To meet the food demand of a growing global population, agricultural production will have to more than double in this century. Agricultural land expansion combined with yield increases will therefore be required. This thesis investigates whether enough water resources will be available to sustain the future food production. Using a global scale hydrology and crop growth model, the combined effect of climate change and socio economic changes on water scarcity and food production were quantified. The first thing to explore was where water for agriculture is currently extracted. Reservoirs behind large dams are found to be very important for agriculture and contribute around 18% of the total irrigation water today. It is shown however that with current reservoir capacities and irrigation efficiencies, not enough water can be supplied to sustain an increased food production. Irrigation water shortage can lead to a loss of 20% of the irrigated crop production globally, but with important regional differences. Regions particularly at risk include basins in Southern Africa and South Asia, where production losses on irrigated cropland can become over 50%. This means that unless major investments are made towards improving irrigation efficiency and increasing storage capacity, water shortage will put a serious constraint on future food production.

To meet the food demand of a growing global population, agricultural production will have to more than double in this century. Agricultural land expansion combined with yield increases will therefore be required. This thesis investigates whether enough water resources will be available to sustain the future food production. Using a global scale hydrology and crop growth model, the combined effect of climate change and socio economic changes on water scarcity and food production were quantified. The first thing to explore was where water for agriculture is currently extracted. Reservoirs behind large dams are found to be very important for agriculture and contribute around 18% of the total irrigation water today. It is shown however that with current reservoir capacities and irrigation efficiencies, not enough water can be supplied to sustain an increased food production. Irrigation water shortage can lead to a loss of 20% of the irrigated crop production globally, but with important regional differences. Regions particularly at risk include basins in Southern Africa and South Asia, where production losses on irrigated cropland can become over 50%. This means that unless major investments are made towards improving irrigation efficiency and increasing storage capacity, water shortage will put a serious constraint on future food production.

Many regions in Africa and the Middle East are vulnerable to drought and to water and food insecurity, motivating agency efforts such as the U.S. Agency for International Development’s (USAID) Famine Early Warning Systems Network (FEWS NET) to provide early warning of drought events in the region. Each year these warnings guide life-saving assistance that reaches millions of people. A new NASA multimodel, remote sensing–based hydrological forecasting and analysis system, NHyFAS, has been developed to support such efforts by improving the FEWS NET’s current early warning capabilities. NHyFAS derives its skill from two sources: (i) accurate initial conditions, as produced by an offline land modeling system through the application and/or assimilation of various satellite data (precipitation, soil moisture, and terrestrial water storage), and (ii) meteorological forcing data during the forecast period as produced by a state-of-the-art ocean–land–atmosphere forecast system. The land modeling framework used is the Land Information System (LIS), which employs a suite of land surface models, allowing multimodel ensembles and multiple data assimilation strategies to better estimate land surface conditions. An evaluation of NHyFAS shows that its 1–5-month hindcasts successfully capture known historic drought events, and it has improved skill over benchmark-type hindcasts. The system also benefits from strong collaboration with end-user partners in Africa and the Middle East, who provide insights on strategies to formulate and communicate early warning indicators to water and food security communities. The additional lead time provided by this system will increase the speed, accuracy, and efficacy of humanitarian disaster relief, helping to save lives and livelihoods.

Climate change and variability will impact water availability and the food security of India. Trend analyses of historical data indicate an increase in temperature and changes in rainfall pattern in different parts of the country. The general circulation models (GCMs) also project increased warming and changes in precipitation patterns over India. This chapter presents examples of model applications in water management and crop yield simulation in India, focusing on climate change impact assessment. Simulation models have been successfully applied for rotational water allocation, deficit irrigation scheduling, etc. in different canal commands. Application of a universal soil loss equation in a distributed parametric modeling approach by partitioning watershed into erosion response units suggests that by treating only 14% of the watershed area, a 47% reduction in soil loss can be achieved. Simulation studies conducted using different hydrological models with different climate change projections and downscaling approaches showed varied hydrological responses of different river basins to the future climate change scenarios, depending on the hydrological model, climate change scenarios, and downscaling approaches used. Crop yield modeling showed decreases in irrigated and rainfed rice (Oryza sativa L.) yields under the future climate change scenarios, but the decrease is marginal for rainfed rice. Maize (Zea mays L.) yields in monsoon may be adversely affected by a rise in atmospheric temperature, but increased rain can partly offset those losses. Wheat (Triticum aestivum L.) yields are likely to be reduced by 6 to 23% and 15 to 25% during the 2050s and 2080s, respectively. A combined bottom-up participatory process and top-down integrated modeling tool could provide valuable information for locally relevant climate change adaptation planning.

