Rainfall Intensity Values Research Articles

Susceptibility to Translational Landslides in Ecuador Caused by Changes in Electrical Permittivity of Andepts Soils Using Software-Defined Radar for Detection

Landslides are widespread and global geological disasters, affecting millions of people and causing numerous deaths each year. Despite technological advances, it is still difficult to accurately prevent landslides. Due to its geography and climatic conditions, Ecuador has been significantly affected by landslides, and the city of Penipe remains one of the most affected. For this reason, a low-cost SDRadar system was designed to detect translational landslide risk levels by measuring the electrical permittivity of Andepts subtype soils. Controlled laboratory tests were performed with soil samples to relate permittivity values to landslide risk levels, and subsequently field tests were carried out in Penipe to determine the efficiency of the methodology. The results showed that moderate humidity is important for soil compaction, regardless of the degree of sloping. However, with permittivity values lower than 1.5 or higher than 20, the risk of landslides is very high on slopes greater than 45°. These results were compared with records of the serious landslides that occurred in June 2024 in Ecuador, in which rainfall intensity values similar to those obtained in this study were recorded, suggesting that this system can prevent future disasters.

Comparison of Climatology of Precipitation Diurnal Cycle in Kalimantan Deduced from Rain Gauge and IMERG Data

Abstract The diurnal cycle is repetitive pattern of changes in weather factors on land and oceans due to the Earth rotation. Kalimantan Island as the largest island in the Maritime Islands region has a complex rainfall pattern that is influenced by local factors and global circulation. The research was conducted to find out the climatological comparison of the diurnal cycle of rain in Kalimantan based on rain gauge data and Integrated Multi-SatellitE Retrievals for GPM Version 07 (IMERG V07) data for the period 2016 - 2022. Data validation using rain gauge data to validate and calibrate IMERG satellite data, improving the accuracy and reliability of satellite rainfall estimates. The diurnal cycle is evaluated through a Precipitation Amount (PA), Precipitation Frequency (PF), and Precipitation Intensity (PI) every hour. The results show that the maximum rainfall occurs in the afternoon and evening along the coast, and in the middle of the night and morning on the Kalimantan plains. Kalimantan has high rainfall intensity values at short rainfall durations, i.e. rain lasting less than 3 hours. This is expected to improve the quality of hydrometeorological disaster mitigation in Kalimantan.

Space–Time Characterization of Extreme Precipitation Indices for the Semiarid Region of Brazil

Various indices of climate variability and extremes are extensively employed to characterize potential effects of climate change. Particularly, the semiarid region of Brazil is influenced by adverse effects of these changes, especially in terms of precipitation. In this context, the main objective of the present study was to characterize the regional trends of extreme precipitation indices in the semiarid region of Brazil (SAB), using daily precipitation data from the IMERG V06 product, spanning the period from 1 January 2001 to 31 December 2020. Twelve extreme precipitation indices were considered, which were estimated annually, and their spatial and temporal trends were subsequently analyzed using the nonparametric Mann–Kendall test and Sen’s slope. The analysis revealed that the peripheral areas of the SAB, especially in the northwest and extreme south regions, exhibited higher intensity and frequency of extreme precipitation events compared to the central portion of the area. However, a negative trend in event intensity was noted in the north, while positive trends were identified in the south. The frequency of extreme events showed a predominance of negative trends across most of the region, with an increase in consecutive dry days particularly throughout the western SAB. The average total precipitation index was above 1000 mm in the north of the SAB, whereas in the central region, the precipitation averages were predominantly below 600 mm, with rainfall intensity values ranging between 6 and 10 mm/day. Over the span of 20 years, the region underwent an average of 40 consecutive dry days in certain localities. A negative trend was observed in most of the indices, indicating a reduction in precipitation intensity in future decades, with variations in some indices. The dry years observed towards the end of the analyzed period likely contributed to the observed negative trends in the majority of extreme precipitation indices. Such trends directly impact the intensity and frequency of extreme weather events in the SAB. The study is important for highlighting and considering the impacts of changes in precipitation extremes in the semiarid region of Brazil. Based on the obtained results, we advocate the implementation of public policies to address future challenges, such as incorporating adaptations in water resource management, sustainable agricultural practices, and planning for urban and rural areas.

