Performance of small-scale irrigation schemes in Lake Tana Basin of Ethiopia: technical and socio-political attributes

This study was conducted to investigate technical and socio-political attributes that lead to the underperformance of two selected irrigation schemes (Shina and Bebeks) in the Lake Tana floodplains, Ethiopia. Irrigation application efficiency (AE) at nine experimental fields showed a wide range, from 20 to 80%, but was mostly between 40 and 60%. Irrigation water-use efficiency (IWUE) varied from 1.9 to 7.2 kg m^?3 for onion and 0.9 to 1.2 kg m^?3 for maize. The lined and earthen canal conveyance losses in Bebeks were 0.037 and 0.047 l s^?1 m^?1, whereas in Shina they were 0.033 and 0.044 l s^?1 m^?1, respectively. The overall consumed ratio (OCR) of water was 0.58 for Bebeks and varied from 0.73 to 1.2 in Shina. Both schemes are performing below the standard based on technical performance indicators. Irrigation water user associations (WUAs) were not implemented, but irrigation committees (ICs), composed of local political leaders, are managing both schemes. Canal and reservoir sedimentation from erosion of upstream catchment areas during the rainy season was the major problem.     

Geostatistical analysis of variations in soil salinity in a typical irrigation area in Xinjiang, northwest China

Characterizing spatial and temporal variability of soil salinity is tremendously important for a variety of agronomic and environmental concerns in arid irrigation areas. This paper reviews the characteristics and spatial and temporal variations of soil salinization in the Ili River Irrigation Area by applying a geostatistical approach. Results showed that:(1) the soil salinity varied widely, with maximum value of 28.10 g/kg and minimum value of 0.10 g/kg, and was distributed mainly at the surface soil layer. Anions were mainly SO_4~(2-) and Cl~-, while cations were mainly Na~+ and Ca~(2+);(2) the abundance of salinity of the root zone soil layer for different land use types was in the following order: grassland cropland forestland. The abundance of salinity of root zone soil layers for different periods was in the following order: March June September;(3) the spherical model was the most suitable variogram model to describe the salinity of the 0–3 cm and 3–20 cm soil layers in March and June, and the 3–20 cm soil layer in September, while the exponential model was the most suitable variogram model to describe the salinity of the 0–3 cm soil layer in September. Relatively strong spatial and temporal structure existed for soil salinity due to lower nugget effects; and(4) the maps of kriged soil salinity showed that higher soil salinity was distributed in the central parts of the study area and lower soil salinity was distributed in the marginal parts. Soil salinity tended to increase from the marginal parts to the central parts across the study area. Applying the kriging method is very helpful in detecting the problematic areas and is a good tool for soil resources management. Managing efforts on the appropriate use of soil and water resources in such areas is very important for sustainable agriculture, and more attention should be paid to these areas to prevent future problems.     

Optimal spatial allocation of irrigation water under uncertainty using the bilayer nested optimisation algorithm and geospatial technology

The optimal spatial allocation of irrigation water under uncertainty has become a serious concern because of irrigation water shortage and uncertain factors that affect irrigation water allocation. In this study, an optimal multi-objective model for irrigation water allocation under uncertainty is developed to maximise the economic benefit of crops and minimise the operation cost and water deficit of crop irrigation. The original and optimal plantation structure, irrigation mode and soil water content are acquired through geospatial technology. A bilayer nested optimisation (BLNO) algorithm is designed to produce multiple individuals of design vectors using an ant colony neural network algorithm for an outer optimisation. Meanwhile, a continuous adaptive ant colony (CAAC) algorithm is used for inner optimisation to calculate the interval values of the uncertain model. The crop distribution and irrigation mode are obtained to parameterise the planting area and the water demand of each crop and each block in the multi-objective model. This model is then solved and analysed. Compared to the optimal schemes obtained from an inexact two-stage fuzzy-stochastic programming and the CAAC, respectively, BLNO can effectively and efficiently solve the optimal spatial allocation of irrigation water under uncertainty. This method can spatially maximise the economic benefit of crops and minimise the operation cost and water deficit of crop irrigation using lower and upper bound maps whilst visually obtaining the exact crop type, reasonable irrigation method and precise water demand for each block and for the entire irrigated area.     

