Terrain Processing for Efficient 1D and 2D H&H Modeling. Dean Djokic and Zichuan Ye, Esri Inc.

Transcription

1 Terrain Processing for Efficient 1D and 2D H&H Modeling Dean Djokic and Zichuan Ye, Esri Inc.

2 Overview Overview of GIS for H&H modeling support (why do we do this) Terrain processing techniques 1D vs. 2D modeling with GIS GIS techniques for data simplification Schematization Lumping /characterization Weeding /VIP identification 2D (terrain) 1D Discussion

3 GIS for H&H modeling support

4 Model and Data Integration!? Integration of data, data models, and analyses in a functional system used to support decision process (spatial decision support system) USGS EPA Local Other GIS ICPR RAS HMS Other Data Providers Models

5 Types of Model Integration Linked (most commonly used approach) GIS is linked to external models GIS internal tools preprocess and post process model data for costefficient and visually effective results GIS and models maintain their distinctive user interfaces

6 Integration Issues Data providers Data consumers (often both) Unspecified at the beginning of the integration exercise Proprietary Data Control Independence from integration platform Development out of control Maintenance curse Long term cost of ownership Complexity increase (multiplicative)

7 Integration Issues (direct interfacing) N RAS MIKE 11 MIKE 21 GIS SWMM FLDWAV HMS Other N * (N - 1) Bi-directional

8 Integration Issues (intermediary interfacing) N RAS MIKE 11 MIKE 21 GIS XML SWMM FLDWAV HMS Other 2 * N Bi-directional

9 Integration Issues (number of interfaces) Number of models Direct integration Intermediary integration N N * (N-1) 2 * N

10 Model Integration Approach Whatever works for particular situation different conditions even for the same integration problem can result in a different integration method Tight or loose coupling Technical issues Legal issues Access to the underlying model structure or not (NSS vs. Excel) Check out the existence of 3 rd party solutions Almost always cheaper to buy a solution than to develop one except for simple tasks.

11 Data Exchange Methods GIS is a database any application that can read and write into one of supported databases has already an interface to GIS data (feature attributes). No direct access to geometry, projection parameters, Use RDBMS native development tools (VBA, ORACLE Forms, ) Custom ArcObjects code full access to every element of ArcGIS in COM environment Allows tight coupling of GIS and numerical models Using other software that can read/write to the same structures as the meeting ground (e.g. Excel, shape files) Data exchange tools/extension built into Arc Hydro (XML route)

12 Terrain processing techniques

13 Terrain Preprocessing Building an interconnected set of spatial data: Raster data: DEM, flow direction, flow accumulation, drainage lines, sinks, Vector data: Drainage lines, catchments, adjoint catchments, sinks, lakes, Different types of terrain morphologies and related tools: Dendritic (no internal drainage areas) Deranged (sinks) Combined

14 Terrain Processing Workflows, Workflows, Workflows (1) Basic dendritic preprocessing Start Burning streams DEM Start 1 DEM Stream segmentation Legend Grid datasset Start Fill sinks DEM HydroDEM (1) LegendDEM Reconditioning River feature class Bowling lakes Fill sinks HydroDEM (1) Stream link Catchment delineation Feature class dataset Function River feature class Fill sinks DEM Reconditioning HydroDEM (1) HydroDEM (2) Grid datasset HydroDEM (2) Start Feature class dataset DEM Fill sinks (2) Legend Grid datasset Fill sinks (2) Fencing Flow direction Flow direction Flow accumulation Flow accumulation Catchment Catchment polygon processing Catchment feature class Drainage line processing Alternative Processing Fill sinks (2) HydroDEM (3) Flow direction Flow direction Alternative Processing Function HydroDEM (3) Fill sinks Optional Function HydroDEM Flow direction (1) Flow direction DEM Reconditioning Adjust flow HydroDEM direction in (2) lakes Inner wall feature class Outer wall feature class River feature class Feature class HydroDEM dataset (3) Function Build walls HydroDEM Optional (4) Function Flow direction Legend Grid datasset Feature class dataset Function Stream definition Stream Drainage line feature class Adjoint catchment processing Continue dendritic processing with flow accumulation function Flow direction Grid (2) Continue dendritic processing with flow accumulation function Flow direction Adjust flow direction in lakes Optional Function Flow direction Grid (2) 1 Adjoint catchment feature class End Continue dendritic processing with flow accumulation function 14