A STUDY OF SUBSURFACE OUTFLOW OF PERMEABLE FRICTION COURSE PAVEMENT BASED ON FINITE ELEMENT ANALYSIS

Permeable friction course pavement is designed with high porosity so that water can infiltrate into its pores and drain out laterally through the side. This study observes the subsurface outflow of a permeable friction course pavement via the finite element analysis program SV Flux 2D. A series of analyses were conducted for the permeable friction course pavement with different slope and rainfall intensity values. The results showed that different slope values provided different results for the subsurface outflow. As the slope increased, the subsurface outflow of the permeable friction course pavement increased. It is noticed that the effect of slope on the subsurface outflow decreased when the slope increased from 6% to 8%. In addition, this study also found that as the time of rain events increased, the subsurface outflow pavement was reduced. The investigation of the effect of rainfall intensity on the subsurface outflow of the permeable friction course pavement showed that as the rainfall intensity increased, the subsurface outflow steadily increased. However, it is noted that at the higher rainfall intensity, the pavement became saturated faster and the overflow happened earlier. In the future, further studies focused on the drainage of permeable friction course pavement including subsurface and surface outflow should be carried out.

Adjustment of 1 min rain gauge time series using co-located drop size distribution and wind speed measurements

Abstract. A procedure to adjust rainfall intensity (RI) measurements to account for the wind-induced measurement bias of traditional catching-type gauges is proposed and demonstrated with an application to a suitable case study. The objective is to demonstrate that adjustment curves derived from numerical simulations and disdrometer measurements allow for a posteriori correction of rainfall time series based on the wind velocity measurements alone. To quantify the impact of wind on long-term records, 1 min RI measurements from a cylindrical tipping-bucket rain gauge installed at the Hong Kong Observatory are adjusted. Catch ratios derived from the instrument's aerodynamic behaviour under varying wind speed and drop size combinations are obtained by fitting computational fluid-dynamic simulation results already available in the literature. Co-located high-resolution wind speed measurements from a cup and vane sensor and drop size distribution measurements from an optical video disdrometer (the 2DVD or two-dimensional video disdrometer) are used to infer the collection efficiency of the gauge as a function of wind speed and RI alone and to adjust raw data from a 4-year dataset (2018–2021) of 1 min RI measurements. Due to the specific local climatology, where strong wind is often associated with intense precipitation, 80 % of the dataset adjustments are limited to 4 % of the observed RI values. This, however, results in a significant amount of available freshwater resources that would be missing from the calculated hydrological and water management budget of the region should the adjustments be neglected. This work raises the need to quantify the impact of the wind-induced bias at other sites where disdrometer data support a characterisation of the relationship between the drop size distribution and the measured RI. Depending on the local rain and wind climatology, the correction may account for a significant portion of the annual rainfall amount.

Rainfall infiltration and slope stability of alpine colluvial terraces subject to storms (NE Italy)

In the alpine environment, rainfall-induced shallow landslides can involve thin covers of colluvial soil (50–300 cm) on terraced belts that were formed as a result of fill-and-cut sedimentary processes that followed the deglaciation of the alpine valleys. Notably, research on shallow slope failures involving alpine terraces consisting of a near-flat upper ground surface (“tread”) and a moderately steep scarp (“riser”) is lacking in the literature. This paper describes the engineering geological characteristics and failure mechanisms of a large number of shallow landslides (soil slips or slide-debris flows) that were activated on alpine stratified colluvial terraces due to a rainstorm that hit the mountain area of the Friuli Venezia Giulia Region (NE Italy) on 21–22 June 1996. The paper reports data on the geomorphological and engineering geological characteristics of the soil slips acquired through extensive fieldwork and shows the outcomes of some two-dimensional seepage and slope stability analyses that were carried out in order to investigate the critical hydrological conditions and mechanisms that were responsible for the soil slip activation during and after rainfall. The soil slip activation can occur at two different stages during the infiltration process, based on the interacting water flows through the terrace tread and riser. The first critical stability condition is reached during the phases of greater precipitation intensity or at the end of the rainstorm because of the saturation of the top soil layer on the terrace riser and the subsequent formation of an ephemeral water table accompanied by a seepage sub-parallel to the slope face. The second critical condition is achieved some hours after the end of rainfall as a result of a tread-to-riser water outflow that is supplied by the water amount stored within the near-flat terrace tread during the peak rainfall stages (reservoir-like effect). This study also shows that a critical value of rainfall intensity of about 40–45 mm/h can cause the activation of soil slips in mountain basins characterised by a humid continental climate and by the occurrence of colluvial deposits with a high content of fine fraction. This critical value of rainfall intensity should be considered as a rainfall threshold for a basin-scale under geomorphological and geological conditions similar to those investigated in this paper.

