A Comparative Study on Environmental Flows Assessment Methods in Lower Reach of Mahanadi River

Environmental flows assessment is a process which determines the allocated water for maintaining aquatic habitats and ecological processes in a environment. The river system attains zero flow in low flow period due to construction of hydropower generating structures, water retaining structure and withdrawal of water by water users, which possesses a tremendous threat to the environment, ecology & aquatic life. Therefore a need arises to regulate the reservoirs for releasing the adequate water in the river throughout the year as well as a flushing flow once in a year. Thus environmental flows assessment is done in Lower Mahanadi sub-basin and recommended to provide the EFRs on average 26 % of MAF with a range of Low flow 56% of mean low flow & High flow 21% of mean high flow to be ensured at any circumstances to avoid any degradation of river ecosystem. In the present study the assessment of the environmental flows on the basis of Tennant method, Tessman method, VMF method, Q90_Q50 method, Smakhtin method,  low flow index (7Q10) method and FDC (EMC shifting technique) method using Global Environmental Flow Calculator (GEFC) software. Keywords: EFR, GIS, Tennant, Tessman, VMF, Q90_Q50, 7Q10, FDC method

Spatial and temporal precipitation trends of proposed smart cities based on homogeneous monsoon regions across India

The conservation of rainwater and augmentation of groundwater reserve is necessary to meet the increased water demands. Precipitation occurring in the smart cities need to be understood for a better water management action plan. Therefore, monotonic precipitation trend analysis was performed for eight smart cities drawn from six monsoon homogeneous regions across India. The precipitation data were investigated for trends using the modified Mann–Kendall (MMK) test and Sen’s slope estimator at annual, seasonal and monthly scales. The trend analysis was carried out over 118 years (from 1901 to 2018) at 95% significance level. The Dehradun city (Northern Himalayan region) showed a significant increasing annual precipitation trend (Z = +3.22). Indore and Bhopal cities from West Central region showed significant increasing annual trend (Z = +2.01) and non-significant decreasing annual trend respectively. Although, Vadodara and Jaipur are lying in the same Northwest region, the trends are opposite in nature. Jaipur city showed a significant increasing annual pre-monsoon trend (Z = +2.44). The winter rainfall in the city of Vadodara is showing a significant decreasing trend (Z = –2.16). The pre-monsoon rainfall in Bhubaneswar (Central Northeast region) and monsoon precipitation in Trivandrum (Peninsular region) are showing significant increasing (Z = +2.56) and decreasing (Z = –2.71) trends, respectively. A non-significant decreasing trend was seen in Guwahati city (Northeast region). The eight smart cities selected for investigation are not truly representing the entire country. However, the study is clearly pointing towards the regional disparity existing in the coun-try. These findings will be helpful for water managers and policymakers in these regions for better water management