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The paper demonstrates the application of a new water accounting plus (WA+) framework to produce information on depletion of water resources, storage change, and land and water productivity in the Indus basin
. It shows how satellite-derived estimates of land use, rainfall, evaporation (E), transpiration (T), interception (I) and biomass production can be used in addition to measured basin outflow, for water accounting with WA+. It is demonstrated how the accounting results can be interpreted to identify existing issues and examine solutions for the future. The results for one selected year (2007) showed that total annual water depletion in the basin (501 km3) plus outflows (21 km3) exceeded total precipitation (482 km3). The water storage systems that were effected are groundwater storage (30 km3), surface water storage (9 km3), and glaciers and snow storage (2 km3). Evapotranspiration of rainfall or "landscape ET" was 344 km3 (69 % of total depletion). "Incremental ET" due to utilized flow was 157 km3 (31% of total depletion). Agriculture depleted 297 km3, or 59% of the total depletion, of which 85% (254 km3) was through irrigated agriculture and the remaining 15% (44 km3) through rainfed systems. Due to excessive soil evaporation in agricultural areas, half of all water depletion in the basin was non-beneficial. Based on the results of this accounting exercise loss of storage, low beneficial depletion, and low land and water productivity were identified as the main water resources management issues. Future scenarios to address these issues were chosen and their impacts on the Indus Basin water accounts were tested using the new WA+ framework
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Coping with water scarcity and growing competition for water among different sectors requires proper water management strategies and decision processes
. A pre-requisite is a clear understanding of the basin hydrological processes, manageable and unmanageable water flows, the interaction with land use and opportunities to mitigate the negative effects and increase the benefits of water depletion on society. Currently, water professionals do not have a common framework that links depletion to user groups of water and their benefits. The absence of a standard hydrological and water management summary is causing confusion and wrong decisions. The non-availability of water flow data is one of the underpinning reasons for not having operational water accounting systems for river basins in place. In this paper, we introduce Water Accounting Plus (WA+), which is a new framework designed to provide explicit spatial information on water depletion and net withdrawal processes in complex river basins. The influence of land use and landscape evapotranspiration on the water cycle is described explicitly by defining land use groups with common characteristics. WA+ presents four sheets including (i) a resource base sheet, (ii) an evapotranspiration sheet, (iii) a productivity sheet, and (iv) a withdrawal sheet. Every sheet encompasses a set of indicators that summarise the overall water resources situation. The impact of external (e.g., climate change) and internal influences (e.g., infrastructure building) can be estimated by studying the changes in these WA+ indicators. Satellite measurements can be used to acquire a vast amount of required data but is not a precondition for implementing WA+ framework. Data from hydrological models and water allocation models can also be used as inputs to WA+
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The paper describes the application of a new Water Accounting Plus (WA+) framework to produce spatial information on water flows, sinks, uses, storages and assets, in the Indus Basin, South Asia
. It demonstrates how satellite-derived estimates of land use, land cover, rainfall, evaporation (E), transpiration (T), interception (I) and biomass production can be used in the context of WA+. The results for one selected year showed that total annual water depletion in the basin (502 km3) plus outflows (21 km3) exceeded total precipitation (482 km3). The deficit in supply was augmented through abstractions beyond actual capacity, mainly from groundwater storage (30 km3). The "landscape ET" (depletion directly from rainfall) was 344 km3 (69% of total consumption). "Blue water" depletion ("utilized flow") was 158 km3 (31%). Agriculture was the biggest water consumer and accounted for 59% of the total depletion (297 km3), of which 85% (254 km3) was through irrigated agriculture and the remaining 15% (44 km3) through rainfed systems. While the estimated basin irrigation efficiency was 0.84, due to excessive evaporative losses in agricultural areas, half of all water consumption in the basin was non-beneficial. Average rainfed crop yields were 0.9 t ha−1 and 7.8 t ha−1 for two irrigated crop growing seasons combined. Water productivity was low due to a lack of proper agronomical practices and poor farm water management. The paper concludes that the opportunity for a food-secured and sustainable future for the Indus Basin lies in focusing on reducing soil evaporation. Results of future scenario analyses suggest that by implementing techniques to convert soil evaporation to crop transpiration will not only increase production but can also result in significant water savings that would ease the pressure on the fast declining storage
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Groundwater irrigation consumes considerable energy as well as water resources across the globe