Rainfall Intensity-Duration-Frequency Analysis in Turkey, with the Emphasis of Eastern Black Sea Basin

In this study, regional intensity-duration-frequency (IDF) curves for Turkey were developed using the available maximum rainfall intensity values for various durations (D=5, 15 and 30 minutes, and 1, 3, 6, 12 and 24 hours). Multi-nonlinear regression analysis was carried out by using nine kinds of IDF formulas, which were taken by using various IDF formulae in the literature and newly generated formulae. In order to test the reliability of the functions, two criteria were used: the determination coefficient and the mean relative error. IDF analysis in the Eastern Black Sea Basin of Turkey, which is the most raing basin, is also emphasized and studied in detail. It has been concluded that the reliability of the results is high enough and that this paper will motivate and open new horizons to detailed studies on IDF analysis.

Are we ignoring the role of urban forests in intercepting atmospheric microplastics?

Occurrences and characteristics of atmospheric microplastics(MPs) have been widely studied by previous studies, while the mitigation of airborne MPs pollution was not well understood. In this study, atmospheric samples of MPs were collected in pairs on the rooftop and under trees composed of representative afforested species Ficus microcarpa in Chengdu, Southwest China, to explore whether trees could intercept MPs. Results showed that the daily life of human beings and textile industries of urban areas were sources of airborne MPs as revealed by chemical compositions and air trajectories. The trees with the high coverage degree (88%) and large three-dimensional spaces formed by leaves did have the ability to intercept high-density MPs with small sizes under the force of gravity. The intercepting rate was about 16.3%, 12,593 n/m2 of fibers and 347.69 kg of MPs could be intercepted by urban forests for one year. However, threshold values of rainfall intensity (12 mm/d) and rainfall amounts (14 mm) were found to limit the intercepting mechanism, and intercepting effects decrease with the increase of rainfall amounts (r =−0.71). This work provides quantitative evidence that elucidated urban forests may act as receptors of airborne MPs, thus improving the air quality and human health.

PENGARUH TATA GUNA LAHAN TERHADAP FLUKTUASI DEBIT EMBUNG KAMPUNG BANJAR DI WILAYAH PERKANTORAN PROVINSI KALIMANTAN SELATAN

This study was conducted to find out the value of the drainage coefficient of the office area in South Kalimantan under the existing conditions, the effect of land use changes on fluctuations in discharge at Embung Kampung Banjar and the green open space that must be available with the existence of Embung Kampung Banjar. The existence of Embung Kampung Banjar is expected to reduce the impact of excessive rainfall which causes various kinds of natural disasters. This study usesd the Rational Method analysis to get the value of rainfall intensity in determining the planned discharge, the method of analysis of the coefficient of flow and the research method used for discharge fluctuations in Embung Kampung Banjar that is simulated with the synthetic unit hydrograph ITB –2 Kirpich, Snyder and Mononobe which all calculations by useng Microsoft Excel . The results shows that the simulation of land use change by adding the area of residential housing and offices are evidence of reduced open areas. The calculation of the maximum discharge coefficient of the existing flow using the Synthetic Unit Hydrograph (HSS) ITB 2 Timelag Kirpich of 7.83 m3/s and the results of flood tracking caused a decrease in peak discharge of 5.4 m3/s the largest land use change was found in the flow coefficient is 0.499 with a maximum discharge of 9.69 m3/s where the housing area is 0.85 km2 and offices are 0.47 km2. In Indonesian Law Number 26 of 2007 on Spatial Planning Article 29 paragraph 3 regarding the proportion of Green Open Space (RTH) about 20 percent of the city area. The calculation results of the peak discharge capacity of Embung Banjar Kampung which is equal to 6.8963 m3/s equal to 15 percent of the flow area of Embung Kampung Banjar which is obtained from the maximum discharge calculation, which is 9.69 m3/s. Then the results of the routing flood that caused a decrease in the discharge amounted to 6.6 m3/s, so the overall result is that the reservoir is still safe if overflow occurs in the reservoir.

