The evaluation of the meteorological drought is fundamental for the management of the water resource. One of the most used indices to evaluate the drought is the standardized precipitation index (SPI) due to its practicality and evaluation in a variety of time scales, however, this uses precipitation as the only variable, depending on the deviations in the precipitation values. This is important when evaluating the SPI, because in some ecosystems close to the equatorial zone, there are very warm periods with low rainfall, in which a large proportion of the data collected by the meteorological stations corresponds to zero. In this research, the SPI was calculated in the Pechelín basin located in Colombia, in which there is zero precipitation in a large proportion of the data, registering zero precipitation in the month of January and February in 67% and 70% respectively. As a result, the SPI values increased to “wet” ranges, only when the amount of data with zero precipitation exceeded half of the total data; this means that the SPI determines wrong values when it is calculated with zero-precipitation data in large proportions. Based on this finding, this study aims to modify the index by typing the distribution (using a correction factor K), finally correcting the SPI values, this correction was called SPI-C. The results indicate that the SPI-C improved the identification of drought, obtaining corresponding values that better represent the high frequency of zero precipitation existing in the study area.

This article presents the results of analyzing the use of dispersed storage tanks as a low impact development (LID) alternative to mitigate the flash flood risk in consolidated urban watersheds in Barranquilla, Colombia. Fieldwork, rainfall and flow rate monitoring, and numerical modeling were conducted to evaluate different scenarios combining storage tank capacity, two types of storage operations, and different locations by land use and watershed sectoring. These results showed that it is possible to reduce significantly the peak flow with small-capacity tanks distributed in the urban watershed with hydraulic structures that divide the discharge during the peak-flow time interval. By storing 3–17% of the runoff volume, equivalent to a dispersed storage capacity from 4 to 19 mm rainfall, it is possible to reduce the peak flow from 25 to 75%. These results demonstrate the advantages of using low impact development for stormwater management in consolidated cities with limited space, if regulatory p...

Numerical models are important tools for analyzing and solving water resources problems; however, a model’s reliability heavily depends on its calibration. This paper presents a method based on Design of Experiments theory for calibrating numerical models of rivers by considering the interaction between different calibration parameters, identifying the most sensitive parameters and finding a value or a range of values for which the calibration parameters produces an adequate performance of the model in terms of accuracy. The method consists of a systematic process for assessing the qualitative and quantitative performance of a hydromorphological numeric model. A 75 km reach of the Meta River, in Colombia, was used as case study for validating the method. The modeling was conducted by using the software package MIKE-21C, a two-dimensional flow model. The calibration is assessed by means of an Overall Weighted Indicator, based on the coefficient of determination of the calibration parameters and within a range from 0 to 1. For the case study, the most significant calibration parameters were the sediment transport equation, the riverbed load factor and the suspended load factor. The optimal calibration produced an Overall Weighted Indicator equal to 0.857. The method can be applied to any type of morphological models.

The ability of catchbasin sumps and hydrodynamic separators to remove sediment must be balanced with their ability to retain the previously captured material by preventing scour. The sediment scour process in these storm-water structures differs from the unidirectional scour and sediment transport process that occurs in pipes and channels. The hydrodynamics is affected by the particular characteristics of the hydraulic structure. The study of sediment scour in these devices requires incorporation of all the factors involved in the scour phenomenon and is best supported through computational fluid dynamic modeling (CFD) verified experimentally. Scour can be documented in the effluent as suspended sediment or total suspended solids concentration, a parameter of critical importance in storm-water quality management. This paper presents two simplified models for estimating effluent suspended sediment concentration attributable to scour of previously captured sediment. These models are based on results obtained from full-scale physical experimentation and calibrated and validated CFD modeling over a wide range of operating conditions where different particles sizes would be scoured. This paper also shows the effects of the armoring layer and of homogeneous and heterogeneous sediment sizes on the effluent concentration patterns.

Soil erosion caused by rain is the detachment and movement of soil particles caused by the impact of raindrops on the surface. Erosivity factor R is a measure of the rain erosive power used for estimating the erosion rate with the RUSLE method (Revised Universal Soil Loss Equation). Estimating R factor requires rainfall intensity records of storms greater than 12.5 mm or greater than 6 mm but longer than 15 min. However, most of the Colombian rainfall stations have daily rainfall records with which it is not possible to estimate the intensity of each storm and, therefore, makes it difficult to estimate the R factor for a specific area. In this paper a methodology for estimating the erosivity factor R for the department of Atlántico, Colombia from daily records of 16 IDEAM stations is presented. The spatial distribution of the erosivity factor R in the department and its temporal distribution throughout the year are also shown. The results showed a minimum erosivity factor R of 6,894 MJ∙mm∙Ha-1∙Hr-1∙yr-1 and a maximum of 10,925 MJ∙mm∙Ha-1∙Hr-1∙yr-1. The average erosivity factor R for the department of Atlántico was 8,697 MJ∙mm∙Ha-1∙Hr-1∙yr-1. This methodology might be used for estimating the erosion factor R in different Colombian regions where high-resolution precipitation data is limited, but seasonal and orographic conditions should be considered for selecting the rain gages and the area of study.

This article shows the design and development of a reactive early warning model as part of a reactive early warning system for urban flash flood management in the city of Barranquilla, Colombia. The system is divided into four components: (i) measuring equipment with rainfall and flow rate gauges, datalogging and transmission, (ii) a system for database processing and a web interface, (iii) a numerical rainfall-runoff model in PCSWMM calibrated and validated, and (iv) a reactive early warning model for determining the hazard level, and for making decisions of alertness along the main streets. Twelve (12) rainfall gauges were installed in the city, covering around 150 Km². The numerical model in PCSWMM was calibrated and validated with rainfall and flow rate data measured in a typical subcatchment of the city. A time of concentration equation was developed from the characteristics of the subcatchment such as slope and length. A pilot urban watershed was selected to test the system, from which hazard alerts every minute with forecasting of up to 40 minutes ahead on the lower parts of the watershed were determined. That time may allow people to make prompt decisions regarding their mobility over the city and reducing accidents caused by flash floods.