. Using a case study from Iran, this paper explores how enhanced farm water management can help in reducing groundwater exploitation and subsequently limiting energy consumption and the carbon footprint of the groundwater economy. Groundwater use for irrigated agriculture in Iran has increased vastly over the last three decades. We estimate that groundwater pumping consumes 20.5 billion kWh electricity and 2 billion liters of diesel and contributes to 3.6% of the total carbon emission of the country. Thus there is an opportunity to reduce energy use and carbon emissions by pumping less water. However, groundwater use remains important for food security. To identify opportunities for water conservation within agricultural fields, the SWAP model was applied to simulate crop growth and field water balance for three major irrigated crops, i.e. wheat, maize, and sugar beet in the Gamasiab River Basin, one of the highest groundwater using irrigated areas of Iran. The model simulations showed that by adopting improved irrigation schedules and improving farm application efficiencies, water productivity will increase, and irrigation water withdrawals from groundwater can be reduced significantly with no reduction in yields. While these improvements may or may not result in water saving and retarding the ground water decline, depending on the fate of excess application, they will have significant water quality, energy, and carbon implications. Such reduction in irrigation application can result in 40% decline in energy consumption and subsequently carbon emission of groundwater use
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Coping with water scarcity requires improvement in the way that water is managed in most areas of the world
. Underpinning water management is the basic information on the availability and use of water resources. However, reliable information about water resources is hard to obtain for several reasons, one of which is availability of data. Even where data are available the task of identifying who uses how much water remains difficult because of hydrologic complexities of water use, storage and water reuse, especially in heavily developed river basins. The objective of the chapter is to introduce the International Water Management Institute (IWMI) Water Accounting Framework (IWMI WA), developed in 1997, and recent developments related to this water accounting system. IWMI WA provides information on supply and use of water and relates water use to the economy. It is a multiscale method to account for the amount of water available, how much is used by various sectors and the value derived from the use to promote understanding of water use and assist with improved water management. In illustrating the IWMI WA system, concepts and definitions plus examples from different areas and scales are discussed in this chapter. In a basin context, water accounting defines water availability and helps users to understand water use and benefits and costs derived from its use
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The Nile provides freshwater not only for domestic and industrial use, but also for irrigated agriculture, hydropower dams and the vast fisheries resource of the lakes of Central Africa
. The Nile River Basin covers the whole Nile Basin and is based on the results of three major research projects supported by the Challenge Program on Water and Food (CPWF). It provides unique and up-to-date insights on agriculture, water resources, governance, poverty, productivity, upstream-downstream linkages, innovations, future plans and their implications. Specifically, the book elaborates the history and the major current and future challenges and opportunities of the Nile river basin. It analyzes the basin characteristics using statistical data and modern tools such as remote sensing and geographic information systems. Population distribution, poverty and vulnerability linked to production system and water access are assessed at the international basin scale, and the hydrology of the region is also analysed. This text provides in-depth scientific model adaptation results for hydrology, sediments, benefit sharing, and payment for environmental services based on detailed scientific and experimental work of the Blue Nile Basin. Production systems as they relate to crops, livestock, fisheries and wetlands are analyzed for the whole Blue and White Nile basin including their constraints. Policy, institutional and technological interventions that increase productivity of agriculture and use of water are also assessed. Water demand modeling, scenario analysis, and tradeoffs that inform future plans and opportunities are included to provide a unique, comprehensive coverage of the subject
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This article summarizes the results of water productivity assessment in 10 river basins across Asia, Africa and South America, representing a range of agro-climatic and socio-economic conditions
. Intensive farming in the Asian basins gives much greater agricultural outputs and higher water productivity. Largely subsistence agriculture in Africa has significantly lower water productivity. There is very high intra-basin variability, which is attributed mainly to lack of inputs, and poor water and crop management. Closing gaps between ?bright spots? and the poorly performing areas are the major tasks for better food security and improved livelihoods, which have to be balanced with environmental sustainability
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This article summarizes the results of water productivity assessment in 10 river basins across Asia, Africa and South America, representing a range of agro-climatic and socio-economic conditions
. Intensive farming in the Asian basins gives much greater agricultural outputs and higher water productivity. Largely subsistence agriculture in Africa has significantly lower water productivity. There is very high intra-basin variability, which is attributed mainly to lack of inputs, and poor water and crop management. Closing gaps between ?bright spots? and the poorly performing areas are the major tasks for better food security and improved livelihoods, which have to be balanced with environmental sustainability
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