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Delineate a Watershed Area and Find the Streams of the Rivers Using Spatial and 3D Analyst Candra Dewi G051060021

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Study Area And Data <ul><li>Study Area </li></ul><ul><ul><li>Location : Malang, East Java, Indonesia </li></ul></ul><ul><ul><li>Coordinate : UTM Projection , WGS84 Datum </li></ul></ul><ul><li>Data </li></ul><ul><ul><li>SRTM data : S08E111.hgt </li></ul></ul><ul><ul><li>DEM data : exported from SRTM Data using Global Mapper software, 90m x 90m resolution with interpolate to fill small gaps in data </li></ul></ul>

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Study Area And Data S08E111.hgt

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General steps to determine watershed : <ul><li>Filling the sinks of the DEM </li></ul><ul><li>increasing the elevation of the points that are fictitious pits </li></ul><ul><li>Determining the flow direction </li></ul><ul><li>identifying the cell towards which water will flow </li></ul><ul><li>Calculating the flow accumulation </li></ul><ul><li>evaluating the drainage area in units of grid cells </li></ul><ul><li>Identifying the stream cells </li></ul><ul><li>flagging those cells with a flow accumulation value greater than a certain user-defined threshold value </li></ul><ul><li>Labeling the sinks </li></ul><ul><li>assigning a label (number) to each reach of the stream network </li></ul><ul><li>Delineating the watershed for each link </li></ul><ul><li>determining the incremental drainage area associated with each link </li></ul>

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DEM Data

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Sink Filling

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Flow Direction <ul><li>( [Filled DEM].FlowDirection(FALSE)) </li></ul>

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Flow Accumulation <ul><li>([Flow Dir].FlowAccumulation(NIL)) </li></ul>

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Identifying Stream <ul><li>([Flow Acc] < 750.AsGrid).SetNull(1.AsGrid) </li></ul>

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Labeling the Link <ul><li>([Stream750].StreamLink([Flow Dir])) </li></ul>

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Determining Watersheds <ul><li>([Flow Dir].Watershed([Stream Link])) </li></ul>

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3D Scene