Paul Block

Bio: Paul Block is an academic researcher from University of Wisconsin-Madison. The author has contributed to research in topics: Climate change & Hydropower. The author has an hindex of 21, co-authored 76 publications receiving 1421 citations. Previous affiliations of Paul Block include CGIAR & Columbia University.

A streamflow forecasting framework using multiple climate and hydrological models.

Abstract: Water resources planning and management efficacy is subject to capturing inherent uncertainties stemming from climatic and hydrological inputs and models. Streamflow forecasts, critical in reservoir operation and water allocation decision making, fundamentally contain uncertainties arising from assumed initial conditions, model structure, and modeled processes. Accounting for these propagating uncertainties remains a formidable challenge. Recent enhancements in climate forecasting skill and hydrological modeling serve as an impetus for further pursuing models and model combinations capable of delivering improved streamflow forecasts. However, little consideration has been given to methodologies that include coupling both multiple climate and multiple hydrological models, increasing the pool of streamflow forecast ensemble members and accounting for cumulative sources of uncertainty. The framework presented here proposes integration and offline coupling of global climate models (GCMs), multiple regional climate models, and numerous water balance models to improve streamflow forecasting through generation of ensemble forecasts. For demonstration purposes, the framework is imposed on the Jaguaribe basin in northeastern Brazil for a hindcast of 1974-1996 monthly streamflow. The ECHAM 4.5 and the NCEP/MRF9 GCMs and regional models, including dynamical and statistical models, are integrated with the ABCD and Soil Moisture Accounting Procedure water balance models. Precipitation hindcasts from the GCMs are downscaled via the regional models and fed into the water balance models, producing streamflow hindcasts. Multi-model ensemble combination techniques include pooling, linear regression weighting, and a kernel density estimator to evaluate streamflow hindcasts; the latter technique exhibits superior skill compared with any single coupled model ensemble hindcast.

Interannual Variability and Ensemble Forecast of Upper Blue Nile Basin Kiremt Season Precipitation

Abstract: Ethiopian agriculture and Nile River flows are heavily dependent upon the Kiremt season (June–September) precipitation in the upper Blue Nile basin, as a means of rain-fed irrigation and streamflow contribution, respectively. Climate diagnostics suggest that the El Nino–Southern Oscillation phenomenon is a main driver of interannual variability of seasonal precipitation in the basin. One-season (March–May) lead predictors of the seasonal precipitation are identified from the large-scale ocean–atmosphere–land system, including sea level pressures, sea surface temperatures, geopotential height, air temperature, and the Palmer Drought Severity Index. A nonparametric approach based on local polynomial regression is proposed for generating ensemble forecasts. The method is data driven, easy to implement, and provides a flexible framework able to capture any arbitrary features (linear or nonlinear) present in the data, as compared to traditional linear regression. The best subset of predictors, as dete...

Economic Analysis of Large-Scale Upstream River Basin Development on the Blue Nile in Ethiopia Considering Transient Conditions, Climate Variability, and Climate Change

Abstract: The upper Blue Nile Basin in Ethiopia harbors considerable untapped potential for irrigation and large-scale hydropower development and expansion. Numerous water resources system models have been developed to evaluate these resources, yet often fail to adequately address critical aspects, including the transient e.g., filling stages of reservoirs, relevant streamflow retention policies and downstream consequences, construction staggering, and the implications of stochastic modeling of variable climate and climate change. This omission has clear economic impacts on benefits and costs and could be pivotal in national policy and decision making. The Investment Model for Planning Ethiopian Nile Development dynamic water resources system model is outlined and applied to address these aspects. For the hydropower and irrigation development projects specified, model results disregarding transient and construction stagger aspects demonstrate overestimations of $6 billion in benefits and 170% in downstream flows compared to model results account- ing for these aspects. Benefit-cost ratios for models accounting for transient conditions and climate variability are found to range from 1.2-1.8 under historical climate regimes for the streamflow retention policies evaluated. Climate change scenarios, represented either by changes in the frequency of El Nino and La Nina events or by the Special Report on Emissions Scenarios projections, indicate potential for small benefit-cost increases, but also reflect the potential for noteworthy decreases, relative to the historical climate conditions. In particular, stochastic modeling of scenarios representing a doubling of the historical frequency of El Nino events indicates benefit-cost ratios as low as 1.0, even under perfect foresight optimization modeling, due to a lack of timely water. However, even at this ratio, Ethiopia, at current growth rates, may still be unable to absorb all the potential energy developed, reinforcing the need for significant economic planning and the necessity of securing energy trade contracts prior to extensive expansion.

