Rainfall Episodes Research Articles

Measuring the Impact of Insurance on Recovery after Extreme Weather Events Using Nightlights

Abstract Climate change is predicted to make extreme weather events worse and more frequent in many places around the world. In New Zealand, the Earthquake Commission (EQC) was created to provide insurance for earthquakes. In some circumstances, however, homeowners affected by extreme weather events can also make claims to the EQC – for landslip, storm or flood events. In this paper, we explore the impact of this public natural hazard insurance on recovery from weather-related events. We do this by using a proxy for short-term economic recovery: satellite imagery of average monthly night-time radiance. Linking these night-time light data to precipitation data records, we compare areas which experienced damage from extreme rainfall episodes to those that suffered no damage even though they experienced extreme rainfall. Using data from three recent intense storms, we find that areas that experienced property damage, and were paid in a timely manner by EQC, did not fare any worse than areas that suffered no property damage but were exposed to these extreme precipitation events. This finding suggests that EQC insurance is serving its stated purpose by protecting claimants from the adverse impact of extreme weather events.

Dynamic Pluvial Flash Flooding Hazard Forecast Using Weather Radar Data

Pluvial flash floods are among the most dangerous weather-triggered disasters, usually affecting watersheds smaller than 100 km2, with a short time to peak discharge (from a few minutes to a few hours) after causative rainfall. Several warning systems in the world try to use this time lag to predict the location, extent, intensity, and time of flash flooding. They are based on numerical hydrological models processing data collected by on-ground monitoring networks, weather radars, and precipitation nowcasting. However, there may be areas covered by weather radar data, in which the network of ground-based precipitation stations is not sufficiently developed or does not even exist (e.g., in an area covered by portable weather radar). We developed a method usable for designing an early warning system based on a different philosophy for such a situation. This method uses weather radar data as a 2D signal carrying information on the current precipitation distribution over the monitored area, and data on the watershed and drainage network in the area. The method transforms (concentrates) the 2D signal on precipitation distribution into a 1D signal carrying information on potential runoff distribution along the drainage network. For sections of watercourses where a significant increase in potential runoff can be expected (i.e., a significant increase of the 1D signal strength is detected), a warning against imminent flash floods can be possibly issued. The whole curve of the potential runoff development is not essential for issuing the alarm, but only the significant leading edge of the 1D signal is important. The advantage of this procedure is that results are obtained quickly and independent of any on-ground monitoring system; the disadvantage is that it does not provide the exact time of the onset of a flash flooding or its extent and intensity. The generated alert only warns that there is a higher flash flooding hazard in a specific section of the watercourse in the coming hours. The forecast is presented as a dynamic map of the flash flooding hazard distribution along the segments of watercourses. Relaying this hazard to segments of watercourses permits a substantial reduction in false alarms issued to not-endangered municipalities, which lie in safe areas far away from the watercourses. The method was tested at the local level (pluvial flash floods in two small regions of the Czech Republic) and the national level for rainfall episodes covering large areas in the Czech Republic. The conclusion was that the method is applicable at both levels. The results were compared mainly with data related to the Fire and Rescue Service interventions during floods. Finally, the increase in the reliability of hazard prediction using the information on soil saturation is demonstrated. The method is applicable in any region covered by a weather radar (e.g., a portable one), even if there are undeveloped networks of rain and hydrometric gauge stations. Further improvement could be achieved by processing more extended time series and using computational intelligence methods for classifying the degree of flash flooding hazard on individual sections of the watercourse network.

The Results of Applying Different Methodologies to 10 Years of Quantitative Precipitation Estimation in Catalonia Using Weather Radar

The single polarization C-Band weather radar network of the Meteorological Service of Catalonia covers the entire region (32,000 km2), which allows it to apply a series of corrections that improve preliminary estimations of the rainfall field (hourly and daily). In addition, an automatic re-processing using automatic weather stations helps to incorporate ground-based information. The last process of the quantitative precipitation estimation (QPE) is running the end-product again eight days later, when the data have been reviewed and corrected in the case of detecting anomalies in the radar or gauge data. These corrections are applied operationally, with the fields generated and stored automatically. The QPE fields are generated in the GeoTIFF format, allowing easy use with multiple applications and simplifying processes such as quality control. In this way, the analysis of a 10 year period of GeoTIFF QPE daily data compared with ground rainfall values is introduced. The results help to understand different points regarding the functioning of the network such as the dependance on the type of precipitation and the seasonality. In addition, the description of a heavy rainfall episode (22 October 2019) shows the variations and improvements in the different products. The main conclusions refer to how using GeoTIFF combined with point data (rain gauges), it is possible to ensure simple but effective quality control of an operational radar network.

