Polar Expertise - Supporting Development Working in the Polar Regions, BAS has developed expertise, instrumentation and modelling techniques that have wider applicability, e.g. where research can contribute to development goals. We propose two strands of research in ODA countries that build upon the strengths of BAS as an interdisciplinary survey and research institute, and which continue strands of research begun in recent years under grant funding: one focused on water resources in the Indian section of the Indus river basin, and the other on the long term security of ecosystem services on South Atlantic Islands.   Access to water in India is a key development challenge (UN SDG 6) as population growth, a rapidly expanding economy and a large agricultural sector compete for increasingly scarce or variable supplies, and this is likely to be exacerbated by predicted climate change. Already, almost 95% of Indus river flow is extracted to feed the world's largest system of irrigated agriculture, particularly in Indian and Pakistani Punjab, which supports 237 million people and growing.   The Indus river system originates in the western Himalayas, fed by snow and glacier melt and precipitation.  Snow cover and glaciers in this region have shrunk dramatically in recent years, posing a serious threat to this water supply, but almost none of its thousands of glaciers have any ice thickness measurements and so the size of the region's ice reserves is unknown. Furthermore, the fundamental precipitation inputs to this river basin are sparsely measured and poorly understood.   This proposal will address these deficiencies by adapting existing BAS polar radar techniques to survey glacier volumes from the air, and developing a high resolution atmospheric model to characterise local climate variability (particularly by improving its representation of cloud microphysics and how this affects simulated precipitation). When linked to wider glacio-hydrological modelling studies (e.g. those to be undertaken by partners in India) this will lead to better understanding of present-day and future water availability, resulting in better informed policy decisions on Indus river water use.  The food security and economies of isolated island communities in the South Atlantic, in particular Tristan da Cunha and St Helena, are heavily reliant on harvesting marine resources and, to a lesser degree, tourism. Most of these resources are taken from the small coastal shelf areas and seamounts that are isolated in vast areas of deep ocean. Understanding how vulnerable these resources are to current and future harvesting, climate change and species invasion will be key to maintaining the future economic and cultural security of these communities.   We propose to deploy a multi-disciplinary team to construct a food-web for the exploited marine populations that will allow us to identify critical links in the food chain and to assess their vulnerability. Scientific cruises and land-based fieldwork, complemented by ocean model simulations, will allow us to understand the variability and eventually to identify any longer term trends, including climate change signals.  The key to this project is that it will integrate all previous studies to develop a long term study methodology that will improve our understanding of the causes and consequences of environmental change to the coastal shelf ecosystem. It would leave a legacy of robust oceanographic and food web modelling that will provide the scientific information necessary to develop policies to manage marine ecosystem resources, especially those relating to food security and eco-tourism. Moreover, whilst feeding directly into Island governmental planning, the outputs from this research will also feed into a number of International organisations that are actively involved in conservation of marine biodiversity. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.