# Presentation: 163346

## Advanced Hydrologic Prediction Service (AHPS)

- National Weather Service
- West Gulf River Forecast Center
- Tracy Howieson

## Outline

**Introduction to AHPS**
**AHPS Modeling**
**AHPS products and services**
**Future AHPS Improvements**

## Advanced Hydrologic Prediction Service

**AHPS Goals:**
**Enhance current services and products through:**
- Recalibration of existing river models
- Probabilistic Forecasts
- Graphical Products
- Flood Inundation Mapping

## Slide 4

## Advanced Hydrologic Prediction Service

**Better forecast accuracy**
**More specific and timely information on fast-rising floods**
**New types of forecast information **
**Longer forecast horizons**
**Easier to use products**

**What services will AHPS provide to the public?**

## Advanced Hydrologic Prediction Service

**Determine how to utilize reservoir storage capacity to reduce flood impacts on people and businesses. **
**Help to make decisions about when and where to evacuate people from potential flood areas.**
**When to move goods and industrial property from flooded areas.**

**How will AHPS help water managers and city officials?**

## Advanced Hydrologic Prediction Service

**Provide standardized web pages that contain hydrologic data and forecasts.**

## Advanced Hydrologic Prediction Service

**Provide probabilistic river forecasts that will improve flood warnings and water resource forecasts nationwide to meet the diverse and evolving needs of our partners and customers.**

## Advanced Hydrologic Prediction Service

## AHPS Modeling

## Model Requirements

**Model Implementations needed for AHPS**
**Creation of historical time series**
**Recalibration of SAC-SMA model**
**Reservoir Modeling**
**Implementation of ESP model**

## Historical Time Series

**Mean Areal Precipitation - (MAP)**
**Time-series span water years 1953-2003**
**Values derived using Thiessen polygon weighting method using daily cooperative station data and time-distributing with hourly data**
**Mean Areal Potential Evaporation-(MAPE)**

## Model Calibration

**Calibration of SAC-SMA Model**
**Conceptual Model **
**Historical time period **
**Oct 1953 to September 2003**
**Utilizes historical streamflow and precipitation within calibration process**
**Allows model parameters to be defined such that historical events can be accurately simulated**

## Reservoir Modeling

**Contracted with Riverside Technologies Inc. to model Trinity Reservoirs using RES-J operation**
**RES-J models systems of reservoirs**
**Simplifying assumptions made to model Trinity Reservoir System**
**Calibrated reservoir operation using rules and historical operation of reservoir**
**Calibrated to higher flow events**

## AHPS Techniques

**Utilizes the Ensemble Streamflow Prediction (ESP) model. **
**Incorporates:**
**Historical Climate Data**
**Short and Long Term Forecast Information**
**Current Basin Conditions**
**Utilizes the ESP Analysis and Display Program (ESPADP) to produce forecast graphics**

- ESP and ESPADP

## AHPS Techniques

**A component of the National Weather Service River Forecast System (NWSRFS)**
**Requires a continuous rainfall-runoff model**
**Sacramento Soil Moisture Accounting Model**
**Creates a simulated hydrograph for each year of historical data**

- What is ESP  and what does it do?

## AHPS Techniques

**Output data types: **
**Stage**
**Flow**
**Volume**
**Reservoir inflow volumes****    **
**Statistical Analysis**
**Exceedance Probabilities**

- What is ESP  and what does it do?  (continued)

## AHPS Techniques

- Historical Data
- (Precip, Temp)

- Forecast Conditions
- (QPF, CPC Temps)

- Mean Areal
- Time Series
- (MAP, MAT)

- NWS Hydrologic
- Models

- Current Model States
- •Soil Moisture
- •Snow Pack
- •Reservoir Levels
- •Streamflow

- Streamflow
- Hydrographs

## ESP and ESPADP

**Produces trace simulations for each year in the period of record**
**Each trace simulation reflects what would happen  if that particular years’ historical weather regime occurred with the current soil moisture conditions**
**(Conditional Simulation)**