Role of PBL and Microphysical Parameterizations During WRF Simulated Monsoonal Heavy Rainfall Episodes Over Mumbai

Role of PBL and Microphysical Parameterizations During WRF Simulated Monsoonal Heavy Rainfall Episodes Over Mumbai

Analysis of meteorological parameters triggering rainfall-induced landslide: a review of 70 years in Valtellina

Abstract. This paper presents an extended reanalysis of the rainfall-induced geo-hydrological events that have occurred in the last 70 years in the alpine area of the Lombardy region, Italy. The work is focused on the description of the major meteorological triggering factors that have caused diffuse episodes of shallow landslides and debris flow. The aim of this reanalysis was to try to evaluate their magnitude quantitatively. The triggering factors were studied following two approaches. The first one started from the conventional analysis of the rainfall intensity (I) and duration (D) considering local rain gauge data and applying the I–D threshold methodology integrated with an estimation of the events' return period. We then extended this analysis and proposed a new index for the magnitude assessment (magnitude index, MI) based on frequency–magnitude theory. The MI was defined considering both the return period and the spatial extent of each rainfall episode. The second approach is based on a regional-scale analysis of meteorological triggers. In particular, the strength of the extratropical cyclone (EC) structure associated with the precipitation events was assessed through the sea level pressure tendency (SLPT) meteorological index. The latter has been estimated from the Norwegian cyclone model (NCM) theory. Both indexes have shown an agreement in ranking the event's magnitude (R2=0.88), giving a similar interpretation of the severity that was also found to be in accordance with the information reported in historical databases. This back analysis of 70 years in Valtellina identifies the MI and the SLPT as good magnitude indicators of the event, confirming that a strong cause–effect relationship exists among the EC intensity and the local rainfall recorded on the ground. In respect of the conventional I–D threshold methodology, which is limited to a binary estimate of the likelihood of landslide occurrence, the evaluation of the MI and the SLPT indexes allows quantifying the magnitude of a rainfall episode capable of generating severe geo-hydrological hazards.

Classifying compound coastal storm and heavy rainfall events in the north-western Spanish Mediterranean

Abstract. The north-west (NW) Mediterranean coastal zone is a populous and well-developed area in which the impact of natural hazards like flash floods and coastal storms can result in frequent and significant damages. Although the occurrence and impacts of such hazards have been widely covered, few studies have considered their combined impact on the region, which would result in more damage. Within this context, this study analyses the occurrence and characteristics of compound extreme events of heavy rainfall episodes (as a proxy for flash floods) and coastal storms (using the maximum significant wave height) along the Catalan coast as a paradigm of the NW Mediterranean. Two different types of events are considered: multivariate, in which the two hazards occur at the same location, and spatially compounding, in which they occur within the same limited time window, and their impacts accumulate at distinct and separate locations. The analysis is regionally performed along a coastline extension of about 600 km by considering seven coastal sectors and their corresponding river catchment basins. Once the compound events are analysed, the synoptic atmospheric pressure fields are analysed to determine the prevailing weather conditions that generated them. Finally, a Bayesian network is used to fully characterize these events over the territory. The obtained results show that the NW Mediterranean, represented by the Catalan coast, has a high probability of experiencing compound extreme events. Despite the relatively small size of the study area, there are significant variations in the event characteristics along the territory, with the most frequent type being spatially compound, except in the northernmost sectors where multivariate events dominate. These northern sectors also present the highest correlation in the intensity of both hazards. Three representative synoptic situations have been identified as dominant for the occurrence of these events, with different relative importance levels of the compounding drivers (rainfall and waves) and different distributions of impacts across coastal basins. Overall, results obtained from specific events indicated that heavy rainfall is related to the most significant impacts despite having a larger spatial reach.

