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Watershed Hydrology and Management
Published in Abrar Yousuf, Manmohanjit Singh, Watershed Hydrology, Management and Modeling, 2019
Precipitation provides the primary input of water into the watershed. Precipitation is the moisture or water that falls from the atmosphere in the form of rain, snow, sleet, fog or hail. It varies in its amount, intensity, and form by season and the geographic location of the watershed. However rain and snowfall contribute water significantly to the watershed hydrologic system. In most parts of the world, snow and rainfall are observed and records are maintained. The watersheds located in Himalayas that are at the mean sea level of around 2000 m generally receive precipitation more as snowfall and less as rainfall, and those located in foot-hills or lower hills and plain areas including coastal regions receive that as rainfall. Precipitation is influenced by the elevation of the watershed. However, rainfall being the predominant form of precipitation causing flood flow, the term precipitation is synonymous with rainfall. Himalayan as well as the coastal watersheds tends to have higher amounts of precipitation than the plain lowlands. It may be due to the orographic effect, in which rising air mass currents cool, condense and release moisture as precipitation. The leeward side of the mountains or barriers receive less precipitation than the windward sides because most of the available moisture in the air mass is lost to precipitation before it reaches the leeward side. The snow packed watersheds contribute stream flow significantly as these act as source of water round the year for the major perennial river systems of the world. In fact the factors such as rainstorm characteristics that is; amount, duration, intensity and average return period determines whether the rain water will flow into streams or infiltrate into the ground. And this information is crucial for crop planning and management as well as for engineering design of water harvesting and flood control structures in the watershed.
Sanitary Engineering
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Types of natural waters: Following are the natural waters into which the sewage can be discharged for dilution: CreeksEstuariesGroundwatersLakesOcean or seaPerennial rivers and streamsCreeks: A creek is an inlet on sea coast and it is likely to not have dry weather flow for some periods in the year.Estuaries: The river’s wide lower tidal part is known as an estuary and the dilution of sewage in estuaries is affected by ocean water in addition to the river water. Therefore, the process of dilution of sewage in estuaries is generally satisfactory.Groundwaters: The sewage, when applied on land, ultimately filters out through different layers of solids and it meets groundwaters at great depths. If groundwater flows through favorable strata of soil, the dilution of sewage is satisfactory.Lakes: A lake is an enclosed water space and it may be used for the purpose of dilution of sewage. The various characteristics of lake such as its size, flowing in it, etc., must be studied carefully before its self-purifying capacity is decided.Ocean or sea: The ocean or sea has water in abundance, and hence, its capacity to dilute sewage is practically unlimited. The sewage of any quality can be diluted into ocean. It can be observed that the sewage reacts with sea water and forms precipitates giving milky color to the sea water. This is known as sludge banks. These sludge banks are undesirable because its interaction with the sulfate-rich sea water produces hydrogen sulfide gas, resulting in bad odor.Perennial rivers and streams: The perennial rivers and streams possess some flow throughout the year. But it may have maximum and minimum limits. The minimum limit generally occurs in summer. The dilution of sewage in summer becomes difficult due to the fact that in summer the solubility of oxygen is reduced because of the high temperature of water. The sewage, under such circumstances, should be properly treated before allowing dilution with perennial rivers and streams.
Numerical investigations on performance improvement of cross flow hydro turbine having guide vane mechanism
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Gaurav Saini, R. P. Saini, S. K. Singal
With the ever increasing demand of energy and for a safe and clean environment, the trends are now shifting toward the renewable energy resources(Bansal and K 2001). Around the world, there has been a great excitement to exploit and find the solutions with new and innovative renewable energy extraction systems(Brunel 2021). India is endowed with lot of renewable energy sources viz. solar, wind, geothermal, hydro, and biomass (Demirbaş 2006). Among all the renewable energy resources, hydropower is a proven, predictable, and last long source of energy (Saini and Saini 2020a). Due to large perennial rivers in hilly areas, water is usually available at different hydro potential sites throughout the year (Kaygusuz 1999). These potential sites have been the source of renewable energy for more than a century, leading to reduction in burning of fossil fuels which negatively impact the ecology and environment (Bansal and K 2001).
Streamflow prediction using machine learning models in selected rivers of Southern India
Published in International Journal of River Basin Management, 2023
Rajat Kr Sharma, Sudhanshu Kumar, D. Padmalal, Arka Roy
Water touches every aspect of development and is tightly linked with the sustainable development goals (SDGs). It supports ecosystems, drives economic growth, and is essential and fundamental for the existence of life on the planet. Water use has increased more than six times in the past century and is rising by 1% yearly. Today, most countries are placing immense pressure on water resources, and at present, around half of the world’s population (47%) live in areas facing water-scarce conditions for at least a month in a year. It is projected that by 2050 more than half of the global population will live in regions that suffer water scarcity at least once a month yearly (UN World Water Development Report, 2018). In countries already experiencing water stress, it is estimated that climate change, along with increased intensity and frequency of hydrologic extremes, will aggravate the situation, making it challenging to tackle these situations (flood and drought). Poor water management tends to exacerbate the impact of climate change on water resources and society (UN World Water Development Report, 2020). Surface water and groundwater resources are used conjunctively to meet a region’s agricultural, domestic, and industrial water demand. Due to temporal and spatial variability in surface water availability, groundwater resources have been exploited unsustainably in the past few decades to meet various water demands, leading to groundwater resources in a critical stage. Excessive groundwater withdrawals lowered the groundwater table and hence relatively decreased (or no) groundwater contribution to streamflow (Mukherjee et al., 2018), turning perennial rivers into ephemeral ones in many parts of the world.