Irrigation area, efficiency and water storage mediate the drought resilience of irrigated agriculture in a semi-arid catchment

We examined the effects of hydrological variables such as irrigation area, irrigation efficiency and water storage on the resilience of (mostly commercial) irrigated agriculture to drought in a semi-arid catchment in South Africa. We formulated a conceptual framework termed 'Water, Efficiency, Resilience, Drought' (WERD) and an accompanying spreadsheet model. These allow the resilience of irrigated agriculture to drought to be analysed via water accounts and a key resilience indicator termed Days to Day Zero (DDZ). This represents the number of days that a pre- and within-drought supply of catchment water available to irrigation is withdrawn down to zero in the face of a prolonged drought. A higher DDZ (e.g. >300 days) indicates greater resilience whilst a lower DDZ (e.g. <150 days) signals lower resilience. Drought resilience arises through land and water management decisions underpinned by four types of resilience capacities; absorptive, adaptive, anticipative and transformative. For the case study, analyses showed that irrigators, with currently approximately 23,000 ha under irrigation, have historically absorbed and adapted to drought events through construction of water storage and adoption of more efficient irrigation practices resulting in a DDZ of 260 days. However, by not fully anticipating future climate and water-related risks, irrigators are arguably on a maladaptive pathway resulting in water supply gains, efficiency and other practices being used to increase irrigation command areas to 28,000 ha or more, decreasing their capacity to absorb future droughts. This areal growth increases water withdrawals and depletion, further stresses the catchment, and reduces future DDZs to approximately 130 days indicating much lower drought resilience. Our approach, supported by supplementary material, allows stakeholders to understand the resilience consequences of future drought in order to; reconcile competition between rising water demands, consider new water storage; improve agricultural and irrigation planning; and enhance catchment governance.

Exploring the Critical Role of Water in Regenerative Agriculture; Building Promises and Avoiding Pitfalls

This article seeks greater clarity in the connections between water and regenerative agriculture (RA). We first review existing soil/water knowledge and argue that desired “RA and water” outcomes depend on the management and optimal levels of two key soil properties; readily available moisture and infiltration rate. Secondly, we hypothesize these help define a range of RA beneficial outcomes or “promises,” such as improved vegetative growth, reduced risk of erosive runoff, higher soil organic matter content and biological fertility, easier irrigation management, resilience to drought, better water filtration and less variable streamflow hydrology. Thirdly we show that by not fully understanding water's multiple roles for achieving desired RA outcomes, risks, contradictions and “pitfalls” can arise. With these three parts we observe that carefully explained and quantified roles of water in the existing RA literature are often missing, neglected, over-generalized or poorly explained. We also suggest that narratives and terms (e.g., “net zero” or “net positive”) for describing the benefits and aims of RA and water can lack context and situational fit, or are misleading and incorrect. Cautions also apply to water quantities additionally required for soil regeneration activities, recognizing stiff competition for scarce river basin water and its allocation. How necessary quantities overlap with local and catchment policies for water allocations and hydrology, incorporating farmers' views and choices and informed by field, farm and system water accounting, are critical to successful agricultural practices including those that are “regenerative.” Accordingly, we suggest that scientists and decisions-makers should more thoroughly interrogate how “RA and water” is being analyzed so that relevant policies develop its promises whilst avoiding pitfalls.

The delusive accuracy of global irrigation water withdrawal estimates

Miscalculating the volumes of water withdrawn for irrigation, the largest consumer of freshwater in the world, jeopardizes sustainable water management. Hydrological models quantify water withdrawals, but their estimates are unduly precise. Model imperfections need to be appreciated to avoid policy misjudgements.

Gender differences and practice implications of risk factors for frequent hospitalization for heart failure in an urban center serving predominantly African-American patients

To identify the clinical correlates of recurrent heart failure hospitalization in a large urban hospital serving predominately African-American patients, and to provide further insight into modifiable risks for heart failure readmissions, a retrospective period prevalence review of the records of all adult patients admitted with a primary diagnosis of heart failure (International Classification of Diseases-9 code 428.0) between January and December 1995 was performed. The main outcome was the number of heart failure hospitalizations over 12 months. Twelve hundred patients were identified. Mean age was 64 +/- 16 years, 94% were black, 57% were women, and 40% were > or = 65 years old. Ninety-eight percent had a history of systemic hypertension and 55% had uncontrolled hypertension. Other comorbidities were left ventricular (LV) hypertrophy (64%), coronary artery disease (52%), and tobacco abuse (28%). Sixty-five percent of patients were on angiotensin-converting enzyme (ACE) inhibitors, 51% on calcium antagonists, and 8% on beta blockers. Most patients had suboptimal dosing of ACE inhibitors and there was inappropriate use of calcium antagonists in 56% of patients with moderate or severe systolic dysfunction. Diabetes mellitus and echocardiographic wall motion abnormality were independently associated with frequent admissions for women but not for men. Medication-related increase in heart failure hospitalization was seen for calcium antagonists in patients with severe LV dysfunction (odds ratio 2.24, 95% confidence intervals 1.0 to 5.03; p <0.03). Uncontrolled hypertension, underdosing of ACE inhibitors, and overuse of calcium antagonists in patients with significant LV dysfunction are potential targets for intervention.