Problems of the solution: intervention into small-scale irrigation for drought proofing in the Mekele Plateau of northern Ethiopia

The Mekele Plateau, located in the semi-arid northern highland region of Ethiopia, is a drought-prone, highly degraded area. It has long been neglected by policymakers and thus recurring famine, widespread poverty, armed conflicts and mass outmigration have contributed to the near collapse of the farming systems and the livelihoods of the population. Traditional stream diversion irrigation has been practised in this area for several centuries. The systems of water management in particular may be considered inappropriate owing to the need for thriftiness in water use imposed by the local environment. The systems of headworks and canals are crude and wasteful on water. Recent interventions to improve the small-scale irrigation systems of the area have not been successful. Most interventions have preferred to introduce rainwater harvesting systems using micro-dams rather than trying to upgrade the traditional diversion schemes. Evaluation of irrigation structures in the field, interviews with key informants in government, analysis of documents and discussions with irrigators indicate that both the Ministry of Agriculture and SAERT-Commission's rainwater harvesting programmes have generally failed. The case of the most recent intervention by SAERT has failed because of myopic project planning, inadequate engineering studies, unsound designs, too short a time for implementation, and lack of full farmer involvement at different levels of project planning and implementation.     

Integration of smallholder wetland aquaculture–agriculture systems (fingerponds) into riparian farming systems on the shores of Lake Victoria, Kenya: socio-economics and livelihoods

This paper presents the results of experimental fingerponds: an integrated flood recession aquaculture–agriculture production system in the Lake Victoria wetlands in Kenya. The overall aim of the study is to assess the potential of fingerponds as a sustainable wetland farming system for improving food security at the subsistence level and within the context of the existing livelihood activities. The contribution of this new activity to rural household livelihoods is evaluated. Since it is a sustainable technology, based on natural events, the production level is intermediate and the benefits may not be high in the short term. Economic analysis shows that the gross margin and net income of fingerponds is about 752 and 197 Euros per hectare per year, respectively. This is about an 11% increase in the annual gross margin of an average rural household around Lake Victoria. The additional per capita fish supply is 3 kg per season or more from a 192 m² pond. The potential fish protein supply of 200 kg/ha is high compared with most existing terrestrial protein production systems. Fingerponds have the potential to contribute to household food security and to improve livelihoods. Sensitivity analysis indicates that biophysical variations, which may occur from one wetland to another, have implications for the functioning, and consequently the economic performance, of fingerponds. This reinforces the need for the integration of these systems into other household activities to buffer the household against potential risk.     

Two Mediterranean irrigation communities in front of water scarcity: A comparison using satellite image time series

Although a number of studies have analysed the methods to monitor crop water needs, the integration of phenological dynamics and irrigation using water stored in reservoirs has received little attention. This study is an example of such analysis applied to two irrigation communities (IC) located in a Spanish Mediterranean area, one with less water resources than the other, which it was carried out between 2002 and 2008. These years comprised periods of water surplus and water scarcity including the 2007–2008 drought considered by the Catalan public water authority the worst since 1944. The dynamics of maize, alfalfa, fruit trees and poplars were analysed using greenness and wetness extracted from remote sensing data. A statistical analysis was applied in order to find out the relationship between crop wetness and stored water. Results show that the IC used two methods for water-saving: crop substitution, by decreasing the area of maize, and timing the crop cycle, delaying or advancing sowing depending on water availability. In conclusion although one IC is drier in rainfall terms than the other, a similar crop wetness status was detected and no difference was observed between periods of water scarcity and water surplus.     

灌溉与施氮对黑河中游新垦沙地春小麦生长特性、耗水量及产量的影响

在黑河中游边缘绿洲新垦沙地设计大田试验,研究了不同灌溉量(估算春小麦生育期需水量的0.6、0.8、1.0倍)与施氮量(0、140、221和300 kg/hm2)对春小麦生长特性、耗水量及产量的影响.结果表明,灌溉与施氮对春小麦植株高度产生一定的影响,但其效果不明显.高灌溉量加大作物的耗水量,春小麦全生育期,高灌溉处理的耗水量比中等灌溉处理与低灌溉处理分别增加16.68%与36.88%.当施氮量小于221 kg/hm2时,增加施氮量可以提高地上部干物质量、单位面积粒数、单穗粒重与产量,从而提高水分利用效率(WUE);当施氮量大于221 kg/hm2时,高施氮量使大量干物质滞留于营养器官,导致成熟前物质的转移不充分,同时在土壤水分亏缺的条件下,高施氮处理加重干旱胁迫,从而使221 kg/hm2处理的地上部干物质量(4 159 kg/hm2)、单位面积粒数(3 774)、单穗粒重(259.42 mg)、产量(2 132.83 kg/hm2)与WUE(3.85 kg·mm-1·hm-2)在各施氮处理中最高.地上部干物质量、籽粒产量及产量构成要素随灌溉量的增加而增加.低灌溉处理的WUE显著高于中等灌溉处理与高灌溉处理处理,中等灌溉处理与高灌溉处理之间的WUE差异不显著.结果表明,低灌溉处理(春小麦全生育期灌溉量378 mm)与221 kg/hm2施氮是黑河中游边缘绿洲新垦沙地农田可以获得相对较高的经济产量与高WUE的最佳组合.     

