyst nematode, Globodera rostochiensis, is a devastating plant pathogen of global economic importance. This biotrophic parasite secretes effectors from pharyngeal glands, some of which were acquired by horizontal gene transfer, to manipulate host processes and promote parasitism. G. rostochiensis is classified into pathotypes with different plant resistance-breaking phenotypes. RESULTS: We generate a high quality genome assembly for G. rostochiensis pathotype Ro1, identify putative effectors and horizontal gene transfer events, map gene expression through the life cycle focusing on key parasitic transitions and sequence the genomes of eight populations including four additional pathotypes to identify variation. Horizontal gene transfer contributes 3.5 % of the predicted genes, of which approximately 8.5 % are deployed as effectors. Over one-third of all effector genes are clustered in 21 putative ‘effector islands’ in the genome. We identify a dorsal gland promoter element motif (termed DOG Box) present upstream in representatives from 26 out of 28 dorsal gland effector families, and predict a putative effector superset associated with this motif. We validate gland cell expression in two novel genes by in situ hybridisation and catalogue dorsal gland promoter element-containing effectors from available cyst nematode genomes. Comparison of effector diversity between pathotypes highlights correlation with plant resistance-breaking. CONCLUSIONS: These G. rostochiensis genome resources will facilitate major advances in understanding nematode plant-parasitism. Dorsal gland promoter element-containing effectors are at the front line of the evolutionary arms race between plant and parasite and the ability to predict gland cell expression a priori promises rapid advances in understanding their roles and mechanisms of action.SE-vdA is supported by BBSRC grant BB/M014207/1. Sequencing was funded by BBSRC grant BB/F000642/1 to the University of Leeds and grant BB/F00334X/1 to the Wellcome Trust Sanger Institute). DRL was supported by a fellowship from The James Hutton Institute and the School of Biological Sciences, University of Edinburgh. GK was supported by a BBSRC PhD studentship. The James Hutton Institute receives funding from the Scottish Government. JAC and NEH are supported by the Wellcome Trust through its core funding of the Wellcome Trust Sanger Institute (grant 098051). This work was also supported by funding from the Canadian Safety and Security Program, project number CRTI09_462RD

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Genome annotation. (XLSX 9 kb