Modelling sheet erosion on steep slopes of clay loess soil using a rainfall simulator

The process of sheet erosion has a dramatic influence on the development of soil erosion. To successfully model sheet erosion it is necessary to establish a suitable erosion prediction model for regions with clay loess soil. This study strives to achieve the following: 1) understanding and quantifying sheet erosion patterns caused by different variations of the rainfall intensity, slope steepness, and flow velocity, and 2) evaluate the influence of hydrodynamic parameters on sheet erosion for clay loess soil. A series of simulation experiments of rainfall on clay loess soil were carried out using a range of values of rainfall intensity (54, 78, 102, 126 and 150 mm h −1 ) and gradient (8.7, 17.6, 26.8, 36.4 and 46.6%). The simulation outcomes demonstrated that the rate of sheet erosion followed a power function of rainfall intensity and also gradient with a coefficient of determination R 2 of 0.98 and a Nash–Sutcliffe efficiency (NSE) of 0.96. The sensitivity of the sheet erosion rate to rainfall intensity was higher than its sensitivity to slope steepness. Furthermore, the sheet erosion rate could be predicted using its power-law dependence on flow velocity with R 2 of 0.88 and NSE of 0.82. The sheet erosion rate was optimally and linearly fitted with the shear stress with R 2 of 0.95 and NSE of 0.95, it was optimally fitted through power functions with either the stream power (with metrics of R 2 of 0.94 and NSE of 0.93) or the unit stream power (with R 2 of 0.74 and NSE of 0.68). Thus stream power represented a reliable predictor of the sheet erosion rate, and the shear stress was the better predictor. By contrast, the unit stream power was found to be a poor predictor of the sheet erosion rate. The findings of this study can help to accurately predict sheet erosion for clay loess soil on steep slopes. • Response of sheet erosion to rainfall intensity and slope gradient. • Response of sheet erosion to hydraulic parameters. • Shear stress is a preferred hydraulic parameter for estimating sheet erosion. • Some reliable models were obtained to predict sheet erosion for clay loess region.

Estimating Rainfall Intensity Using an Image-Based Deep Learning Model

Urban flooding is a major issue worldwide, causing huge economic losses and serious threats to public safety. One promising way to mitigate its impacts is to develop a real-time flood risk management system; however, building such a system is often challenging due to the lack of high spatiotemporal rainfall data. While some approaches (i.e., ground rainfall stations or radar and satellite techniques) are available to measure and/or predict rainfall intensity, it is difficult to obtain accurate rainfall data with a desirable spatiotemporal resolution using these methods. This paper proposes an image-based deep learning model to estimate urban rainfall intensity with high spatial and temporal resolution. More specifically, a convolutional neural network (CNN) model called the image-based rainfall CNN (irCNN) model is developed using rainfall images collected from existing dense sensors (i.e., smart phones or transportation cameras) and their corresponding measured rainfall intensity values. The trained irCNN model is subsequently employed to efficiently estimate rainfall intensity based on the sensors’ rainfall images. Synthetic rainfall data and real rainfall images are respectively utilized to explore the irCNN’s accuracy in theoretically and practically simulating rainfall intensity. The results show that the irCNN model provides rainfall estimates with a mean absolute percentage error ranging between 13.5% and 21.9%, which exceeds the performance of other state-of-the-art modeling techniques in the literature. More importantly, the main feature of the proposed irCNN is its low cost in efficiently acquiring high spatiotemporal urban rainfall data. The irCNN model provides a promising alternative for estimating urban rainfall intensity, which can greatly facilitate the development of urban flood risk management in a real-time manner.

Study of Adequacy of Drainage Channels in Suburban Residential Areas(A Case Study of Residential Wirolegi Regency 2 Jember City, of Indonesia)

Wirolegi Regency 2 Housing is located on the outskirts of the city which is located in Pakusari District, Jember Regency, when there is quite heavy rain, puddles of water often occur, this is caused by environmental damage. The impact of environmental damage can be of various kinds, one of which is due to climate change. In the dry season, it can have an impact on drought and in the rainy season, it can have an impact on flooding. When there is high rainfall, it has the potential to cause flooding in the residential area. Another factor is the condition of the existing drainage channels which are inadequate and affect the occurrence of flooding in the housing area. On the basis of the above, it is necessary to conduct a research entitled "Study on Adequacy of Drainage Channels in Suburban Residential Areas". From the results of the study, it was concluded that the watershed in the residential area of ​​Wirolegi Regency II Jember has a watershed area of ​​148.75 km2. The value of rainfall intensity at the 5-year return period is 9.02 mm/hour, the design flood discharge value is 12131.7 m3/second, the runoff discharge value is 1473.8 m3/second, the total discharge is 157.280 m3/sec, dirty water discharge is 7.058 m3/second, total capacity discharge is 84.7 m3/second. For the drainage network, there are primary, secondary, and tertiary canals, totaling 3 outlets where all outlets lead to rivers. For channels that are not able to accommodate discharge, namely channels F, G, H, I, J, K, L, and M channels. For channels that require repairs, the dimensions of the channel are changed from 0.8 meters to 1 meter. It is recommended for each housing estate to pay attention to the discharge flowing in each channel by using a calculation formula that is in accordance with the conditions and criteria requirements of the formula and method used.