灌区渠系特征与灌溉水利用系数的Horton分维

灌区渠系和自然河流水系存在着诸多相似之处,因此,对于灌区渠系体系是否存在及在何种程度下满足Horton 河系定律值得研究。以2010 年广东省53 宗样点灌区为研究对象,分类进行了适用性分析,发现只有四级渠系类灌区满足Horton 河系定律。在此基础上计算了各级渠系类灌区的渠系特征参数和分维值,并利用2007-2011 年实测数据,对其与灌溉水有效利用系数之间的作用关系进行了定性和定量分析,结果表明：渠系工程状况参数（0.1084） >下垫面参数（-0.3554） >渠系结构参数（-0.5189） >面积尺度参数（-0.5392） >渠系分维特征参数（-0.5536）。本研究对于定量表征灌区形态和渠系特征对灌溉水有效利用系数的影响提供了新的途径,研究结果对于指导灌区渠系规划建设,提高用水效率具有积极现实意义。     

基于电磁感应数据的膜下滴灌土壤水分动态变化研究

快速、无损监测农田土壤水分含量,是智慧农业的重要研究内容.以新疆南疆阿拉尔国家农业科技园区膜下滴灌棉田为研究对象,运用EM38-MK2大地电导率仪快速、高效的获取了4组不同时期的棉田土壤表观电导率数据,并同步采集表层土壤(0～20 cm)样品,通过构建表观电导率数据与室内测定含水量数据间的反演模型获取了测点的含水量数据...     

溶液结构的X射线衍射──3.粉末衍射仪液体样品池窗口强度校正的相对透明因子

从衍射几何学出发，推导出0－2θ型X射线衍射仪液体样品池窗口强度校正的相对透明因子，解释了由于超厚液体样品池上的窗口的吸收，反射法引起的低角强度损失和透射法引起的高角强度损失，获得了令人满意的的校正结果。     

旅游开发的居民满意度驱动因素——以广西阳朔县为例

运用结构方程模型方法,构建旅游开发居民满意度假设模型,对旅游开发居民满意度的关键驱动因素(居民期望、居民社区归属感、旅游获益和利益分配、正面旅游影响感知、负面旅游影响感知)进行了探讨。结果表明:(1)居民期望、居民社区归属感、旅游获益和利益分配、正面旅游影响感知、负面旅游影响感知是影响居民满意度的5个重要驱动因素。(2)居民社区归属感、旅游获益和利益分配、正面旅游影响感知等变量与居民满意度之间呈正相关关系;而居民期望、负面旅游影响感知则与居民满意度呈负相关。(3)在5个驱动因素中,正面旅游影响感知对居民满意度的直接影响最大,而旅游获益和利益分配对居民满意度的总效应最大。     

点-轴系统的分形结构及其空间复杂性探讨

本文对社会经济点-轴系统空间结构的分形演化及其复杂性规律进行了初步探讨。首先分析一般点-轴系统的演化过程,揭示其从低度有序的空间结构向高度有序的分形结构演化的一般规律;然后借鉴复杂性科学研究中的“球-棍”模式,论证点-轴系统的数理本质乃是空间复杂性中“惟一巨型组件(UGC)”。文章以豫北地区的郑、汴、洛城镇体系为实例验证了点-轴体系的分形性质,并讨论了系统的空间复杂性特征及其现实意义。文章最后指出了有关课题今后研究的主要方向。     

Correlation of icing events with meteorological variables, and two statistical models to discriminate freezing days

In this paper, the characteristics of meteorological variables are statistically correlated with icing events (i.e., glaze and rime) in China, using daily observations of air temperature, relative humidity, wind speed, and weather phenomena from 700 stations in China from 1954 to 2008. The weather conditions most favorable for icing events are investigated and two statistical models are developed to discriminate potential freezing days. Low air temperature, high relative humidity, and low wind speed are shown to be important conditions for occurrence of icing events; also, the favorable daily mean air temperature is shown to have a decreasing trend from north to south in China, while the favorable relative humidity and wind speed varies little across the country. The statistical model developed with the daily mean temperature combined with precipitation, fog, and mist weather phenomena proved to be well able to determine the possible occurrence of freezing days. The accuracy of model outputs is well above 60% for northwestern Yunnan, Guizhou, northern Guangxi, southern Hunan, and southern Jiangxi, among other regions where icing events are more frequent, and the average false alarms are few. Using observations or forecast products of conventional meteorological variables, this model has high performance and is practical and applicable for early warning and monitoring of icing events.     

