Predicted impacts of land use change on groundwater recharge of the upper Berg catchment, South Africa

Land use change is a major factor influencing catchment hydrology and groundwater resources. In South Africa, the management of scarce water resources is a big concern. The study area, the upper Berg catchment, Western Cape, South Africa, contains strategic water resources. The catchment has undergone many changes in recent years, not least of all the construction of a dam on the upper reach. To reduce water loss due to evapotranspiration, non-native hill slope vegetation upstream of the Berg River Dam was cut down. It was hypothesised that recharge has been increased due to this change in vegetation. The objectives of this study were to determine land use changes in upper Berg catchment using multi-temporal Landsat images from 1984, 1992, 2002, and 2008, and to predict the impact of these land use changes on groundwater recharge. For the simulation of groundwater recharge the distributed hydrological model WetSpa was used. Forest plantations lost 72% (18.8 km2) of their areal extent between 1984 and 2008, due to deforestation as part of a plan to implement the ecological Reserve as required by national water policy; the area of barren land increased by 15.7 km2 in the same period. The high increase in precipitation, especially in the period of 2005–2009, combined with the change in land use in the study area resulted in a highly increased (278%) predicted mean groundwater recharge. Simulated groundwater recharge shows strong spatial differences for each evaluated year. The effect of the rapid clearing of non-native hill slope vegetation upstream of the Berg River Dam for the land use scenario of 2008 was tested to check if clearing is an important factor in the increase of groundwater recharge. Hence, we simulated the whole time-series from 1984–2004 (21 years) with the land use map from 2008 instead of the land use maps for 1984, 1992 and 2002. A systematic increase of about 8% per year for the 21-year period, due to the change in land use from the different years to that of 2008, is predicted , which confirms that the clearing of the non-native hill slope vegetation is of considerable importance for the increase in groundwater recharge.Keywords: Berg catchment, ecological Reserve, WetSpa, remote sensin

Application of multi‑method approach to assess groundwater–surface water interactions, for catchment management

Globally, the dependence of river systems to delayed discharge of subsurface water to augment flows during dry seasons is well documented. Discharge of fresh subsurface water can dilute concentrated river flow quality during reduced flow. Observed and reported results on the Berg River’s declining water quantity and quality are a concern to the regions socio-economic growth and environmental integrity. Understanding the role of subsurface water discharges on the quantity and quality of receiving surface water courses can improve their management during dry periods. A case study was designed and implemented in the upper Berg River catchment in the Western Cape Province of South Africa to assess the influence of groundwater–surface water interaction on water quantity and quality. This study aimed to quantify and characterize the quality of subsurface water available in the upper catchment to improve observed declining water quality downstream. Hydrograph separation provided estimates of water fluxes during 2012–2014 low and high flow periods, while hydrochemical analysis provided insights on impacts of major land use activity in this catchment on water resources. Hydrograph separation analysis indicated that the Berg River is 37.9% dependent on subsurface water discharges annually. Dominant Na–Cl-type water indicates the quality of water from the upper Berg River is largely affected by natural processes including short residence times of aquifer water, rock–water interactions and atmospheric deposition of NaCl ions. These results provide insights for suggesting management options to be implemented to protect subsurface water for continued dilution and water resources management in the lower catchments

Estimation of Length Limits for Integral Bridges Built on Clay

In this paper, the maximum length limits for integral bridges built on clay are determined as a function of the ability of steel H-piles supporting the abutments to sustain thermal-induced cyclic displacements and the flexural capacity of the abutment. First, H-pile sections that can accommodate large plastic deformations are determined considering their local buckling instability. Then, a low-cycle fatigue damage model is used to determine the maximum cyclic deformations that such piles can sustain. Next, nonlinear static pushover analyses of two typical integral bridges are conducted to study the effect of various geometric, structural, and geotechnical parameters on the performance of integral bridges subjected to uniform temperature variations. Using the pushover analyses results, design guidelines are developed to enhance and determine the maximum length limits for integral bridges built on clay. It is recommended that the maximum length of concrete integral bridges be limited to 210 m (689 ft) in cold climates and 260 m (853 ft) in moderate climates and that of steel integral bridges be limited to 120 m (394 ft) in cold climates and 180 m (590 ft) in moderate climates

Maximum length of integral bridges supported on steel H-piles driven in sand

This paper presents design recommendations for the maximum length of integral bridges built on sand. The maximum length limits for integral bridges is determined as a function of the ability of steel H-piles supporting the abutments to sustain thermal-induced cyclic lateral displacements and the flexural capacity of the abutment. First, steel H-pile sections that are capable of sustaining large inelastic deformations under monotonic loading are determined. Then, a low-cycle fatigue damage model is employed to determine the maximum cyclic deformations that such piles can sustain. Next, the nonlinear behavior of the piles and soil-bridge interaction effects are implemented in nonlinear structural models of two typical integral bridges. Static pushover analyses of these bridges are conducted to study the effect of various geometric, structural and geotechnical parameters on the performance of integral bridges subjected to uniform temperature variations. Using the pushover analyses results, design guidelines are developed to enhance and determine the maximum length of integral bridges. It is recommended that the maximum lengths of concrete integral bridges be Limited to 190 m in cold climates and 240 m in moderate climates and that of steel integral bridges are limited to 100 m in cold climates and 160 m in moderate climates