Post landslide Investigation of Shallow Landslide: A case study from the Southern Western Ghats, India

Many mountainous regions in the tropics witnessed extreme orographic rainfall episodes in the recent past. The portions of the Western Ghats that fall on the Kerala state also experienced extreme climatic conditions in floods and landslides in 2018 and 2019. More than a thousand small and large landslides occurred during that period in the State's Western Ghats regions. The landslide at Kavalapara in the Malappuram district in 2019 is at the top in the state regarding the causalities, financial loss, and spatial spread. This study is based on a comprehensive field investigation at the Kavalappara landslide site and we developed a detailed landslide susceptibility map with the local community's involvement. The massive landslide covers 0.34 Sq.km (34 hectares) triggered by the unprecedented monsoon rainfall coupled with unsustainable agricultural practices. The area's risk zones have been identified and spatially mapped with the help of a detailed field investigation using Geographic Information System (GIS) and remote sensing technology. The output of the study can be used for the policymakers and planners working in landslide-prone areas.

Identifying Storm Hotspots and the Most Unsettled Areas in Barcelona by Analysing Significant Rainfall Episodes from 2013 to 2018

Urban floods repeatedly threaten Barcelona, damaging the city infrastructure and endangering the safety of the population. The urban planning of the city, the socioeconomic distribution, its topography, and the characteristics of precipitation systems translate into these flood events having a heterogeneous effect across the city. It means that the coping capacity has a strong dependence on local factors that must be considered when management plans are developed by the municipality. This work aims to contribute to the better knowledge of precipitation structures associated with heavy rainfall events and floods in Barcelona based on radar data and an urban rain gauge network. Radar data have been provided by the Meteorological Service of Catalonia (SMC), while precipitation data, impact data, and early warnings, have been provided by Barcelona Cicle de l’Aigua S.A. (BCASA), for the period 2013–2018. A new radar-based methodology has been developed to identify convective rainfall structures from radar reflectivity volumes (CAPPI and TOP products) to make the analysis easier. The high computing speed of the procedure allows efficient analysis of a large set of convective cells without scarifying temporal resolution of radar data. Both rainfall fields (radar and rain gauge, respectively) have been compared. Then through the identified rainfall convective structures, thunderstorm hotspots have been identified. Considering an alert indicator from BCASA and the reported incidents, episodes with the highest impact have been analysed in depth. Results show 207 significant rainfall episodes in the ROI for the six years, which are mainly concentrated between September and November. The fact that significant episodes are usually produced by highly convective rain corroborates the advantage of using radar images as a tool to detect any maxima even when no rain gauge is there. In 64 of the episodes, the level of pre-alert was achieved with a maximum frequency between August and September. The proposed algorithm shows more than 8000 centroids of convective cells from 189 cases. Whilst maximum surface reflectivity over 45 dBZ is more prone to occur near the coastline, the centroids of storm cells tend to concentrate more inland. The final objective is to improve the actions taken by the organisation responsible for managing urban floods, which have seen Barcelona recognised as a model city for flood resilience by the United Nations.

Fire in Semi-Arid Shrublands and Woodlands: Spatial and Temporal Patterns in an Australian Landscape

Semi-arid landscapes are of interest to fire ecologists because they are generally located in the climatic transition zone between arid lands (where fires tend to be rare due to lack of fuel, but are enhanced following large rainfall episodes) and more mesic regions (where fire activity tends to be enhanced following severe rainfall deficits). Here we report on the characteristics of the contemporary fire regimes operating in a semi-arid region of inland south-western Australia with rainfall averaging around 300 mm per annum. To characterize fire regimes, we analyzed a geodatabase of fire scars (1960–2018) to derive fire preferences for each major vegetation type and fire episode and used known fire intervals to model fire hazard over time and calculate typical fire frequencies. We also used super epoch analysis and correlations to explore relationships between annual fire extent and rainfall received before the fire. We found fires strongly favored sandplain shrublands, and these tended to experience hot crown fires once every 100 years (median fire interval), with fire hazard increasing linearly over time. In contrast, fires were rare in eucalypt woodland and other vegetation types, with a median interval of 870 years and broadly consistent fire hazard over time. Annual fire extent was most strongly linked with high rainfall in the year prior to fire, and this was particularly so for eucalypt woodlands. Large-scale fires in shrublands tended to favor areas burnt in previous large fires, whereas in woodlands they favored edges. In conclusion, we found divergent fire regimes across the major vegetation types of the region. Sandplain shrublands were similar to Mediterranean shrublands in that they experienced intense stand-replacing wildfires which recovered vigorously although slowly, meaning burnt shrublands did not experience fires again for at least 25 and 100 years on average. In contrast, eucalypt woodlands were fire sensitive (trees readily killed by fire) and experienced fires mostly around the edges, spreading into core areas only after large rainfall events elevated fuel levels. Overall, both vegetation types subscribed to typical arid-zone fire regimes where elevated rainfall, and not drought, promoted fires, although the role of fuel accumulation over time was more important in the shrublands.