Bridging critical gaps in climate services and applications in Africa

Abstract: Sound climate risk management requires access to the best available decision-relevant climate information and the ability to use such information effectively. The availability and access of such information and the ability to use it is challenging, particularly throughout rural Africa. A gap analysis published by the International Research Institute for Climate and Society (IRI) and the Global Climate Observing System (GCOS) in 2005 explored these challenges in detail and identified four key gaps: (i) gaps in integration of climate into policy; (ii) gaps in integration of climate into practice at scale; (iii) gaps in climate services; and (iv) gaps in climate data. Though this document was published nearly nine years ago, the gaps it highlighted are still relevant today. In the last decade, IRI has been making efforts to address these critical issues in a systematic way through projects and partnerships in Africa. This paper describes IRI’s efforts in Ethiopia, a country particularly prone to climate related risks. Here we outline a creative solution to bridge the gaps in the availability, access and use of national climate information through the Enhancing National Climate Services (ENACTS) initiative. We then discuss how policy and practice has changed as a result of IRI engagement in the development of climate services in the water, public health and agricultural sectors. The work in Ethiopia is indicative of the efforts IRI is implementing in other countries in Africa and in other parts of the world.

Micro-Level Analysis of Farmers’ Adaptation to Climate Change in Southern Africa

Abstract: "Adaptation to climate change involves changes in agricultural management practices in response to changes in climate conditions. It often involves a combination of various individual responses at the farm-level and assumes that farmers have access to alternative practices and technologies available in the region. This study examines farmer adaptation strategies to climate change in Southern Africa based on a cross-section database of three countries (South Africa, Zambia and Zimbabwe) collected as part of the Global Environment Facility/World Bank (GEF/WB) Climate Change and African Agriculture Project. The study describes farmer perceptions to changes in long-term temperature and precipitation as well as various farm-level adaptation measures and barriers to adaptation at the farm household level. A multivariate discrete choice model is used to identify the determinants of farm-level adaptation strategies. Results confirm that access to credit and extension and awareness of climate change are some of the important determinants of farm-level adaptation. An important policy message from these results is that enhanced access to credit, information (climatic and agronomic) as well as to markets (input and output) can significantly increase farm-level adaptation. Government policies should support research and development on appropriate technologies to help farmers adapt to changes in climatic conditions. Examples of such policy measures include crop development, improving climate information forecasting, and promoting appropriate farm-level adaptation measures such as use of irrigation technologies." from Authors' Abstract

Anthropogenic stresses on the world’s big rivers

Abstract: The world’s big rivers and their floodplains were central to development of civilization and are now home to c. 2.7 billion people. They are economically vital whilst also constituting some of the most diverse habitats on Earth. However, a number of anthropogenic stressors, including large-scale damming, hydrological change, pollution, introduction of non-native species and sediment mining, challenge their integrity and future, as never before. The rapidity and extent of such change is so great that large-scale, and potentially irreparable, transformations may ensue in periods of years to decades, with ecosystem collapse being possible in some big rivers. Prioritizing the fate of the world’s great river corridors on an international political stage is imperative. Future sustainable management, and establishment of environmental flow requirements for the world’s big rivers, must be supported through co-ordinated international funding, and trans-continental political agreement to monitor these rivers, finance their continual upkeep and help ameliorate increasing anthropogenic pressures. To have any effect, all of these must be set within an inclusive governance framework across scales, organizations and local populace. Stressors such as large-scale damming, hydrological change, pollution, the introduction of non-native species and sediment mining are challenging the integrity and future of large rivers, according to a synthesis of the literature on the 32 biggest rivers.

Adaptation to climate change in Africa: Challenges and opportunities identified from Ethiopia

Abstract: Africa is widely held to be highly vulnerable to future climate change and Ethiopia is often cited as one of the most extreme examples. With this in mind we seek to identify entry points to integrate short- to medium-term climate risk reduction within development activities in Africa, drawing from experiences in Ethiopia. To achieve this we employ a range of data and methods. We examine the changing nature of climate risks using analysis of recent climate variability, future climate scenarios and their secondary impacts. We assess the effects of climate variability on agricultural production and national GDP. Entry points and knowledge gaps in relation to mainstreaming climate risks in Ethiopia are identified using the Government's plan for poverty reduction. We end with a case study incorporating climate risks through drought insurance within the current social protection programme in Ethiopia, which provides support to 8.3 million people. Rainfall behaviour in Ethiopia shows no marked emergent changes and future climate projections show continued warming but very mixed patterns of rainfall change. Economic analysis highlights sensitivities within the economy to large-scale drought, however, while the effects are clear in major drought years in other years the relationship is weak. For social protection fairly small positive and negative effects on the number of recipients and frequency of cash payments during drought occur under the extreme range of climate model rainfall projections (2020s). Our analysis highlights several important challenges and opportunities for addressing climate risks. Challenges primarily relate to the large uncertainties in climate projections for parts of Africa, a weak evidence base of complex, often non-deterministic, climate–society interactions and institutional issues. Opportunities relate to the potential for low-regrets measures to reduce vulnerability to current climate variability which can be integrated with relatively modest effort within a shift in Africa from a disaster-focused view of climate to a long-term perspective that emphasises livelihood security and vulnerability reduction.