Assessment of Climate Change Impacts on Hydrological Processes in Usangu Catchment of Tanzania, 2020

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Climate change is anticipated to have long-term effects on hydrological processes and patterns that lead to water stress in agro-ecological catchments. Climate change escalates water scarcity in the Usangu catchment, evidenced by drying up of rivers during dry season. Therefore, this study was undertaken to assess climate change impacts on hydrology by utilizing SWAT model and an ensemble mean of five Global Circulation Models (GCMs) under two shared socio-economic pathways (SSPs) emission scenarios. Downscaling of GCMs was performed by LARS-WG statistical downscaling tool. In comparison to the baseline period, short rain intervals are expected to occur between 2030 and 2060, with mean annual precipitation increase of 7% and 17% in SSP 2-4.5 and SSP 5-8.5 respectively. Maximum and minimum temperatures are expected to rise by 0.6°C-2°C. Corresponding to future temperature increase, evapotranspiration would increase to about 30% and decrease more water yield and groundwater recharge by 7% and 26% in SSP 2-4.5 than in SSP 5-8.5. However, the effect of precipitation increase is shown by increased surface runoff and streamflow during wetter months. These findings provide watershed managers with crucial information for planning and managing the catchment in light of a changing climate.

Sustainable water resource development remains elusive because development has largely externalized costs to the environment and vulnerable people. There is a need for novel research theory, methodologies & practice in order to meet the UN SDGs and realise the Africa Water Vision 2025. We propose to launch an innovative research approach: the Adaptive Systemic Approach (ASA). Our aim is to apply transformative, transdisciplinary, community-engaged research, to shift water development outcomes towards achieving the SDGs. We focus on continental water development priorities: water supply and pollution. This collaboration brings together the ARUA Water Centre of Excellence (CoE) and UK partner, the University of Sheffield (UoS). The 8 CoE nodes are: i) Addis Ababa U, Ethiopia; U Rwanda, Rwanda; U Cheikh Anta Diop, Senegal; Dar es Salaam U, Tanzania, Makerere U, Uganda (DAC least developed); ii) U Lagos, Nigeria (DAC lower-middle income); and iii) U Cape Town, Rhodes U (CoE Hub), South Africa (DAC upper-middle income). We propose a country-based Case Study structure to support local research development and pathways to local impact (Figure 1 in Case for Support). We use an SDG6 (water and sanitation) centred model, that links SDGs related to landscape water resources with SDGs related to water services. (This model underpins the successful UKRI:GCRF Capability Grant:"Water for African SDGs"). We raise three research questions (RQ) related to water development priorities. Three catchment-based Case Studies address RQ1: HOW IS WATER USED, TO WHOSE BENEFIT? (Rufigi R Tanzania, Senegal R Senegal, and Blue Nile R Ethiopia). Two Case Studies focus on urban water pollution (Kampala City Uganda and Lagos City Nigeria), addressing RQ2: WHAT ARE THE SOURCES, PATHWAYS AND IMPACT OF POLLUTION IN URBAN WATER SYSTEMS? A cross-cutting Case Study addresses water resource protection and biodiversity in all CSs, and a biodiversity site in Rwanda. By the completion of the project we commit to leaving local people effectively linked with institutions making decisions about water that affect them. Therefore all Case Studies address the question RQ3: HOW CAN LOCAL CAPACITY TO ENGAGE IN PARTICIPATORY GOVERNANCE BE DEVELOPED FOR: I) EQUITABLE WATER SHARING, II) COMMUNITY POLLUTION RESILIENCE, AND III) ECOSYSTEM PROTECTION AND RESTORATION? The novel Adaptive Systemic Approach (ASA) provides a coherent methodological framework that will support Case Study comparisons, changed water development practice, and will embed pathways to impact throughout the project. The ASA requires engaged research, and draws on three core theoretical concepts, with associated methods: Complex Social-Ecological Systems, Transdisciplinarity, and Transformative Social Learning (Elaborated in Case for Support). These concepts underpin four ASA steps, followed in each Case Study: 1. BOUND: Researchers engage with a full range of stakeholders to identify a relevant, local, water-development issue, and scope the Case Study. 2. ADAPTIVE PLANNING PROCESS: Stakeholders co-create a contextually informed vision of the future state of their selected local issue, and co-develop an objectives hierarchy to move towards resolving the issue. 3. CONCURRENT ACTIVITIES 3.1 RESEARCH Each Case study team addresses the specific research questions, delivering data for resolving the problem. 3.2 PARTICIPATORY GOVERNANCE DEVELOPMENT Local people, formal, and traditional, water governance institutions together move towards local people being part of land and water decision-making. 3.3 STRATEGIC ADAPTIVE MANAGEMENT (SAM) - stakeholders will be trained in a process for systemic, responsive, contextual, co-management. 4. PARTICIPATORY MONITORING AND EVALUATION OF REFLEXIVE LEARNING Researchers and stakeholders co-develop indicators, co-monitor, co-reflect on progress, co-learn and adapt, using SAM. Following the ASA in the case studies embeds the theory of change, and the pathways to impact.