Inter-sectoral Water Use in South Africa: Efficiency Versus Equity

While water supply sources are dwindling in South Africa, the demand for the scarce water resource is increasing. This situation requires a switch from supply to demand management of water in the country. The study updates the 1999 social accounting matrix for South Africa, using the Trade and Industrial Policy Strategies (TIPS) time series data, STATSA's 2001 census report and 2000 water accounts, the 2002 national income accounts, published by the South African Reserve Bank (SARB) and the Water Resource Management Strategy (WRMS) registration data. Using the updated SAM, the contribution of water to economic development in South Africa is estimated through the traditional SAM multiplier analysis. The paper then investigates the impact of reallocating water among the production sectors, on the basis of economic efficiency, on output growth, factor remuneration and households' income generation. The computational and simulation results show that, though agriculture is among the sectors that have the least marginal value of water, water reallocation based on marginal values will reduce the incomes of the poorest households, and put at stake the livelihoods of the most vulnerable population. Scenario analyses suggest that this effect will be minimal if marginal productivity consideration for inter-sectoral water reallocation is reduced to 30%, while intra-sectoral water reallocation on the basis of efficiency is currently viewed as the most viable option.SAM multipliers, output growth, factor remuneration, income generation, efficiency, equity, R20, Resource /Energy Economics and Policy, C67, D57, L60, Q25,

Households’ welfare analyses of the impact of global change on water resources in South Africa

Most of the climate change models for South Africa predict a reduction in freshwater availability by 2050. Population growth is projected at 3% per annum, implying increased domestic water use. In addition to these factors, the concern for ecological sustainability and increased water pollution due to increased industrial, mining and agricultural activities, water availability for sectoral production activities is expected to decline. This decline has an impact on sectoral output, value added and households’ welfare. Using a computable general equilibrium approach, this study investigates the possible impact of global change on households’ welfare. The simulation results show that water scarcity due to global change can potentially lead to a general deterioration in households’ welfare. The poor households, whose incomes are adversely impacted, are the most vulnerable to the consequences of the impact of global change on water resources in South Africa. This vulnerability can only be reduced if welfare policies that maintain food consumption levels for the least and low-income households are implemented.Resource /Energy Economics and Policy,

THE VALUE OF THE HIGH ASWAN DAM TO THE EGYPTIAN ECONOMY

The High Aswan Dam converted a variable and uncertain flow of river water into a predictable and controllable flow. We use a computable general equilibrium model of the Egyptian economy to estimate the economic impact of the High Aswan Dam. We compare the 1997 economy as it was to the 1997 economy as it would have been for 72 historical, pre-dam water flows. The steady water flow increased transport productivity, while the seasonal shift in water supply allowed for a shift towards more valuable summer crops. These static effects are worth LE 4.9 billion. Investments in transport and agriculture increased as a consequence. Assuming that Egypt is a small open economy, this is worth another LE 1.1 billion. The risk premium on the reduced variability is estimated to be LE 1.1 billion for a modest risk aversion, and perhaps LE 4.4 billion for a high risk aversion. The total gain of LE 7.1 billion equals 2.7% of GDP.Egypt, High Aswan Dam, computable general equilibrium model, risk premium, water supply

Modeling Water Withdrawal and Consumption for Electricity Generation in the United States

http://globalchange.mit.edu/research/publicationsWater withdrawals for thermoelectric cooling account for a significant portion of total water use in the United States. Any change in electrical energy generation policy and technologies has the potential to have a major impact on the management of local and regional water resources. In this report, a model of Withdrawal and Consumption for Thermo-electric Systems (WiCTS) is formalized. This empirically-based framework employs specific water-use rates that are scaled according to energy production, and thus, WiTCS is able to estimate regional water withdrawals and consumption for any electricity generation portfolio. These terms are calculated based on water withdrawal and consumption data taken from the United States Geological Survey (USGS) inventories and a recent NREL report. To illustrate the model capabilities, we assess the impact of a high-penetration of renewable electricity-generation technologies on water withdrawals and consumption in the United States. These energy portfolio scenarios are taken from the Renewable Energy Futures (REF) calculations performed by The U.S. National Renewable Energy Laboratory (NREL) of the U.S. Department of Energy (DOE). Results of the model indicate that significant reductions in water use are achieved under the renewable technology portfolio. Further experiments illustrate additional capabilities of the model. We investigate the impacts of assuming geothermal and concentrated solar power technologies employing wet cooling systems versus dry as well as assuming all wet cooling technologies use closed cycle cooling technologies. Results indicate that water consumption and withdrawals increase under the first assumption, and that water consumption increases under the second assumption while water withdrawals decrease.The authors gratefully acknowledge the financial support from and collaborative efforts with the National Renewable Energy Laboratory. The authors would also like to thank Joan Kenny and Molly Maupin from the United States Geological Survey for their help in clarifying some questions we had surrounding the data in the recent USGS water use report. The authors also gratefully acknowledge the financial support of the MIT Joint Program on the Science and Policy of Global Change through a consortium of industrial sponsors and Federal grants

