Tobias Siegfried

Will climate change exacerbate water stress in Central Asia

Millions of people in the geopolitically important region of Central Asia depend on water from snow- and glacier-melt driven international rivers, most of all the Syr Darya and Amu Darya. The riparian countries of these rivers have experienced recurring water allocation conflicts ever since the Soviet Union collapsed. Will climate change exacerbate water stress and thus conflicts? We have developed a coupled climate, land-ice and rainfall-runoff model for the Syr Darya to quantify impacts and show that climatic changes are likely to have consequences on runoff seasonality due to earlier snow-melt. This will increase water stress in unregulated catchments because less water will be available for irrigation in the summer months. Threats from geohazards, above all glacier lake outbursts, are likely to increase as well. The area at highest risk is the densely populated, agriculturally productive, and politically unstable Fergana Valley. Targeted infrastructural developments will be required in the region. If the current mismanagement of water and energy resources can be replaced with more effective resource allocation mechanisms through the strengthening of transboundary institutions, Central Asia will be able to successfully address these future climate-related challenges.

Climate change and international water conflict in Central Asia

We engage in a critical assessment of the neo-malthusian claim that climatic changes can be an important source of international tensions, in the extreme even militarized interstate disputes. The most likely scenario is conflict over water allocation in international catchments shared by poorer, less democratic, and politically less stable countries, governed by weak international water management institutions, and exposed to severe climatic changes. The Syr Darya corresponds quite well to all these characteristics. If the neo-malthusian specter of conflict over water is empirically relevant, we should see signs of this in the Syr Darya. The riparian countries of the Aral Sea basin have experienced international disputes over water allocation ever since the USSR collapsed and, with it, existing water management institutions and funding. The worst such dispute concerns the Syr Darya, one of the two largest rivers in Central Asia. Based on hydrological data and other information we find that the only existing international water management institution in the Syr Darya has failed. Based on a coupled climate, land-ice and rainfall-runoff model for the Syr Darya, we then examine whether, in the absence of an effective international water allocation mechanism, climate change is likely to make existing international tensions over water allocation worse. We find that climate change-induced shifts in river runoff, to which the Uzbek part of the Syr Darya catchment is particularly vulnerable, and which could contribute to a deterioration of already strained Kyrgyz–Uzbek relations, are likely to set in only in the medium to long term. This leaves some time for the riparian countries to set up an effective international framework for water allocation and prevention of climate-induced geohazards. By implication, our findings suggest that a climate change-induced militarized interstate dispute over water resources in Central Asia is unlikely.

Multiobjective Groundwater Management Using Evolutionary Algorithms

Sustainable management of groundwater resources is of crucial importance for regions where freshwater supply is naturally limited. Long-term planning of groundwater usage requires computer-based decision support tools: on the one hand, they must be able to predict the complex system dynamics with sufficient accuracy, on the other, they must allow exploring management scenarios with respect to different criteria such as sustainability, cost, etc. In this paper, we present a multiobjective evolutionary algorithm for groundwater management that optimizes the placement and the operation of pumping facilities over time, while considering multiple neighboring regions which are economically independent. The algorithm helps in investigating the cost tradeoffs between the different regions by providing an approximation of the Pareto-optimal set, and its capabilities are demonstrated on a three-region problem. The application of the proposed methodology can also serve as a benchmark problem as shown in this paper. The corresponding implementation is freely available as a precompiled module at http://www.tik.ee.ethz.ch/pisa.

Estimating the Performance of International Regulatory Regimes: Methodology and Empirical Application to International Water Management in the Naryn/Syr Darya Basin

We develop a methodology for estimating the performance of international regulatory regimes in the context of transboundary surface waters. Our performance metric relies on assessments, over time, of actual performance, counterfactual performance, and optimal performance. The metric is of practical relevance as a diagnostic tool for policy evaluation. Thus it provides a starting point for policy improvement. To demonstrate the empirical relevance of this methodology we examine international water management in the Naryn/Syr Darya basin, a major international river system in Central Asia. The emphasis is on the Toktogul reservoir, the main reservoir in the Naryn/Syr Darya basin, and its downstream effects. The biggest policy challenge in this case has been to design and implement international trade-offs among water releases for upstream hydropower production in winter and water releases for downstream irrigation in summer. We find that the international regime in place since 1998 is characterized by low average performance and high variability.

Modeling Irrigated Area to Increase Water, Energy, and Food Security in Semiarid India

Abstract Because of declining public investments in irrigation projects in India, the growth of irrigated agricultural production has increasingly become reliant on unsustainable allocation of groundwater. As a result, groundwater resources are increasingly depleted and their role in buffering climate variability is lost. Given future climate and food supply uncertainty under mounting population pressure, it is vital that the connections between climate variability, unsustainable irrigation practices, and their impacts on regional-scale agricultural production are quantified. Here, the focus is on rice and maize production in the semiarid Telangana region in Andhra Pradesh, where the advent of inexpensive pump technology in the late twentieth century, coupled with governmentally subsidized electricity, has allowed year-round planting of water-intensive crops. Using a 35-yr climate and agricultural dataset from Telangana, nonlinear Gaussian process district-level regression models are developed to model dr...