ABSTRACT Tirta Sanita Bogor brine water contains high concentrations of sodium (Na). It also contains calcium (Ca) and magnesium (Mg). The purpose of this research is to make the food grade salt with relatively low Ca and Mg content. The process was carried out in two methods, the first method was chemical precipitation which was divided into two stages, the removal of the Mg element using a limestone compound (CaCO3) which has been calcined at 900 ̊C for 6 hours, and the removal of Ca element using Li2CO3 compound. The second method was traditional evaporation which was conducted using prism greenhouse technology. The brine filtrate was reacted with Na2CO3 and the results were analyzed using the ICP-OES. The results showed that the NaCl content was 80% by the chemical precipitation and traditional evaporation methods. Keywords: Brine water, Precipitation, Evaporation, Food grade salt

In the tropics, the water potential of a region cannot be adequately assessed from precipitation alone due to the seasonal character of rainfall and even more so owing to the changing climate scenario. It is therefore necessary that in any agro-climatological program, there must be a clear understanding of the actual amount of water that evaporates and transpires (AET), and the amount of water that would evaporate and transpire if water were always readily available (PET). This could be done through the method of the water balance. The present work examines the water budget of parts of the Imo river basin and its implications for improved crop production through supplementary irrigation schedules. It was observed, that the study area is already facing moisture-stress. This is because even during rainy months supplementary irrigation is required to compensate for the occasionally moisture deficit due to increased evapotranspiration. The study showed that cultivation of maize, rice and tomatoes can be carried out on an all-year round basis under a scientific irrigation scheme. Thus the study provided farmers with guideline on the period and quantity of water required for supplementary irrigation, a development which will prevents wilting of plants before the application of needed water.

Most food globally is produced from soil moisture that comes exclusively from precipitation, or “green” water. Moreover, most of the water reaching plants in irrigated systems also stems from precipitation. Despite this, irrigation or “blue” water has typically been the focus for policy analysis in the past, given the possibility for human manipulation of these resources. This paper analyzes alternative water futures using a combined green and blue water accounting framework embedded within the water simulation components of IFPRI's International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT). Recently developed future scenarios for the International Assessment of Agricultural Knowledge, Science and Technology for Development (IAASTD) and other work are assessed with this adjusted green/blue water accounting framework. Accounting explicitly for green water resources broadens the scope of options for decision-makers trying to improve agricultural production in the face of rising food and energy prices and a degrading water and land resource base in the face of increasing demands. Results highlight the importance of green/blue water accounting presenting a wider range of agricultural science and technology policy options for increasing global crop productivity across a span of potential futures.

Water scarcity is a critical issue for food production in the poor developing countries because agriculture is the primary consumer of the dwindling freshwater around the globe. This paper calls for strategies for the sustainable use of water in agriculture. Most food in the world is produced using soil moisture from precipitation - known as &ldquo;green&rdquo; water. Irrigation is the source of &ldquo;blue&rdquo; water. <br /><br />This paper analyses alternative water futures using a combined green and blue water accounting framework embedded within the water simulation components of IFPRI&rsquo;s International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT). It uses a series of scenario results to 2050 for the Limpopo and Nile River Basins, which are representative of the wide range of irrigation and rainfed agricultural conditions.<br /><br />The paper presents the following policy recommendations:<br /> an accounting framework that distinguishes between green and blue water should be included in projections to enable enhanced analysis of alternative policies for improving agricultural production in the face of growing water scarcity. to identify policy options an examination of the relative contribution of precipitation to total water consumption and that by irrigated areas can be useful. alternative investments in agricultural productivity and irrigation expansion, can lead to major water savings from both irrigation and precipitation. In the Limpopo Basin, growing water scarcity suggests the need for investment in technologies aimed at enhancing irrigated and rainfed crop yields while in the Nile Basin, the focus needs to be on expanding irrigated areas and improving rainfed crop productivity. many existing technologies should be embedded into the support and extension systems to enable new research and development addressing rainfed crop water use to benefit the rural poor in developing countries. an integrated approach for the development of strategies aimed at helping humanity adapt to climate change and increased climate variability should be adopted. The authors conclude that an approach that combines blue- and green-targeted water management strategies with other complementary rural agricultural development investments, has the potential to positively impact the lives of many poor people.