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HYD_reviewppt - Lock-step decision-making process...

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Lock-step decision-making process - Scientific uncertainties contribute to indecision, lack of consensus - Institutional structures, policy-making methods, economic valuation not adequate Darcy’s Law Flow rate = K x A x i K: hydraulic conductivity A: cross sectional area of flow i: hydraulic gradient hydraulic conductivity: ability of soil or rock to transmit water under a given hydraulic gradient hydraulic gradient: the change in total potential over the change in flow length Ohm’s Law Current = x A x (V/L) ρ : electrical conductivity of the wire ρ A: cross sectional area of the wire V: voltage drop L: length of wire Groundwater Overdraft: pumping more groundwater than the system can sustain Consequences: Land subsidence Water quality degradation (salt-water intrusion = movement of saline water into freshwater aquifers) Increased energy consumption Run out of water Mulholland St. Francis Dam Disaster Owens Valley Dust Problem Chronology of L.A. Aqueduct • 1913: Original aqueduct completed, intercepted Owens River. 250 miles in length. – Completely gravity driven. Cost $24.6 million (bond financed) – Aqueduct capacity ~290,000 ac-ft/yr • 1941: Aqueduct extended to streams feeding Mono Lake. 388 miles from L.A. – water level ~ 6420-6430 ft above msl before diversions – 56,000 ac-ft/yr diverted Mono Basin to Owens River (Mono Committee, 1993). • 1970: 2nd aqueduct completed further south in Owens Valley. – Increases water delivery to L.A. by 50% (Ingersoll, 1996). – 90,000 ac-ft/yr total diversion Mono Basin to Owens River (Mono Committee, 1993).8 Mono Lake chronology post- 1970: • 1976: Biologist David Gaines receives NSF grant to study
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Mono Basin Ecology • 1981: water level 6372 ft above msl (historic low); salinity doubled • 1985: court orders creek water flows to protect trout (Fish • 1989: court order decrees halt diversions until water level back to 6,377 ft above msl • 1994: California SWRCB votes to require lake level maintained at 6,392 ft above msl; – long-term diversions L.A. at this lake level is ~30,000 ac-ft/yr (Mono Committee, 1993) Water Budget Concepts Savings Account Analogy Deposits – Withdrawals = Change in account balance Inflow – Outflow = Change in storage I – O = S (“change in” storage)
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HYD_reviewppt - Lock-step decision-making process...

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