Presentations 2016

The Yakima basin in south-central Washington is a major contributor to irrigated agricultural production in the State’s 40 billion dollar agricultural industry. Climate change forecasts suggest that the snowpack providing water for the basin is expected to diminish in the next decade, bringing more frequent and more severe agricultural irrigation water curtailment to several major irrigation districts in the basin. The economic impact of the 2015 drought on Washington State Agriculture has been estimated by the state to be around $1 billion, including direct and indirect economic impacts. There are many drought mitigation strategies that can be pursued at either the individual farm or irrigation district level including crop choice, the use of holding ponds, water market leasing, and emergency groundwater use for those who have invested in emergency wells. These wells may only be used with permission from the Washington State Department of Ecology during a formal State-recognized drought emergency. To the extent that these emergency groundwater wells reduce agricultural losses to the farmers using them, they will reduce the aggregate economic impacts. The economic benefits of groundwater use would be attenuated, however, if their use has downstream consequences on other surface water users through surface-groundwater interaction, or through impacts on other groundwater users during the high-demand season of late summer. Several recent studies have estimated the economic impact of drought in the Yakima Basin, but no study to date has estimated the value of emergency groundwater pumping in the basin. The objective of this study is to take a first step toward accurately estimating the value of emergency groundwater pumping in terms of its effect in reducing economic impact of drought. This analysis uses an existing hydrologic model of the Yakima Basin based on RiverWare, agricultural crop distributions and water value data for the major proratable irrigation districts in the Basin, and newly compiled emergency well-log data from these districts for the drought years of 2001, 2005, and 2015. We will also use curtailment histories for the Yakima Basin Project (a US Bureau of Reclamation Irrigation Project) as well as simulated curtailment distributions based on available CMIP3 climate scenarios to estimate the aggregate expected present value of emergency pumping in terms of economic loss reduction. While we are not yet able to estimate the indirect effects of emergency pumping on other users, this model will ultimately be integrated with a groundwater model of the Basin, which will allow us to estimate these effects. We also empirically examine which water rights holders use emergency wells and which do not to assess the importance of spatial location, terrain, soil type, and farm size.

Agricultural crop yields depend largely on soil moisture conditions in the root zone. Climate change leads to more prolonged drought periods that alternate with more intensive rainfall events. With unaltered water management practices, reduced crop yield due to drought stress will increase. Therefore, both farmers and water management authorities search for opportunities to manage risks of decreasing crop yields. Available groundwater sources for irrigation purposes are increasingly under pressure due to the regional coexistence of land use functions that are critical to groundwater levels or compete for available water. At the same time, treated wastewater from industries and domestic wastewater treatment plants are quickly discharged via surface waters towards sea. Exploitation of these freshwater sources may be an effective strategy to balance regional water supply and agricultural water demand. We present results of two pilot studies in drought sensitive regions in the Netherlands, concerning agricultural water supply through reuse of industrial and domestic treated wastewater. In these pilots, excess wastewater is delivered to the plant root zone through sub-irrigation by drainage systems. Sub-irrigation is a subsurface irrigation method that can be more efficient than classical, aboveground irrigation methods using sprinkler installations.Domestic wastewater treatment plants in the Netherlands produce annually 40-50 mm freshwater. A pilot project has been setup in the eastern part of the Netherlands, in which treated wastewater is applied to a corn field by sub-irrigation during the growing season of 2015, using a climate adaptive drainage system. The chemical composition of treated domestic wastewater is different from rainfall excess water and agricultural drainage water. In the pilot project, specific chemicals in the treated wastewater are used as a tracer to describe water and solute transport in the soil system. Focus of this pilot study is on quantifying potential contamination of both the root zone and the deeper groundwater with pharmaceutical residues. We have installed a field monitoring network at several locations on the vadose zone and the upper part of the local groundwater system, which enables us to measure vertical solute profiles in the soil water by taking samples. Based on field data obtained during the experiments, combined with SWAP (1D) and Hydrus (2D) model simulations, flow and transport of the sub-irrigated treated wastewater are quantified. In the south of The Netherlands, the Bavaria Beer Brewery discharges treated wastewater to the surface water. Nevertheless, neighboring farmers invest in sprinkler irrigation to maintain their crop production during drought periods. In this region, increasing pressure is put on the regional groundwater and surface water availability. Within a pilot study, a sub-irrigation system has been installed, by using subsurface drains, interconnected through a collector drain, and connected to an inlet control pit for the treated wastewater to enter the drainage system. We combine both process-based modeling of the soil-plant-atmosphere system and field experiments to i) investigate the amount of water that needs to be and that can be sub-irrigated, and ii) quantify the effect on soil moisture availability and herewith reduced needs for aboveground irrigation.

