Effect of Extreme Storms on Treaty Obligations in the Rio Conchos

1. Effect of Extreme Storms on Treaty Obligations in the Rio Conchos Samuel Sandoval-Solis | CE 397 | Statistics in Water Resources

2. Rio Grande/Rio BRAVo Basin

3. Rules of the game:Treaty of 1944 – Rio Grande / Bravo • For Mexico: • 2/3 of 6 Mexican Tributaries (Including the Conchos) • ½ of Gains – Losses • All waters from San Juan And Alamos River • For the U.S.: • All water from US tributaries • 1/3 of 6 Mexican Tributaries, this 1/3 shall not be less than 431 MCM/year on 5 year cycles. • ½ Gains Losses • Re-set of treaty cycles • Every 5 years or • If the U.S. active storage in both international dams is filled with U.S. water Amistad Dam 1 – Rio Conchos 2 – Las Vacas 3 – San Diego 4 – San Rodrigo 5 – Escondido 6 – Salado Falcon Dam

4. Objectives • Obtain a PDF and CDF for the Rio Conchos • Evaluate how the occurrence of extreme storms are related with wet conditions . • Evaluate how extreme storms have influenced the re-start of treaty cycles • Evaluate how a change in the occurrence frequency of extreme storms will affect the re-start of treaty cycles.

5. PDF and CDF for the Rio Conchos Basin Annual Dataset: 1955 - 2008

6. PDF and CDF for the Rio Conchos Basin Chi-Square test for goodness of fit. Theoretical =15.5 > Calculated 14.4

7. PDF and CDF for the Rio Conchos Basin

8. PDF and CDF for the Rio Conchos Basin

9. Extreme storms and wet conditions in the Rio Conchos Basin Storms from the Pacific Storms from the Gulf National Hurricane Center <http://www.nhc.noaa.gov/index.shtml>

10. Extreme storms and wet conditions in the Rio Conchos Basin Storms from the Pacific 16 Extreme Storms National Hurricane Center <http://www.nhc.noaa.gov/index.shtml>

11. Extreme storms and wet conditions in the Rio Conchos Basin

12. Extreme storms and wet conditions in the Rio Conchos Basin 6 Storms 13 years 7 Storms 30 years 3 Storms 11 Years

13. Extreme storms and wet conditions in the Rio Conchos Basin Poisson Distribution *Period Considered before 1968 when both international dams were built. # of Hurricanes = 11;, # of years = 40

14. Extreme storms and re-set in treaty cycles 3out of 11 Extreme Storms influenced the re-set of treaty cycles: Orlene (24/Sep/1974) Cycle 6 Paul (26/Sep/1978) Cycle 8 Norbert (8/Oct/2008) Cycle 28 Only 3 cycles out of 21 were re-set due to Extreme Storms P(Re-Set|Storm)=3/11=0.2727

15. Extreme storms and re-start in treaty cycles

16. Extreme storms and re-start in treaty cycles Increase the occurrence of Extreme storms by a 20% (Arbitrary) P ( Re-Set) = 0.0785 = 7.85%

17. Conclusions • The PDF and CDF for the Rio Conchos was estimated • Extreme Storms from the Pacific has more influence in the Rio Conchos Basin. • The occurrence of stream storms is not a liability of wet periods in the basin • A Poisson distribution was used to determine the PDF and CDF for extreme storms in the Conchos basin P(Ex. St. ≥1) =0.240. • The occurrence of extremes storms is not a definitive factor to Re-Start the treaty cycles • Combining the occurrence of extreme storms and the re-start of treaty cycles due to extreme storms, there is a 0.0722 probability that the treaty cycles are re-set at the begging of each year. • Increasing by 20% the occurrence of extreme storms does not significantly increase the probability to re-start the treaty cycles (0.0785)

18. Procedure Outflow Hist. Data : 1955-2008 Goodness of fit Chi-Square Test 1) PDF and CDF for the Rio Conchos CDF and IQR = Define Dry, Normal and Wet Cond Hurricanes Hist. Data : 1957-2008 Influence: Pacific or Gulf? Frequency of Occurrence 2) Conditions + Frequency Storms = Influence of Storms in Wet Periods 3) Influence of Extreme Storms in Re-Start of Treaty Cycles P(Re-Start|Storm) Treaty Cycles Records : 1957-2008 Frequency of Occurrence of Extreme Storms PDF and CDF (Poisson Distribution) for extreme Storms 4)Change the PDF for Extreme Storms + P (Re-start|Storm) = Evaluate how a change in the Storm Occurrence will affectthe Re-start of Treaty Cycles