Decentralising Zimbabwe’s water management: The case of Guyu-Chelesa irrigation scheme     

《Physics and Chemistry of the Earth》2013

Smallholder irrigation schemes are largely supply driven such that they exclude the beneficiaries on the management decisions and the choice of the irrigation schemes that would best suit their local needs. It is against this background that the decentralisation framework and the Dublin Principles on Integrated Water Resource Management (IWRM) emphasise the need for a participatory approach to water management. The Zimbabwean government has gone a step further in decentralising the management of irrigation schemes, that is promoting farmer managed irrigation schemes so as to ensure effective management of scarce community based land and water resources. The study set to investigate the way in which the Guyu-Chelesa irrigation scheme is managed with specific emphasis on the role of the Irrigation Management Committee (IMC), the level of accountability and the powers devolved to the IMC. Merrey’s 2008 critique of IWRM also informs this study which views irrigation as going beyond infrastructure by looking at how institutions and decision making processes play out at various levels including at the irrigation scheme level. The study was positioned on the hypothesis that ‘decentralised or autonomous irrigation management enhances the sustainability and effectiveness of irrigation schemes’. To validate or falsify the stated hypothesis, data was gathered using desk research in the form of reviewing articles, documents from within the scheme and field research in the form of questionnaire surveys, key informant interviews and field observation. The Statistical Package for Social Sciences was used to analyse data quantitatively, whilst content analysis was utilised to analyse qualitative data whereby data was analysed thematically. Comparative analysis was carried out as Guyu-Chelesa irrigation scheme was compared with other smallholder irrigation scheme’s experiences within Zimbabwe and the Sub Saharan African region at large. The findings were that whilst the scheme is a model of a decentralised entity whose importance lies at improving food security and employment creation within the community, it falls short in representing a downwardly accountable decentralised irrigation scheme. The scheme is faced with various challenges which include its operation which is below capacity utilisation, absence of specialised technical human personnel to address infrastructural breakdowns, uneven distribution of water pressure, incapacitated Irrigation Management Committee (IMC), absence of a locally legitimate constitution, compromised beneficiary participation and unclear lines of communication between various institutions involved in water management. Understanding decentralization is important since one of the key tenets of IWRM is stakeholder participation which the decentralization framework interrogates.  相似文献   

Changes in the Level of Proteins,Free Amino Acids and Protease Activities of Clarias batrachus in Response to Sodium meta‐arsenite Intoxication     

Randhir Kumar  Tarun K. Banerjee 《洁净——土壤、空气、水》2013,41(12):1196-1200

Increased hazard of arsenic toxicity at many provinces of India causing extensive contamination of their wetlands. To illustrate the consequences of the arsenic menace on the aquatic fauna, a nutritionally important freshwater catfish Clarias batrachus (Linn.) was subjected to the stress of sublethal concentration (1 mg/L; 5% of 96‐h LC₅₀ value) of sodium meta‐arsenite. The alterations induced by the arsenic salt on certain biomolecules (proteins, free amino acids (FAA), and protease activities) in five tissue components (muscle, liver, brain skin, and gills) of the fish using biochemical techniques were estimated. Significant (p < 0.01) decrease in the concentration of proteins in all the tissues (19.74–44.84% in muscles; 3.17–49.39% in liver; 10.05–36.16% in brain; 12.62–52.01% in skin and 7.34–61.69% in gills), and significant (p < 0.01) increase in FAA (6.84–269.89% in muscles; 125.89–358.03% in liver; 1.07–152.90% in brain; 29.31–401.62% in skin and 38.53–165.07% in gills), and protease activities (43.59–183.33% in muscles; 19.52–131.90% in liver; 8.85–46.72% in brain; 33.33–261.53% in skin and 25.39–50.79% in gills) of the exposed fish were observed. This increase in amino acids and enzyme activity point out toward breakdown of protein leading to their depletion.  相似文献   

Comparison of dew point temperature estimation methods in Southwestern Georgia     

Marcus D. Williams  Scott L. Goodrick  Andrew Grundstein  Marshall Shepherd 《自然地理学》2013,34(4):255-267

Recent upward trends in acres irrigated have been linked to increasing near-surface moisture. Unfortunately, stations with dew point data for monitoring near-surface moisture are sparse. Thus, models that estimate dew points from more readily observed data sources are useful. Daily average dew temperatures were estimated and evaluated at 14 stations in Southwest Georgia using linear regression models and artificial neural networks (ANN). Estimation methods were drawn from simple and readily available meteorological observations, therefore only temperature and precipitation were considered as input variables. In total, three linear regression models and 27 ANN were analyzed. The two methods were evaluated using root mean square error (RMSE), mean absolute error (MAE), and other model evaluation techniques to assess the skill of the estimation methods. Both methods produced adequate estimates of daily averaged dew point temperatures, with the ANN displaying the best overall skill. The optimal performance of both models was during the warm season. Both methods had higher error associated with colder dew points, potentially due to the lack of observed values at those ranges. On average, the ANN reduced RMSE by 6.86% and MAE by 8.30% when compared to the best performing linear regression model.  相似文献   

Knowing Climate Change: Local Social Institutions and Adaptation in Indian Groundwater Irrigation     

Trevor Birkenholtz 《The Professional geographer》2013,65(3):354-362

SHORE FEATURES. Patrick C. Moyer.

