WATERSHED ANALYSIS

Using GIS

From Higherto lower

to lower …. etc

DEM

0

2

4

6

8

10

row0

24

68

10col

725

750

775

800

825

jen1_ele

740 760 780 800 820

jen1_ele

778 765 750 740 747 759 765 766 769 776 786 795

770 758 745 737 741 751 753 761 777 789 802 814

777 763 747 736 735 743 750 767 787 806 820 832

786 767 750 737 733 739 752 769 785 797 808 822

791 773 756 741 733 733 744 759 772 779 789 806

799 782 763 750 737 733 733 745 757 767 782 801

802 788 771 761 751 736 733 738 751 764 779 798

799 790 780 772 762 746 733 737 754 770 784 794

811 799 787 771 757 741 728 730 745 765 779 783

823 807 790 774 762 748 733 725 733 750 764 763

830 814 801 787 776 761 743 728 725 737 748 751

822 818 811 801 791 776 757 739 726 725 735 751

Fill Sinks:Removing Small imperfections in the data.

Sink

Fill to lowest

Neighboring cell

Flow Direction

Cell Elevation Elevation difference

Flow direction Flow direction Number

Flow AccumulationA flow accumulation raster tabulates for each cell the number of cells that will flow to it.

Flow direction Flow accumulation

Con (Conditional Elevation)

• put a condition to appear certain values of cell to enhance the visualization of water

flows.

• If condition ( if value > number ) put 1 … so all pixels which have value bigger than this

number will be 1.

60

25

25

55 60

90

0

58

48

5080

72 58

64

13

25

1

ND

ND

1 1

1

ND

1

ND

ND1

1 1

1

ND

ND

Value > 50

Put 1

ND for no data

Stream Order

STRAHLER

Method

Snap Pour Points

Tool used to ensure the selection of points of high accumulation flow where original pour point locations are snapped to locations of higher accumulated flow.

Snap pour point with snapdistance around specified point for cell of high accumulation.

Watershed

Area that defined by the lower elevation .so it carry water after rain or floods.

water channeled in soil makingits way to larger river.

Basin

Is multipurpose environmental analysis to help regional perform watershed and water amount.

Uses of Basin

• Make watershed and water quality study easier

• Useful tool for those interested in watershed management development.

Flow Length

A primary use of the Flow Length tool is to calculate the length of the longest flow path within a given basin. This measure is often used to calculate the time of concentration of a basin.

It’s distance that water travel through area . It compute by upstream or down stream.

• Down stream: distance the drop of water would travel to reach the pour point of the basin.

• Upstream: longest distance along the flow path at the top of basin.

Stream to feature

Tool used to convertraster data to vector.

Make high show for flow.

PRACTICALPART

Using GIS

1-Opening the DEM on ARC map

This DEM which we

will make watershed

for it

Open ARC toolbox

Select on spatial analysis

and click on fill

2-Make fill to the DEM

Output of fill

3-Make flow Direction

Output of flow direction

4- Flow Accumulation

Output of flow accumulation

5- Con Step

Output of con step

6-Covert con_500 from raster to vector

Output of stream to feature

7-stream order

Output of stream order

8-convert stream order from raster to vector

Output of conversion

9-Creating point shape file in arc catalog &add it in arc map

10-start edit & select the pour point

11-watershed step

Output of watershed

12-Basin step to get all watersheds in an area

Output of basin step

13-Flow length step

Output of flow length step