The regulation of non-urban groundwater extraction in Australia has undergone major policy reform over the last 15 years. In this regard, the clear policy ‘winner’ has been the adoption of a top-down policy approach that relies on caps (based on sustainable yield) and the market-based trading of groundwater permits (decoupled from land title). This paper uses survey and interview data collected from landholders and policy makers in the Murray Darling Basin in New South Wales, Australia, to explore three potential shortcomings of this approach for managing groundwater, and then considers policy alternatives for future reform.The first shortcoming is structural impediments to optimal trading. In an ideal market, there are few impediments. However, the practical experience in Australia reveals problems in trading between groundwater and surface water sources; difficulties in trading between discrete groundwater aquifers; and the presence of ‘sleeper’ groundwater licences.The second issue is deficiencies in the regulatory tools that support market trading. In essence, market trading is a hybrid policy instrument – it relies on the effective security of value of the permits being trading. And yet there is reason to doubt this security due to inadequate compliance and enforcement by water regulators, who have tended to focus on surface water issues, together with a slow embrace of transformative technologies like real-time, remote metering.The third issue is the ‘crowding out’ of other policy/regulatory options. The use of market trading of water can be incompatible with other regulatory approaches that undermine the purity of the market. There has been little exploration of alternatives, particularly the use of bottom-up, collaborative governance approaches that engage local communities, build ownership and provide tailored solutions.Having identified these three problems, the paper canvasses possible groundwater policy reforms, in particular, whether or not such reforms can be conceived within an exclusively top-down, market based approach, as presently exists.

The paper develops a sustainability model for groundwater economics utilizing concepts from macroeconomics. Sustainability is defined as intertemporal efficiency (Pareto optimality), and intergenerational equity (non-declining utility). The standard groundwater model maximizes present value of net benefits subject to an equation of motion for the resource stock. This model cannot be used as is for sustainability analysis since it is reporting income flows from aquifer usage, while sustainability is defined over consumption streams. Accordingly, the standard model is extended here to include household utility over consumption, a budget constraint, and investment in a human-generated capital stock. The subsequent analysis is conducted utilizing theoretical derivations and a computational model.Normative sustainability conditions are first derived. These include an investment allocation condition analogous to Hotelling’s rule to guarantee efficiency in the economy, as well as sufficient aggregate investment in the economy to maintain intergenerational equity. These normative conditions are then applied to the behavioral regimes of common property, present value optimality and sustainability. Common property is not sustainable due to externalities; however, it can be equitable depending on the household discount rate. Utility present value optimization corrects the externality but does not necessarily result in an equitable solution. The sustainability regime optimizes present value of utility subject to a non-declining utility constraint, thereby ensuring efficiency and equity.Several qualitative conclusions and general insights follow from this setup. First, declining resource stocks can be entirely consistent with sustainability; they are not necessarily indicators of non-sustainability. In fact, resource rents greater than the steady-state may be necessary for sustainability since they provide additional income for investment in capital stocks. Second, common property (unregulated usage) is not the only – or even necessarily the main – cause of non-sustainability, as externality correction alone does not guarantee intergenerational equity. In particular, for the empirical study here, the inefficiency is relatively small, and so sustainability is driven more by rent investment than resource management. Additional policy implications such as sustainability shadow values, extension to uncertainty, and the Hartwick-Solow rule are also investigated.

Quantifying the role of agricultural groundwater use for drought mitigationThe 2015 drought in Washington State had a severe impact on the more than 300 crops grown in the state, including an initial estimated loss of $86.52 million on the iconic Washington apple industry alone [Washington State Department of Agriculture, Interim Report: 2015 Drought and Agriculture, 2015]. The full agricultural impact of the Washington drought has yet to be assessed. Groundwater plays an important role in drought mitigation in Washington’s agricultural industry, just as it does in California’s Central Valley. However, a key difference is Washington’s requirement for permit applications to use emergency drought wells, only after the governor makes an official drought declaration. This contrasts with an overall historical lack of regulatory structure for groundwater use in California, though this will change with the 2014 Sustainable Groundwater Management Act. In either location, the decision to use supplemental groundwater is rooted in a farmer’s cost-benefit analysis that may be a function of crop types, seniority of water rights holdings, and capital cost to access groundwater. The cost-benefit analysis is dynamic in time and space, and will likely change as a function of groundwater availability. Climate change is predicted to decrease the availability and accessibility of surface water supplies into the future, leading to greater dependence on groundwater. As a result, an improved understanding of how today’s groundwater mitigation for drought impacts groundwater availability into the future is necessary for sustainable groundwater planning. The goal of this study is to create a baseline to quantify the value of groundwater for drought mitigation in agricultural regions, with a comparison of Washington and California’s recent droughts. An analysis is conducted to estimate the total amount of groundwater use in the Columbia River Basin in Washington based on a combination of drought well permits, provided by the Washington State Department of Ecology for 2001, 2005, and 2015, and additional observation wells. In addition, we assess the potential for value-added information on groundwater use with NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite mission to understand regional scale impacts. By comparing the increased reliance on groundwater during drought in the Central Valley and Columbia River Basin, we can better understand how groundwater dependence changes as a function of drought severity, drought length, and crop distribution. Ultimately, this work lays the foundation to assess the economic value of groundwater to mitigate crop losses in agricultural regions, especially into the future with changing regulatory structures and climate change.