膜缝沟灌技术要素试验研究

试验选择了膜缝宽度、土壤初始含水率、土壤密度及水深四个因素,通过四因素-三水平的正交试验设计方案,采用极差分析方法,以入渗速率和水平与垂向湿润锋推进距离的比值为评价指标,得出了适宜室内试验条件下膜缝沟灌较为合理的技术要素组合,即当初始含水率为9%、土壤密度为1.45g/cm3时,最优膜缝宽度为5 cm,最佳水深为12 cm。这对提高田间水利用率和灌溉水利用率,有一定的理论和实践意义。     

干旱区滴灌核桃树根系空间分布特性研究

为了研究核桃树根系空间分布特性,本文使用分层分段挖掘法对干旱区滴灌方式下核桃树根系总根长、根重、有效吸收根根长的空间分布规律进行了研究。研究表明：核桃树根系总根长水平方向主要分布在0～120cm处,占其总分布的90．84％;垂直方向主要分布在0～90cm处,占其总分布的78．75％。根重水平方向主要分布在0～30cm处,占其总分布的52．49％;垂直方向主要分布在15～75em处,占其总分布的61．12％。有效吸水根根长在水平距离60cm和垂直深度60cm处为分布密集区。在距离树干水平距离60cm和垂直深度60cm附近的根区,应作为核桃树水肥管理的重点区域。     

The Afghan water law: “a legal solution foreign to reality”? 1

In this article the suggested permit and licence systems included in the draft Afghan Water Law of 2008 (superseding those laws of 1981 and 1991) are examined by comparing them with main canal data from two pilot studies within the Kunduz Basin. The comparison highlights the difficulty of making these proposed legal frameworks operative. Overall, it appears that the sections within the law on permits and licences are not implementable within or even useful for the traditional irrigation systems, but mainly play into the hands of the national hydrocracy and please international donors.     

Integrated Water Resources Management in the Republic of Uzbekistan

Abstract

The Uzbek socio-economic structure is characterized by the transition from a centrally-planned to a market-orientated economy, with a shifting from agricultural production to industrial development. However, the agricultural sector continues to play a significant role in a general economy of the country. The major water sector strategy is to decrease the dependence of agricultural production on climate by introducing advanced irrigation techniques and water saving methods to achieve future sustainable socio-economic development and environmental protection. Water management policy should be flexible enough to adapt to new demands. The regulation of consumption through demand management tools, such as appropriate pricing policies, has recently received greater attention in Uzbekistan. The main thesis of this paper is that allocation of water resources cannot be separated from ecological and economic considerations. The establishment of development objectives and the identification of constraints are also discussed. In the coming years, special attention will need to be paid to the control of water pollution and land salinization, water resources conservation, and acknowledging that actions to increase water productivity are as important as finding additional sources of water.     

Redefining the Water Poverty Index

Abstract

The Water Poverty Index (WPI) of arid and semiarid climatic zones is redefined by introducing the contribution of rainfed agriculture into WPI calculations and by making the WPI equation account for diversities in climatic conditions within arid and semiarid zones and for recycled household water used in irrigation.     

Global Water Demand and Supply Projections

Abstract

This paper presents a modeling approach for projections of water demand and supply for domestic, industrial, livestock, and irrigation at the basin or country level in a global scope. Particular emphasis is put on simulating water availability for crops taking into account total renewable water, non-irrigation water demand, water supply infrastructure, and economic and environmental policies at the basin or country level. This paper focuses on concepts and methodology involved in the modeling exercise. Data assessment and results are presented in a companion paper (Rosegrant and Cai, 2002).     

Model-based Regional Assessment of Water Use An Example for Semi-arid Northeastern Brazil

Abstract

Water use assessments are a necessary prerequisite for sustainable water resources management and planning in river basins, federal states, or countries. For reasons of transparency, flexibility, ease of update, and the possibility to generate scenarios of future water use, such assessments are best carried out by applying a water use model. To support water resources planning in two federal states of semi-arid Northeastern Brazil, Ceará and Piauí, the regional-scale water use model NoWUM was developed. It computes withdrawal and consumptive water use for each of 332 municipalities, distinguishing five water use sectors: irrigation, livestock, households, industry, and tourism. The model is suited to simulate the impact of global change and of management measures on water demand. Using NoWUM, the present-day water use situation in Ceará and Piauí is assessed. In addition, the impact of inter-annual climate variability and long-term climate change on irrigation requirements is considered. Scarce and uncertain input data lead to a high level of uncertainty in the model results. It is likely that water use in the most important sector, irrigation, is underestimated, while industrial water use is possibly overestimated. With some modifications, NoWUM has the potential to be applied for water use assessments in other data-poor regions of the globe.     

Transforming River Basin Management in South Africa

Abstract

This paper analyzes the transformation of river basin management in South Africa by focusing on the political processes involved in the creation of new water management bodies and irrigation infrastructure in the Lower Komati sub-basin. Institutional reform is described and analyzed in terms of the collaboration theory of Gray (1985). Attention is paid to the absence of mutual collaboration in the water domain through the analysis of three phases that are characteristic of collaborative management: problem setting, direction setting, and structuring. The perceptions and strategies of stakeholders in the change process are informed by the skewed access to land and water, the protracted struggle for redress of historical inequities, the quest for autonomy in water management by commercial farmers, and large political power differentials. This has resulted in differential access to decision making and political influence and in the materialization of these skewed relations in water control technology. The reluctance of stakeholders to explicitly recognize their interdependence and the role of the state as the convener of the change process has hampered the emergence of a shared appreciation of the problems in the water domain. Despite efforts by government to move towards equitable and inclusive water management, little redress of past inequities has taken place, and the majority of small farmers are uninformed and excluded from the change process. This suggests that the proposed Catchment Management Agency will not be representative nor attain equitable water management unless a well-conceived redistribution of water entitlements and land rights is carried out as part of an encompassing program to strengthen political democracy.     

Economic Benefits of Reservoirs in the Irrigated Agriculture

Abstract

In the Jordan Valley of Jordan, the demand for water and ability to control its location, timing, quality, and quantity are becoming critical. The competition for water between the urban and agricultural sectors is increasing. There is a general trend in Jordan to reduce water allocated for agricultural use. Increasing the price of irrigation water or restricting the planted areas of water consuming crops, such as bananas, has been implemented during the recent growing season. The main objective of this paper is to highlight the impact of optimal allocation of irrigation water by building storage capacity on the economy of Jordan Valley. A linear programming technique is used, and the main results show that for proper management of water storage capacity, the suggested cropping pattern would generate $88.2 million, whereas the actual cropping pattern generated $74.4 million. The optimal water demand schedule is distributed according to the needs of the planted crops, and water demand has been allocated in an efficient way. In addition, appropriate management of storage capacity has solved the problem of water scarcity during the summer months, when peak production takes place. Storage-transfer system between locations played a significant role in reallocating irrigation water through the storage system. This compensates to a high degree in keeping the agricultural production more stable in physical and monetary units.     

Irrigation infrastructure development in the Limarí Basin in Central Chile: implications for adaptation to climate variability and climate change

One option to deal with climate variability in agriculture is to build irrigation infrastructure, although this may lead to the overdevelopment of water resources, leading to ‘basin closure’. The Limarí Basin, in central north Chile, has relied on irrigation infrastructure over the last 30 years to increase water supply reliability and extend irrigated acreage, especially for permanent crops. This situation has reduced adaptation opportunities in the basin, which is currently experiencing a severe drought that, according to climate change projections, is expected to persist in the future, with important consequences for the sustainability of agriculture production.