- Streamflow Hydrographs

## Trace Ensemble

## Conditional vs. Historical Simulation

**Conditional simulation **
**Resets the model to the current model states when each water year interval is simulated**
**Historical simulation **
**Starts the model at current model states and runs nonstop through the entire input record. The model is allowed to become “wetter” or “drier” than current conditions prior to the run interval simulated**

## ESP and ESPADP

**Trace simulations are then used in statistical calculations to produce the probabilistic  forecasts.**
**Since ESP output is conditional simulations based upon current conditions, this separates the NWS probabilistic forecasts from any other types issued from other sources.**

- Streamflow Hydrographs

## Conditional Probabilities - Discharge

## AHPS Products and Services

## Trinity River System – FY 2004

## Trinity River System – FY 2005

## Weekly Exceedance Products

**Product Descriptors**
**90 day Forecast Window**
**Weekly Interval**
**Conditional Simulation **
**Maximum Values (Stage, Flow, and Volume)**
**Empirical Distribution**
**Probability Levels**
**90 %, 75 %, 50 %, 25 %, 10 %**
**Updated monthly (midmonth)**

## Weekly Exceedance Products

- Crockett (Stage) – Weekly Exceedance Histogram

## Weekly Exceedance Analysis

## Weekly Exceedance Probabilities

## 90 Day Exceedance Probabilities

**Product Descriptors**
**90 day Forecast Window**
**Conditional and Historical Simulations**
**Stage, Flow, and Volume**
**Empirical Distribution**
**Updated monthly (midmonth)**

## 90 Day Exceedance Probabilities

- Crockett (Stage) - 90 Day Exceedance Probabilities

## Exceedance Probability Example

**This example is designed to help you understand how the 90 Day Exceedance Probability products are calculated.**
_**Steps:**_
**	****1) Extract ***maximum flows*** from the ESP traces for the forecast period.**
**	****2) Sort maximum flows in descending order.**
**	****3) Apply a rank for each flow value.**
**	****4) Determine probability.**
**	****5) Plot probability.**

## ESP Traces

*****

*****

*****

*****

*****

*****

*****

*****

*****

**6294**

**1815**

**4987**

**758**

**1410**

**1678**

**50**

**13760**

**1609**

## Exceedance Plotting

**Exceedance Plotting**

**P=m/(n+1)**

**m**

**n=9**

## Exceedance Plotting

**Exceedance Plotting**

**1950 cfs**

**20%**

## AHPS –Trinity Product Suite

**ESG**** **
**Text Product that details the probability levels depicted in the graphical product.**
**90 day Exceedance Product (Stage)**
**Conditional Simulation only**

- Text Products

## AHPS –Trinity Product Suite

**All Locations**
**Trace Simulations (for internal use only)**
**Streamflow Locations**
**Stage, Flow, and Volume**
**Weekly Exceedance Histograms (CS)**
**90 day Exceedance Probabilities (CS and HS)**
**Reservoir Locations****	**
**Flow and Volume**
**Weekly Exceedance Histograms (CS)**
**90 day Exceedance Probabilities (CS and HS)**

## AHPS Product Suite - Webpage

**AHPS Product Suite is available on the WFO Webpage.  **
_**[http://www.](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[srh](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[.](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[noaa](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[.](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[gov](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[/](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[cgi](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[-bin/](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[ahps](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[.](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[cgi](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[?](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**__**[hgx](http://www.srh.noaa.gov/cgi-bin/ahps.cgi?hgx)**_

## Future AHPS Implementation

**FY 2006:**
**Neches River System**
**FY 2007:**
**Sabine River System**
**Coastal Basins**
**San Bernard**
**Lavaca - Navidad**

## Slide 42

## Questions or Comments

## Contact Information

**WGRFC:**
**Tracy Howieson**
_**[Tracy.Howieson@noaa.gov](mailto:Tracy.Howieson@noaa.gov)**_
**(817) 831-3289 x 212**
**Houston WFO:**
**Dave Schwertz**
_**[Dave.Schwertz@noaa.gov](mailto:Dave.Schwertz@noaa.gov)**_
**(218) 337-5074 x 228**