Return Waters Research Articles

Water Security in Uzbekistan: Implication of Return Waters on the Amu Darya Water Quality

Amu Darya river, one of the main water resources of Uzbekistan, shows a relevant longitudinal enrichment of soluble contents which strongly limits the human uses of its waters. Because of the low natural run-off processes, salts and pollutants are mainly driven to the river by the return waters used for washing and irrigating the surrounding lands. The influence of return waters on stream quality is dramatically relevant in the lower reaches of the river where almost all the flowing waters have been previously used for the agriculture practises. To provide analytical evidence on the potential effects of return waters on the quality of the Amu Darya river, the paper reports and comments data on salinity and metals contents of the waters flowing in the artificial channel network of Bukhara and in the Amu Darya river, from Bukhara up to the dam forming the Tuyamuyn Hydro Complex (THC). A total of 15 sampling sites were selected for the analytical survey: Two sites were located on the Amu Darya river downstream from the inflow of the return waters from Bukhara, two in the river entering in the THC, and three downstream from the dam forming the reservoir complex. The waters entering and leaving the Bukhara agricultural area were sampled in two main collectors, while the waters flowing in the channel system were sampled in six distinct collectors. The following parameters were considered in the survey: pH, Oxygen, Hardness, Salinity, Conductivity, P-PO4(3-), P tot, N tot, N-NO3(2-), N-NO2-, COD, Ca2+, Mg2+, Fe, Mn, Zn, Cr, Cu, Ni, Cd, Pb. Salt concentrations below 1000 mg/l were measured in the Amu Darya waters upstream to Bukhara. In the drainage system, salinity exceeds the palatability limit and reaches the maximum peak of 3200 mg/l in the outflow collector. Due to dilution effects, salinity returns to lower values (400-700 mg/l) along the Amu Darya river downstream from Bukhara; calcium and magnesium resulted the major constituents of the overall salinity. No serious metal contaminations were detected in the waters entering and leaving the examined channel system. Differently, the Amu Darya waters upstream to the THC showed a relevant metal contamination, with Cr, Ni, Fe concentrations exceeding the limits for human consumption. In the downstream sites, located in the Tuyamuyn Hydro Complex and in the Amu Darya river flowing out from this reservoir, excluding Fe, all the examined metals showed lover concentrations and values below the normative limits. The direct human consumption of the lower Amu Darya waters is strongly limited by salinity and by metal contamination. Although the salinity of the return waters from the Bukhara drainage system results in above normal limits, no corresponding increases were measured in the Amu Darya river downstream from the return water inflow at the time of the survey. As for the metal contamination of the Amu Darya river, the survey revealed the presence of relevant sources of metal contamination downstream from Bukhara external to the agricultural drainage system. This contamination resulted in reduced sedimentation processes taking place in the limnetic zones of the Amu Darya river upstream to the dam forming the Tuyamuyn Hydro Complex. To fully understand the longitudinal increase of Amu Darya salinity, an evaluation of the cumulative effects of the loads from the main agricultural areas is required, also by using mass-balance models. As for the metals, an investigation should be addressed to identify the anthropogenic sources of contaminations present in the lower Amu Darya region and the metal loads should be diverted.

The importance of sullage (grey‐water) treatment in the restoration and conservation of urban streams