Formulated Ampelomyces quisqualis CPA-9 applied on zucchini leaves: influence of abiotic factors and powdery mildew mycoparasitization

Even though the potential of the fungus Ampelomyces quisqualis against powdery mildew has been largely demonstrated, the efficacy of the commercialised product AQ10 Biofungicide is not consistent. Recently, a solid formulation of A. quisqualis strain CPA-9 that included biodegradable coatings on its composition was developed to overcome the major shortcomings of the biocontrol agents applied under practical conditions. The aims of the present study were to show the compatibility of CPA-9 with different phytosanitary products, and to confirm the potential of this novel formulation in different approaches: (i) under different conditions of temperature (20 and 30 °C) and relative humidity (40, 60 and 85%) on different surfaces (glass and zucchini leaves), (ii) after different rainfall episodes, and (iii) verifying Podosphaera xanthii parasitization by dried conidia of CPA-9. It was demonstrated that CPA-9 was compatible with several phytosanitary products, so it might be included in integrated management programmes. Moreover, the solid formulation showed better resilience than non-formulated conidia, both applied on a glass surface and on zucchini leaves. Adherence of both treatments on zucchini leaves did not show significant differences after simulated rainfall and all tested concentrations of dried conidia were able to produce pycnidia in P. xanthii hyphae. Therefore, the developed fluidised-bed spray-dried formulation of A. quisqualis CPA-9 together with coatings compounds has all the makings of becoming a biocontrol product, although their efficacy under practical conditions should be assessed.

Characteristics of extreme rainfall and rainbands evolution of Super Typhoon Lekima (2019) during its landfall

As one of the most devastating tropical cyclones over the western North Pacific Ocean, Super Typhoon Lekima (2019) has caused a wide range of heavy rainfall in China. Based on the CMA Multi-source merged Precipitation Analysis System (CMPAS)-hourly data set, both the temporal and spatial distribution of extreme rainfall is analyzed. It is found that the heavy rainfall associated with Lekima includes three main episodes with peaks at 3, 14 and 24 h after landfall, respectively. The first two rainfall episodes are related to the symmetric outburst of the inner rainband and the persistence of outer rainband. The third rainfall episode is caused by the influence of cold, dry air from higher latitudes and the peripheral circulation of the warm moist tropical storm. The averaged rainrate of inner rainbands underwent an obvious outburst within 6 h after landfall. The asymmetric component of the inner rainbands experienced a transport from North (West) quadrant to East (South) quadrant after landfall which was related to the storm motion other than the Vertical Wind Shear (VWS). Meanwhile the outer rainband in the vicinity of three times of the Radius of Maximum Wind (RMW) was active over a 12-h period since the decay of the inner rainband. The asymmetric component of the outer rainband experienced two significant cyclonical migrations in the northern semicircle.

Climatological intraseasonal oscillation in the middle–upper troposphere and its effect on the northward migration of the East Asian westerly jet and rain belt over eastern China

