Presentations 2016

Models to Inform Policy on Agricultural Groundwater Use in the Upper Midwest

S.S. Papadopulos & Associates, Inc.

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Groundwater use for agricultural has expanded tremendously in the upper Midwest in the past two decades as a result of longer growing seasons and advances in irrigation technology. As a result, a region that has been always considered water abundant now has conflicts between agricultural, recreational and ecological interests with many talking of water shortages. This has occurred with little legal precedent for managing conflicts and for appropriately dealing with surface-groundwater interactions. This paper will focus on the Central Sands region of Wisconsin where irrigated agriculture for growing potatoes, corn and other vegetable crops has become common in the past decades resulting in lowered lakes levels, with lakefront homes now far from the water, and drying up of headwater streams. The paper will describe the regulatory rules that apply to groundwater use in Wisconsin and how these rules have evolved with time and will discuss the challenges in the near term as sound scientific based rules struggle to keep up with rapidly increasing water use. This paper will describe the author’s experience in working on the permitting of large high capacity wells for a number of large agricultural projects in the Central Sands region. For all of these permits, detailed groundwater models were developed to evaluate alternative well locations and pumping rates to select pumping configurations and use that minimized impacts to surface water resources. In the upper Midwest, the effect of irrigation pumping is directly related to the increase in evapotranspiration that results from change land cover from non-irrigated vegetation to irrigated row crops. This paper will describe the difficulties in determining the changes in evapotranspiration that occur and the resultant uncertainty in predictions of the effect of irrigated agriculture on groundwater and surface water resources. This uncertainty is confounded by the fact the climate has been changing and unlike many areas average annual precipitation has increased significantly over the past several decades.The paper will also discuss briefly nutrient management issues related to irrigated agriculture in the Central Sands and the ubiquitous nature of nitrate contamination in shallow aquifers. The use of soil-groundwater models to evaluate nitrate leaching as part of the permitting process and the use of models to select crop rotation and fertilizer application amounts and timing to reduce nitrate leaching will be discussed.

Drought Governance and Response Strategies including Mission Kakatiya in Telangana, India

Centre for Good Governance

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Telangana, formed as 29th state in India about two years ago is struggling to sort its issues concerning agriculture, which contributes to only 12.8% to the State Gross Domestic Product (GSDP) but supports 55.49 % of population. Farming in the state is mainly rain fed (60%) and is often prone to droughts due to climate change. The state is in its third year of successive droughts and is currently in the midst of one of the most severe droughts in its history with 22 % rains below normal. Considering the geography and climate of the region, huge number of tanks were constructed that helped to manage droughts for centuries. Water levels in major reservoirs under Godavari and Krishna basins have gone down to an all-time low during the last decade. The ground water table has been reducing and the state government has declared 231 mandals out of 443 rural mandals as drought affected.This warrants governance of drought with response strategies like in other natural hazards comprising, a system of early warning, a system of government preparedness and an enabling system that provides support and assistance to imperilled communities. Based on the proven drought planning mechanisms elsewhere, a drought governance framework is developed for the state of Telangana with suitable modifications. Several drought management strategies like conservation agriculture, integrated farming systems, managing water resources, drought management practices like selection of drought resistant varieties, early maturing varieties, crop specific agronomic recommendations suitable to the state have been identified and proposed.Historically tanks have been a part of the irrigation landscape of Deccan Plateau of India for centuries. Due to topography, Kakatiya rulers constructed thousands of tanks for drinking and as well as irrigation in Telangana. However, their use has been declining over a period of time mainly due to government attention and lack of community involvement in tank management and Maintenance, inadequate and unreliable water supply to the tank resulting in actual decline in the area irrigated by tanks. Tank irrigation which peaked to 5, 30,565 ha in 1956-57 has declined to 2, 18, 124 ha by 2009. Due to impending crisis of groundwater irrigation, there is a renewed attention for restoration of all minor numbering 46,531 irrigation tanks under Mission Kakatiya (Mana Ooru – Mana Cheruvu meaning our village our tank ) in a decentralised manner through community involvement. The objective of Mission Kakatiya is to enhance the development of Minor Irrigation infrastructure, strengthening community based irrigation management, adopting a comprehensive programme for restoration of tanks. The mission activities began, needed rules have been framed and efforts are being made to ensure proper execution of stipulated procedures.The tanks restoration as a major response to combat drought is expected in the coming years. The program will be implemented in a phased manner in the next five years, the inputs to make the program successful, progress and impacts will be reported.

