Lecture-9-Climate Change Effect on Runoff And Sediment Yield.

Abstract

There is a robust scientific consensus that Earth's climate has changed and will continue to change as human activities increases the concentrations of green house gases in the atmosphere. Since the beginnings of concern over the possible consequences of global warming, it has been widely recognized that changes in the cycling of water between land, sea, and air could have very significant impacts across many sectors of the economy, society, and the environment. The hydrologic system is an integrated component of the earth geophysical system and both affects and is affected by climatic conditions. Water vapor is one of the main greenhouse gases, and changes in climate affect all aspects of the hydrologic cycle. As the atmosphere warms due to human-induced greenhouse gas emissions, water vapor increases, further enhancing the warming. Changes in temperature affect evapotranspiration rates, cloud characteristics, soil moisture, and snowfall and snowrnelt regimes. Changes in precipitation affect the timing and magnitude of floods and droughts, shift run off regimes, and alter groundwater re charge characteristics. Synergistic effects alter cloud formation and extent, vegetation patterns and growth rates, and soil conditions. On a larger scale, climatic changes can affect major regional atmospheric circulation patterns and storm frequencies and intensities. All of these factors are, in turn, very important for water planning and management decisions. Erosion is a natural geomorphic process occurring continually over the earth's surface and it largely depends on topography, vegetation, soil and climatic variables and, therefore, exhibits pronounced spatial variability due to catchment heterogeneity and climatic variation. Soil erosion by water is one of the most important land degradation problems and a critical environmental hazard of modem times worldwide. Accelerated erosion due to human-induced environmental alterations at a global scale is causing extravagant increase of geomorphic process activity and sediment fluxes in many parts of the world. Land use beyond its capability and without proper conservation measures enhances erosion in uplands and sedimentation downstream. One of the principles of watershed management is to use the land as per its capability or suitability. So that erosion therefore water pollution from sediment remains low. This helps to protect the water source such as springs, lakes/ ponds, and rivers and enhance their suitability for human use.