AbstractUsing daily atmospheric circulation data for 1981–2010, we identify the climatological intraseasonal oscillation (CISO) in the mid–upper troposphere and reveal its critical role in anchoring the Meiyu season to the period from mid‐June to mid‐July and the rainfall episode of northeastern China to begin in late July. Wavelet analysis shows a significant 20–90‐day period in the climatological 200‐ and 500‐hPa zonal winds during boreal summer, indicating the existence of the zonal wind CISO in the mid–upper troposphere. The leading mode of zonal wind CISO features a dipole pattern along the coast of East Asia controlled by convection over the southeastern China–western North Pacific (SC–WNP). In mid‐June, suppressed convection over the SC–WNP induces the negative phase of intraseasonal Pacific–Japan pattern, leading to the strong anticyclone with a poleward tilt with height to dominate over the WNP. Consequently, more moisture are transported to the middle and lower reaches of the Yangtze River Valley (YRV), and the mid‐tropospheric (upper‐tropospheric) East Asian westerly jet (EAWJ) is shifted north of 32°N (36°N), which further increases the YRV rainfall through enhancing warm advection and upper‐tropospheric divergence, thus facilitating the initiation of Meiyu season. In mid‐July, active convection occupies the SC–WNP instead, with the reversed circulation pattern terminating the Meiyu season. In late July, active convection shifts from the equator to the tropical western Pacific, leading to the second mode of zonal wind CISO, which is characterized by a quasi‐barotropic Mongolian anticyclone in the mid–upper troposphere. The upper‐tropospheric EAWJ is further shifted to 45°N, displacing the induced upper‐tropospheric divergence northward, thus initiating the rainfall episode of northeastern China.

Dynamical evolution of vertical profile of rain structures observed using ground-based radar over a tropical station

In this study, measurements of vertical profiles of rain parameters have been made using vertically pointing micro rain radar (VPMRR) at Akure (7.30° N, 5.13° E). Rain parameter data collected over seven-month rainfall episodes during the intense rainy season (April to October) have been analyzed for a dynamical evolutionary trend over the site. Nearly all the episodes observed followed a similar pattern, hence, a single continuous rainfall episode occurring between 20:45:00 h and 21:14:00 h Greenwich Meridian Time (GMT) local time on 6th August 2018 is presented in this report. The results show no significant changes to the rain parameters (such as rain rate and liquid water content) nor contributed to the raindrop size distribution, based on average fall velocity of 6.55 m s−1 and rain rates within 1.3 and 2.6 mm h−1. This is to enable a stable fall for the dominant drops during the period. Further, the results revealed the transformation and collision of smaller drops to enhance a stable fall of larger drops during the rain event. The information from the study will be useful for radar meteorologists and microwave engineers in their designs.

Rainfall Influences Occurrence of Pharmaceutical and Personal Care Products in Landfill Leachates: Evidence from Seasonal Variations and Extreme Rainfall Episodes.

Unused or expired pharmaceutical and personal care products (PPCPs) are usually discharged into municipal solid wastes, then travel to landfills, and eventually percolate into leachates. However, knowledge of their occurrence and temporal dynamics in leachates is limited, making landfill leachate an underappreciated emission source of PPCPs. Furthermore, the differences in PPCP variations in landfill leachates emphasize the necessity for identifying the influencing factors and elucidating the mechanisms for PPCP fluctuations. In this study, successive monthly monitoring of PPCPs in leachates throughout an entire year was performed to determine their seasonal variations and identify their influencing factors. Furthermore, five pairs of additional sampling campaigns were conducted before and after rainfall events during wet seasons to elucidate the influencing mechanisms. The results showed that there was a distinct seasonal variation in PPCPs in landfill leachates-elevated levels during the wet period (from April to September, with a mean concentration of 17.0 μg/L for total monitored PPCPs)-when compared to other months (mean concentration of 3.8 μg/L). Rainfall played a considerable role in mediating PPCP concentrations in leachates. The PPCP responses to five rainfall episodes further verified the influence of rainfall and demonstrated that the tendency to PPCP concentration increase was related to rainfall precipitation. Torrential rain events (i.e., 24 h cumulative precipitation of 50-99.9 mm) led to the most significant increases in PPCP concentrations in landfill leachates. In addition, the hydrophilicity of PPCPs contributed to the different fluctuations during the 1 year investigation and different responses to rainfall. To the best of our knowledge, this study provides the first direct evidence supporting the influence of rainfall on PPCPs in landfill leachates, which can help better understand the occurrence and behavior of emerging contaminants in this underappreciated emission source.