CLM-AG: An Agriculture Module for the Community Land Model version 3.5

It is estimated that 40% of all crops grown in the world today are grown using irrigation. As a consequence, shifting precipitation patterns due to climate change are viewed as a major threat to food security. This report presents the Community Land Model-Agriculture module (CLM-AG), which models crop growth and water stress. The CLM-AG model is a global generic crop model built in the framework of the Community Land Model version 3.5. This report describes the structure and main routines of the model. Two different evaluations of the model are then considered. First, at a global level, CLM-AG is run under a historic climatology and compared to the Global Agro-Ecological Zones, an existing model of irrigation need. Second, the irrigation need computed for the United States is compared to survey data from the United States Department of Agriculture. For both evaluations, CLM-AG results are comparable to either the model results or the surveyed data.Development of the IGSM applied in this research was supported by the U.S. Department of Energy, Office of Science (DE-FG02-94ER61937); the U.S. Environmental Protection Agency, EPRI, and other U.S. government agencies and a consortium of 40 industrial and foundation sponsors. For a complete list see http://globalchange.mit.edu/sponsors/current.htm

Projections of Water Stress Based on an Ensemble of Socioeconomic Growth and Climate Change Scenarios: A Case Study in Asia

The sustainability of future water resources is of paramount importance and is affected by many factors, including population, wealth and climate. Inherent in current methods to estimate these factors in the future is the uncertainty of their prediction. In this study, we integrate a large ensemble of scenarios—internally consistent across economics, emissions, climate, and population—to develop a risk portfolio of water stress over a large portion of Asia that includes China, India, and Mainland Southeast Asia in a future with unconstrained emissions. We isolate the effects of socioeconomic growth from the effects of climate change in order to identify the primary drivers of stress on water resources. We find that water needs related to socioeconomic changes, which are currently small, are likely to increase considerably in the future, often overshadowing the effect of climate change on levels of water stress. As a result, there is a high risk of severe water stress in densely populated watersheds by 2050, compared to recent history. There is strong evidence to suggest that, in the absence of autonomous adaptation or societal response, a much larger portion of the region’s population will live in water-stressed regions in the near future. Tools and studies such as these can effectively investigate large-scale system sensitivities and can be useful in engaging and informing decision makers

Competition for water for the food system

Although the global agricultural system will need to provide more food for a growing and wealthier population in decades to come, increasing demands for water and potential impacts of climate change pose threats to food systems. We review the primary threats to agricultural water availability, and model the potential effects of increases in municipal and industrial (M&I) water demands, environmental flow requirements (EFRs) and changing water supplies given climate change. Our models show that, together, these factors cause an 18 per cent reduction in the availability of worldwide water for agriculture by 2050. Meeting EFRs, which can necessitate more than 50 per cent of the mean annual run-off in a basin depending on its hydrograph, presents the single biggest threat to agricultural water availability. Next are increases in M&I demands, which are projected to increase upwards of 200 per cent by 2050 in developing countries with rapidly increasing populations and incomes. Climate change will affect the spatial and temporal distribution of run-off, and thus affect availability from the supply side. The combined effect of these factors can be dramatic in particular hotspots, which include northern Africa, India, China, parts of Europe, the western US and eastern Australia, among others

Modeling the Global Water Resource System in an Integrated Assessment Modeling Framework: IGSM-WRS

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/)The availability of water resources affects energy, agricultural and environmental systems, which are linked together as well as to climate via the water cycle. As such, watersheds and river basins are directly impacted by local and regional climate variations and change. In turn, these managed systems provide direct inputs to the global economy that serve and promote public health, agricultural and energy production, ecosystem surfaces and infrastructure. We have enhanced the Integrated Global System Model (IGSM) framework capabilities to model effects on the managed water-resource systems of the influence of potential climate change and associated shifts in hydrologic variation and extremes (i.e. non-stationarity in the hydro-climate system), and how we may be able to adapt to these impacts. A key component of this enhancement is the linkage of the Water Resources System (WRS) into the IGSM framework. WRS is a global river basin scale model of water resources management, agricultural (rain-fed and irrigated crops and livestock) and aquatic environmental systems. In particular, WRS will provide the capability within the IGSM framework to explore allocation of water among irrigation, hydropower, urban/industrial, and in-stream uses and investigate how society might adapt water resources due to shifts in hydro-climate variations and extremes. This paper presents the overall design of WRS, its linkages to the land system and economic models of the IGSM, and results of test bed runs of WRS components to address issues of temporal and spatial scales in these linkages.This study received support from the MIT Joint Program on the Science and Policy of Global Change, which is funded by a consortium of government, industry and foundation sponsors

