Water Quality Resilience and Policy in an Integrated Urban and Agricultural Water Basin

Transcription

1 Water Quality Resilience and Policy in an Integrated Urban and Agricultural Water Basin Linda Fernandez and Daniel McGarvey Virginia Commonwealth University 1

2 Overview Will pollution be managed by more than one state when regulations separate each state in a transboundary watershed? How is variability of hydrology and pollution runoff from urban and agricultural sectors accounted for? Empirical analysis of Potomac River nutrient loads Cost effectiveness of implementing agricultural, stormwater and wastewater abatement of phosphorus to improve watershed water quality 2

3 Objective Apply an integrated economic, environmental, hydrologic, and institutional quantitative model to answer these questions Develop noncooperative and cooperative game scenarios to compare unilateral and multilateral pollution control across transboundary watershed Estimate abatement cost functions, pollution dynamics with variability in hydrology and pollution runoff from different sectors in the watershed for game solutions 3

4 Booker et al. (2012): Some Literature Need for integration of economic, environmental, hydrologic and institutional detail for watershed wide analysis Bayramoglu (2016): Utility maximization with agriculture and fisheries goals to balance in Black Sea McConnell and Strand (1998): Lament lack of coordination with states in Chesapeake Bay for pollution control. 4

5 Empirical Analysis of a Chesapeake Bay Watershed Total Maximum Daily Load Regulation of Clean Water Act, EPA announced in 2009 to reach goal by 2025 Estimate abatement cost functions for agriculture, urban wastewater and stormwater (increasing, convex and continuous) Chopra and Sogzoni (1979) phosphorus dynamic state equation; Beaulac and Reckhow (1982) runoff coefficients from sectors 1000 Monte Carlo iterations (18 years x 1000 per year) of original hydrologic measures (U.S.G.S.) to sample at random for empirical distributions of different water flow, runoff measures 5

6 Potomac River Interstate Watershed of Chesapeake Bay 6

7 Phosphorus Abatement Costs 5 years of data from VA, MD, of capital, operation and maintenance costs (materials, equipment, labor) Agricultural abatement: Natural Resource Conservation Service data (filter strips, crop rotation, cover crops, conservation tillage, water and sediment control basins) Stormwater abatement: biorentention, grass buffers, riparian wetlands restoration Wastewater treatment plant technology changes Estimate cost of abatement efficiency percentage of phosphorus reduction 7

8 Phosphorus Pollution Abatement Cost Functions Each state minimizes costs of phosphorus pollution abatement in the Potomac Watershed (upstream and downstream of the Shenandoah River confluence) VA (1): 5,997,116,283x 3 2,980,897,224x ,000,000x + 25,000,000 MD (3): -200,000,000,000x ,599,636,013x 2 40,498,000,000x + 3,078,000,000 These abatement cost functions are aggregated across three sectors (agriculture, urban wastewater and stormwater) from expenditures for abating phosphorus through best management practices in the noncooperation game 8

9 Nash Cournot Game of Pollution Abatement Time horizon is 2009 through 2025 for both games Cooperative Game with both VA and MD jointly minimizing costs of pollution abatement draws on Interstate Commission on the Potomac River Basin that jointly plans water quality improvement and monitoring x % discount rate over time horizon of cost minimization 9

10 dp dt = Wx + Q bp b Qp Phosphorus Dynamics p = total suspended phosphorus (TP) concentration (g/m 3 ) t = time (yr) W = direct mass loading of TP to the Potomac (lbs/yr) x = abatement Q b = advective water flow upstream of the Shenandoah/Potomac confluence (m 3 /yr) p b = TP concentration upstream of the Shenandoah/Potomac confluence (g/m 3 ) Q = advective water outflow (m 3 /yr) downstream of Chain Bridge, below the Shenandoah/Potomac confluence 10

11 Noncooperation Results VA chooses 27% reduction of TP pollution through abatement in three sectors with 1,608,173 lbs/year remaining of TP loadings from the cost minimization problem over the time horizon of 2009 through VA Cost of abatement is $4,297,129 MD chooses 54% reduction of TP pollution over three sectors with 225,178 lbs/year remaining of TP loadings for the same time horizon. MD Cost of abatement is $8,213,978,867 Combined 1,833,351 lbs/year of TP loadings at a total cost of $8,218,275,996 11

12 Noncooperation, Total Maximum Daily Load 12

13 Cooperation, Total Maximum Daily Load 13

14 Cooperation Results Pollution Abatement is: 54% or 1,457,159 lbs/year reduction in TP from 2009 levels with 1,246,144 QP remaining load The required reduction by 2025 is 30% of historical TP The total cost of abatement is $7,584,842,550 Shapley value share for each state of the total costs means each state is able to abate cost effectively and meet the regulation goal. VA with 2/3 share has cost of $5,115,996,083 MD with 1/3 share has cost of $2,502,998,

15 Conclusions With 5 years of abatement options for cost minimization of phosphorus abatement, VA and MD meet phosphorus TMDL goals jointly with a savings of $633,433,446 from noncooperation VA has difficulty meeting goal under noncooperation MD saves significantly from cooperation Further sensitivity analysis may explore the institution for cooperation (the Commission). 15