OutDet: an algorithm for extracting the outer surfaces of building information models for integration with geographic information systems

The integration of Building Information Modelling (BIM) and geographic information systems (GIS) is a promising but challenging topic to solve problems in construction industry. However, loading and rendering rich BIM geometric data and large-scale GIS spatial information in a unified system is still technologically challenging. Current efforts mainly simplify the geometry in BIM models, or convert BIM geometric data to a lower level of detail (LOD). By noticing that only exterior features of BIM models are visible from outdoor observation points, culling BIM interior facilities can dramatically reduce the computational burden when visualizing BIM models in GIS. This study explores the outline detection problem and presents the OutDet algorithm, which selects representative observation points, transforms & projects the BIM geometric data into the same coordinate system, and detects the visible facilities. Empirical study results show that OutDet can cull a large portion of unnecessary features when rendering BIM models in GIS. The use of outlines of BIM models is not an alternative but rather a supplementary approach for current solutions. Jointly using LOD and outer surface can help improve the efficiency of integrated BIM-GIS visualization.Because OutDet retains BIM geometry and semantics, it can be applied to more BIM-GIS applications..     

The complex nonlinear systems with fractal as well as chaotic dynamics of annual runoff processes in the three headwaters of the Tarim River

This paper attempted to identify fractal and chaotic characteristics of the annual runoff processes in headwaters of the Tarim River. Methods of fractal analyses were used to explore several aspects of the temporal changes from 1957 to 2002. The main findings are as follows: (1) The annual runoff processes of the three headwaters of the Tarim River are complex nonlinear systems with fractal as well as chaotic dynamics. (2) The correlation dimensions of attractor derived from the time series of the annual runoff for the Hotan, Yarkand and Aksu rivers are all greater than 3.0 and non-integral, implying that all three rivers are chaotic dynamical systems that are sensitive to initial conditions, and the dynamic modeling of their annual runoff process requires at least four independent variables. (3) The time series of annual runoff in each river presents a long-term correlation characteristic. The Hurst exponent for the period of 1989 to 2002 suggests that we may expect to see an increasing trend in the annual runoff of the Aksu and Yarkand rivers in the years after 2002, but a decreasing tendency for the Hotan River in the same period.     

塔里木盆地三源河年径流过程的非线形特征

This paper attempted to identify fractal and chaotic characteristics of the annual runoff processes in headwaters of the Tarim River. Methods of fractal analyses were used to explore several aspects of the temporal changes from 1957 to 2002. The main findings are as follows: (1) The annual runoff processes of the three headwaters of the Tarim River are complex nonlinear systems with fractal as well as chaotic dynamics. (2) The correlation dimensions of attractor derived from the time series of the annual runoff for the Hotan, Yarkand and Aksu rivers are all greater than 3.0 and non-integral, implying that all three rivers are chaotic dynamical systems that are sensitive to initial conditions, and the dynamic modeling of their annual runoff process requires at least four independent variables. (3) The time series of annual runoff in each river presents a long-term correlation characteristic. The Hurst exponent for the period of 1989 to 2002 suggests that we may expect to see an increasing trend in the annual runoff of the Aksu and Yarkand rivers in the years after 2002, but a decreasing tendency for the Hotan River in the same period. Foundation: Knowledge Innovation Project of CAS, No.KZCX2-XB2-03; Major Direction of Knowledge Innovation Project of CAS, No.KZCX2-YW-127; Shanghai Academic Discipline Project (Human Geography), No.B410 Author: Xu Jianhua (1965–), specialized in geographical quantitative methods and GIS.     

Three-dimensional visualization of an emotional map with geographical information systems: a case study of historical and cultural heritage in the Yeongsan River Basin,Korea

The objective of this study is the production and visualization of an emotional map to reveal the unique emotions inherent to the areas surrounding the Yeongsan River, which is often referred to as ‘the cradle of civilization’ in Korea. The sites selected for this study are the 11 cities and districts (5667.6 km²) that cut across the vast granary in the southeastern region of Korea, near the Yeongsan River. The emotional map was produced by extracting features of historical and cultural heritage distributed throughout this region and by using a geographic information systems program and its functions for spatial analysis. A database was constructed through interviews with locals and Global Positioning System to index 4318 pieces of cultural heritage to achieve the visualization of emotions. Among the 558 historical relics considered for representing the regional culture, 100 with the largest emotional impact were selected. It was determined that loyalty (), justice (), courtesy (), resentment (), and anger () should be the major emotional elements. Methodologically, a set of regional, periodic, historical, and emotional classification codes were first systematized. After subjecting this data to inverse distance weight interpolation and vertical exaggeration coefficients, the three-dimensional emotional map could be visualized.