Comparison between different Intensities of Rainfall to identify overflow points in a combined sewer system using Storm Water Management Model

<abstract> <p>Increasing urbanization related to land pressure and the soil arising from it are aggravating factors of flood risk in urban areas, including storm water runoff. Therefore, urban sanitation networks face an excess of water that exceeds their absorption capacity. This article deals with the effect of impermeability in densely populated urban areas and the function of a combined sewer system under higher rainfall intensities using the Storm Water Management Model (SWMM). The objective is to simulate a possible increase in rainfall intensities for reducing overflow points in the combined sewage system at the study area, which was the city of Ahmed Rachdi, Mila in Algeria. The excessive rainfall intensities were modeled using the SWMM software program to estimate maximum water volumes inside the combined sewage system of the study area. To evaluate the model's performance, a comparison process was used between the values of the flow rates of the pipelines of the sewerage system combined with the design flow rates in the current state and the flow rates of a single modeling of future events available during the study interval. The comparison results showed a good and convergent performance for these models. The results of the flooding volumes using different values of rainfall intensities and different return periods, which were 2, 5, 10 and 25 years, in the modeling of the combined sewage system are 3626, 6888, 8636 and 12676m<sup>3</sup>, respectively. The suggested scenario included increasing diameters of some pipes in the combined sewage system pipelines. The results using this scenario showed reductions in the total percentage of overflow points from the integrated sewage system of 52.42%, 40.63%, 31.83% and 20.51% using the rainfall intensities for the return periods of 2, 5, 10 and 25 years, respectively. The present study can provide technical support for using software in the planning, controlling and tests of the sewer systems, which contribute to solving the sewer systems' problems.</p> </abstract>

An alternative approach to estimate any subdaily extreme of rainfall and wind from usually available records

A wide variety of engineering applications requires the use of maximum values of rainfall intensity and wind speed related to short recording intervals, which can often only be estimated from available less exhaustive records. Given that many locations lack exhaustive climatic records that would allow accurate empirical correlations between different recording intervals to be identified, generic equations are often used to estimate these extreme values. The accuracy of these generic estimates is especially important in fields such as the study of wind-driven rain, in which both climatic variables are combined to characterise the phenomenon. This work assesses the reliability and functionality of some of these most widespread generic equations, analysing climatic datasets gathered since 2008 in 109 weather stations in Spain and the Netherlands. Considering multiple recording intervals at each location, it is verified that most of these generic estimations, used especially in the study of wind-driven rain, have functional limitations and can cause significant errors when characterising both variables for subdaily intervals and extreme conditions. Finally, an alternative approach is proposed to accurately extrapolate extreme values of both variables related to any subdaily recording interval in a functional manner and from any available records.

A novel quality control model of rainfall estimation with videos – A survey based on multi-surveillance cameras

The widespread use of surveillance cameras has become an emerging means for rainfall observations. With the advantages of high spatial–temporal resolution, rainfall information obtained from surveillance videos is highly suitable for meteorological-related research and has bright prospects. However, due to the complex and variable monitoring scenarios, the quality of the rainfall data estimated by each camera is always inconsistent, resulting in low practical value. Dense ground-level surveillance cameras have temporal and spatial correlations that can be used to improve the accuracy of rainfall estimation through mutual verification. In this study, we first introduce camera parameters to refine the spatial volume of rainfall (SVoR)11Most acronyms used in this study appear in the Appendix 1. perceived by cameras to improve the accuracy of rainfall intensity (RI) estimation. Next, a novel quality control (QC) model of rainfall estimation with multi-surveillance camera collaboration that takes the rainfall observations of all cameras as input is proposed. (i) We build a reliability evaluation (RE) model for the estimation of RI in accordance with raindrop imagery features to provide a reference for the subsequent correction of RI estimation; (ii) inspired by the first law of geography (Tobler, 1970), we then construct a spatial–temporal consistency filter and a situation consistency filter by using the spatial–temporal constraints between cameras to coarsely evaluate the RI values; and (iii) the correlation between cameras is calculated based on the fuzzy method to further build a correlation filter for the fine-grained correction of RI values. Experiments show that our method can effectively eliminate RI outliers and improve the accuracy and reliability of rainfall estimation results. Moreover, our method is highly suitable for heavy and violent rainfall application scenarios and can provide high-resolution rainfall data support for flooding warnings and simulations in urban areas.