Sullage (grey‐water) is one of the major point pollution sources, which is discharged from residential and commercial areas into the rivers without any treatment. This study was conducted to determine the pollution characteristics of sullage from a 6.14‐hectare residential area where it is discharged into an urban stream without any treatment; and thereafter, to evaluate its probable consequences on the water quality of urban streams. Analyses of the hourly samples revealed that the sullage from residential area was polluted due to high concentration of BOD, COD, Ammoniacal Nitrogen (AN), Orthophosphate (PO4) and TKN, and low concentration of DO. Mean concentrations of the above‐mentioned parameters from 72 samples were 51, 123, 5.4, 2.15, 2.15 and 1.62 mg/l, respectively. Further analyses of data revealed that, on average, the sullage was equivalent to Class V water as defined by the water quality index (WQI) in National Water Quality Standards (INWQS) of Malaysia. Most of the urban streams drain return water (wastewater) from the settlements and lack adequate baseflow to dilute the wastewaters. As such, if the return waters are not treated then the urban streams shall never be able to achieve the required goals. Domestic sewage and industrial wastewaters are treated to some extent, to achieve the standards stated in Environmental Quality Act, 1979. On the contrary, although quantity and quality of sullage plays important role on stream water quality, it is neither taken care of by any agency nor controlled by any standard. As such, it is important to make necessary technical, institutional and legal arrangement to treat sullage up to certain standard before it find its way into the urban streams.

The response of river water quality and quantity to the development of irrigated agriculture in the last 4 decades in the Yellow River Basin, China

Irrigation agriculture is a major economic activity throughout the Yellow River Basin and has doubled in area in the last 5 decades. Monitoring data for major ions at 63 monitoring stations in the Yellow River system, ranging from 1960 to 2000, were studied. The concentration of major ions in much of the basin, and especially in downstream of the major irrigation areas of the upper basin, increases significantly between 1960 and 2000. We conclude that this increasing trend is mainly a result of saline irrigation return waters, especially from irrigated lands in arid zones of northern China where sodium increases by 100% and total dissolved solids increases by 29% in the main stem. Since 1972 a critical water quantity issue, “duanliu,” has appeared, which refers to the drying up of the lower reach of the Yellow River. This phenomenon is due mainly to increasing irrigation water withdrawal, which is officially reported to be 91% of all surface water abstraction from the Yellow River. High rates of evapotranspiration and loss to groundwater, especially in the arid irrigated areas in two large irrigation areas in Ningxia and Inner Mongolia, where abstracted water is some 25–30% of annual main stem flow, creates major water losses. There is a need to develop and enforce more rational water quotas as part of a reform of water management in the basin so that basin‐wide management is given at least as much importance as provincial‐level benefits.

Strategy of transboundary return flow use in the Aral Sea basin

The Aral Sea Basin, which is shared by 5 countries of the former Soviet Union — Kazakhstan, Kyrgyzstan, Tadjikistan, Turkmenistan and Uzbekistan is well known to the world due to the large scale water development in the Soviet period, which caused many ecological problems in the region. One of them is the problem of return waters, which are unmanaged and unused in now acceptable form. The total Transboundary Return Water (TRW) volume formed in the territory of 5 states is 36–40 km2. The two main reasons for the worsening of water quality in the major rivers of the Aral Sea basin — Amudarya and Syrdarya are: water withdrawal from the rivers for irrigation purposes and release return flow to the river of a large content of salts and other pollutants from irrigated lands. Spontaneous formation, dissemination and accumulation of return waters can, and already have caused considerable negative effects in environment and social development. For the development of a program for the use and management of these waters and its approval by the region's countries, measures preventing these effects must be taken in order to be of mutual benefit to all the countries involved and, simultaneously, to transform these waters into a source of life, biodiversity, sustainability and prosperity in the Aral Sea basin on a scale, that would influence the world community. For stabilization of these water bodies at the regional, and, thus at a global scale, it is necessary to eliminate the following threats: instability of whole scope and especially TRW regime in terms of quantity and quality; uncontrolled allocation and use of such waters; injurious use, including poaching. It must be taken into account that transboundary waters' sustainable development and use require permanent monitoring and management over a range of criteria, providing their ecological stability and safety as well as long-term bioproductivity and biodiversity of ecosystems supported by them. The principle provisions of management system on TRW are proposed for each stage: type of return water use; direction of possible use; stability criterion; restrictions; control.

