This research tested the value of regional groundwater level information to improve landslide predictions with empirical models based on the concept of threshold levels. In contrast to precipitation-based thresholds, the results indicated that relying on threshold models exclusively defined using hydrological variables such as groundwater levels can lead to improved landslide predictions due to their implicit consideration of long-term antecedent conditions until the day of landslide occurrence.

The density of rain gauge networks plays an important role in radar rainfall bias correction. In this work, we aimed to assess the extent to which daily rainfall observations from a dense network of citizen scientists improve the accuracy of hourly radar rainfall estimates in the Tubma Basin, Thailand. Results show that citizen rain gauges significantly enhance the performance of radar rainfall bias adjustment up to a range of about 40 km from the center of the citizen rain gauge network.

GPS drifters that float down rivers are important tools in studying rivers, but they can be expensive. Recently, both GPS receivers and cellular modems have become available at lower prices to tinkering scientists due to the rise of open hardware and the Arduino. We provide detailed instructions on how to build a low-power GPS drifter with local storage and a cellular model that we tested in a fieldwork in Myanmar. These instructions allow fellow geoscientists to recreate the device.

Knowing the isotopic composition of water vapor in the air is a difficult task. The estimation of δ¹⁸O and δ²H has to be done carefully, because it is accompanied by a high risk of methodological errors (if it is sampled) or wrong assumptions that can lead to incorrect values (if it is modeled). The aim of this work was to compare available sampling methods for water vapor in the air and estimate their isotopic composition, comparing the results against direct measurements of the sampled air.

The measurement of stable isotopes in water vapor has been improved with the use of laser technologies. Its direct application in the field depends on the availability of infrastructure or the budget of the project. For those cases when it is not possible, we provide an alternative method to sample the air for its later measurement. This method is based on the use of a low-cost polyethylene bag, getting stable measurements with a volume of 450 mL of air reducing the risk of sample deterioration.

In many river basins, the development of hydrological models is challenged by poor discharge data availability and quality. In contrast, water level data are more reliable, as these are direct measurements and are unprocessed. In this study, an alternative calibration method is presented using water-level time series and the Strickler–Manning formula instead of discharge. This is applied to a semi-distributed rainfall-runoff model for the semi-arid, poorly gauged Mara River basin in Kenya.

We investigate the influence of imprecise identification of triggering instants on landslide early warning thresholds by perturbing an error-free synthetic dataset. Combined impacts of uncertainty with respect to temporal discretization of data and criteria for singling out rainfall events are assessed as well. Results show that thresholds can be significantly affected by these uncertainty sources.

The vast majority of shallow landslides and debris flows are precipitation initiated and predicted using historical landslides plotted versus observed precipitation information. However, this approach has severe limitations. This is partly due to the fact that it is not precipitation that initiates a landslide or debris flow but rather the hydrological dynamics in the soil and slope. We propose to include hydrological information in the regional hydro-meteorological hazard assessment.

The effect of preferential flow on the stability of landslides is studied through numerical simulation of two types of rainfall events on a hypothetical hillslope. A model is developed that consists of two parts. The first part is a model for combined saturated/unsaturated subsurface flow and is used to compute the spatial and temporal water pressure response to rainfall. Preferential flow is simulated with a dual-permeability continuum model consisting of a matrix/preferential flow domain.