15 Terrain Processing Workflows (2) Additional tools and workflows for deranged and combined morphologies Deranged Combined Dendritic Function \Use Case UC1 UC2 UC3 UC4 UC5 UC6 UC7 UC8 UC9 Sink Evaluation X X X Create Sink Structures X X X X X X Flow Direction X X X X X X X X X Adjust Flow Direction in Sinks X X X X X X Sink Watershed Delineation X X X X X X Append Coastal Catchments X X X X X X X X X Assign CatType Attribute to Catchment FC X X X X X X X X X Fill Sinks X X X X X X X X Level DEM X X X Flow Accumulation X X X X Stream Definition X X X X Stream Segmentation X X X X Combine Stream Link and Sink Link X X X Drainage Line Processing X X X X Adjust Flow Direction in Lakes X X X Catchment Grid Delineation X X X X X X Catchment Polygon Processing X X X X X X Adjoint Catchment Processing X X X X X X Create Drainage Line Structures X X X DEM Reconditioning X X X X Adjust Flow Direction in Streams X X X 15

16 Terrain Processing Workflows (3) Capture in model builder models (but beware of the super buttons ) 16

17 Watershed Delineation (1) Arc Hydro watershed delineation functions leverage preprocessed data. Interactive local and global watershed delineation Batch local and global watershed delineation Batch subwatershed delineation Characterization functions leverage preprocessed data where possible. Preprocessed data allow limitation of processing extent for raster processing thus speeding up the processing. Analytical caching

18 Watershed Delineation (2) Limit the extent of processing to the catchment the point is in to speed up the SA watershed function.

19 Watershed Delineation (3) Delineate watershed within the catchment.

20 Watershed Delineation (4) Append the local watershed with the adjoint catchment to get the full watershed to the point of interest.

21 Role of Threshold Controls the size of catchments. Smaller catchments speed up local processing for watershed delineation and characterization (very important for responsiveness of the system). But there is operational overhead so reducing the catchment size has a limit with respect to performance gains. Smaller catchment slow down preprocessing and generate larger analytical dataset (but this is done only once and HD space is cheap). Quality control does general flow pattern match expected patterns. NOT to match some geomorphological expectations or some specific application requirements.

22 Global Delineation (1) Deal with scalability issues related to DEM size (large areas/high resolution) Approach Combine raster analysis on individual areas (any size) that are manageable from DEM point of view, and network analysis between the individual areas Example 10 HUC8 cataloging units

23 Global Delineation (2) Start with well defined database design structure Apply it independently to all DEM processing units HydroID does not have to be unique across GDBs Construct the extended network Some work involved for HUC 8 processing units

24 Global Delineation (3) Define the point Delineate local watershed Trace upstream Identify contributing catchements Merge shapes and store

25 Global Delineation (4) Currently area and few topographic characteristics are computed other parameters of interest are being added Aggregation types additive, min, max, special Potentially interesting issues Geometry size and complexity Speed in aggregation (preprocessing option)

26 Practical Implementation (1) Global watershed delineation service Global flow path tracing service 90m SRTM based for the world 30m NHDPlus V2 based for the USA

27 Practical Implementation (2) Consume in desktop and/or web client

28 1D vs. 2D modeling with GIS

29 Data representation within GIS GIS is by nature a 2D/3D system GIS data structures driven by the data content (where the data are not how they will be modeled) GIS data structures driven by the source of data/data collection techniques (vector/raster) Easy manipulation of spatial data (ETL) structures

30 Data representation within models Type of model defines its data structure (1D/2D/3D) Model data structures driven by the solvers (how the data are modeled e.g. FE/FD/FV) Not always easy (or often any) manipulation of spatial data structures

31 Typical GIS role in modeling support Loose coupling (GIS for model pre/post processing) Space discretization Space characterization Data formatting Visualization/results presentation

32 Typical GIS role in modeling support Model type/function 1D 2D Discretization Characterization Formatting Development of node-link or wireframe representation Spatial averaging/lumping over discretized spatial elements Simpler data structures, smaller volumes Development of modeling schema (triangulation, fishnet) Spatial averaging/lumping over discretized spatial elements and/or push-pin data extraction More complex data structures, larger volumes

33 GIS techniques for data simplification

34 Schematization 1D Node link representation Wireframe representation

35 Schematization 2D Thiessen polygon TIN Fish net Can get tricky need to understand solvers for optimal tessellation!

36 Schematization 2D Topology to ensure spatial consistency within and across layers

37 Lumping /characterization Push pin (not much to do unless it needs vertical aggregation) Lumping /characterization Zonal stats operations Can do interpolation first, then stats

38 Weeding /VIP identification 2D (terrain/surface) Terrain dataset (terrain pyramids) Window size Z tolerance

39 Weeding /VIP identification 1D

40 Summary One terrain representation does not fit all Understanding modeling techniques and their requirements on data preparation (model schematization in particular) Techniques for ensuring data consistency Techniques for geometry simplification before going into 2D models

41 Questions / Discussion