CRWR-PrePro Francisco “Paco” Olivera, Ph.D. Center for Research in Water Resources University of Texas at Austin Francisco Olivera 1998 ESRI User Conference GIS Hydro 98 - Preconference Seminar CRWR-PrePro July 26, 1998

The Team zBrian Adams zXiming Cai zAubrey Dugger zFerdinand Hellweger zDavid Maidment zFrancisco Olivera  Seann Reed

Overview

What is CRWR-PrePro? Spatial Data Input file for non-GIS applications CRWR-PrePro

What is CRWR-PrePro today? Spatial Data Basin file for HEC-HMS Not all HMS options are included yet. CRWR-PrePro

CRWR-PrePro Components Watershed Characterization Hydrologic Model Extraction Model schematic and HEC-HMS basin file

What is HEC-HMS? z“It is a new generation software for precipitation-runoff simulation that supersedes the HEC-1 Flood Hydrograph Package.” HEC-HMS User’s Manual zIt is a Windows version of HEC-1.

HEC-HMS Components Control File Time-related information for a simulation Precipitation File Meteorological data Basin File Parameter and connectivity data for hydrologic elements HEC-HMS Simulation

Previous Work Watershed Delineator ArcView Extension [ESRI-TNRCC] Flood Flow Calculator ArcView Extension [CRWR-TxDOT] HECPREPRO ArcView Project [CRWR-HEC] CRWR-PrePro ArcView Project [CRWR]

Watershed Characterization

Terrain Analysis Stream-Watershed Delineation Calculation of Hydrologic Parameters

Watershed Characterization Terrain Analysis

Burn-In Streams [Grid] Fill Sinks [Grid] Flow Direction [Grid] Flow Accumulation [Grid] DEM [Grid] Digitized Stream Network [Line Coverage]

Hydrologic GIS Functions Flow direction codes Digital elevation model (DEM) Flow direction grid Stream Network Flow accumulation grid

Burn-In Streams DEM creek Digitized creek Raised DEM Burned-in DEM

DEM and Digitized Stream Network

Burned-In DEM zElevation is increased by a fixed value in all DEM cells, except in those that coincide with the digitized stream network.

Flow Direction zWater flows to one of its neighbor cells according to the direction of the steepest descent. zFlow direction takes one out eight possible values.

Flow Accumulation zFlow accumulation is a measure of the drainage area in units of grid cells.

Watershed Characterization Stream-Watershed Delineation

Stream Network Definition Watershed Delineation Watershed Outlet Definition Raster to Vector Conversion

Stream Network Definition Automatic Cells draining more area than a user-defined threshold value. Interactive Cells located downstream of user-identified cells. Stream Network [Grid]

Stream Network zAll grid cells draining more than a user-defined threshold value (blue streams), or located downstream of user-defined cells (red streams) are part of the stream network.

Stream Segmentation zStream segments (links) are the sections of a stream channel connecting two successive junctions, a junction and an outlet, or a junction and the drainage divide.

Watershed Outlet Definition Automatic Most downstream cells of the stream segments Interactive User-identified cells [outlets, reservoirs, control points, etc.] Watershed Outlets [Grid]

Watershed Outlets zThe most downstream cells of the stream segments (brown cells), and the user-defined points (red dots) are the watershed outlets.

Modified Stream Segmentation zThe interactively defined outlets modify the stream segmentation by subdividing the segment in which are located into two segments.

Watershed Delineation Watershed Outlets

Watershed Delineation zThe drainage area of each watershed outlet (stream segment) is delineated.

Raster to Vector Conversion Watershed Vectorization Stream Vectorization Merging of Watersheds Dissolving Spurious Polygons

Raster to Vector Conversion zStreams and watersheds are converted from raster to vector format.

Dissolving Spurious Polygons zCells connected to the main watershed polygon through a corner are defined as a separate polygon (spurious polygon). zThese polygons are dissolved into the main polygon.

Merging of Watersheds zAdjacent watershed polygons can be merged into a single polygon, if they share their outlet or one flows into the other.

Merging of Watersheds zThe attribute tables are updated so that the watershed code (WshCode) of the streams is modified and the area of the new polygon is calculated.

Watershed Characterization Calculation of Hydrologic Parameters

Flow Length Downstream to the Watershed Outlet

Flow Length Upstream to the Watershed Divide

Longest Flow-Path

Watershed Lag-Time (SCS) Flow length upstream and downstream Average Curve Number Length and slope of the longest flow-path Identification of the longest flow-path Lag-time

Watershed Lag-Time (SCS) t p :watershed lag-time (min) L W :length of longest flow-path (ft) CN :average Curve Number S :slope of the longest flow-path (%)

Watershed Lag-Time (L/V) Flow length upstream and downstream Longest flow-path average velocity Length of the longest flow-path Lag-time

Watershed Lag-Time (L/V) t p :watershed lag-time (min) L w :length of longest flow-path (ft) V w :longest flow-path average velocity (m/s)

Watershed Abstractions Average Curve Number SCS Method Initial + Constant Method Initial Loss (mm) Constant Loss (mm/hr)

Watershed Parameters

Stream Routing Method Flow time (L s /V s ) L s /V s <  t Muskingum Routing L s /V s >  t Pure Lag Routing

t lag :stream lag-time (min) L s :length of longest flow-path (m) V s :longest flow-path average velocity (m/s)

Muskingum Routing K :Muskingum K (hr) X :Muskingum X L s :length of longest flow-path (m) V s :longest flow-path average velocity (m/s) n :number of sub-reaches

Stream Parameters

Hydrologic Model Extraction

Watersheds Polygons Streams and source streams Shape Files of Watersheds and Streams

Hydrologic Model Extraction

Model Schematic and HEC-HMS Basin File

Hydrologic Model

Connection to HEC-HMS Model SchematicParameter Transfer HEC-HMS Basin File

ArcView Schematic

HEC-HMS Basin File (1)

HEC-HMS Basin File (2)

HEC-HMS Basin File (3)

HEC-HMS

Basin File System Schematic

Basin File Watershed Parameters

Basin File Stream Parameters

Precipitation File

Control File

Hydrograph Time Table

Hydrograph Summary

Hydrograph Plot

Where do we want to go?