Water quality response to hydropeaking regulation of the Three Gorges Dam and Gezhouba Dam, China

Hydropeaking as the most prominent feature of flow alterations resulting from hydropower plants has received attention worldwide. Ramifications of hydropower on the downstream river systems mainly focus on hydrological regimes or long-term water quality changes. Exceptional knowledge is expected on the sub-daily changes of water qualities in the downstream river reach that is affected by the hydropeaking. In this study, we investigate the dynamics of hydropeaking and thermopeaking at the outlet of the Three Gorges Dam TGD using a high temporal resolution dataset, and inspect its association with water chemistry indices. Hourly measurements are analysed for the downstream station Yunchi , and compared with the upstream station Nanjinguan. The results show that along with water temperature, water quality indices such as dissolved oxygen, total Phosphorus, total nitrogen, PH, and electricity conductivity all show evident ‘peaking’ phenomenon in a short time. These divergent variations, however, are not valid for non-hydropeaking affected indicators including turbidity, permanganate index, and ammonia nitrogen. These hydropeaking-induced perturbations are mitigated by the flood control operation from July to September. This study demonstrates that water quality indices are sensitive to hydropeaking and thermopeaking with respect to the magnitude of change and the seasonal component during a year. The results provide additional evidence for the environmental impacts of hydropower regulation on the receiving river reach, and bridge the gap between hydropeaking studies and thermopeaking, and study water qualities variations that were seldom connected from the same temporal perspective in river research.

Evaluation of surface water quality using water quality indices (WQIs) in Lake Sukhna, Chandigarh, India

To assess the surface water quality of Sukhna Lake, 13 physico-chemical parameters like temperature, pH, transparency, dissolved oxygen, electrical conductivity, total dissolved salts, chloride, total Aalkalinity, total hardness, calcium, magnesium, nitrate and phosphate were investigated on monthly basis for a period of two year (July 2016–June 2018) by using standard procedures. The results were compared with the values or ranges mentioned by standard organizations (WHO and BIS) for assessing the water quality and these revealed that the lake water was turbid and under DO distress. Various water quality indices like water quality index (WQI), Canadian Council Ministry of Environment (CCME)-WQI and comprehensive pollution index (CPI) were used to assess the water quality status in the Sukhna Lake. The range of WQI (59.74–83.49) indicated that the water quality status of the lake belonged to good category while those of CCME-WQI (52.4–81.61) revealed that water quality fallen from marginal to good category and those of CPI (0.4–0.7) indicated fair state of water in the lake. Overall the water quality in Sukhna Lake has been found deteriorated during second year in comparison the first year during the study time.

AN EVALUATION OF WATER QUALITY INDEX VARIATION IN DOMESTIC DRINKING WATER RESERVOIRS

This study investigates the variation in water quality parameters due to short term storage in reservoirs in north-east Nigeria. The objective of the study is to determine the water quality, testing selected vital parameters and determining the DWQI of the samples from selected water sources and their respective reservoirs. The World Health Organization (WHO), as well as the Canadian Council of Ministers of the Environment (CCME) standards of water quality test and drinking water quality indices, were adopted. Samples were collected at both source and reservoir from five different points in the same area. The quality of water was analyzed in order to determine the variation in water quality and drinking water quality indices when stored over time in a storage system. The result of the quality test revealed that the level of all the parameters were within the limit set by WHO except that of Iron and Manganese which were slightly above the standard limits. The correlated variables revealed that a very strong relationship exists between all the samples with the highest R2 as 0.99 and the lowest R2 as 0.94. The drinking water quality indices were found to be good for all samples with an index value of 88.45%. This study strongly recommends further investigation as well as regular monitoring of the drinking water quality in the area.

Micro-Clustering and Rank-Learning Profiling of a Small Water-Quality Multi-Index Dataset to Improve a Recycling Process

The efficiency improvement of wastewater recycling has been prioritized by ‘Goal 6’ of the United Nations Sustainable Development initiative. A methodology is developed to synchronously profile multiple water-quality indices of a wastewater electrodialysis (ED) process. The non-linear multifactorial screener is exclusively synthesized by assembling proper R-based statistical freeware routines. In sync with current trends, the new methodology promotes convenient, open and rapid implementation. The new proposal unites the ‘small-and-fast’ data-sampling features of the fractional multifactorial designs to the downsizing, by microclustering, of the multiple water quality indices—using optimized silhouette-based classification. The non-linear multifactorial profiling process is catalyzed by the ‘ordinalization’ of the regular nominal nature of the resulting optimum clusters. A bump chart screening virtually eliminates weak performances. A follow-up application of the ordinal regression succeeds in assigning statistical significance to the resultant factorial potency. The rank-learning aptitude of the new profiler is tested and confirmed on recently published wastewater ED-datasets. The small ED-datasets attest to the usefulness to convert limited data in real world applications, wherever there is a necessity to improve the quality status of water for agricultural irrigation in arid areas. The predictions have been compared with other techniques and found to be agreeable.