The Hydrograph the graph that represents the variation

The Hydrograph the graph that represents the variation of stream discharge with time. Description of hydrograph: Discharge (m 3) Hydrograph : is ﺭﻛﻮﺩ Time (hr)

The water of the stream represents the surface runoff, inter flow , and base flow components. Factors affecting flood hydrograph: There are two main groups of factors that affecting the shape of the hydrograph : A. Natural geographic factors B. Climatic factors. Natural geographic factors includes: 1 -The shape of the basin:

2 -Drainage density: is the ratio of the total length of the tributaries of the stream course to the catchment area. As this ratio increases the peak of the hydrograph will be higher and sharper, and vise versa.

3 -Basin Size: in. the small basins the flow is as sheet flow , while in large area basins the flow is in stream courses (turbulent) 4 -Slope of the basin: large slopes of land surface produces high and sharp peak hydrographs. Steeper catchment ﺧﺸﻦ Less rough catchment Lesser storage capacity More connections between impervious areas

B-Climatic factors: 1 - The influence of partial rainfall: : ﺗﺎﺛﻴﺮ ﺍﻻﻣﻄﺎﺭ ﺍﻟﺠﺰﺋﻲ

2 -The influence of storm direction

Hydrograph Separation or Base flow Separation methods: The following methods are used for this purpose a- Stright line or constant slope method. b- Fixed base length method. (N= 1. 25 A 0. 2) c- Variable slope method.

Relationship Between GW & SW Gaining and Losing streams ﻣﺘﺪﻓﻖ Gaining (effluent) stream – base flow entering stream - typical in humid regions - as you move down stream, more water in stream even though no tributaries exist ﻣﺆﺜﺮ Losing (influent) stream - water table lower than bottom of stream channel - water loss as you go down stream - rate of loss is a function of the depth of water and hydraulic conductivity of the underlying alluvium - In some cases (mountainous arid regions), you start with a gaining stream and move into a losing stream. .

Effluent and influent streams Gaining or Effluent stream Losing influent stream with shallow watertable Base flow Losing stream with deep watertable

Types of Aquifers