A new approach for assessing the future of aquifers supporting irrigated agriculture

Abstract

Aquifers supporting irrigated agriculture are under stress worldwide as a result of large pumping‐induced water deficits. To aid in the formulation of more sustainable management plans for such systems, we have developed a water balance approach for assessing the impact of proposed management actions and the prospects for aquifer sustainability. Application to the High Plains aquifer (HPA) in the state of Kansas in the United States reveals that practically achievable reductions in annual pumping (<22%) would have stabilized areally averaged water levels over much of the Kansas HPA from 1996 to 2013. This demonstrates that modest pumping reductions can have a significant impact and highlights the importance of reliable pumping data for determining the net inflow (capture) component of the water balance. The HPA is similar to many aquifers supporting critically needed agricultural production, so the presented approach should prove of value far beyond the area of this initial application.

A case study of field-scale maize irrigation patterns in western Nebraska: implications for water managers and recommendations for hyper-resolution land surface modeling

“…We also note that the difference between historical irrigation practices and the lower bound of simulated irrigation provides a potential irrigation savings value in the study area. This irrigation savings value will be important for evaluating the economics of new irrigation technologies as well as providing critical information to policy makers and local stakeholders on the sustainable management of the HPA (Butler et al, 2016). Table 1 provides a summary of key needed inputs and a list of tunable parameters for each routine.…”

“…In the northern HPA (Butler et al, 2016), where this study area is located, intense irrigation pumping has led to localized water table declines (specifically in Box Butte County and widespread throughout the neighboring Upper Republican Natural Resources District) but has yet to be widespread across the region . Given low recharge (Szilágyi and Jozsa, 2013;Gibson, 2015;Wang et al, 2016) relative to irrigation pumping, rising global food and water demands (FAO, 2009), and the concomitant effects of climate change (Kumar, 2012), the sustainability of this study area and the overall HPA system in support of long-term irrigation agriculture is uncertain (Butler et al, 2016). The study presented here is an important first step in assessing water-saving technologies to continue to make irrigation agriculture sustainable; there is a critical need for this in meeting rising global food demands.…”

Geochemical Recharge Estimation and the Effects of a Declining Water Table

“…It was observed that precipitation and irrigation return did not directly result in recharge—although this was not surprising—because of the locally 60 to 100 m thick vadose zone. Further evidence for greater inflow than estimated precipitation recharge was subsequently found for the region based on relationships between annual water‐level changes and climatic indices and annual water use (Whittemore et al, 2016; Butler et al, 2016b). Given the importance of the resource to the region and ongoing efforts to improve sustainability there is a clear need to identify the source of this recharge.…”

“…Water‐level responses to pumping and barometric pressure changes indicate the saturated unconsolidated interval at this site acts as an unconfined aquifer (Butler et al, 2013). Although the rate at which water levels decline is clearly linked to climate, as less pumping occurs during wet years (Whittemore et al, 2016), water balance calculations and long‐term water‐level recovery in response to pumping clearly indicates a source of recharge to the aquifer (Butler et al, 2013; 2016b). Boundaries limiting regional flow were identified by applying pumping‐test interpretation methods to long‐term water‐level records; thus, the inflow was postulated to occur as a relatively steady vertical flow to the unconfined aquifer (Butler et al, 2013).…”

The Effects of Irrigation and Climate on the High Plains Aquifer: A County‐Level Econometric Analysis

“…Butler et al () use the simple water balance concept (water volume change is equal to the difference between inflow and pumping) to estimate the pumping level that would lead to a stable average water level (water volume change is zero). They use this approach in a small area of the HPA in Kansas, and argue this approach is well‐suited for areas where the aquifer is fairly deep.…”