Publicação
Assessment of sustainable efficiency (sefficiency) and water allocation under uncertainty in Kano River basin
| Resumo: | The ever-increasing population and climate change have placed a considerable pressure on Kano city water supply (KCWS) and Kano River Irrigation Project (KRIP), major water users on Kano River, the most upstream tributary of Yobe River flowing directly to Lake Chad which is an important transboundary basin in West Africa. Under water scarcity and competing water uses, improved knowledge of the performance of water use systems (WUS) is essential for policy formulation and sustainable development of water sector. This study is carried out in semi-arid Kano River basin of Nigeria, where water is a limiting factor, but a comprehensive knowledge on the performance of different water users across the basin are lacking. The main objective is to assess the performance of main water users and provide a thorough analysis of the impacts of drivers of change on their performances using new and innovative methodological framework called Sefficiency (Sustainable efficiency). However, crop requirements were estimated using CROPWAT 8.0. In evaluating KRIP, two major stakeholders were contacted, namely, farmers and water managers and their views on the value of water flows were registered through interviews. The results indicated that useful consumption relative to effective consumption of farmers is significantly lower than management, showing a higher relative consumptive impact on both KRIP and Kano River. Also, the useful outflow per unit of useful inflow is lower according to the farmers relative to the managers. Classical efficiency in use globally gives much lower values than meso-efficiency. The synthesis of the results for Kano River model reveals that effective consumption that is useful consumption is lower relative to beneficial consumption which is an indication of pollution that increases effective consumption and consequently decreases efficiency. The difference between beneficial inflow and beneficial consumption indicated that water consumption is through non-reusable water flow paths that do not consider quality, i.e., evaporation. Moreover, beneficial consumption efficiency is lower than inflow efficiency due to a combination of relatively high return flow and pollution impact. The low value of MicroEs suggests that the WUS itself is not efficient in using its water resources. The temporal changes in the performance of the WUSs according to uncertainty related to the drivers of change were also explored as part of the system analysis. The performance of KRIP and Kano River were degraded significantly under projected population and future climate conditions. However, Kano River is less sensitive to global warming impacts suggesting that population growth is the dominant driver of change. Moreover, cumulative effects of population and climate change impact in Kano River basin resulted in a reduction of downstream water by 70% to below the recommended volume. Generally, potential demands for water will far exceed the available supply by 2050 thereby affecting water allocation. The study concludes that the regional water managers have a much broader view of water needs and impacts, such as pollution and groundwater depletion, than farmers, and consequently, can better relate useful flows and (effective) consumptions for sustainable management, including technological investments. Water quality has a dominant influence on the performance of Kano River model under population growth. The quantitative efficiency values show decreasing trends mostly due to the assertion that evaporation have less beneficial value under climate change scenario. For KRIP, quantitative meso-efficiency values for climate change show increasing trends because water quality is not considered and relative quantities remain the same while beneficial consumption increases. Increasing the effective consumption in terms of decreasing the pollution caused by anthropogenic activities is the pathway to achieving better results. The study recommends that Kano River basin should be properly managed by employing Sefficiency framework, which puts water as the central issue for policy making. It would be helpful to improve the set of data using remote sensing and GIS and use of smart systems particularly for improving water balance flow paths and their qualities. The Sefficiency model application demonstrated in this study should be extended by testing other “what if” scenarios (e.g., water user associations, before and after the TRIMING intervention project funded by World Bank, and wastewater treatment plants). Our results point to the need for in-depth studies to understand the dynamics of the trade-offs that influences Sefficiency. |
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| Autores principais: | Ahmad, Muhammad Tajuri |
| Ano: | 2018 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | português |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | The ever-increasing population and climate change have placed a considerable pressure on Kano city water supply (KCWS) and Kano River Irrigation Project (KRIP), major water users on Kano River, the most upstream tributary of Yobe River flowing directly to Lake Chad which is an important transboundary basin in West Africa. Under water scarcity and competing water uses, improved knowledge of the performance of water use systems (WUS) is essential for policy formulation and sustainable development of water sector. This study is carried out in semi-arid Kano River basin of Nigeria, where water is a limiting factor, but a comprehensive knowledge on the performance of different water users across the basin are lacking. The main objective is to assess the performance of main water users and provide a thorough analysis of the impacts of drivers of change on their performances using new and innovative methodological framework called Sefficiency (Sustainable efficiency). However, crop requirements were estimated using CROPWAT 8.0. In evaluating KRIP, two major stakeholders were contacted, namely, farmers and water managers and their views on the value of water flows were registered through interviews. The results indicated that useful consumption relative to effective consumption of farmers is significantly lower than management, showing a higher relative consumptive impact on both KRIP and Kano River. Also, the useful outflow per unit of useful inflow is lower according to the farmers relative to the managers. Classical efficiency in use globally gives much lower values than meso-efficiency. The synthesis of the results for Kano River model reveals that effective consumption that is useful consumption is lower relative to beneficial consumption which is an indication of pollution that increases effective consumption and consequently decreases efficiency. The difference between beneficial inflow and beneficial consumption indicated that water consumption is through non-reusable water flow paths that do not consider quality, i.e., evaporation. Moreover, beneficial consumption efficiency is lower than inflow efficiency due to a combination of relatively high return flow and pollution impact. The low value of MicroEs suggests that the WUS itself is not efficient in using its water resources. The temporal changes in the performance of the WUSs according to uncertainty related to the drivers of change were also explored as part of the system analysis. The performance of KRIP and Kano River were degraded significantly under projected population and future climate conditions. However, Kano River is less sensitive to global warming impacts suggesting that population growth is the dominant driver of change. Moreover, cumulative effects of population and climate change impact in Kano River basin resulted in a reduction of downstream water by 70% to below the recommended volume. Generally, potential demands for water will far exceed the available supply by 2050 thereby affecting water allocation. The study concludes that the regional water managers have a much broader view of water needs and impacts, such as pollution and groundwater depletion, than farmers, and consequently, can better relate useful flows and (effective) consumptions for sustainable management, including technological investments. Water quality has a dominant influence on the performance of Kano River model under population growth. The quantitative efficiency values show decreasing trends mostly due to the assertion that evaporation have less beneficial value under climate change scenario. For KRIP, quantitative meso-efficiency values for climate change show increasing trends because water quality is not considered and relative quantities remain the same while beneficial consumption increases. Increasing the effective consumption in terms of decreasing the pollution caused by anthropogenic activities is the pathway to achieving better results. The study recommends that Kano River basin should be properly managed by employing Sefficiency framework, which puts water as the central issue for policy making. It would be helpful to improve the set of data using remote sensing and GIS and use of smart systems particularly for improving water balance flow paths and their qualities. The Sefficiency model application demonstrated in this study should be extended by testing other “what if” scenarios (e.g., water user associations, before and after the TRIMING intervention project funded by World Bank, and wastewater treatment plants). Our results point to the need for in-depth studies to understand the dynamics of the trade-offs that influences Sefficiency. |
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