Assessment of Pollutants from Diffuse Pollution through the Correlation between Rainfall and Runoff Characteristics Using EMC and First Flush Analysis

Urban stormwater runoff is an important source of pollution in receiving water bodies, mainly in cities in development. However, strategies to deal with the impacts caused by the runoff discharges, such as implementing a sustainable urban drainage system (SUDS) with optimized management, need information usually obtained through monitoring studies. Brasília is a city that has one of the highest urban growth rates in Brazil, with significant impacts on urban water resources, including diffuse pollution, generated by new unregulated urban developments that initially start being built with precarious sanitation infrastructure. The Vicente Pires (VP) watershed is highly urbanized and comprises two areas that have been intensively occupied more recently, at a fast pace, and do not have yet basic sanitation systems fully implemented. Stormwater quality at the outlet of the VP watershed was analyzed by monitoring the rainfall, runoff flows, and pollutant concentration. Event Mean Concentration (EMC) and first-flush (FF) phenomenon were calculated, and hydrologic characteristics were compared for different events through correlation analysis. During dry periods the flow varied between 0.5 and 1.29 m3/s, while in flood periods the maximum value was 72.17 m3/s, forming floods with great volume. Nitrate during dry periods stands out with its high concentration; the maximum was 1.49 mg/L, while the maximum concentration during the flood events was 0.43 mg/L, probably due to dilution. Ammonia results showed very low values, probably because nitrification is occurring up to the collection point. The EMC values of solids in flood events were higher and can be attributed to river bed scour along the VP watershed. The EMC SS values for the VP watershed are also similar to areas in the initial stages of building development. The EMC values in the dry season indicate strong correlations between some water quality parameters such as NH+3-N and SS, TS and NO−3-N; NO−3-N, and COD. These correlations indicate that these pollutants are probably being generated by the same source, probably sewage discharges. During flood events, the correlation between pollutant loads and peak flow can be associated with the scouring during surface washing off, because greater concentrations of solids and organic matter occur in events with greater flow rates. For the first 30% of the initial runoff volume, about 29% of SS, 38% of NH+3-N, and 35% of reactive P were carried during flood events. It was verified that large values of maximum or mean rainfall intensity are related to the occurrence of First Flush (FF) for most pollutants. Antecedent dry days (ADD) did not influence build-up processes in this watershed; however, they are related to FF occurrence. Data indicate that the sewage and stormwater collection networks were being installed caused a high impact on observed water quality, with high concentrations of solids during flood events. On the other hand, the wastewater collection after the sewer network installation led to a decrease in COD concentrations over time. For sustainable management of diffuse pollution, the adoption of distributed SUDS to enhance runoff volume reduction is a recommended solution for the case.

Telemetering of Rainfall Measurement Results Using 433 MHz Wireless Transmission

The line of sight (LOS) microwave communication system, especially those operating at frequencies above 10 GHz, is very susceptible to rain attenuation, particularly in tropical countries such as Indonesia. Therefore, it is essential to calculate rain attenuation estimation values as a basis for consideration in designing a line of sight microwave communication system to get stable communication. In this study, telemetering was designed to measure the rainfall intensity from a rain gauge device through a 433 MHz wireless transceiver. Measurement of rainfall intensity values via an Arduino-controlled rain gauge was transmitted directly to the monitoring room, which then processed to be displayed in graphical form in real time and can also be stored as data loggers. The rainfall telemetering device users can measure rainfall remotely and without having to wait for the rain like the rainfall manual measurement.

