‘Overuse-charge’ agricultural water price mechanism in groundwater overdraft areas

The irrigation water price is an indispensable element for the modernization of agriculture and the realization of rural revitalization. As a pilot initiative for agricultural water price reform, Hebei Province has explored various effective patterns. This study analyzed 714 first-hand data points obtained from agricultural irrigation areas in Hebei Province. The ‘two lines and three grades’ water price policy is difficult to implement in practice. The ‘overuse-charge’ includes two levels of water use standards, the water price and reward standards in each level are inconsistent, especially, actual irrigation water use far more than Individual Allowable Water Volume (IAWV). Similarly, there is a negative relationship between irrigation water use and water fees at the critical point of IAWV, that is, the more water used, the less water fees paid. The ‘one line and two grades’ water price policy is proposed. The water volume less than the irrigation quota should be purchased by the government or rewarded farmers, on the contrary, the water price should be increased. It is suggested to improve the installation of irrigation metering facilities, popularization of field water-saving technology and quota management in the groundwater water irrigation region.

Performance of community-based water-saving technology under land fragmentation: evidence from groundwater overexploitation in the North China Plain

The current water shortage crisis has necessitated an increased focus on improving the irrigation efficiency in groundwater overdraft areas. Consequently, the Chinese government has supported small farmers in installing community-based water-saving technologies (WSTs) providing high irrigation efficiency. Based on the data collected from 620 households located in the groundwater overdraft area of Hebei, North China Plain, this study conducts a stochastic frontier analysis to measure farmers' irrigation water use efficiency (WUE) and analyzes the impact of land fragmentation and WST types on their WUE. The results show that the average WUE of groundwater irrigation is 0.606. The WUE between community-based and household-based WSTs differs based on the degree of land fragmentation. A high degree of land fragmentation restricts community-based WSTs from efficiently improving farmers' WUE, whereas household-based WSTs perform better and are easier to adopt. For high land fragmentation, the WUE of the community-based WST is 9.12% lower than that of the household-based WST. However, the WUE of the community-based WST is 12.55% higher than that of the household-based WST when the degree of land fragmentation is low. Therefore, the government should pay attention to small farmers' adaptability toward WST and promote community-based WSTs on a low degree of land fragmentation.

Solar Pumps and Water-Energy Nexus in Gujarat, India: First Assessment of the World’s Largest Pilot on Grid-connected Solar Irrigation Pumps

The epicentre of Gujarat’s perverse nexus between electricity subsidy and groundwater depletion lies in its legacy of 485,000 unmetered tubewell owners who have fiercely resisted metering for 20 years. These comprise 40 percent of Gujarat’s irrigation connections but account for 49 percent of agricultural load, 71 percent of energy use in groundwater abstraction and 90 percent of farm power subsidies. Suryashakti Kisan Yojana (SKY), a large, state-wide pilot project which solarised and net-metered 4215 tubewells and began paying farmers for evacuating surplus solar energy, has been enthusiastically embraced by unmetered and metered farmers alike. SKY promises politically acceptable resolution of a wicked energy-water conundrum that afflicts much of India and west Asia. Mainstreaming SKY can significantly reduce groundwater overdraft, GHG emissions and subsidy burden. It will increase farm incomes while radically improving energy-water accounting and management. Gujarat government should invest in compulsory, free-of-cost solarisation of tubewells. We show that doing so is profitable for government and beneficial for farmers, climate and environment.

Determining initial viability of local scale managed aquifer recharge projects in alluvial deposition systems

Critical groundwater overdraft is one of the greatest water issues of our time. In California, decades of overdraft have resulted in the passage of the 2014 Sustainable Groundwater Management Act, which requires critically overdrafted groundwater basins to create groundwater sustainability plans for future groundwater management. Many managers are using managed aquifer recharge (MAR) in their overall sustainability portfolio, in an attempt to balance groundwater use. Soil maps have been used in the past to determine viability of managed aquifer recharge sites. However, soil maps do not account for the high permeability pathways that exist in the subsurface, which have the potential to provide high efficiency recharge to the water table. This paper emphasizes the utility of creating data dense fine resolution geostatistical models and generating many realizations of the subsurface, which can then be used for analysis to understand the variability in recharge potential for specific recharge sites. These geostatistical realizations were investigated using connectivity metrics to evaluate the spread of highly conductive pathways throughout the subsurface. Connectivity analyses of high conductivity pathways show confidence that the study site- three vineyards located in the floodplain between the Cosumnes River and Deer Creek in Elk Grove, CA - has the potential to provide efficient recharge to the water table. These connectivity analyses can be completed prior to running computationally expensive and time intensive groundwater models and can be used as a way to understand variance between realizations of these geostatistical models.