IMDAA: High Resolution Satellite-era Reanalysis for the Indian Monsoon Region

AbstractA high resolution regional reanalysis of the Indian Monsoon Data Assimilation and Analysis (IMDAA) project is made available to researchers for deeper understanding of the Indian monsoon and its variability. This 12 km resolution reanalysis covering the satellite-era from 1979 to 2018 using 4D-Var data assimilation method and the UK Met Unified Model is presently the highest resolution atmospheric reanalysis carried out for the Indian monsoon region. Conventional and satellite observations from different sources are used, including Indian surface and upper air observations, of which some were not used in any previous reanalyses. Various aspects of this reanalysis, like quality control and bias correction of observations, data assimilation system, land surface analysis, and verification of reanalysis products, are presented in this paper. Representation of important weather phenomena of each season over India in the IMDAA reanalysis verifies reasonably well against India Meteorological Department (IMD) observations and compares closely with ERA5. Salient features of the Indian summer monsoon are found to be well represented in the IMDAA reanalysis. Characteristics of major semi-permanent summer monsoon features (e.g., Low-level Jet and Tropical Easterly Jet) in IMDAA reanalysis are consistent with ERA5. The IMDAA reanalysis has captured the mean, inter-annual, and intra-seasonal variability of summer monsoon rainfall fairly well. IMDAA produces a slightly cooler winter and a hotter summer than the observations; the reverse for ERA5. IMDAA captured the fine-scale features associated with a notable heavy rainfall episode over complex terrain. In this study, the fine grid spacing nature of IMDAA is compromised due to the lack of comparable resolution observations for verification.

Convective precipitation trends in the Spanish Mediterranean region

This paper aims to analyse the distribution and temporal evolution of convective precipitation in the Mediterranean region of Spain. To accomplish this goal, we used 148 sets of 5-min rainfall rate data from the 1989–2015 period. The selected regions were the Júcar Hydrographic Confederation (CHJ) and the Internal Basins of Catalonia (CIC), which cover most of the autonomous communities of Catalonia and the Valencian Community (east Spain). The average 5-min intensity threshold of 35 mm/h and the β parameter, defined as the ratio between convective precipitation versus total precipitation in any period, were used to characterise convective precipitation. Convective episodes were categorised as “very convective”, “moderately convective”, and “slightly convective” based on the β value. After quality control, the series of 129 stations were clustered into homogeneous precipitation zones that also include β as one of the variables of characterisation. The results show that convective precipitation can contribute to total annual precipitation by up to 16% on average, but it is generated by a very small percentage of convective events (between 3% and 6% across all the stations) in comparison with the total number of rainfall episodes. In this sense, moderately convective events are the most common, with a predominantly unimodal monthly distribution of β, with summer the most convective season. Trends show a significant increase in precipitation, convective precipitation, and convective episodes in the CHJ. On the other hand, a positive trend of convective events is predominant in the CIC region, despite an overall precipitation decrease in the analysed period. These results are relevant given that extreme daily rainfall does not show a positive or significant trend, and they are in line with the impact of climate change on increased atmospheric instability and water vapour in the atmosphere. They highlight the need to work with sub-daily precipitation series in the case of the Mediterranean, which is mainly affected by flash floods.

Monitoring of Rainfall and Soil Moisture at the Rebaixader Catchment (Central Pyrenees)

ABSTRACT The instrumental monitoring of torrential catchments is a fundamental research task that provides necessary information to improve our understanding of the mechanisms of debris flows. While most monitoring sites include meteorological sensors and analyze the critical rainfall conditions, very few contain soil moisture measurements. In our monitoring site, the Rebaixader catchment, 11 debris flows and 24 debris floods were detected during the last 9 years. Herein, the initiation mechanisms of these torrential flows were analyzed, focusing on the critical rainfall conditions and the soil water dynamics. Comparing the temporal distribution of both rainfall episodes and torrential flows, the Kernel density plots showed maximum values for rainfalls at the beginning of June, while the peak for torrential flows is on July 20. Thus, the antecedent rainfall, and especially the soil moisture conditions, may influence the triggering of torrential flows. In a second step, a new updated rainfall threshold was proposed that included total rainfall duration and mean intensity. The analysis of soil moisture data was more complicated, and no clear trends were observed in the data set. Therefore, additional data have to be recorded in order to quantitatively analyze the role of soil moisture on the triggering of torrential flows and for the definition of thresholds. Some preliminary results show that the soil moisture at the beginning of a rainfall event affects the maximum increase of soil moisture, while a slight trend was visible comparing the initial soil moisture with the necessary rainfall amount to trigger a torrential flow.

