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Detailed Notes on Hydrograph Concepts with Examples 1. Hydrograph Definition A hydrograph is a graphical representation of stream discharge (flow rate) over time at a specific point in a river or stream. It typically illustrates how a river's flow changes in response to a precipitation event, showing the relationship between rainfall and runoff. Discharge Units: Cubic meters per second (m³/s) in the metric system Cubic feet per second (cfs) in the imperial system Example: After a heavy rainfall, a hydrograph for a river might show a sharp rise in discharge, peaking after a few hours, and then gradually falling as the water drains from the watershed. --- 2. Hyetograph Definition A hyetograph is a bar graph representing rainfall intensity over time, commonly used in hydrological analysis to understand how rainfall contributes to runoff. Graph Representation: X-axis: Time (in hours or minutes) Y-axis: Rainfall intensity (in mm/h or inches/h) Example: For a 6-hour rainfall event, a hye...

Watershed characteristics directly influence hydrological processes, impacting runoff volume, peak flow, and timing. Understanding these characteristics is crucial for effective watershed management and predicting runoff behavior. http://ecoursesonline.iasri.res.in/mod/page/view.php?id=2172 (Source:  http://cas.umkc.edu/geosciences/env-sci/module9/h20shed.GIF  accessed on 2 October 2013) Source: http://ecoursesonline.iasri.res.in/mod/page/view.php?id=2172 Diagram Defining Basin Length. (Source:  Zavoianu, 2011) ( Source: http://www.fgmorph.com/fg_4_8.php) C haracteristic/Term Formula/Description Significance for Hydrology & Runoff Drainage Basin/Watershed Area draining to a point Defines the area contributing to runoff. Drainage Divide Boundary between basins Separates adjacent watersheds. Concentration Point Outlet point Measurement location for stream flow. Time of Concentration (Tc) Time for water to reach outlet from farthest point Determines peak flow timing...

Potential and Actual Evapotranspiration Evapotranspiration is the total water loss from a vegetated surface to the atmosphere. It encompasses two primary processes:   Evaporation: The loss of water vapor from the soil surface and surrounding water bodies.   Transpiration: The release of water vapor from plant leaves through stomata.   Therefore, evapotranspiration is the sum of evaporation and transpiration.   Potential Evapotranspiration (PET): PET represents the maximum possible evapotranspiration rate under ideal conditions. These conditions assume an unlimited water supply, ensuring that plants' water needs are fully met. Essentially, PET reflects the atmospheric demand for water. Actual Evapotranspiration (AET): AET is the real evapotranspiration occurring in a specific environment. It accounts for the actual water availability, which may be limited by factors like soil moisture.   Therefore, AET reflects the actual water loss under exist...

Measurement of Transpiration This document outlines the process of transpiration in plants and methods for its measurement, as well as related concepts like evapotranspiration. Transpiration: Definition: Transpiration is the process by which plants release water vapor into the atmosphere from their leaves, stems, and trunks. It's a significant water loss mechanism, with up to 99% of absorbed water being transpired.   Mechanism: Water is absorbed by roots and transported to leaves.   During photosynthesis, stomata (pores) on leaves open to allow CO2 intake.   Water vapor escapes through these stomata. Transpiration Ratio (T.R.): T.R. = (Weight of water transpired) / (Weight of dry matter produced) Typical T.R. values for crops range from 300 to 800. Factors Affecting Transpiration: Temperature: Higher temperatures increase transpiration.   Wind velocity: Increased wind speed enhances water vapor removal, thus increasing transpiration.  ...