Irrigation Impacts in the Northern Great Lake States

University of Wisconsin - Stevens Point

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Irrigated agriculture is expanding rapidly into the humid and traditionally nonirrigated eastern US, bringing fresh environmental challenges that have yet to be assessed and needs for management frameworks that have yet to be constructed. The northern great lake states region of Minnesota, Wisconsin, and Michigan is one part of the eastern US where irrigation expansion is rapid, rising from negligibility in the 1950s to 290,000 ha by 1978 and to 639,000 ha in 2013. Irrigation in the northern great lake states is mostly groundwater-sourced and commonly occurs in areas containing coarse-grained glacial sediments, droughty soils, and productive aquifers. Unlike much of the arid US west, irrigation in the northern lake states is “supplemental.” By augmenting rainfall, periods when soil moisture might be limiting are bridged, allowing high water demand agriculture and greater profitability. In contrast with the west, where irrigation water is often supplied by surface water, aquifers poorly connected to local hydrologic processes, or the valley aquifers of large rivers, lake states irrigation source water is predominantly locally-recharged groundwater with strong connections to local lakes and streams.We characterized the impacts of groundwater irrigation in the northern lake states in the Wisconsin central sands, a 6500 km2 region composed of 30-60 m of coarse glacial sediments overlying less permeable bedrock. The area receives about 800 mm y-1 of precipitation of which about 250 mm y-1 recharges groundwater. Groundwater feeds numerous lakes, wetlands, and nearly 1000 km of headwater streams that support coldwater ecosystems. Over 2000 high capacity wells tap the same groundwater to irrigate field corn, potato, sweet corn, and other processing vegetables. Irrigation effects on central sands surface waters have been substantial and include complete drying of some lakes and streams. Commonly, baseflows are reduced by a third or more in stream headwaters and water levels are reduced in aquifers and lakes by more than a meter. Observed flow and stage reductions can be explained by an increase of 45 to 142 mm y-1 in evapotranspiration on irrigated land compared with pre-irrigated land cover.We conclude that irrigation water availability in the northern lake states and other regions with strong groundwater-surface water connections is tied to concerns for surface water health. Thus a management framework will require a focus on the upper few meters of aquifers on which surface waters depend rather than the depletability of the aquifer.

Hydroeconomic Modeling of Sustainable Groundwater Management

ERA Economics, LLC

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In 2014 California passed legislation requiring the sustainable management of critically overdrafted groundwater basins, located primarily in the Central Valley agricultural region. Hydroeconomic modeling of the agricultural economy, ground, and surface water system is critically important to simulate the alternate transition paths to sustainable management of the basins. While the fundamental dynamic relationships of groundwater are fairly well established, unfortunately there are no mass balance checks that can be applied to human behavior. Accordingly, we argue that integrating response functions that represent the key biophysical relationships from a hydrologic model into an economic model of groundwater use is preferable to embedding the economic response in a hydrologic model as is more commonly done. We develop a dynamic hydroeconomic model using this approach for the Kings and Tulare subbasins of California’s Central Valley and evaluate three groundwater management institutions – open access, perfect foresight, and managed (sustainable) pumping. We quantify the costs and benefits of sustainable groundwater management, including the energy pumping savings and heretofore omitted benefits which we term the drought reserve value and avoided capital costs. Our analysis finds that short-run losses in crop revenue are offset by the long-run benefits of drought reserve value and avoided capital costs, which provides a counter example to the Gisser and Sanchez Paradox.

Field kites: Evaluating supplemental irrigation with climate change

McGill University

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Field kites are a novel tool to evaluate agricultural production under water compromised conditions by explicitly considering the farmers’ capacity to manage their water resources. Supplemental and deficit irrigation are necessary initiatives to increase agricultural and water productivity, and to buffer the vulnerabilities of precipitation-fed agriculture. Under water limiting conditions, the crop-water production function quantitatively evaluates the relationship between seasonal water use and crop yield, and previous efforts have attempted to describe the crop-water production function as a function of seasonal water use. However, these representations do not account for the effects of temporal distribution and trivialize the associated variability in yields by assuming an optimized or arbitrary temporal distribution of water use. This over-simplification renders these functions inappropriate for recommendations related to water management and assessing the role of supplemental and deficit irrigation, in particular given projections of increasing climatic variability. We propose Field Kites, an interpretation of the crop-water production function that determines crop yield as a function of both seasonal water use and irrigation agency, defined as the ability of farmers to manage and determine both the quantity and temporal distribution of irrigation water. Assuming maximum irrigation agency may be inappropriate for farmers subject to pre-defined irrigation schedules and amounts, while it may be appropriate for farmers irrigating with groundwater with generally more facility to tailor both the timing and amount of water. However, the assumption of optimized water use distribution is particularly inappropriate for evaluating supplemental irrigation on mainly precipitation-fed agriculture where water use from precipitation is significant. Field kites are constructed using AquaCrop and previously validated cultivar-specific variables and the climate- and cultivar-specific field kite for spring wheat characteristic of western Canada is presented. The soil- and climate-specific field kites are then constructed for each cell over a grid at local-scale in the region of southern Alberta, Canada and evaluated under both the present and future period of 2041-2070 using different regional climate models. The simulations range in potential precipitation, temperature, and CO2 changes and allow us to evaluate the potential for supplemental and deficit irrigation to increase or stabilize crop yields, prevent crop failure, or increase water productivity. Supplemental and deficit irrigation are appropriate initiatives for regions experiencing increased competition for water resources, rising costs associated with water withdrawal and irrigation application, compromised surface water and groundwater availability, and a declining health of associated ecosystems. It is essential to consider the effect of varying levels of irrigation agency on crop yields for water managers and policy makers to evaluate developing and supporting the necessary infrastructure for supplemental and deficit irrigation to both increase agricultural production and buffer the vulnerabilities of precipitation-fed agriculture.