University of California, Davis Department of Land, Air and Water Resources Water Management for Environmental Restoration Flows In the Big Bend reach, Rio Grande Rio Bravo 46 th Annual Meeting 8 9 March, 212 Alpine, TX Samuel Sandoval Solis Assistant Professor Cooperative Extension Specialist in Water Resources
Rio Conchos Coyame DR 9 Johnson Ranch % 85 mi. Amistad Int. Reservoir Maderas del Carmen, Cañon de Santa Elena, Ocampo RGB 2% 137 mi. 6 mi. 51 mi. 17 mi. 186 mi. 9% Big Bend Nat & St. Park 3% Luis L. Leon Reservoir DR 5 DR 9 St. Nat. Big Bend Amistad Maderas del Carmen Cañon de Santa Elena Ocampo Quantify the maximum amount of water for Env. Restoration flows in the Big Bend Constraints Q Env. Do not affect Water Supply Q Env. <= 1944 Treaty Establishes Q Env. < Presidio Levees Capacity
Natural Conditions or Healthy River? 1946 Caballo (1938) Francisco I. Madero (1949) Channel Narrowing * Dean, D.J., Schmidt, J.C., 211, The role of feedback mechanisms in historic channel changes of the lower Rio Grande in the Big Bend region, Geomorphology, 126, 333 349
5 45 4 T=1 Hydrograph Volume: 1,5 million m 3 /year 2<T<3 1,292X1 6 m 3 197X1 6 m 3 1,489X1 6 m 3 Small Flood 2<T<3 Small Flood T 1 Flow (m 3 /s) 35 3 25 2 15 5 Small Floods 224 m 3 /s 56 m 3 /s Pulses High Flows 2<T<3 High Flows T 1 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
5 Hydrograph Volume: 6 million m 3 /year Flow (m 3 /s) 45 4 35 3 25 2 15 T=1 2<T<3 Small Floods 224 m 3 /s Pulses 492X1 6 m 3 94X1 6 m 3 586X1 6 m 3 High Flows 2<T<3 High Flows T 1 Small Flood 2<T<3 High Flows 2<T<3 5 56 m 3 /s Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
River Basin Specific Tool Broad Spatial Coverage Luis L Leon to Amistad Allows Scenario Analysis Useful Project Partners Capable of Flows Prioritized Water Allocation Link to Groundwater Rainfall Runoff Hydrology Economic Calculations Links to Water Quality 4 Tributary Inflows Incremental Flows Hist. Flows 2 Reservoirs Luis L Leon Amistad
25 2 15 5 Efficiency Agreement (Nash) (Willmott) Monthly =.976.994 Annual =.983.996 Streamflow (million m 3 ) Oct 69 Oct 71 Oct 73 Oct 75 Oct 77 Oct 79 Oct 81 Oct 83 Oct 85 Oct 87 Oct 89 Oct 91 Oct 93 Oct 95 Oct 97 Oct 99 Oct 1 Oct 3 Oct 5 Oct 7 4 35 3 25 2 15 5 Historic Grande Johnson Model Grande Johnson Annual flow (million m 3 ) 197 1972 1974 1976 1978 198 1982 1984 1986 1988 199 1992 1994 1996 1998 2 22 24 26 28 Historic Grande Johnson Model Grande Johnson
Soln. for Env. Flows that satisfy the Constraints Yes No Satisfy the Constraints? Identify / Propose a Hydrograph Pre 1946 Field work Define Objectives and Constraints Presidio Levees Water Supply 1944 Treaty Hydrograph, Water Supply, Treaty obligations Flooding Risk Results Evaluate the System Propose a Policy LLL Operation Re shape the releases Run the Model
Max. Hydrograph: 1, million m 3 /year Streamflow (m 3 /s) 5 45 4 35 3 25 2 15 2 < T < 3 T = 1 Small Floods P(95)=224 m 3 /s Pulses 342X1 6 m 3 64X1 6 m 3 982X1 6 m 3 T=1 T=3 T=2 T=1 T=2 5 P(75)=56 m 3 /s Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Env Base Release t = Q t + Q t Small Floods 9 Storage (million m 3 ) 8 7 6 5 4 3 2 Flood Control Zone Q t Base Environmental Flow Zone Transition Zone Drought Zone Dead Storage Jan Feb Mar Apr May Jun Median Q t + Q t Small Floods Q t Base Base Q t Jul Aug Sep Oct Nov Dec Avoid Flooding Secure Human Water Supply Env Release t = Dry Season Wet If I Season 1 < 2 Wet Season Dry If I Season 1 < Drought Forecasting
Flow (m 3 /s) 7 6 5 4 3 2 1 Base Flows Historic Model J F M A M J J A S O N D RGB at Johnson Ranch Small Floods High Flows Return Period (years) Every year Every 2 3 years Hist. 3 6 Model 2 3
Constraint: Do not harm the water supply for water users 8 6 4 2 8 6 4 2 DR 9 Bajo Rio Conchos 52 Historic Rel. (Time) 24 Env. Rest. Flows 86 Other Users 65 Rel. (Time) Rel. (Vol) 75 99 Rel. (Vol) Other Users: Municipal Rio Conchos Ag. Rio Conchos Ag. Rio Grande/Bravo DR 9
Constraint: Do not increase the flooding risk during monsoon season 2 15 1 5 18 13 Risk (%) 5.5 8 Return Period (years) Historic Presidio/Ojinaga Env. Rest. Flows 3 25 2 15 5 Sep Oct/28 Sep Oct/1958 Sep Oct/1978 Sep/1991 Sep/1966 Aug/199 Sep/1968 Flow (million m 3 ) 5 million m 3 /month Threshold Flood Sep 1978
5 4 RGB at Johnson Ranch 3 2 Historic Model Hist* Model Mean 4 138 St. Dev 675 764 Median 832 85 IQR 621 762 Historic Env. Rest. Flows RGB at Johnson Ranch 4, 3, 2, 1, Rio Conchos at Ojinaga Historic Model Presidio/Ojinaga Hist* Model Mean 782 732 St. Dev. 583 611 Median 661 69 IQR 624 649 * IBWC, Period 1955 29
Constraint: Do not release water above what the 1944 treaty establishes Treaty Obligations (%) (million m 3 ) Historic 6 782 Model 56 732 Presidio/Ojinaga * Average Volume from the Conchos to Treaty = 55% 712 million m 3 /year * IBWC, Period 1955 29
5 Base Flow (million m 3 /year) 8 7 6 5 4 3 2 Different Feasible Solutions Base Flow Jul Aug Sep Oct 1. 2. 3. 4. 5. Return Period (years) Streamflow (m 3 /s) Base flow (m 3 /s) 4 3 2 8 7 6 5 4 3 2 1 J F M A M J J A S O N D J F M A M J J A S O N D
samsandoval@ucdavis.edu A river seems a magic thing. A magic, moving, living part of the very earth itself Laura Gilpin (1949) The Rio Grande: River of Destiny