Toward evaluating the effect of climate change on investments in the water resources sector: insights from the forecast and analysis of hydrological indicators in developing countries

The World Bank has recently developed a method to evaluate the effects of climate change on six hydrological indicators across 8951 basins of the world. The indicators are designed for decision-makers and stakeholders to consider climate risk when planning water resources and related infrastructure investments. Analysis of these hydrological indicators shows that, on average, mean annual runoff will decline in southern Europe; most of Africa; and in southern North America and most of Central and South America. Mean reference crop water deficit, on the other hand, combines temperature and precipitation and is anticipated to increase in nearly all locations globally due to rising global temperatures, with the most dramatic increases projected to occur in southern Europe, southeastern Asia, and parts of South America. These results suggest overall guidance on which regions to focus water infrastructure solutions that could address future runoff flow uncertainty. Most important, we find that uncertainty in projections of mean annual runoff and high runoff events is higher in poorer countries, and increases over time. Uncertainty increases over time for all income categories, but basins in the lower and lower-middle income categories are forecast to experience dramatically higher increases in uncertainty relative to those in the upper-middle and upper income categories. The enhanced understanding of the uncertainty of climate projections for the water sector that this work provides strongly support the adoption of rigorous approaches to infrastructure design under uncertainty, as well as design that incorporates a high degree of flexibility, in response to both risk of damage and opportunity to exploit water supply 'windfalls' that might result, but would require smart infrastructure investments to manage to the greatest benefit

The Future of Global Water Stress: An Integrated Assessment

We assess the ability of global water systems, resolved at 282 large river basins or Assessment Sub Regions (ASRs), to the meet water requirements over the coming decades under integrated projections of socioeconomic growth and climate change. We employ a Water Resource System (WRS) component embedded within the MIT Integrated Global System Model (IGSM) framework in a suite of simulations that consider a range of climate policies and regional hydroclimatic changes through the middle of this century. We find that for many developing nations water-demand increases due to population growth and economic activity have a much stronger effect on water stress than climate change. By 2050, economic growth and population change alone can lead to an additional 1.8 billion people living in regions with at least moderate water stress. Of this additional 1.8 billion people, 80% are found in developing countries. Uncertain regional climate change can play a secondary role to either exacerbate or dampen the increase in water stress due to socioeconomic growth. The strongest climate impacts on relative changes in water stress are seen over many areas in Africa, but strong impacts also occur over Europe, Southeast Asia and North America. The combined effects of socioeconomic growth and uncertain climate change lead to a 1.0 to 1.3 billion increase of the world's 2050 projected population living in regions with overly exploited water conditions— where total potential water requirements will consistently exceed surface-water supply. Under the context of the WRS model framework, this would imply that adaptive measures would be taken to meet these surface-water shortfalls and would include: water-use efficiency, reduced and/or redirected consumption, recurrent periods of water emergencies or curtailments, groundwater depletion, additional inter-basin transfers, and overdraw from flow intended to maintain environmental requirements.We assess the ability of global water systems, resolved at 282 large river basins or Assessment Sub Regions (ASRs), to the meet water requirements over the coming decades under integrated projections of socioeconomic growth and climate change. We employ a Water Resource System (WRS) component embedded within the MIT Integrated Global System Model (IGSM) framework in a suite of simulations that consider a range of climate policies and regional hydroclimatic changes through the middle of this century. We find that for many developing nations water-demand increases due to population growth and economic activity have a much stronger effect on water stress than climate change. By 2050, economic growth and population change alone can lead to an additional 1.8 billion people living in regions with at least moderate water stress. Of this additional 1.8 billion people, 80% are found in developing countries. Uncertain regional climate change can play a secondary role to either exacerbate or dampen the increase in water stress due to socioeconomic growth. The strongest climate impacts on relative changes in water stress are seen over many areas in Africa, but strong impacts also occur over Europe, Southeast Asia and North America. The combined effects of socioeconomic growth and uncertain climate change lead to a 1.0 to 1.3 billion increase of the world's 2050 projected population living in regions with overly exploited water conditions— where total potential water requirements will consistently exceed surface-water supply. Under the context of the WRS model framework, this would imply that adaptive measures would be taken to meet these surface-water shortfalls and would include: water-use efficiency, reduced and/or redirected consumption, recurrent periods of water emergencies or curtailments, groundwater depletion, additional inter-basin transfers, and overdraw from flow intended to maintain environmental requirements