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Geographical Database Development for the TxRR Surface Water Model

Introduction of the Texas Rainfall-Runoff (TxRR) model based on the Soil Conservation Service’s Curve Number Method to estimate direct runoff from precipitation events. The model includes parameters like Initial Abstraction, Soil Retention, Maximum Soil Moisture, and Base Flow for streamflow simulation. Monthly Depletion Factor is used for optimization and historical data processing with GIS tools for data preprocessing.

kaseem-sullivan
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Geographical Database Development for the TxRR Surface Water Model

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  1. Geographical Database Development for the TxRR Surface Water Model Richard Gu

  2. Introduction of TxRR model TxRR (Texas Rainfall-Runoff) Model: Based on the Soil Conservation Service’s Curve Number Method to estimate the direct runoff from a precipitation event.

  3. TxRR Model Precipitation P InitialAbstraction Direct runoff QD Soil Retention S Maximum Soil Moisture SMMAX Stream Flow Base Flow QB Soil Moisture SM Percolation

  4. Soil Moisture The depletion process of the soil moisture: SM2i=SM1i-1*exp(-amti) SM2i: soil moisture right before the I-th precipitation SM1i-1: soil moisture right after the I-1st precipitation am: monthly depletion factor for the m-th month ti: arrival time in days of the I-th precipitation

  5. Soil Retention Si=SMMAX-SM2i Si: soil retention SMMAX: maximum soil moisture

  6. Direct Runoff QDi=Pei2/(Pei+Si) Pei=Pi-Iai Iai=abst1*Si Qdi: direct runoff Pei: effective precipitation abst1: initial abstraction coefficient

  7. New Soil Moisture Soil moisture is renewed by the infiltration caused by new precipitation. The renewal process is described by: SM1i=SM2i+Fi Fi=Pi-Iai-QDi SM1i: new soil moisture right after ith precipitation Fi: infiltration

  8. Base Flow QB2=QB1*K t2-t1 K: recession constant QB2, QB1: base flow at time t2, t1 t2-t1: the elapse time

  9. Daily Streamflow Simulation NDAYS=INT(Tb/24)+1 Tb=5Tp, Tp=12+Tl, Tl=b*A 0.6 NDAYS: base time in days Tb: base time Tp: time to peak Tl: lag time A: drainage area

  10. Monthly Depletion Factor & Parameter Optimization • Important feature of TxRR model. • Monthly depletion factor used for monthly streamflow simulation. • Optimization based on the historical data.

  11. GIS Data Preprocessing • Goal: to prepare time-series streamflow & precipitation data for defined watershed. • Sources data: historical data of USGS & NCDC stations. • Sample area: Nueces Estuary. • Tools: Arc/Info, CRWR-Vector, Arcview Geoprocessing & Spatial Analyst.

  12. DSS database

  13. DSS Rainfall & stream flow, area% DSPLAY Macro NEW DSS file with Average rainfall & stream flow data for each watershed DSPLAY DSSMATH DSPLAY Macro REPGEN Data Retrieval Customized Reports Text file converter TxRR Input File

  14. Project Components TxRR model: source code in FORTRAN GIS: CRWR_Vector (Projection, Thiessen Polygon) Geoprocessing (Intersect two polygon coverages) Arcview Script (Create station point coverage)

  15. DSS: Data storage format tool (C/C++) Data format conversion from DSS file to TxRR input file (C/C++) Data format conversion from TxRR output file to DSS file (C/C++) DSPLAY: MS-DOS batch file & display control macro (Continue)

  16. Experience and Future Work DSS is efficient in time-series data storage. Data format conversion is not a big overhead. Display tools still need to be exploited. Avenue is not efficient in file reads/writes. An algorithm for combining historical data need to be developed. Data missing.

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