EVALUATION OF INORGANIC AND ORGANIC NUTRIENT SOURCE IMPACTS IN NUTRIENT TMDLS

There is a resurgence of interest in controlling the excessive fertilization (eutrophication) of surface waters in order to protect domestic water supplies and other beneficial uses of waters from impairment (pollution) by excessive growths of algae or other aquatic plants whose growth is stimulated by nitrogen and phosphorus. An area of particular concern is the nutrients added to waterbodies through the land application of inorganic fertilizers and management of domestic wastewater sludges (biosolids), animal manure, and compost that could lead to surface and ground water pollution. With the development of TMDLs to control excessive fertilization of waterbodies and the emphasis on protecting domestic water supply watersheds from pollution (source protection), the use of fertilizers as well as the regulation of the management of waste residues on land needs to be focused on controlling surface and ground water pollution. Those who fertilize lands as part of crop production as well those who dispose of waste residues (biosolids, animal manure, and compost) on land will be required as part of nutrient TMDLs to conduct comprehensive, reliable monitoring programs to ensure that the fertilizer nutrients and the constituents in the waste do not cause pollution – impairment of uses – of surface and ground waters associated with the waste management activities. The current federal and state regulatory agency guidance on management of biosolids needs to be amended to include a monitoring program to determine if nitrogen, phosphorus and, for that matter other constituents, in the biosolids cause surface or ground water pollution. It is important that the groundwater monitoring program be pro-active in detecting pollution before the groundwaters are polluted, such as through the use of unsaturated flow monitoring of the groundwater underlying the areas receiving the waste residues. This paper provides guidance on the use of the OECD eutrophication study results to evaluate the potential impacts of nutrient releases from agricultural lands and other sources on the eutrophication related water quality in many types of waterbodies. It also provides guidance on how to establish allowable nutrient loads to waterbodies to protect the eutrophication related designated beneficial uses. Particular attention is given to assessing the water quality significance of nitrogen and phosphorus present in stormwater runoff/irrigation return waters from the areas that receive land application of inorganic fertilizers and waste residues. It discusses monitoring programs needed to ensure that land application of inorganic fertilizers and waste

Diffuse agricultural water pollution in India

Concern over agricultural diffuse pollution sources in integrated water quality management has been growing recently. Such sources are likely to be even more critical in developing countries, including India, where agriculture and rural habitats are still dominant, unlike the G7 or other affluent industrialised nations. A number of special features of the Indian scene need to be considered. These include: (i) extremely varying rainfall and stream-flow patterns; (ii) still largely traditional agricultural practices with average application of fertilizers and pesticides and significant areas under dry farming or only marginal irrigation; (iii) a very large cattle population, with agriculture almost always linked with animal husbandry; (iv) a culture of living close to the river (if not in the river) with dominating instream uses of bathing, washing, cattle wading, waste disposal, etc. and large-scale floodplain farming; and (v) scant respect for rules, regulations and laws alongside an extremely weak law-enforcement machinery. The paper shows that in the non-monsoon (non-flood) periods, which may account for all but 2 months of a year, agricultural diffuse pollution sources seem to have no impact on stream water quality. During these periods flows are low to minimal and pollution is dominated by the in-stream uses, sullage waters of rural communities and point discharges from urban/industrial sources, if any. Pollution due to agricultural return waters, either as wash-off or as seepage, appears to be rare during the 8-10 fair weather months. However, surface wash-off of pollutants from agricultural sources becomes the dominant factor during flood flows, and seepage/drainage from agricultural fields/soils continues to pollute streams for a month or two after the monsoons are over. Application of chemical fertilizers and pesticides (or any other agricultural chemicals) in India is still low compared to developed countries, and while eutrophication due to high levels of washed-off nutrients is observed in rural ponds and other stagnant bodies of water receiving agricultural drainage, and excessive pesticide residuals are often reported for vegetables, fodder, milk, etc., monitoring of streams and rivers does not show any significant pollution due to nutrients or pesticides from agricultural diffuse pollution during fair weather months. High nitrate concentrations have been reported in groundwater and in many areas, such as Punjab and Haryana, these can often be linked directly to diffuse agricultural sources. The major problem of agricultural diffuse pollution appears to be the heavy silt loads, along with large quantities of dissolved salts, nutrients, organics and even heavy metals and bacterial contaminants washed off during floods. The silt tends to clog up the flow channel to further encourage seasonal floodplain agriculture. This results in a vicious circle, which degrades the channel, increases flood-damage and is undesirable from ecological and sustainability points of view. High concentrations of salts and nutrients encourage growth of weeds and macrophytes after the floods have passed. The presence of organics, heavy metals and bacterial contamination renders the streamwater unfit for in-stream use or abstraction. With the introduction of intensive agriculture and adoption of modern farming techniques involving the application of much irrigation water and agricultural chemicals, the problems caused by diffuse agricultural pollution are bound to grow. Routine pollution control methods of discharge permits (or consent letters), EIAs or environmental audits, and normal enforcement measures by regulatory agencies are not likely to work for control of such pollution. Using the example of a small river in central India, Paisuni (Mandakini), the paper brings out the nature of the problems, and suggests a possible management approach.

