The integrated project will combine a socio-economic approach (Dr. Thomas Uhlendahl, Inst. of Cultural Geography), a hydrological system-oriented approach (working group Dr. C. Kuells, Dipl.Hydr. Vera Marx, Inst. of Hydrology) and an eco-hydrological approach to water resources management.

The common idea is to develop an integrated method of socio-economic and system-oriented hydrological approaches to water resources management applicable in Africa.

The approach involves a socio-economic analysis based on participative methods in which relevant issues and problems affecting social, ecological and economic systems are identified by local experts. Stakeholders and the local population are involved as local experts. These issues are then analysed by disciplinary teams of hydrologists and ecologists. Their contributions will be integrated by interactive eco-hydrological models. In the final step of the analysis, participative and adaptive modeling techniques are used (Individuum-based and Multi-Agent Models) to allow for interaction between ecological and hydrological system properties with stakeholder actions. The integrated analysis will result in recommendations translated into behavioral rules valid for a specific eco-hydrological system.

This approach is based on the balance between social equity, environmental sustainability and economic efficiency. The parties involved recognize the complementarity of their approaches and commit themselves to interdisciplinary cooperation. Interdisciplinary cooperation is achieved through the translation of disciplinary results into guidelines.

Resilience of water resources and their distribution infrastructures in Southern Africa.

We suggest to assess the risk and adaptation time of ecological and hydrological systems in South Africa to climate change, especially systems being intensively used e.g. for water supply. We will characterize the response time of systems to changes in either direction – increase or decrease of climatic driving forces such as rainfall.

The residence time of water in hydrological systems varies between days or weeks for soils, weeks or months for rivers and months to millennia for groundwater. Climate variability and long term climate changes will affect the hydrological regime causing a specific response of the hydrologic system. This can be either fast and direct or very slow and almost undetectable at the time-scale of human life.

Deterministic approaches based on a process chain of causes and effects suffer from error propagation and resulting uncertainty. Especially biological and socio-economic systems with inherent adaptation capacity render deterministic impact analysis difficult. On the other hand safe water supply and access to water are critical for social peace and socio-economic development. Hence, prediction of climate change impacts on these systems are needed. We propose to focus on the system properties that can be assessed with much less uncertainty and to build adaptation strategies on the inherent properties of ecological and hydrological systems.

The adaptation of water supply structures, planning and execution of water diversion plans, dam construction and regional groundwater schemes, or artificial recharge require time. Therefore, it is critical to know the response time of natural systems that can range from years to millennia and to assess the risk of water supplies failing for given impacts. The proposed approach will provide information on the stability of systems and will help to develop adaptation strategies for vulnerable and relevant systems first. The analysis of system dynamics will also help to identify resilient and rather safe systems that can act as temporary backup-systems. We suggest to develop specific protection strategies for these resilient systems and to create integrated adaptation and response strategies for resilient and vulnerable systems.

We hypothesize that preparedness for climate change impacts and adaptation strategies need to be optimized by understanding ecological and hydrological system response and response time. This approach uses climate predictions but does not depend on their inherent uncertainty as it is decoupled from regional climate models.

We propose to characterize the response time of hydrologic systems in South Africa that are being used intensively and that are critical for water supply (Cape Town, Johannesburg), for economic activities and for major ecological systems. The study shall cover typical socio-economic and ecological zones (e.g. Namaqualand: hardrock dominated rural landscape, Kalahari: sedimentary basins with rural population). The approach will be based on a combination of system analysis, environmental tracer application for age dating of water and innovative modeling approaches for regional modeling of ecological and hydrological system dynamics.

Modeling will include 3 innovative elements:

• adaptation will be based on optimality principles and on equilibrium state models (e.g. based on the emergy theory)
• equilibration time will be described by kinetic models of eco-hydrological systems and will be calibrated with and validated against measured residence time
• integrated socio-economic and eco-hydrological models will be implemented that are based on social, economic and physiological rules coupled to physical models of resources availability.

The system analysis will consist of a topologic analysis of the basin structure. Each system will be characterized consistently by an input function, permeability, gradient and storage based on available data. Based on the application of different environmental tracers the age of groundwater at different locations in the system will be determined. Finally, a regional flow model will be developed that includes the parameters of the system analysis and fits the measured age.

The calibrated flow model will be used to generate response and adaptation times for different impact scenarios. The results will be regionalized to provide maps of minimal and maximal groundwater residence time. Thematic maps on impacts for specific scenarios and resilience will be developed. Based on the results of response time analysis the risk and magnitude of climate change impacts for selected water supply systems will be quantified. Recommendations on the adaptation of water supply schemes will be developed. We suggest to develop ‘rules of sustainability’, simple applicable sets of rules for sustainable and safe water supply.