The in-depth knowledge on management and reducing annual acidic pollution is important for improving the sustainable livelihood of people living in areas with acid sulphate soils (ASS). This study involved a long-term (2001-2006), large-scale canal water quality monitoring network (87 locations) and a field experiment at nine sites to quantify the dynamic variability of acidic pollution and its source in a coastal area with ASS in the Mekong River Delta of Vietnam. Widespread acidic pollution (pH <5) of surface water occurred at the beginning of the rainy season, while pH of the canal water remained high (7-8) at the end of the rainy season and during the dry season. The study identified canal embankment deposits, made of ASS spoils from canal dredging/excavation, as the main source of acidic pollution in the surrounding canal network. The findings suggested that there was a linkage between the amount of acidic loads into canal networks and the age of the embankment deposits. The most acute pollution (pH ~ 3) occurred in canals with sluggish tidal water flow, at 1-2 years after the deposition of excavated spoils onto the embankments in ASS. The amount of acidic loads transferred to the canal networks could be quantified from environmental parameters, including cumulative rainfall, soil type and age of embankment deposits. The study implied that dredging/excavation of canals in ASS areas must be carried out judiciously as these activities may increase the source of acidic pollution to the surrounding water bodies.

The livelihoods of poor people living in rural areas of Indus Basin Irrigation System (IBIS) of Pakistan depend largely on irrigated agriculture. Water duties in IBIS are mainly calculated based on crop-specific evapotranspiration. Recent studies show that ignoring the spatial variability of factors affecting the crop water requirements can affect the crop production. The objective of the current study is thus to identify the factors which can affect the water duties in IBIS, map these factors by GIS, and then develop the irrigation response units (IRUs), an area representing the unique combinations of factors affecting the gross irrigation requirements (GIR). The Lower Chenab Canal (LCC) irrigation scheme, the largest irrigation scheme of the IBIS, is selected as a case. Groundwater quality, groundwater levels, soil salinity, soil texture, and crop types are identified as the main factors for IRUs. GIS along with gamma design software GS + was used to delineate the IRUs in the large irrigation scheme. This resulted in a total of 84 IRUs in the large irrigation scheme based on similar biophysical factors. This study provided the empathy of suitable tactics to increase water management and productivity in LCC. It will be conceivable to investigate a whole irrigation canal command in parts (considering the field-level variations) and to give definite tactics for management.

In this paper given are basic characteristics and projected functions of the DTD (Danube-Tisza-Danube) Hydrosystem (Yugoslavia), then types, origin and some characteristics of muds - sediments in the hydrosystem channels. It is estimated that in hydrosystem channels gets in averagely about 1.28x10**6 tons of deposits annually, and of that amount in channels are settled about 0.64 x 10**6 cubic meter annually. In 1980-1996 period, it is mudded from channels of the main channel network averagely about 0.19 x 10**6 cubic meter/year, and in 1991-1996 period, usually only about 0.056 x 10**6 cubic meter/year, i.e. about 10 of average amounts which are deposited during the year. Also explained are numerous undesirable influences of muds - sediments on water quality in channels, as well as functions of the DTD (Danube-Tisza-Danube) Hydrosystem in general. At the end, measures for gradually improving conditions that are influenced by muds - sediments are, proposed.

During the period 1990-1997, the content of 11 trace metals (Fe, Cr, Co, Al, Mn, Cd, Cu, Ni, Pb, Zn, Sr) was studied in muscle and other organs of fish from DTD (Danube-Tisza-Danube) channel system (Yugoslavia). According to obtained and analysed data, the trace metal bioaccumulation can possibly act as enviromental indicator in biomonitoring. DTD (Danube-Tisza-Danube) Channel System can, therefore, be classified as the 3rd class, concerning analysed trace metal content.

On the basis of the enzymatic (phosphatase) activity and microbiological analysis as well, the influence of the oil refinery "Vital" - Vrbas (Serbia, Yugoslavia) wastewater to the recipient DTD (Danube-Tisza-Danube) canal water from the microbiological point of view was determined. In addition the efficiency of the factory's waste water purification plant was estimated. The obtained results of the complex microbiological-enzymological analyses indicated a good water quality at the point where the refinery's water supplies plant is situated (site 1). Very low water quality was determined downstream (site 4) and upstream (site 2) from the inflow of the refinery's wastewater's inflow. The later results might indicated the influence of an unknown pollutant in the region. However, the obtained O/H index value suggests that the self-purification ability of the canal waters is still preserved.

In the period of 1993-1996 water quality of the Bajski canal (Serbia, Yugoslavia) was followed using certain chemical and biological parameters. Oxygen control ranged from its deficiency to its supersaturation recorded in spring and early summer which moved down in summer and early autumn. A smaller amount of suspended particles points to a sedimentation process provoked also in the canal bed, clearing the way for the development of macrophytes. A diverse zooplankton showed typical seasonal variations. A total of 73 species was recorded including 13 Protozoa (17.8%), 44 Rotatoria (60.3%), 10 Cladocera (13.7%), and 6 Copepoda (8.2%). In summary, the process of water quality deterioration is less evident in this section of the DTD (Danube-Tisza-Danube) hydrosystem (Serbia, Yugoslavia).

In the period from May to August in 1996, the samples for hydro-biological and inchthyological from the following localities were collected: the Klaicka river, the Radevacka river, the Sumanka river and the Lipovacka river (Serbia, Yugoslavia). The water quality was determined n the basis of bioindicator values and the abundance of particular species of phytoplankton, zooplankton, bottom fauna and fish community. According to the portion of plankton organisms, the saprobic index for the Klaicka river was between 2.01 and 2.57, for the Radevacka river it was between 2.83 and 2.93, for the Sumanka river between 2.59-2.78 and for the Lipovacka river this index had a value between 2.72 and 2.83. Among the botton fauna, 10 zoobenthic groups were determined. The highest frequency and abundance was registered in the groups of Ephemeroptera and Trichoptera, and the water quality is between oligo- o-beta-mesosaprobic (the Lipovacka river), -beta-mesosaprobic (the Klaicka river), o-beta to alfa-mesosaprobic (the Radevacka river) and beta to alfa-mesosaprobic (the Sumanka river). The ichthyofauna of the Klaicka and Sumanka rivers include the species like southern barbel, chub and spirlin. Basing on the fact, the water quality was determined as beta-mesosaprobic (1.65). The majority of results point to the satisfactory biological quality of water in this hydroecosystem, which is, therefore, considered to be one of the potential sources of water supply.