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Evaluation of historic, current and future water demand in the Olifants River Catchment, South Africa
Water resource development has played a significant role in the expansion of agriculture and industry in the Olifants River Catchment. However, currently water deficit is one of the major constraints hampering development in the catchment; both the mining and agricultural sectors are producing below optimal levels because of their reliance on insufficient supplies. In this study, the Water Evaluation and Planning (WEAP) model was used to evaluate scenarios of historic, current and future water demand in the catchment. For each scenario, the WEAP model was used to simulate demand in five different sectors (rural, urban, mining, commercial forestry and irrigation) over a 70-year period of varying rainfall and hydrology. Levels of assured supply were estimated for each sector and the economic cost of failing to provide water was predicted. For the future scenarios, the impact of infrastructure development and water conservation measures were assessed. The study illustrates how a relatively simple model can provide useful insight for resource planning and management.
Application of the Water Evaluation and Planning (WEAP) Model to Assess Future Water Demands and Resources in the Olifants Catchment, South Africa
The Olifants catchment is one of 19 Catchment Management Areas in South Africa. Different water users (i.e., rural, urban, mining, subsistence and commercial irrigated agriculture, commercial forestry, industry and power generation) are present in the catchment. Rising population andincreasing water provision in rural areas, in conjunction with the development of the mining industry, the construction of new power generation plants, the implementation of environmental flows andthe need to meet international flow requirements are going to greatly exacerbate the complexity of future water resources management in what is already a water-stressed catchment. Being able to assess the ability of the...
Importance of irrigated agriculture to the Ethiopian economy: capturing the direct net benefits of irrigation
Irrigation development has been identified as a means to stimulate economic growth and rural development in Ethiopia. However, little attempt has been made to quantify the contribution of irrigation to national income. Using data from selected irrigation schemes, representing small, medium and large-scale schemes of modern or traditional typologies; the present coverage and planned growth of irrigation, actual and expected contributions of irrigation to the national economy were quantified following the approach of adjusted gross margin analysis. Our results show that irrigation yields 219.7% higher income compared to the rainfed system while its current and future contribution to agricultural GDP is estimated to be about 5.7 and 12% although irrigation covers about 5 and 9% of the total cultivated land area, respectively.
Trees and water: smallholder agroforestry on irrigated lands in Northern India
Trees are increasingly grown on-farm to supply wood and biomass needs within developing countries. Over the last several decades, within the irrigated rice-wheat growing lands of northern India, fast-growing poplar trees have been planted on tens of thousands of small farms. Recent debate regarding afforestation has raised the issue that water use is often increased when trees are planted. This ongoing debate focuses primarily on afforestation or reforestation of upland and rain-fed agricultural areas, and off-site impacts such as reduced streamflow. Adoption of poplar agroforestry in northern India, in contrast, is occurring in areas where land and water are already intensively used and managed for agricultural production. This study based on farmer survey data, used remote sensing and spatial hydrological modeling to investigate the importance and role of the poplar trees within the agricultural landscape, and to estimate their water use. Overall, results illustrate a potential for addressing the increasing global demand for wood products with trees grown on-farm within irrigated agroforestry systems.
Drivers and characteristics of wastewater agriculture in developing countries: results from a global assessment
In 4 out of 5 cities in developing countries, wastewater is used to cultivate perishable crops for urban markets. Such practices create a health risk but provide important livelihood benefits. This study through an analysis of 53 cities in developing countries, contributes to understanding the factors that drive wastewater use. The main drivers are (1) increasing urban water demand without wastewater treatment causing pollution of irrigation water sources; (2) urban food demand favoring agriculture close to cities where water sources are polluted; and (3) lack of cheaper, similarly reliable or safer water sources. Poverty, which constrains the infrastructure needs of urbanization, is an added factor. The study makes policy recommendations stressing on, effectively applying the WHO guidelines, linking investments in water supply with sanitation for maximum beneficial impact on water pollution, and involving actors at both the national and local level, for water quality improvements and health risk reduction
Shifting Waterscapes: Explaining Basin Closure in the Lower Krishna Basin, South India
Progressive agricultural and water development in the Krishna Basin in South India has led to a rising over commitment of water resources and signs of basin closure are apparent during dry periods. As human consumptive uses are approaching the limits of water availability, this report focuses on the Lower Krishna Basin that bears the brunt of any intervention upstream. Capturing the process of basin closure requires an understanding of the political dimension of access to water and the scope for change. As basin closure intensifies the interconnectedness of ecosystems and water users, adjustments and management decisions result in spatial re-appropriation of water and basin-wide strategies for water management and development that start with the definition and the implementation of water allocation mechanisms are increasingly needed.
Climate change impacts on hydrology and water resources of the Upper Blue Nile River Basin, Ethiopia
The report evaluates the impacts of climate change on the hydrological regime and water resources of the Blue Nile River Basin in Ethiopia. It starts from the construction of the climate change scenarios based on the outcomes of several general circulation models (GCMs), uses a simple hydrological model to convert theses scenarios into runoff, and examines the impacts by means of a set of indices. The results, however uncertain with existing accuracy of climate models, suggest that the region is likely to have the future potential to produce hydropower, increase flow duration, and increase water storage capacity without affecting outflows to the riparian countries in the 2050s.
Changing consumption patterns: Implications on food and water demand in India
Increasing income and urbanization are triggering a rapid change in food consumption patterns in India. This report assesses India’s changing food consumption patterns and their implications on future food and water demand. According to the projections made in this study, the total calorie supply would continue to increase, but the dominance of food grains in the consumption basket is likely to decrease by 2050, and the consumption of non-grain crops and animal products would increase to provide a major part of the daily calorie supply. Although the total food grain demand will decrease, the total grain demand is likely to increase with the increasing feed demand for the livestock. The implications of the changing consumption patterns are assessed through consumptive water use (CWU) under the assumptions of full or partial food self-sufficiency.
The lower Krishna Basin trajectory: relationships between basin development and downstream environmental degradation.
Basin water development and rural dynamics in the Krishna Basin have led to a degradation of downstream ecosystems manifesting itself by salinizing soil and groundwater, increasing pollution, disappearing mangroves and desiccating wetlands. Reversing this evolution requires the formal recognition of the environment as a water user in its own right and the implementation of an environmental water provision. This provision should be based on a two-tier allocation system with assured discharges in the irrigation canals of the delta and to the ocean. This will lead to further commitment of water resources but this is needed to reconcile the social, economic and environmental objectives of a sustainable development. Other measures facilitating integrated natural resources management from the local to the basin level are needed too.
India's water future to 2025-2050: business-as-usual scenario and deviations
With a rapidly expanding economy many changes are taking place in India today. The business-as-usual (BAU) scenario, which assumes the continuation of current trends of key water demand drivers, will meet the future food demand. However, it leads to a severe regional water crisis by 2050, where many river basins will reach closure, will be physically water-scarce and will have regions with severely overexploited groundwater resources. While the alternative scenarios of water demand show both optimistic and pessimistic water futures, the scenario with additional productivity growth is the most optimistic, with significant scope for reducing future water demand.