Surface Water Quality Regulation as a Driver for Groundwater Recharge

Water scarcity commonly motivates managed aquifer recharge projects, but other factors can motivate recharge efforts, including in relatively water-rich areas. Surface water quality regulation has been a major driving force behind a large-scale recharge project in development in Virginia’s Coastal Plain region, where nutrient pollution from agricultural and urban sources has degraded the Chesapeake Bay’s ecosystems, leading state and federal regulators to require dischargers to reduce their nutrient contributions to the watershed over time. Hampton Roads Sanitation District is pursuing the Sustainable Water Initiative for Tomorrow, an innovative, multi-benefit initiative designed to address both nutrient pollution in the Chesapeake Bay watershed and regional groundwater overdraft in the Coastal Plain. When fully implemented, the initiative is expected to recharge approximately 100 million gallons per day of drinking-water quality, treated municipal wastewater into the Potomac Aquifer System through injection facilities located at five of the District’s wastewater treatment plants. As a result, the District expects to reduce its nutrient discharges from those plants by approximately 90%, enabling it to meet its own mandated nutrient limits while also generating nutrient credits that it can trade to other dischargers. Modeling suggests that the initiative will increase regional water pressure within the confined aquifer system, helping to combat groundwater overdraft and its negative impacts, including aquifer compaction and related land subsidence, falling water levels in wells, and saltwater intrusion. This case study provides insights into the influence of institutional context on managed aquifer recharge and on multi-benefit water resource projects more generally.

Incentivizing Groundwater Recharge in the Pajaro Valley Through Recharge Net Metering (ReNeM)

Decades of groundwater overuse in the Pajaro Valley have contributed to an estimated groundwater overdraft of 12,100 acre-feet per year (AFY) in the basin. In response, the Pajaro Valley Water Management Agency adopted a pilot groundwater recharge program, called Recharge Net Metering (ReNeM). ReNeM encourages development of infiltration projects on private or public land by offering a rebate on groundwater pumping fees based on the net increase in infiltration. The rebate uses the following equation: Rebate = W50x (Inftot − Infinc), where Infinc is the incidental infiltration that would have occurred without the project, Inftot is total measured infiltration, and W50 represents the proportion (50%) of the pumping fee assessed to the landowner based on location. The goal of Pajaro Valley’s ReNeM pilot program is to infiltrate 1,000 AFY to the aquifer by creating and operating infiltration projects at multiple sites. This effort will help reduce groundwater overdraft and associated undesirable consequences (seawater intrusion, disconnection with surface water, and degradation to water quality). This case study analyzes the local conditions and institutions that make the ReNeM pilot program feasible, including previously established groundwater pumping fees, metered wells, and the existence of third-party certifiers able to verify the results of project sites. The ReNeM pilot has enabled increased recharge by creating new incentives that have drawn PV Water, landowners, and tenant farmers to develop recharge projects. The ReNeM pilot is the first and thus far only application of this approach, but the methods used by ReNeM may have potential applicability elsewhere. This potential will hinge on whether the pilot can prove the effectiveness of the rebate scheme and demonstrate measurable benefits in the Pajaro Valley.

Agricultural managed aquifer recharge — water quality factors to consider

The resilience and productivity of California's agriculture is threatened by groundwater overdraft, reduction in aquifer water quality, increased land subsidence damage to infrastructure and an irreversible reduction in groundwater storage capacity. Intentionally flooding agricultural fields during winter — a practice referred to as agricultural managed aquifer recharge (AgMAR) — can help counteract overdraft. However, the potential for AgMAR to exacerbate nitrate/salt leaching and contamination of at-risk aquifers remains a critical concern. To quantify the risk of groundwater contamination with AgMAR, we took 30-foot-long soil cores in 12 almond orchards, processing tomato fields and wine grape vineyards on low- and high-permeability soils, measured nitrate and total dissolved solids concentrations and calculated stored nitrate-N. Wine grape vineyards on permeable soils had the least nitrate leaching risk observed. However, almond orchards and tomato fields could be leveraged for AgMAR if dedicated recharge sites were established and clean surface water used for recharge. Historical land use, current nitrogen management and soil permeability class are the main factors to consider before implementing AgMAR.

Evaluation of Groundwater Overdraft Governance Measures in Hengshui City, China

Groundwater overdraft is a worldwide phenomenon, resulting in environmental issues, such as water contamination, land subsidence, seawater intrusion, streamflow reduction, and deterioration of the ecological environment. Located in the central North China Plain, Hengshui City has experienced a regional groundwater depression cone due to excessive pumping of groundwater, resulting in the largest overdraft area in the North China Plain. Since 2014, Hebei Province has adopted measures to realize the comprehensive governance of groundwater overdraft in partial areas of Hengshui City, including adjusting planting structures, promoting agronomic water-saving techniques, strengthening hydraulic engineering construction, and innovative management systems. These measures have been in effect for two years, such that their effectiveness must be assessed for the beneficial recovery of groundwater levels to determine the means for their continuation and extension. However, the change in regional groundwater levels is not gradual, but reflects a process of sudden increase due to the intervention of government behavior, and many existing groundwater recharge models are difficult to apply. Therefore, establishing a reasonable, scientific evaluation system of the measures is a key problem that requires a solution. Using field surveys and experiments, this study establishes a quantitative analysis evaluation method to assess the performance of governance measures adopted by Hengshui City in 2015, with full consideration of the crop water demand process and rainfall frequency. The results show that governance measures had a significant positive outcome on reducing groundwater overdraft in pilot areas. Approximately 98.4% of the agricultural governance target was achieved, with confined groundwater rebounding by approximately 4.92 m as compared to 2015. According to the analysis, the three most efficient measures (the top three largest amounts of groundwater-saved per mu) adopted by the government were (1) non-agricultural crops replacement (forestry), (2) planting pattern adjustments, and (3) integration of water and fertilizer-vegetable, which can be promoted in future measures. However, considering the size of the implementation area and total governance capacity, water-saving during spring irrigation of wheat and replacement by surface water are the two most important conservation measures, which are required to further strengthen the management and implementation effect.