The Status and Trend of Water Pollution Control Technology in China

ABSTRACT

The feasibility of predicting total summer crop water use by grassland, based on early or pre-season soil moisture reserves, was investigated. Tests were based on the correlation over time between simulated soil moisture and related variables at six South African climate stations. A weather driven computer budget model was used to simulate daily soil moisture reserves. Results indicate that early prediction of seasonal crop water use is not feasible, but that deep soil moisture is stable enough over time to be a reliable monitoring variable for crop growing conditions. Moisture stored in the deep soil has good potential for monitoring more severe drought conditions.     

A Conceptual Model For River Bank Erosion

ABSRTACT

A conceptual model was developed to predict bank migration in a single river or a system of streams. The model is based on dividing the river into stream links. The methodology for estimating the volume of bank materials that would be entrained in the river flow, as well as the sediment sources and deposition of materials detached by river flow, have been described and incorporated into the model. The model considers the mechnanics of the river bank erosion processes and can serve as a tool, among others, in conservation and land management.     

Economic Aspects of Soil Conservation Programs in Less-Developed Countries (LDCs)

ABSTRACT

This article evaluates the prospects for rainfall-runoff water harvesting as a means of increasing water supplies in Greater Amman and the Hashemite Kingdom of Jordan. Rain/all-runoff water harvesting is a small-scale water conservation approach for catching/storing rainfalls and certain runoff waters in a localized area. before the waters enter the usual hydrologic cycle. Generally the methods are small basic impounding concepts as compared with larger-scale river dams and reservoirs. Catchment of rainfall drainage from a building roof with tank storage is the commonest practice. This is an age-old practice used to sustain populations, mostly in arid areas of the world, but also in areas where water distribution systems are unavailable. In the following text, water harvesting yields are calculated for residential roofs and for the potential from commercial and industrial areas. as of 1990 and projected to 2005. The results show that rainfall-runoff water harvesting is an increasingly attractive consideration in arid areas facing acute water supply shortages, for both villages and urban centers.     

Water Quality Management in California

ABSTRACT

California is a land of contrasts. Within its boundaries are the highest and lowest elevations in the continental United States. The climate varies from subtropical to alpine and regional rainfall ranges from less than 50mm to more than 2,500mm annually. Water is a scarce and precious resources in California.

The basic approach used in Californias water quality control program is first to identify beneficial uses of the waters and then to develop water quality standards that are sufficient to protect the waters for those uses. The water quality control plan (basic plan) provides the technical basis for determining waste discharge requirements, taking enforcement actions, and evaluating clean water grant proposals. The paper discusses the background and philosophy of water pollution control practices in California with a specific example in the Sacramento River Basin.     

The Study and Planning of Reservoir Desilting in Taiwan

ABSTRACT

Taiwan is an island located in the western Pacific Ocean, about 36 000 km² in size. It has a banana shape with high mountains running roughly in the north-south direction with many peaks exceeding 3000 m in elevation. Consequently, the streams on the island are generally short and steep, many with high sediment loads. The climate is semitropical, with high precipitation between May and September and relatively dry during the rest of the year. In southern Taiwan nearly 70% of the annual rainfall occurs in the period of June through August, another 15% in the months of May and September.

In order to store the large amount of runoff water in the wet summer season for later use, 27 reservoirs have been constructed, some are under construction and several are being planned. For streams having a heavy sediment load such as those in southern Taiwan, the reservoir will be silted in a short time. One possible approach to prolong the useful life of the reservoir is to flush the sediment in the reservoir periodically by using sluice valves. Although the scheme is still under study, some tryouts have been implemented effectively. The proposed dam-reservoir project that adopts a special scheme will be presented in conjunction with the basic design procedures.     

IV World Congress on Water Resources,September 3–11, 1982, Argentina,on “Water for Human Consumption,Man and his Environment”

ABSTRACT

The major hydroclimatic cause of the 1993 Upper Mississippi River Basin flood was the persistence of heavy rains over a period of several months. As a result, precipitation totals for April-September 1993 were unprecedented, exceeding by a large margin any previous six-month precipitation total since 1895. Using standard hydrometeorological methods, the frequency of occurrence of these precipitation totals is expected to be less than once every 200 years. The core of the heavy rain area was located in Iowa and Missouri near the main stems of the Mississippi and Missouri Rivers. Thus, runof from many of the heavy rain events was deposited directly into these main stems. The persistence of the heavy rains maintained high soil moisture levels throughout the summer period. Thus, the heavy rains during the summer were accompanied by very high runoff rates. Also, the frequent rains were accompanied by many cloudy days. Primarily for this reason (and to a lesser extent because of lower temperatures), potential evapotranspiration was considerably below the long-term average. This was a contributing factor to maintaining the high soil moisture levels and high runoff.     

