The CARISMA project (Catchment Risk Assessments using Multi-Scale Data) aims to address issues of data scarcity in catchment water balance assessments through integrating independent sources of information from community-led monitoring (hydrological 'citizen science') and recent developments in remote sensing. The project focusses on two study areas in sub-Saharan Africa, in Ethiopia and Tanzania, where such problems are particularly acute, but aims to develop a more generally applicable methodology. Many catchments or river basins undergo water stress due to a combination of over-abstraction, changes in land-use, or climatic variability and changes. Water stresses may be felt as long-term trends over whole catchment areas, but more often are seen as episodic events such as seasonal or multi-annual drought, and may be spatially located in certain river tributaries or sub-catchments. It is then difficult to identify the underlying causes of water stress, and how particular groups of water users could contribute to potential solutions, if insufficient data are available in the right place and at the right time. Our recent research has demonstrated the viability of community-led monitoring to provide credible key hydrological information to improve understanding of surface and groundwater resources, and that multi-level governance approaches are a feasible way of addressing water management policy. Our work has shown that data-sharing platforms (such as 'Environmental Virtual Observatories' or 'Decision Theatres') have potential to help integrate and present information is ways that support decision making at all levels, but their design needs to be user-driven to facilitate their adoption. These emerging paradigms open up new opportunities for better environmental management, but require participatory development of open and transparent systems for integration of multiple sources of information to provide successful outcomes. This project aims to build on our previous research by co-developing with partners and stakeholders in two catchment in Ethiopia (Abay River Basin Authority) and Tanzania (Rufiji River Basin Authority) a prototype data integration and presentation platform that will quantify key hydrological indicators of catchment water balances at spatial scales appropriate to developing sustainable water management policies and practices in water-stressed catchments. Indicators relevant to stakeholder groups representing community, ecosystem, business, and governance interests will be identified using a participatory approach. The proposed platform uses publicly available remote sensing data for spatial assessments of key hydrological components, particularly rainfall and evapotranspiration, and community-led low-cost monitoring of ground-based variables (including rainfall, river levels and flows, and groundwater levels) to complement available formal monitoring networks. Evaluation of how uncertainty in each component can contribute to overall understanding of water balances will be assessed using a standardised water accounting modelling framework. This can then support better quantification of contributors to catchment water scarcity, to inform multi-stakeholder decision making. Understanding of uncertainty reduction from the different data sources will provide the basis for guidance on appropriate design of monitoring networks, and evidence to support a risk-based approach to water management. The project output of a prototype data platform will provide a key step towards our partner WWF-UK's strategy of working towards a generic capability for developing and sharing better hydrological data to underpin their global activities, particularly through their Water Stewardship Programme. Close involvement of WWF-Tanzania in this project will provide a tangible first step towards this goal.

A reliable and acceptable quantity and quality of water, and managing water-related risks for all is considered by the United Nations to be "the critical determinant of success in achieving most other Sustainable Development Goals (SDGs)". Water is essential for human life, but also necessary for food and energy security, health and well-being, and prosperous economies. However, some 80% of the world's population live in areas with threats to water security; the impacts of which cost $500bn a year. Progress in meeting SDG6 (Ensure availability and sustainable management of water and sanitation for all), has been slow and in May 2018 the United Nations reported that "The world is not on track to achieve SDG6". Improvements that increase access to water or sanitation are undone by pollution, extreme weather, urbanization, over-abstraction of groundwater, land degradation etc. This is caused by significant barriers that include: (1) Insufficient data to understand social, cultural, environmental, hydrological processes; (2) Existing service delivery / business models are not fit for purpose - costs are too high, and poor understanding of local priorities leads to inappropriate investments; (3) Water governance is fragmented and communities are engage with, and take responsibility for, water security; (4) Pathways to water security are not adaptable and appropriate to local context and values. These barriers are inherently systemic, and will require a significant international and interdisciplinary endeavour. The GCRF Water Security and Sustainable Development Hub brings together leading researchers from Colombia, Ethiopia, India, Malaysia and the UK. Each international partner will host a Water Collaboratory (collaboration laboratories) which will provide a participatory process, open to all stakeholders, to jointly question, discuss, and construct new ideas to resolve water security issues. Through developing and demonstrating a systems and capacity building approach to better understand water systems; value all aspects of water; and strengthen water governance we will unlock systemic barriers to achieving water security in practice.