Assessing two methods of defining rainfall intensity and duration thresholds for shallow landslides in data-scarce catchments of the Colombian Andean Mountains

Rainfall thresholds are intensity-duration relations that are supposedly able to distinguish precipitation events that may or may not trigger landslides. The most common method for defining rainfall thresholds relies on observed landslides and the corresponding values of rainfall intensity and duration that caused each failure. Alternative methods to define rainfall thresholds, using physically-based models, recently gained importance, as they may provide complementary information to other methods. Still, their applicability in most of the world's regions, including the mountainous basins of the Colombian Andes, has not been demonstrated or validated. In this study, we evaluated the applicability of the physically-based model TRIGRS to define rainfall intensity and duration thresholds in individual basins from the Colombian Andes. We obtained rainfall thresholds using two different methods and compared them with landslide-triggering rainfall events in two distinct basins, namely La Arenosa and La Liboriana. Furthermore, we used a (presumably incomplete) landslide database from Medellín to rebuild the rainfall events associated with individual landslides and compared them with the physically-based thresholds. The rainfall thresholds calculated in the three study areas and the applicability of the methods in data-scarce environments were assessed. Results showed that both methods for defining rainfall intensity and duration thresholds have merits and represent potential tools for improving or complementing landslide early warning systems, especially in data-scarce regions.

Determination of NPS Pollutant Unit Loads from Different Landuses

This study aimed to estimate pollutant unit loads for different landuses and pollutants that reflected long-term runoff characteristics of nonpoint source (NPS) pollutants and recent environmental changes. During 2008–2014, 2026 rainfall events were monitored. The average values of antecedent dry days, total rainfall, rainfall intensity, rainfall duration, runoff duration, and runoff coefficient for each landuse were 3.8–5.9 d, 35.2–65.0 mm, 2.9–4.1 mm/h, 12.5–20.4 h, 12.4–27.9 h, and 0.24–0.45, respectively. Uplands (UL) exhibited high suspended solids (SS, 606.2 mg/L), total nitrogen (TN, 7.38 mg/L), and total phosphorous (TP, 2.27 mg/L) levels, whereas the runoff coefficient was high in the building sites (BS), with a high impervious surface ratio. The event mean concentration (EMC) for biological oxygen demand (BOD) was the highest in BS (8.0 mg/L), while the EMC was the highest in BS (in the rainfall range <10 mm) and UL and forest land (in the rainfall range >50 mm). The unit loads for BOD (1.49–17.76 kg/km2·d), TN (1.462–10.147 kg/km2·d), TP (0.094–1.435 kg/km2·d), and SS (15.20–327.70 kg/km2·d) were calculated. The findings can be used to manage NPS pollutants and watershed environments and implement relevant associated management systems.

Predictive Performance Analysis of PDF – IDF Model Types Using Rainfall Observations from Fourteen Gauged Stations

The design of structures for flood mitigation depends on the adequate estimation of rainfall intensity over a given catchment which is achieved by the rainfall intensity duration frequency modelling. In this study, an extensive comparative analyses were carried out on the predictive performance of three PDF – IDF model types, namely: Gumbel Extreme Value Type 1 (GEVT – 1), Log-Pearson Type 3 (LPT – 3) and Normal Distribution (ND) in 14 selected cities in Southern Nigeria. This is to rank the order of best performance. The principle of general model development was adopted in which rainfall intensities at different durations and specified return periods were used as input data set. This is not same as return period specific model that involves rainfall intensities for various durations and a given return period. The predicted rainfall intensity values with the PDF – IDF model types indicate high goodness of fit (R2) and Mean Squared Errors (MSE) ranging from: (a) R2 = 0.875 – 0.992; MSE = 33.17 – 224.6 for GEVT – 1; (b) R2 = 0.849 – 0.990; MSE = 65.34 – 405.5 for LPT – 3 and (c) R2 = 0.839 – 0.992; MSE = 29.23 – 200.2 for ND. The comparative analysis of all the 42 general models (14 locations versus 3 model types) considered showed that the order of best performance is LPT – 3 1st, GEVT - 1 2nd and ND 3rd for each return period (10, 50 and 100 years). The Kruskal Wallis test of significance indicates that no significant difference exists in the predictive performance of the three General models across the board. This may be due to the fact that the fourteen locations of the study area are bordering with the Atlantic Ocean and seems to have similar climatology. These developed General models are recommended for the computation of intensities in the fourteen locations for the design of flood control structures; and the order of preference should be LPT – 3 > GEVT – 1 > ND.