Ten years' hydrological investigations at Danum have provided strong evidence of the effects of extremes of drought, as in the April 1992 El Niño southern oscillation event, and flood, as in January 1996. The 1.5 km2 undisturbed forest control catchment experienced a complete drying out of the stream for the whole 1.5 km of defined channel above the gauging station in 1992, but concentrated surface flow along every declivity from within a few metres of the catchment divide after the exceptional rains of 19 January 1996. Under these natural conditions, erosion is episodic. Sediment is discharged in pulses caused by storm events, collapse of debris dams and occasional landslips. Disturbance by logging accentuates this irregular regime. In the first few months following disturbance, a wave of sediment is moved by each storm, but over subsequent years, rare events scour sediment from bare areas, gullies and channel deposits. The spatial distribution of sediment sources changes with time after logging, as bare areas on slopes are revegetated and small gullies are filled with debris. Extreme storm events, as in January 1996, cause logging roads to collapse, with landslides leading to surges of sediment into channels, reactivating the pulsed sediment delivery by every storm that happened immediately after logging. These effects are not dampened out with increasing catchment scale. Even the 721 km2 Sungai Segama has a sediment yield regime dominated by extreme events, the sediment yield in that single day on 19 January 1996 exceeding the annual sediment load in several previous years. In a large disturbed catchment, such road failures and logging-activity-induced mass movements increase the mud and silt in floodwaters affecting settlements downstream. Management systems require long-term sediment reduction strategies. This implies careful road design and good water movement regulation and erosion control throughout the logging process.

Background: Coronavirus disease 2019 (COVID-19) is a worldwide pandemic, with a case mortality ratio of approximately 6.4% at the time of writing (May 2020). Mortality increases in elderly patients with comorbidities. Patients with hip fracture have an average age of 80 years, with an estimated 2.8 comorbidities per patient. Evidence is lacking regarding the mortality rate of patients with hip fracture admitted during the COVID-19 pandemic. Our aim was to investigate the mortality rate among patients with a proximal femoral fracture who were admitted to our hospital during the COVID-19 pandemic. Methods: We conducted a retrospective review of all patients with a proximal femoral fracture admitted to Southend University Hospital in the U.K. from March to April 2020 (during the COVID-19 pandemic). Data collected included demographics (patient age, body mass index, sex), comorbidities, and blood test values along with COVID-19 diagnosis (based on positive microbiological sample and clinical and radiographic findings) and operative characteristics (time to operation, length of stay, American Society of Anesthesiologists [ASA] classification, Nottingham Hip Fracture Score). The primary outcome was the 30-day mortality rate for patients with a hip fracture who were COVID-19 positive or negative. Kaplan-Meier survival analysis was conducted along with Mann-Whitney U tests and Fisher exact tests. Results: Forty-one patients were included in the study, of whom 37 had an available SARS-CoV-2 (severe acute respiratory syndrome-coronavirus 2) swab test result. The overall 30-day mortality was 22%. Eleven patients tested positive for COVID-19. There was a significant difference in the mortality rate between those who tested positive and those who tested negative (54.5% versus 7.69%, respectively; Fisher exact test, p = 0.004) and between the operative patients who tested positive and the operative patients who tested negative (37.5% versus 4.34%, respectively; Fisher exact test, p = 0.043). Conclusions: Patients with a proximal femoral fracture may be at higher risk for mortality during the COVID-19 pandemic. We noted that patients with a proximal femoral fracture who tested positive for COVID-19 had a higher 30-day mortality rate compared with those who tested negative. Additional research is required to ascertain the benefits of a reduction in time to operation. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Ten years' hydrological investigations at Danum have provided strong evidence of the e¡ects of extremes of drought, as in the April 1992 El Nin¬ o southern oscillation event, and £ood, as in January 1996. The 1.5 km 2 undisturbed forest control catchment experienced a complete drying out of the stream for the whole 1.5 km of de¢ned channel above the gauging station in 1992, but concentrated surface £ow along every declivity from within a few metres of the catchment divide after the exceptional rains of 19 January 1996. Under these natural conditions, erosion is episodic. Sediment is discharged in pulses caused by storm events, collapse of debris dams and occasional landslips. Disturbance by logging accentuates this irregular regime. In the ¢rst few months following disturbance, a wave of sediment is moved by each storm, but over subsequent years, rare events scour sediment from bare areas, gullies and channel deposits. The spatial distribution of sediment sources changes with time after logging, as bare areas on slopes are revegetated and small gullies are ¢lled with debris. Extreme storm events, as in January 1996, cause logging roads to collapse, with landslides leading to surges of sediment into channels, reactivating the pulsed sediment delivery by every storm that happened immediately after logging. These e¡ects are not dampened out with increasing catchment scale. Even the 721km 2 Sungai Segama has a sediment yield regime dominated by extreme events, the sediment yield in that single day on 19 January 1996 exceeding the annual sediment load in several previous years. In a large disturbed catchment, such road failures and logging-activity-induced mass movements increase the mud and silt in £oodwaters a¡ecting settlements downstream. Management systems require long-term sediment reduction strategies. This implies careful road design and good water movement regulation and erosion control throughout the logging process.

Three stages of selective commercial logging in a 0.54 km 2 catchment in the Ulu Segama caused great changes in the output of sediment and water over a 27-month period from June 1988. The ratio of monthly suspended sediment yield from the logged catchment to that from a nearby undisturbed catchment changed from the order of 1:1 before disturbance; to 4:1 after a logging road had been built across the head of the catchment; to 5:1 after logging within 37 m of the road; and to 18:1 in the five months after logging of the remainder of the catchment. A year after logging had ceased the largest monthly sediment yields of the whole period were only 3.6 times those of the undisturbed catchment, indicating a degree of recovery. Sediment accumulated in the channel bed and on the narrow flood plain remained to be evacuated, and gullies on abandoned logging trails continued to supply sediment to the drainage system.

The spatial distribution of soil hydrological properties and associated flow pathways within a single 0.01 to 10 km2 catchment are usually poorly defined by typical programmes of point‐scale measurements. This is due not only to “measurement uncertainty” caused by instrument error and inadequate spatial sampling but also to “conceptual uncertainty” resulting from a deficiency in the Darcy‐Buckingham‐Richards description of subsurface flow. This study examines these two sources of uncertainty in the identification of subsurface flow beneath the Bukit Timah forest, Singapore. The two distinct approaches of water‐tracing and Darcy‐Buckingham calculations are compared. Flow estimates resulting from quasi‐steady Darcy‐Buckingham calculations were found to be very sensitive to the magnitude and pattern of the saturated hydraulic conductivity, which itself was sensitive to the permeametry technique used. The use of a Hydro‐Physics ring permeameter in the estimation of subsurface flows gives rates that are far greater than the mean propagation rates of tagged water though the approach identifies the relative difference between the behaviour of the two slopes studied. Whilst the lumped differences between the two tropical slopes may be identified with the Darcy method, the poor correlation with the absolute velocity and direction of the tracer plume means that catchment or even slope scale simulation using parameters of the Darcy‐Buckingham‐Richards equation will be highly uncertain.