Liver cancer understaging in liver transplantation in the current era of radiologic imaging and newer generation locoregional therapies

Background: Discordance in hepatocellular carcinoma (HCC) staging between pre-transplant imaging and explant pathology is associated with an increased risk of recurrence and death. Our aim was to evaluate variables that predicted concordance/discordance in the era of new generation locoregional therapies (LRT) and improved radiologic technology in diagnosis. Methods: A single-center retrospective study was performed on patients who received a liver transplant for HCC between 2008-2019. Pre- and post-LT variables, including type of LRT, downstaging (DS), transplant time period, and radiologic response to LRT, were analyzed for concordance/discordance. Kaplan-Meier analysis was used to assess post-LT survival. Results: Of 146 patients transplanted within Milan Criteria (MC), discordance rates (understaged) were 45%. Discordance was associated with ≥ 3 HCC lesions at diagnosis but not newer generation LRT (transarterial radioembolization/ stereotactic body radiation therapy), traditional LRT or combination. No differences in discordance were seen between transplant periods (2008-2013 vs. 2014-2019), but those within MC in the earlier period had higher concordance rates. A trend was observed between DS and discordance. Conclusion: HCC stage discordance remains common and poorly predictable. Discordance was associated with three or more HCC lesions at the time of diagnosis. Patients within MC transplanted between 2008-2013 was associated with concordance, while a trend was noted between DS and discordance. No other pre- or post- LT variables predicted discordance/ concordance. Discordance was associated with decreased survival

Gut Microbial Signature of Hepatocellular Cancer in Men With Cirrhosis.

The gut microbiome is altered in cirrhosis. Recent evidence has suggested a key role for the gut microbiota in the progression of cirrhosis and the development of hepatocellular carcinoma (HCC). We studied the differences in the microbial composition in patients with cirrhosis with prior and future HCC in the context of other complications (eg, infections, hepatic encephalopathy). The following 2 cohorts were recruited prospectively: the prior HCC cohort, in which outpatients with HCC within 2 years were age-matched, sex-matched, and Model for End-Stage Liver Disease (MELD) score-matched with those without HCC; and the future HCC cohort, in which patients were followed for 2 years and divided into future HCC versus no HCC after age, sex, and MELD-score matching and other complications were also recorded. Microbiota composition and predicted function were analyzed with ribosomal RNA sequencing and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PiCRUST)and compared between (1) prior HCC versus none and (2) future HCC versus none, and in the future cohort, comparisons were also made between those patients who developed (1) HCC only versus without complications, (2) HCC only versus non-HCC complications only, and (3) HCC + other complications versus non-HCC complications only. A total of 142 men (76 total in the prior cohort [38 with/38 without HCC] and 66 total in the future cohort [33 with/33 without future HCC]) were included. The groups had similar etiology, lactulose/rifaximin/proton pump inhibitor use, diabetes mellitus, and non-HCC complications. Microbial diversity was similar between prior HCC/not or future HCC/not. On DESeq2 higher Clostridium sensu stricto and Anaerotruncus were significantly associated with protection from HCC, whereas the reverse was seen with Raoultella and Haemophilus regardless of prior/future HCC comparisons. Functions focused on urea cycle, bioenergetics, tryptophan, and toluene metabolism were different between the groups. Rothia was specific for other complications. Despite age, sex, and MELD-score matching and accounting for other complications, gut microbiota composition and the predicted function are different in men with cirrhosis with and without prior HCC and can be extended toward future HCC development

A Twitter discourse analysis of negative feelings and stigma related to NAFLD, NASH and obesity

International audienceBackground: People with non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are stigmatized, partly since 'non-alcoholic' is in the name, but also because of obesity, which is a common condition in this group. Stigma is pervasive in social media and can contribute to poorer health outcomes. We examine how stigma and negative feelings concerning NAFLD/NASH and obesity manifest on Twitter. Methods: Using a self-developed search terms index, we collected NAFLD/NASH tweets from May to October 2019 (Phase I). Because stigmatizing NAFLD/NASH tweets were limited, Phase II focused on obesity (November-December 2019). Via sentiment analysis, >5000 tweets were annotated as positive, neutral or negative and used to train machine learning-based Natural Language Processing software, applied to 193 747 randomly sampled tweets. All tweets collected were analysed. Results: In Phase I, 16 835 tweets for NAFLD and 2376 for NASH were retrieved. Of the annotated NAFLD/NASH tweets, 97/1130 (8.6%) and 63/535 (11.8%), respectively, related to obesity and 13/1130 (1.2%) and 5/535 (0.9%), to stigma; they primarily focused on scientific discourse and unverified information. Of the 193 747 non-annotated obesity tweets (Phase II), the algorithm classified 40.0% as related to obesity, of which 85.2% were negative, 1.0% positive and 13.7% neutral. Conclusions: NAFLD/NASH tweets mostly indicated an unmet information need and showed no clear signs of stigma. However, the negative content of obesity tweets was recurrent. As obesity-related stigma is associated with reduced care engagement and lifestyle modification, the main NAFLD/NASH treatment, stigma-reducing interventions in social media should be included in the liver health agenda