The document outlines the process of delineating a watershed area and identifying river streams using spatial and 3D analysis in Malang, East Java, Indonesia. It describes the data used, including SRTM digital elevation model (DEM) data, and the general methodology for determining watersheds through flow direction, flow accumulation, and identification of stream cells. The steps include sink filling, determining watershed links, and calculating drainage areas associated with each link.

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

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

3. Study Area And Data S08E111.hgt

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

5. DEM Data

6. Sink Filling

7. Flow Direction ( [Filled DEM].FlowDirection(FALSE))

8. Flow Accumulation ([Flow Dir].FlowAccumulation(NIL))

9. Identifying Stream ([Flow Acc] < 750.AsGrid).SetNull(1.AsGrid)

10. Labeling the Link ([Stream750].StreamLink([Flow Dir]))

11. Determining Watersheds ([Flow Dir].Watershed([Stream Link]))

12. 3D Scene