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Digital elevation models (DEMs) are fundamental data models used for susceptibility assessment of landslides. Due to landscape change and reshaping processes, a DEM can show obvious temporal variation and has a significant influence on assessment results. To explore the impact of DEM temporal variation on hazard susceptibility, the southern area of Sichuan province in China is selected as a study area. Multitemporal DEM data spanning over 17 years are collected and the topographic variation of the landscape in this area is investigated. Multitemporal susceptibility maps of landslides are subsequently generated using the widely accepted logistic regression model (LRM). A positive correlation between the topographic variation and landslide susceptibility that was supported by previous studies is quantitatively verified. The ratio of the number of landslides to the susceptibility level areas (RNA) in which the hazards occur is introduced. The RNA demonstrates a general decrease in the susceptibility level from 2000 to 2009, while the ratio of the decreased level is more than fifteen times greater than that of the ratio of the increased level. The impact of the multitemporal DEM on susceptibility mapping is demonstrated to be significant. As such, susceptibility assessments should use DEM data at the time of study.

Evolutionary trajectories and related control factors of the Fortore River (southern Italy) are analyzed over a 150-year period as to assess channel modifications. A multitemporal GIS analysis of topographic maps and aerial photographs together with topographic and geomorphological field surveys were performed. Attention was focused on the impact caused by human disturbance, above all the presence of the Occhito dam at only 40 km upstream of the Fortore mouth (central Adriatic coast). Results show that channel adjustments occurred in three distinct phases and were primarily driven by human disturbance that diversely affected reaches located upstream and downstream of the dam. From the last decades of the nineteenth century to the 1950s (phase 1), channel widening prevailed along upstream reaches whilst narrowing along downstream reaches. Major channel adjustments occurred from the 1950s until the end of the 1990s (phase 2), especially channel narrowing of up to 81% in upstream reaches and 98% in downstream reaches. Narrowing was accompanied by channel-bed lowering of 1 to 5 m and by pattern changes in prevalence from multithread to largely prevailing single-thread channel configurations. In-channel mining, channel works, and hydraulic interventions are considered key driving factors of observed channel adjustments. The closure of the Occhito dam in 1966 had significant and permanent effects on downstream reaches through overall discharge regulation and permanent sediment trapping as also proved by the progressive retreat of the Fortore river mouth area. From 2000 to 2015 (phase 3), a substantial trend inversion was observed with overall channel widening and partial aggradation of upstream reaches and total stabilization of downstream reaches. As highlighted by an integrated multitemporal analysis of recent channel changes and flood events, the latter have played an important role in channel recovery of upstream reaches. Comparison between the Fortore River and other rivers in southern Italy has allowed us to ascertain that the reconstructed evolutionary trajectories are quite similar and that control factors are essentially the same. In particular, it confirms the role of major hydraulic structures as to the amount of channel adjustments of downstream reaches and the ensuing scarce to nil potential to channel recovery of regulated reaches.

The identification of groundwater chemical characteristics and the controlling factors is of major concern in water environment studies. In this study, we identified the groundwater chemical characteristics, evolution laws and main control factors in a region severely affected by human activities using hydrochemical and multivariate statistical techniques. The results showed that the concentrations of NO3&minus, and TH were the primary pollution factors in the region with intensive human activity because of high concentration and over the standard rates. The major types of groundwater chemistry were HCO3&middot, SO4&ndash, Ca and HCO3&middot, Ca&middot, Mg. The sulfate-type water was as high as 75.0%, 69.2% and 41.2% in the three hydrogeological units. In addition, there were Cl-type and Na-type waters, indicating that the groundwater in this area has been significantly affected by human activities. A principal component analysis (PCA) indicated that the three factors affecting groundwater hydrochemistry in the study area are domestic sewage and fertilizer, water&ndash, rock interactions and industrial wastewater. Therefore, we suggest that the government and water environment management departments should prevent the discharge of domestic and industrial wastewater without standardized treatment first in order to effectively prevent the further deterioration of groundwater quality in this area.

Some major rivers in southern Italy (Trigno, Biferno, Fortore and Volturno), as most of Italy's rivers, have suffered significant channel changes during the last 60 years. Channel adjustments mainly consisted in channel narrowing and bed lowering coupled with pattern changes. Over the last 10-15 years, these rivers have undergone some important modifications in their evolutionary trends. More specifically, the Trigno River and the reaches of the Fortore River located upstream the Occhito dam are interested by moderate channel recovery, while the Volturno and Biferno rivers and the Fortore reaches located downstream the dam are affected by slight channel recovery or no significant changes in morphology. Key driving factors of these recent evolutionary trends seem to be the occurrence of major flood events and the degree of channel mobility that is conditioned by channel works and riparian woody vegetation.

Large landslides (volume greater than or equal to 10 6 m 3 ) usually have disastrous consequences and clearly influence the evolution of the local landscape. In this study, a detailed investigation of large landslides, across 20 towns over an area of 5000 km 2 , was carried out on the northeastern margin of the Bayan Har Block, at the eastern margin of the Tibetan Plateau, China. The results show that there are 129 large landslides in this area. Among them, 79 landslides have volumes within 10 6 –10 7 m 3 , 52 landslides have volumes within 10 7 –10 8 m 3 and 2 landslides have volumes larger than 10 8 m 3 . Most of these landslides are distributed along rivers, and more than 32% are densely concentrated in three small regions. The landslides mainly occur in high slopes and exhibit obvious sturzstrom characteristics. Analysis of the factors controlling landslide occurrence shows that elevation, slope angle, slope aspect, lithology, faults and rivers (valley) clearly influence landslide occurrence, while rainfall has no obvious influence. Earthquakes are considered an important trigger of and contributor to landslide occurrence.