Hydrological, geochemical and land use drivers of greenhouse gas dynamics in eleven sub-tropical streams

Greenhouse gas (GHG) emissions from freshwater streams are poorly quantified in sub-tropical climates, especially in the southern hemisphere where land use is rapidly changing. Here, we examined the distribution, potential drivers, and emissions of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) from eleven Australian freshwater streams with varying catchment land uses yet similar hydrology, geomorphology, and climate. These sub-tropical streams were a source of CO2 (74 ± 39 mmol m−2 day−1), CH4 (0.04 ± 0.06 mmol m−2 day−1), and N2O (4.01 ± 5.98 µmol m−2 day−1) to the atmosphere. CO2 accounted for ~ 97% of all CO2-equivalent emissions with CH4 (~ 1.5%) and N2O (~ 1.5%) playing a minor role. Episodic rainfall events drove changes in stream GHG due to the release of soil NOx (nitrate + nitrite) and dissolved organic carbon (DOC). Groundwater discharge as traced by radon (222Rn, a natural groundwater tracer) was not an apparent source of CO2 and CH4, but was a source of N2O in both agricultural and forest catchments. Land use played a subtle role on greenhouse gas dynamics. CO2 and CH4 increased with catchment forest cover during the wet period, while N2O and CH4 increased with agricultural catchment area during the dry period. Overall, this study showed how DOC and NOx, land use, and rainfall events interact to drive spatial and temporal dynamics of GHG emissions in sub-tropical streams using multiple linear regression modelling. Increasing intensive agricultural land use will likely decrease regional CO2 and CH4 emissions, but increase N2O.

Impact of extreme weather episodes on the Philippine banking sector – Evidence using branch-level supervisory data

There is growing recognition that natural disasters and severe weather-related events pose risks that can potentially and unintentionally affect the financial performance of the banking system. This study provides further indication that severe weather conditions have an impact on the financial performance of smaller banking units. The paper first constructs a regional quarterly rainfall damage index (RDI) based on data from weather stations across the country. A regional branch-level database from supervisory reports is then compiled based on 11,000 banking units from the Bangko Sentral’s (BSP) Branch Regional Information System (BRIS). Using the dynamic panel generalized method of moments (GMM), we find evidence of a deterioration in branch-level loan growth and loan quality as savings and time deposit liabilities contract and nonperforming loans surge following extreme rainfall events from 2014 to 2018. These are particularly evident in regions most vulnerable to severe rainfall episodes and to branches of universal and commercial banks as well as those of rural and cooperative banks. However, the overall negative impact on profitability seems to eventually taper off. These findings are robust across different specifications and alternative estimation methods such as fixed effects and panel vector autoregression estimations.

Using soil water isotopes to infer the influence of contrasting urban green space on ecohydrological partitioning

Abstract. In cities around the world, urban green spaces provide a range of benefits and ecosystem services. However, recent years have shown how prolonged warm and dry periods can affect urban water resources and lead to water stress in vegetation in urban green spaces, even in temperate regions. Consequently, quantitative knowledge about ecohydrological partitioning in different types of urban green space is crucial for balancing sustainable water needs in cities during future challenges of increasing urbanization and climate warming. Using isotopic tracers in precipitation and soil water, along with conventional hydrometric measurements in a plot-scale study in Berlin, Germany, we investigated water partitioning under different generic types of urban vegetation (grassland, shrub and trees). This allowed for the assessment of urban vegetation effects on evapotranspiration, subsurface flow paths and storage during a prolonged drought period with episodic rainfall. Despite higher soil evaporation losses under urban grassland, higher interception and transpiration likely contributed to slower turnover of soil water and older groundwater recharge under urban trees. Shrub vegetation seemed to be most resilient to prolonged drought periods, with lower evapotranspiration losses. Our results contribute to a better understanding of ecohydrological partitioning under mixed urban vegetation communities and an evidence base for better adaptive management of urban water and irrigation strategies to sustainably meet the water demands of urban green spaces in the future.