Management of Sediment in New South Wales,Australia

ABSTRACT

The amount of sediment in major New South Wales rivers and reservoirs is relatively low compared to world averages. This is a result of relatively low erosion rates, the sediment coarseness and numerous sediment sinks between the erodingparts of catchments and the rivers and reservoirs. However, in some locations several problems have required attention. These include: sediment blockage of roads and culverts; sedimentation of small reservoirs and recreational lakes; sedimentation on large alluvial fans; river channel damage casued by low sediment supply; and lack of effective government control over soil erosion and sedimentation in the past. Strategies to overcome these problems start with information collection to pinpoint major problems. This enables the preparation of total catchment management plans. These require proper land-use policies, legislation and education of the public for effective implementation.     

Reservoir Sedimentation in India—Its Causes,Control, and Future Course of Action

ABSTRACT

A survey of Indian reservoirs has shown that they receive on an average about 200 percent more sediment than the design inflow. The causes are the usual, except that they are operating very intensely. In brief ‘misuse and mismanagement’ of the catchment area will describe the causes of higher rates of sedimentation.

Fortunately India is very much aware of this problem and a lot is being done by identifying the priority areas for treatment and implementation of programmes to reduce soil erosion and sediment generation.

While techniques and efficacy of various biological and structural control measures are well known, it is the policy and planning aspects which need greater attention at present. Some of them are:

—It is important that policy and planning should aim at developing the catchment area, reservoir and command area as a package.

—In the developing world sediment is the greatest pollutant and it must be recognised and treated as such.

—A policy for effective water resource and hydropower development, watershed and command area development must take into account the short term and long term, direct and indirect, private and social benefits, and endeavour to involve the people and the employees in such a way that they feel committed to efficient and effective implementation.     

Small-Scale Gravity Flow Water Systems in Phrae Province,Thailand

ABSTRACT

Small gravity flow water systems using small diameter PVC pipe are an increasingly popular technology in the mountains of Phrae Province, Thailand. The systems are appropriate to the needs and capabilities of the rural Thai village users; rural Thai villagers have been able to independently design, finance, and construct systems serving from 10–30 houses.

Technical details about the construction, maintenance, and finance of two systems in Ban Nam Jom Village are described. The systems include sedimentation and sand filtration tanks, and also galvanized iron reservoirs. One system, serving 22 houses, was constructed at a cost of US $904.72.

Low cost gravity flow water systems are a new technology for accessible mountain areas in countries where cheap PVCpipe is available.     

Sedimentation in New Zealand Hydroelectric Schemes

ABSTRACT

Geologically young New Zealand catchments can produce large quantities of relatively coarse sediment which has caused problems in the design and operation of some hydroelectric schemes.

The general sediment producing characteristics of New Zealand catchments are described and are related to the measured sedimentation rates of four reservoirs.

A number of examples of sediment management problems and methods of dealing with them are given to illustrate some of the principles and practice in the design and operation of sediment handling facilities.

Generally sedimentation in New Zealand hydroelectric reservoirs has not been a problem mainly because development has concentrated on rivers where a large proportion of the sediment has been trapped by natural lakes upstream. Usually catchments of major schemes have had less than 200 t/km² sediment yield annually and this has caused no problems. However some smaller schemes in catchments where the annual sediment yield has exceeded 2000 t/km² have encountered problems and the cost of dealing with this has usually been less than 5% of the scheme income.

It is concluded that planning and management of sediment in New Zealand is a long-term problem which can be handled using the existing database and engineering techniques providing the problem is recognised.     

Brazilian Hydroelectric System

ABSTRACT

Electric power generation in Brazil is mainly based on hydropower (97% of total production in 1984). This paper describes the main features Editorial of the Brazilian Hydroelectric System as well as some power generation expansion possibilities. The operation of the system is also described, including a chain of scheduling procedures with different planning horizons and degrees of details in the representation of the system.     