Diffuse agricultural water pollution in India

Concern over agricultural diffuse pollution sources in integrated water quality management has been growing recently. Such sources are likely to be even more critical in developing countries, including India, where agriculture and rural habitats are still dominant, unlike the G7 or other affluent industrialised nations. A number of special features of the Indian scene need to be considered. These include: (i) extremely varying rainfall and stream-flow patterns; (ii) still largely traditional agricultural practices with average application of fertilizers and pesticides and significant areas under dry farming or only marginal irrigation; (iii) a very large cattle population, with agriculture almost always linked with animal husbandry; (iv) a culture of living close to the river (if not in the river) with dominating instream uses of bathing, washing, cattle wading, waste disposal, etc. and large-scale floodplain farming; and (v) scant respect for rules, regulations and laws alongside an extremely weak law-enforcement machinery.The paper shows that in the non-monsoon (non-flood) periods, which may account for all but 2 months of a year, agricultural diffuse pollution sources seem to have no impact on stream water quality. During these periods flows are low to minimal and pollution is dominated by the in-stream uses, sullage waters of rural communities and point discharges from urban/industrial sources, if any. Pollution due to agricultural return waters, either as wash-off or as seepage, appears to be rare during the 8–10 fair weather months. However, surface wash-off of pollutants from agricultural sources becomes the dominant factor during flood flows, and seepage/drainage from agricultural fields/soils continues to pollute streams for a month or two after the monsoons are over.Application of chemical fertilizers and pesticides (or any other agricultural chemicals) in India is still low compared to developed countries, and while eutrophication due to high levels of washed-off nutrients is observed in rural ponds and other stagnant bodies of water receiving agricultural drainage, and excessive pesticide residuals are often reported for vegetables, fodder, milk, etc., monitoring of streams and rivers does not show any significant pollution due to nutrients or pesticides from agricultural diffuse pollution during fair weather months. High nitrate concentrations have been reported in groundwater and in many areas, such as Punjab and Haryana, these can often be linked directly to diffuse agricultural sources. The major problem of agricultural diffuse pollution appears to be the heavy silt loads, along with large quantities of dissolved salts, nutrients, organics and even heavy metals and bacterial contaminants washed off during floods. The silt tends to clog up the flow channel to further encourage seasonal floodplain agriculture. This results in a vicious circle, which degrades the channel, increases flood-damage and is undesirable from ecological and sustainability points of view. High concentrations of salts and nutrients encourage growth of weeds and macrophytes after the floods have passed. The presence of organics, heavy metals and bacterial contamination renders the streamwater unfit for in-stream use or abstraction.With the introduction of intensive agriculture and adoption of modern farming techniques involving the application of much irrigation water and agricultural chemicals, the problems caused by diffuse agricultural pollution are bound to grow. Routine pollution control methods of discharge permits (or consent letters), EIAs or environmental audits, and normal enforcement measures by regulatory agencies are not likely to work for control of such pollution. Using the example of a small river in central India, Paisuni (Mandakini), the paper brings out the nature of the problems, and suggests a possible management approach.