LOKATE. Charles W. Smith.  相似文献   

Water conservation in the Arab region: a must for survival     

Gamal M. Abdo  Abdin M. A. Salih  Abdulmohsen Al-Sheikh 《寒旱区科学》2013,5(1):0157-0164

The Arab region covers an area over 13 million square kilometers in size, with almost 90% of its area classified as arid or extremely arid with very little precipitation, extremely high evaporation and almost no vegetation cover. The region is classified in many international reports as the poorest region in the world in the context of renewable water resources and critical water scarcity which hinders the socio-economic development of many countries in this region. The rapidly increasing population has reduced the per capita share of renewable water to less than the poverty line of 1,000 m 3 /(capita·a) and, in some Arab countries, to less than the extreme poverty line of 500 m 3 /(capita·a). This has led to over-exploitation of non-renewable groundwater and desalination of salty water in many countries with considerable costs and contamination of many renewable sources. Atmospheric processes responsible for aridity in the Arab region are projected to intensify due to climate change, resulting in an alarming decrease in precipitation and increase in evaporation rates. Many concerned entities in the region consider water security as a key element for food security and ultimately political stability. Hence, various efforts have been exerted to identify key problems and suggested solutions. The Arab Water Ministers Council of the Arab League, as well as Reports of the Arab Forum for the Environment and Development (AFED) and the recommendations of the 13th Regional Meeting of the Arab National Committees of the International Hydrological Programme of UNESCO (IHP), have all made similar recommendations on the need to address the issues of water scarcity in the Arab region which will be further discussed in this paper. However, none of these reports focused on "Water Conservation" as an equally important action for coping with water scarcity in the region. There are many definitions for "Water Conservation" in the scientific literature, including huge water savings from irrigation, industrial use, and domestic use as well as methods and approaches for augmenting water supply through non-conventional practices such as water harvesting and waste water reuse. In this paper, a review is provided for definitions, methods and impacts of water conservation and its role in alleviating water scarcity in the Arab region.  相似文献   

双种群进化粒子群算法求解地下水管理模型          下载免费PDF全文

吴睿奇  朱国荣  王佩 《江苏地质》2012,36(1):37-43

为避免粒子群算法(PSO)早熟的缺点,设计了一种双种群进化粒子群算法(DE-PSO)。DE-PSO是基于PSO,引入选择、交叉及差分变异操作,并结合合理有效的粒子评价方法及越界处理方法之后形成的。将DE-PSO应用于两个地下水管理模型算例,第一个算例DE-PSO解的总抽水量分别比遗传算法(GA)、模拟退火算法(SA)和PSO减少了64、256、207 m3/d,第二个算例DE-PSO解的总治理成本分别比GA、SA和PSO减少了57.74、151.93、76.59万元。两个算例中DE-PSO都表现出稳定的进化趋势,寻优效率好于GA、SA和PSO,可以有效求解地下水管理模型问题。  相似文献   

水分胁迫条件下稻田优化灌溉制度的研究   总被引：1，自引：0，他引：1  

董淑喜 《地下水》2012,(1):107-108,146

本文通过对非充分灌溉条件下水稻优化灌溉制度如何制定进行了研究。其特点是将作物产量模型与耗水规律模型相结合,以相对产量最高为目标函数,建立了优化决策系统,并利用多目标规划进行求解。该研究成果可使有限的水量在作物生育期内发挥最大的效率,对优化配置水资源,实现农业高效用水具有重要作用。实例研究结果说明,所建模型及求解方法是合理与可行的,不但提高了水分利用效率,还为查哈阳灌区水资源的优化利用提供了科学依据。  相似文献   

六盘水市地下水污染现状分析及防治对策建议     

尹先娥 《城市地质》2012,7(1):11-14

六盘水市近年来地下水污染日益严重,通过调查、取样分析,初步查明了其地下水污染状况,并结合六盘水市的发展需要,提出了若干污染防治对策。  相似文献   

再生水灌溉之地下水影响的监测研究     

杨庆  林健  杨巧凤 《城市地质》2012,7(2):22-23

依据再生水灌溉对地下水影响途径分析,建立地表再生、包气带土壤水和地下水监测网系统三位一体的综合试验站,研究再生水灌溉对地下水的影响机理。  相似文献   

盆地地下水年龄空间分布规律   总被引：3，自引：2，他引：1       下载免费PDF全文

蒋小伟  万力  王旭升  李海龙 《水文地质工程地质》2012,39(4):1-6

地下水年龄蕴含了地下水循环与演化过程的信息,是研究盆地地下水循环规律的重要信息来源。利用实测示踪剂年龄校正地下水模型,是当前国际水文地质学研究的前沿与热点。在数值模拟计算中,地下水年龄有三种确定方法,分别是利用"活塞流"模型计算对流年龄、根据同位素浓度结合半衰期计算浓度模拟年龄和利用地下水年龄控制方程计算直接模拟年龄。利用地下水年龄控制方程计算的直接模拟年龄适合于从理论上分析盆地中的地下水年龄空间分布规律。研究发现,在各级次流动系统内,从补给区到排泄区,地下水年龄有整体上变老的趋势;盆地下游,地下水年龄在垂向上会发生突变,可作为识别不同级次流动系统的实用指标。研究还发现,驻点位置或者附近,地下水年龄存在一个偏大的峰值。这些规律可为利用地下水年龄校正盆地地下水模型提供理论指导。  相似文献