An expert system for groundwater exploration and exploitation

Work undertaken by the authors for the last ten years in 15 African countries has enabled the modelling of a water points implementation strategy. It has also permitted the quantification of determining criteria within the village water supply frame. Through an expert system approach they explain the possibility of modelling the process used by a hydrogeologist to successfully carry out well‐location studies. This article describes the expert system Hydrolab¹, which is devoted both to computer‐aided decision making and to computer‐assisted learning support.     

Establishing Qualitative Hypotheses on the Influence of El Nifio On Metropolitan Adelaide Water Supply

ABSTRACT

The question is raised whether El Niño, as a symptom of the Southern Oscillation, has an influence on Metropolitan Adelaide water supply. To answer this, four qualitative hypotheses have been established in this paper to indicate that there is an influence. The four hypotheses are described as follows. As Niños and Australian droughts intensify, as represented by increasing negative intensity of the Southern Oscillation, there is a tendency for rainfall deficiency to increase over the catchments of the Mount Lofty Ranges supplying water to Metropolitan intake from the River Murray to supplement the supply deficiency of the Mount Lofty Range catchments. However, the Southern Oscillation may have an influence on River Murray flows into South Australia if such flows are not affected by regulation of up-stream storage. But for regulated River Murray flows into South Australia either at the Entitlement flow level or close to it, the influence of Niños on such regulated flows may be masked by regulation. Finally, as the Southern Oscillation increases in negative intensity, its area of influence could extend to South Australia besides northern and southern Australia. In this situation, below-averge annual rainfall in the Mount Lofty Ranges and below average annual River Murray flows into South Australia could occur in the same year.     

计算机监控供水系统的设计与实现

结合现场实际供水系统的特点,利用现代计算机监控技术设计了一种供水自动监控系统。对系统的总体结构和功能进行了阐述,提出了监测/控制子站、计算机控制中心、查询终端的系统构建方案以及硬件设计方案,并提出了基于Internet的MGIS软件系统的设计方案。结合实际应用情况讨论了计算机监控供水系统的作用与意义。     

An Investigation into the Use of Water by Portuguese Industry

ABSTRACT

The continuous increase in water demand for various uses underlines the importance of supply problems in the general context of water resources management.

In this domain it would clearly be useful to collect and make available all the data currently stored on different paper supports and kept by several regional agencies. This would provide an immediate overview of tbe resources, and also permit forecasting the future demand for tbe various utilizations.

This paper describes a project involving a database to be used for groundwater resources management, conceived not only as a support for research activity, but also as a contribution to developing new and more efficient managementprocedures. The database has been designed to be used on a personal computer, with software readily available on the market.     

The exposure of a fresh fruit and vegetable supply chain to global water-related risks

ABSTRACT

We have combined estimates of the UK’s supply of fresh fruit and vegetables (1996 – 2015) with estimates of water requirements and water scarcity in producing countries, to identify where the supply is exposed to physical, regulatory and reputational water risks and how this has changed over time. Some 76% of the freshwater consumed in the supply of fresh fruit and vegetables to the UK is withdrawn overseas. The supply chain is particularly exposed to water risks in Spain, Egypt, South Africa, Chile, Morocco, Israel and Peru. Exposure has increased over time.     

The water footprint challenge for water resources management in Chilean arid zones

ABSTRACT

The water footprint concept is difficult to apply to water-shortage conditions because of private management and variability in the water balance. Chilean water law stipulates that water allocation depends on water rights and private organization criteria, according to the basin water supply and not necessarily crop irrigation demand, crop yield or irrigation technology. This paper explores the resultant complications.     

The energy trade-offs of adapting to a water-scarce future: case study of Los Angeles

Abstract

Increasing water competition, population growth and global climate change will intensify the tension between water and energy resources in arid climates of the world, since energy costs underscore the challenges facing water security in dry regions. In few places is the tension between water and energy resources more pronounced than in Los Angeles, California. This article analyzes the city’s current water supply and estimates its future energy requirements based on water supply projections from the Los Angeles Department of Water and Power. Results suggest that while increasing local water management strategies could reduce the future energy intensity of the water supply, an increased reliance on water transfers could worsen its future energy intensity.