Agricultural and environmental changes in the upper Euphrates catchment of Turkey and Syria and their political and economic implications

In southeast Turkey a number of large irrigation projects have been planned to utilize the waters of the Euphrates river held in the reservoir behind the Ataturk Dam. When these projects are fully operational the flow of the Euphrates into Syria will be substantially reduced. This has already led to complaints from the downstream countries of Syria and Iraq. The environmental impacts of importing large volumes of water into the watersheds of two tributaries of the Euphrates, the Balikh and the Khabour (which in their lower courses flow through Syria), are expected to be considerable, particularly on the relatively small River Balikh. Problems are most likely to be caused as a result of irrigation return waters, which may be highly saline and may be up to twice the river's natural flow. Downstream effects could be increased still further as Syria is planning a large irrigation scheme in the lower part of the Balikh catchment. One of the aims of the present project is to assess the usefulness of satellite data for estimating agricultural changes within the upper part of the Euphrates basin. Satellite imagery of the two catchments from the mid-1980s, before large-scale irrigation development began, reveals a largely traditional agricultural pattern, characterized by rain-fed cultivation in the extreme northern part of the region and irrigated agriculture along the major floodplains. Modern commercial agriculture was confined to groundwater developments in the upper Khabour and to projects adjacent to the Euphrates floodplain downstream from the Tabqa dam. Throughout the arid southeastern part of the region agriculture was confined to a few small sites where groundwater was available for irrigation. Elsewhere scrub desert vegetation prevailed. It is on to this traditional pattern of agricultural activity that the modern irrigation projects will be superimposed. In Turkey, rainfed agriculture will be replaced by irrigation. In Syria, land that has not previously been cultivated will be utilized for large-scale irrigation activity. Potential problems here are thus likely to be much greater than in Turkey.

Problems of Irrigation Drainage Water Utilization for the Prevention of Surface Water Pollution

The paper analyses results of the inventory of irrigational water derivation in the former USSR. The ways of deriving return and collector-drainage waters, as well as the load exercised by these waters on water bodies, are investigated. The paper discusses the main areas of collector-drainage water re-use and utilization, the latter being regarded as a means of preventing surface water pollution and salinization in the zones of irrigation. Necessity in working out a concept of effective, ecologically substantiated use of collector-drainage waters is substantiated.

Influence of various forms of refractories and firing conditions on the water-soluble chromium content in cement clinker

One of the basic factors hindering the creation of closed asbestos-cement production is the accumulation in the return water of chromium compounds. The question of removal of chromium from the waste and return waters of asbestos-cement production has still not been solved. The proposed methods of purification are economically unacceptable and are relatively ineffective for the highly alkaline asbestos--cement production waters, which is the basic reason for delay in the introduction of these methods into production.

Tamarisk and river-channel management

Tamarisk (Tamarix chinensis, Lour.) an artificially introduced tree, has become a most common species in many riparian vegetation communities along the rivers of the western United States. On the Salt and Gila rivers of central Arizona, the plant first appeared in the early 1890s, and by 1940 it grew in dense thickets that posed serious flood-control problems by substantially reducing the capacities of major channels. Since 1940 its distribution and density in central Arizona have fluctuated in response to combined natural processes and human management. Groundwater levels, channel waters, floods, irrigation return waters, sewage effluent, and sedimentation behind retention and diversion works are major control mechanisms on the growth of tamarisk; on a regional scale of analysis, groundwater levels are the most significant under present conditions.